Attributes { HDF5_ROOT_GROUP { orbit_info { String Dataset "crossing_time", "cycle_number", "orbit_number", "lan", "sc_orient", "rgt", "sc_orient_time"; } METADATA { AcquisitionInformation { lidar { } lidarDocument { } platform { } platformDocument { } } DataQuality { CompletenessOmission { } DomainConsistency { } } ProductSpecificationDocument { } SeriesIdentification { } DatasetIdentification { } Extent { } QADatasetIdentification { } Lineage { Control { } ANC28 { } ANC14 { } ANC06-02 { } ANC06-03 { } ANC25-08 { } ANC33 { } ANC18 { } ANC38-08 { } ANC34 { } ATL03 { } ATL09 { } ANC06-01 { } ANC26-08 { } ANC19 { } ANC36-08 { } } ProcessStep { Browse { } Metadata { } PGE { } QA { } } } String Dataset "ds_metrics", "ds_surf_type"; gt1r { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } land_segments { String Dataset "segment_watermask", "delta_time_end", "rgt", "dem_flag", "msw_flag", "cloud_flag_atm", "snr", "sigma_across", "layer_flag", "segment_snowcover", "beam_azimuth", "solar_azimuth", "psf_flag", "longitude", "latitude", "segment_id_end", "surf_type", "brightness_flag", "segment_landcover", "ph_removal_flag", "asr", "sigma_atlas_land", "segment_id_beg", "sigma_along", "dem_h", "beam_coelev", "sigma_topo", "night_flag", "delta_time_beg", "sigma_h", "last_seg_extend", "atlas_pa", "ph_ndx_beg", "solar_elevation", "delta_time", "cloud_fold_flag", "n_seg_ph", "terrain_flg", "urban_flag", "dem_removal_flag", "h_dif_ref"; canopy { String Dataset "h_canopy", "canopy_rh_conf", "h_median_canopy_abs", "h_min_canopy", "h_mean_canopy_abs", "h_median_canopy", "h_canopy_abs", "toc_roughness", "h_min_canopy_abs", "h_dif_canopy", "h_canopy_quad", "n_ca_photons", "centroid_height", "canopy_h_metrics_abs", "landsat_perc", "h_mean_canopy", "canopy_h_metrics", "n_toc_photons", "canopy_flag", "landsat_flag", "h_max_canopy_abs", "h_canopy_uncertainty", "canopy_openness", "h_max_canopy"; } terrain { String Dataset "h_te_uncertainty", "h_te_mean", "h_te_min", "h_te_interp", "h_te_max", "h_te_skew", "h_te_median", "h_te_best_fit", "h_te_std", "terrain_slope", "n_te_photons", "h_te_mode"; } } } gt2r { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } land_segments { String Dataset "segment_watermask", "delta_time_end", "rgt", "dem_flag", "msw_flag", "cloud_flag_atm", "snr", "sigma_across", "layer_flag", "segment_snowcover", "beam_azimuth", "solar_azimuth", "psf_flag", "longitude", "latitude", "segment_id_end", "surf_type", "brightness_flag", "segment_landcover", "ph_removal_flag", "asr", "sigma_atlas_land", "segment_id_beg", "sigma_along", "dem_h", "beam_coelev", "sigma_topo", "night_flag", "delta_time_beg", "sigma_h", "last_seg_extend", "atlas_pa", "ph_ndx_beg", "solar_elevation", "delta_time", "cloud_fold_flag", "n_seg_ph", "terrain_flg", "urban_flag", "dem_removal_flag", "h_dif_ref"; canopy { String Dataset "h_canopy", "canopy_rh_conf", "h_median_canopy_abs", "h_min_canopy", "h_mean_canopy_abs", "h_median_canopy", "h_canopy_abs", "toc_roughness", "h_min_canopy_abs", "h_dif_canopy", "h_canopy_quad", "n_ca_photons", "centroid_height", "canopy_h_metrics_abs", "landsat_perc", "h_mean_canopy", "canopy_h_metrics", "n_toc_photons", "canopy_flag", "landsat_flag", "h_max_canopy_abs", "h_canopy_uncertainty", "canopy_openness", "h_max_canopy"; } terrain { String Dataset "h_te_uncertainty", "h_te_mean", "h_te_min", "h_te_interp", "h_te_max", "h_te_skew", "h_te_median", "h_te_best_fit", "h_te_std", "terrain_slope", "n_te_photons", "h_te_mode"; } } } gt1l { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } land_segments { String Dataset "segment_watermask", "delta_time_end", "rgt", "dem_flag", "msw_flag", "cloud_flag_atm", "snr", "sigma_across", "layer_flag", "segment_snowcover", "beam_azimuth", "solar_azimuth", "psf_flag", "longitude", "latitude", "segment_id_end", "surf_type", "brightness_flag", "segment_landcover", "ph_removal_flag", "asr", "sigma_atlas_land", "segment_id_beg", "sigma_along", "dem_h", "beam_coelev", "sigma_topo", "night_flag", "delta_time_beg", "sigma_h", "last_seg_extend", "atlas_pa", "ph_ndx_beg", "solar_elevation", "delta_time", "cloud_fold_flag", "n_seg_ph", "terrain_flg", "urban_flag", "dem_removal_flag", "h_dif_ref"; canopy { String Dataset "h_canopy", "canopy_rh_conf", "h_median_canopy_abs", "h_min_canopy", "h_mean_canopy_abs", "h_median_canopy", "h_canopy_abs", "toc_roughness", "h_min_canopy_abs", "h_dif_canopy", "h_canopy_quad", "n_ca_photons", "centroid_height", "canopy_h_metrics_abs", "landsat_perc", "h_mean_canopy", "canopy_h_metrics", "n_toc_photons", "canopy_flag", "landsat_flag", "h_max_canopy_abs", "h_canopy_uncertainty", "canopy_openness", "h_max_canopy"; } terrain { String Dataset "h_te_uncertainty", "h_te_mean", "h_te_min", "h_te_interp", "h_te_max", "h_te_skew", "h_te_median", "h_te_best_fit", "h_te_std", "terrain_slope", "n_te_photons", "h_te_mode"; } } } quality_assessment { String Dataset "qa_granule_fail_reason", "qa_granule_pass_fail"; } gt3l { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } } gt2l { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } } ancillary_data { String Dataset "release", "end_geoseg", "version", "end_region", "atlas_sdp_gps_epoch", "end_rgt", "end_delta_time", "end_orbit", "start_cycle", "data_end_utc", "control", "start_gpssow", "granule_end_utc", "end_cycle", "granule_start_utc", "start_delta_time", "start_geoseg", "start_orbit", "data_start_utc", "end_gpsweek", "start_rgt", "end_gpssow", "qa_at_interval", "start_region", "start_gpsweek"; land { String Dataset "ca_class", "canopy_flag_switch", "up_toc_bnd", "fnlgnd_filter_switch", "psf", "dem_removal_percent_limit", "atl08_region", "can_noise_thresh", "relief_hbot", "dem_filter_switch", "relief_htop", "dseg_buf", "night_thresh", "h_canopy_perc", "up_filt_bnd", "lw_filt_bnd", "ph_removal_percent_limit", "canopy_seg", "max_try", "bin_size_n", "lw_gnd_bnd", "del_mu", "lw_toc_cut", "class_thresh", "lseg_buf", "lw_toc_bnd", "up_toc_cut", "gnd_stat_thresh", "iter_max", "gthresh_factor", "bright_thresh", "dseg", "bin_size_h", "up_gnd_bnd", "min_nphs", "tc_thresh", "te_class", "toc_class", "iter_gnd", "max_atl03files", "noise_class", "outlier_filter_switch", "dragann_switch", "proc_geoseg", "can_stat_thresh", "lseg", "max_atl09files", "ref_dem_limit", "max_peaks", "stat_thresh", "sig_rsq_search", "del_amp", "sseg", "shp_param", "del_sigma", "cloud_filter_switch", "n_dec_mode", "ref_finalground_limit", "p_static"; } } gt3r { signal_photons { String Dataset "classed_pc_flag", "classed_pc_indx", "delta_time", "d_flag", "ph_segment_id"; } land_segments { String Dataset "segment_watermask", "delta_time_end", "rgt", "dem_flag", "msw_flag", "cloud_flag_atm", "snr", "sigma_across", "layer_flag", "segment_snowcover", "beam_azimuth", "solar_azimuth", "psf_flag", "longitude", "latitude", "segment_id_end", "surf_type", "brightness_flag", "segment_landcover", "ph_removal_flag", "asr", "sigma_atlas_land", "segment_id_beg", "sigma_along", "dem_h", "beam_coelev", "sigma_topo", "night_flag", "delta_time_beg", "sigma_h", "last_seg_extend", "atlas_pa", "ph_ndx_beg", "solar_elevation", "delta_time", "cloud_fold_flag", "n_seg_ph", "terrain_flg", "urban_flag", "dem_removal_flag", "h_dif_ref"; canopy { String Dataset "h_canopy", "canopy_rh_conf", "h_median_canopy_abs", "h_min_canopy", "h_mean_canopy_abs", "h_median_canopy", "h_canopy_abs", "toc_roughness", "h_min_canopy_abs", "h_dif_canopy", "h_canopy_quad", "n_ca_photons", "centroid_height", "canopy_h_metrics_abs", "landsat_perc", "h_mean_canopy", "canopy_h_metrics", "n_toc_photons", "canopy_flag", "landsat_flag", "h_max_canopy_abs", "h_canopy_uncertainty", "canopy_openness", "h_max_canopy"; } terrain { String Dataset "h_te_uncertainty", "h_te_mean", "h_te_min", "h_te_interp", "h_te_max", "h_te_skew", "h_te_median", "h_te_best_fit", "h_te_std", "terrain_slope", "n_te_photons", "h_te_mode"; } } } } H5_GLOBAL { String HDF5_OBJ_FULLPATH "H5_GLOBAL"; String granule_type "ATL08"; String short_name "ATL08"; String level "3A"; String description "This data set (ATL08) contains along-track heights above the WGS84 ellipsoid (ITRF2014 reference frame) for the ground and canopy surfaces. The canopy and ground surfaces are processed in fixed 100 m data segments, which typically contain more than 100 sig"; String contributor_name "Thomas E Neumann (thomas.neumann@nasa.gov), Thorsten Markus (thorsten.markus@nasa.gov), Suneel Bhardwaj (suneel.bhardwaj@nasa.gov) David W Hancock III (david.w.hancock@nasa.gov)"; String contributor_role "Instrument Engineer, Investigator, Principle Investigator, Data Producer, Data Producer"; String Conventions "CF-1.6"; String date_type "UTC"; String featureType "trajectory"; String geospatial_lat_units "degrees_north"; String geospatial_lon_units "degrees_east"; String identifier_product_doi "10.5067/ATLAS/ATL08.001"; String identifier_product_doi_authority "http://dx.doi.org"; String identifier_product_type "ATL08"; String license "Data may not be reproduced or distributed without including the citation for this product included in this metadata. Data may not be distributed in an altered form without the written permission of the ICESat-2 Science Project Office at NASA/GSFC."; String naming_authority "http://dx.doi.org"; String spatial_coverage_type "Horizontal"; String standard_name_vocabulary "CF-1.6"; String time_type "CCSDS UTC-A"; String date_created "2019-08-22T21:07:29.000000Z"; String hdfversion "HDF5 1.10.3"; String history "2019-08-22T21:07:29.000000Z;58383667-e9b3-3639-a8de-168784ceb5e9;Created by PGE atlas_l3a_ld Version 3.2"; String identifier_file_uuid "58383667-e9b3-3639-a8de-168784ceb5e9"; String identifier_product_format_version "3.2"; Float64 time_coverage_duration 461.; String time_coverage_end "2018-10-16T12:54:37.000000Z"; String time_coverage_start "2018-10-16T12:46:56.000000Z"; Float64 geospatial_lat_min -78.804759009697463; Float64 geospatial_lon_min -153.81953845733065; Float64 geospatial_lat_max -78.498235427544756; Float64 geospatial_lon_max -153.32549412458567; String publisher_name "NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center"; String publisher_email "nsidc@nsidc.org"; String publisher_url "http://nsidc.org/daac/"; String title "ATLAS/ICESat-2 L3A Land and Vegetation Height"; String identifier_file_product_type "ATL08"; String institution "National Aeronautics and Space Administration (NASA)"; String creator_name "GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System"; String summary "The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics."; String keywords "EARTH SCIENCE > BIOSPHERE > VEGETATION > NONE > NONE > NONE > NONE"; String keywords_vocabulary "NASA/GCMD Science Keywords"; String citation "Cite these data in publications as follows: The data used in this study were produced by the ICESat-2 Science Project Office at NASA/GSFC. The data archive site is the NASA National Snow and Ice Data Center Distributed Active Archive Center."; String processing_level "3A"; String references "http://nsidc.org/data/icesat2/data.html"; String project "ICESat-2 > Ice, Cloud, and land Elevation Satellite-2"; String instrument "ATLAS > Advanced Topographic Laser Altimeter System"; String platform "ICESat-2 > Ice, Cloud, and land Elevation Satellite-2"; String source "Spacecraft"; } /orbit_info/ { String HDF5_OBJ_FULLPATH "/orbit_info/"; String Description "Contains orbit information."; String data_rate "Varies. Data are only provided when one of the stored values (besides time) changes."; } /orbit_info/crossing_time { String HDF5_OBJ_FULLPATH "/orbit_info/crossing_time"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "Ascending Node Crossing Time"; String standard_name "time"; String description "The time, in seconds since the ATLAS SDP GPS Epoch, at which the ascending node crosses the equator. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "POD/PPD"; String CLASS "DIMENSION_SCALE"; } /orbit_info/cycle_number { String HDF5_OBJ_FULLPATH "/orbit_info/cycle_number"; String units "1"; String contentType "referenceInformation"; String long_name "Cycle Number"; String description "A count of the number of exact repeats of this reference orbit."; String source "Operations"; String coordinates "crossing_time"; Int16 valid_min 0; Int16 valid_max 50; } /orbit_info/orbit_number { String HDF5_OBJ_FULLPATH "/orbit_info/orbit_number"; String units "1"; String contentType "referenceInformation"; String long_name "Orbit Number"; String description "Unique identifying number for each planned ICESat-2 orbit."; String source "Operations"; String coordinates "crossing_time"; UInt16 valid_min 1; UInt16 valid_max 65000; } /orbit_info/lan { String HDF5_OBJ_FULLPATH "/orbit_info/lan"; String units "degrees_east"; String contentType "referenceInformation"; String long_name "Ascending Node Longitude"; String description "Longitude at the ascending node crossing."; String source "POD/PPD"; String coordinates "crossing_time"; Float64 valid_min -180.; Float64 valid_max 180.; } /orbit_info/sc_orient { String HDF5_OBJ_FULLPATH "/orbit_info/sc_orient"; String units "1"; String contentType "referenceInformation"; String long_name "Spacecraft Orientation"; String description "This parameter tracks the spacecraft orientation between forward, backward and transitional flight modes. ICESat-2 is considered to be flying forward when the weak beams are leading the strong beams; and backward when the strong beams are leading the weak beams. ICESat-2 is considered to be in transition while it is maneuvering between the two orientations. Science quality is potentially degraded while in transition mode."; String source "POD/PPD"; String coordinates "sc_orient_time"; String flag_meanings "backward forward transition"; Int16 flag_values 0, 1, 2; Int16 valid_min 0; Int16 valid_max 2; } /orbit_info/rgt { String HDF5_OBJ_FULLPATH "/orbit_info/rgt"; String units "1"; String contentType "referenceInformation"; String long_name "Reference Ground track"; String description "The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs."; String source "POD/PPD"; String coordinates "crossing_time"; Int16 valid_min 1; Int16 valid_max 1387; } /orbit_info/sc_orient_time { String HDF5_OBJ_FULLPATH "/orbit_info/sc_orient_time"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "Time of Last Spacecraft Orientation Change"; String standard_name "time"; String description "The time of the last spacecraft orientation change between forward, backward and transitional flight modes, expressed in seconds since the ATLAS SDP GPS Epoch. ICESat-2 is considered to be flying forward when the weak beams are leading the strong beams; and backward when the strong beams are leading the weak beams. ICESat-2 is considered to be in transition while it is maneuvering between the two orientations. Science quality is potentially degraded while in transition mode. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "POD/PPD"; String CLASS "DIMENSION_SCALE"; } /METADATA/ { String HDF5_OBJ_FULLPATH "/METADATA/"; String Description "ISO19115 Structured Metadata Represented within HDF5"; String iso_19139_dataset_xml " ATL08_20181016124656_02730110_002_01.h5 NSIDC DAAC > National Snow and Ice Data Center DAAC nsidc@nsidc.org http://nsidc.org/daac/ pointOfContact 2019-08-22T21:07:29.000000Z ATL08_20181016124656_02730110_002_01.h5 2019-08-22T21:07:29.000000Z creation ATL08 The ECS Short Name 002 The ECS Version ID ATL08_20181016124656_02730110_002_01.h5 ProducerGranuleId The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance. ATL08 002 largerWorkCitation eng AscendingCrossing: 55.413850781199955 StartLatitude: -50.000000000000000 StartDirection:D EndLatitude: -79.000000000000000 EndDirection: D gov.nasa.esdis.umm.orbitparameters OrbitParameters OrbitNumber: 474 EquatorCrossingLongitude: 55.413850781199955 EquatorCrossingDateTime: 2018-10-16T11:46:46.152995Z gov.nasa.esdis.umm.orbitcalculatedspatialdomains OrbitCalculatedSpatialDomains 2018-10-16T12:54:26.671899Z 2018-10-16T12:54:31.250499Z dataset 2019-08-22T21:07:29.000000Z;58383667-e9b3-3639-a8de-168784ceb5e9;Created by PGE atlas_l3a_ld Version 3.2 2019-08-22T21:07:29.000000Z "; String iso_19139_series_xml " ATL08.002 eng utf8 series NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center 303-492-6199 303-492-2468 1540 30th St Campus Box 449 Boulder Colorado 80309-0449 USA nsidc@nsidc.org http://nsidc.org/daac/ 9:00 A.M. to 5:00 P.M., U.S. Mountain Time, Monday through Friday, excluding U.S. holidays. Contact by e-mail first pointOfContact 2015-10-15 ISO 19115-2 Geographic information - Metadata - Part 2: Extensions for imagery and gridded data ISO 19115-2:2009(E) ATLAS/ICESat-2 L3A Land and Vegetation Height 2016-06-09 revision 002 ATL08 The ECS Short Name 002 The ECS Version ID doi:10.5067/ATLAS/ATL08.002 gov.nasa.esdis A Digital Object Identifier (DOI) National Aeronautics and Space Administration (NASA) resourceProvider GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System originator Initial version of the processing software The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance. The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics. The software that generates the ATL08 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland. onGoing NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center distributor HDF 5 EARTH SCIENCE > BIOSPHERE > VEGETATION > NONE > NONE > NONE > NONE EARTH SCIENCE > BIOSPHERE > VEGETATION > VEGETATION COVER > NONE > NONE > NONE EARTH SCIENCE > LAND SURFACE > NONE > NONE > NONE > NONE > NONE EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > SURFACE ROUGHNESS > NONE > NONE > NONE EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > NONE > NONE > NONE theme NASA/GCMD Science Keywords NASA Global Change Master Directory (GCMD) User Support Office NASA Global Change Master Directory, Goddard Space Flight Center Greenbelt MD 20771 USA gcmduso@gcmd.gsfc.nasa.gov http://gcmd.nasa.gov/ http web browser NASA Global Change Master Directory (GCMD) Home Page information http://gcmd.nasa.gov/MailComments/MailComments.jsf?rcpt=gcmduso custodian Global Change Master Directory (GCMD) NASA Global Change Master Directory, Goddard Space Flight Center Greenbelt MD 20771 USA gcmduso@gcmd.gsfc.nasa.gov http://gcmd.nasa.gov/Resources/valids/ http web browser NASA Global Change Master Directory (GCMD) Keyword Page This page describes the NASA GCMD Keywords, how to reference those keywords and provides download instructions. download http://gcmd.nasa.gov/MailComments/MailComments.jsf?rcpt=gcmduso custodian GEOGRAPHIC REGION > GLOBAL place NASA/GCMD Location Keywords NASA/NSIDC_DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center dataCenter NASA/GCMD Data Center Keywords Earth Observation Satellites > NASA Decadal Survey > ICESAT-2 > Ice, Cloud, and land Elevation Satellite-2 platform NASA/GCMD Platform Keywords Earth Remote Sensing Instruments > Active Remote Sensing > Altimeters > Lidar/Laser Altimeters > ATLAS > Advanced Topographic Laser Altimeter System instrument NASA/GCMD Instrument Keywords Cite these data in publications as follows: The data used in this study were produced by the ICESat-2 Science Project Office at NASA/GSFC. The data archive site is the NASA National Snow and Ice Data Center Distributed Active Archive Center. eng geoscientificInformation i SpatialCoverageType=HORIZONTAL, SpatialGranuleSpatialRepresentation=ORBIT, TemporalRangeType=Continuous Range, TimeType=UTC -180.0 180.0 -90.0 90.0 SwathWidth: 36.0 Period: 96.8 InclinationAngle: 92.0 NumberOfOrbits: 0.071428571 StartCircularLatitude: 0.0 gov.nasa.esdis.umm.orbitparameters OrbitParameters 2005-01-01T00:00:00Z 2020-12-31T23:59:59Z 3A 3A HDF 5 NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center distributor http://nsidc.org/data/icesat2/data.html http Data Product Description Page information http://nsidc.org/data/icesat2/order.html http Data Product Order Page order http://dx.doi.org/10.5067/ATLAS/ATL08.002 http Digital Object Identifier URL information ATLAS > Advanced Topographic Laser Altimeter System ATLAS Advanced Topographic Laser Altimeter System Laser Altimeter ATLAS on ICESat-2 determines the range between the satellite and the Earth's surface by measuring the two-way time delay of short pulses of laser light that it transmits in six beams. It is different from previous operational ice-sheet altimeters in that it is a photon-counting LIDAR. ATLAS records a set of arrival times for individual photons, which are then analyzed to derive surface, vegetation, and cloud properties. ATLAS has six beams arranged in three pairs, so that it samples each of three reference pair tracks with a pair of beams; ATLAS transmits pulses at 10 kHz, giving approximately one pulse every 0.7 m along track; ATLAS's expected pointing control will be better than 90 m RMS. ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 ICESat-2 Ice, Cloud, and land Elevation Satellite-2 underDevelopment ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 ICESat-2 Ice, Cloud, and land Elevation Satellite-2 Spacecraft "; } /METADATA/AcquisitionInformation/ { String HDF5_OBJ_FULLPATH "/METADATA/AcquisitionInformation/"; } /METADATA/AcquisitionInformation/lidar/ { String HDF5_OBJ_FULLPATH "/METADATA/AcquisitionInformation/lidar/"; String pulse_rate "10000 pps"; String wavelength "532 nm"; String identifier "ATLAS"; String type "Laser Altimeter"; String description "ATLAS on ICESat-2 determines the range between the satellite and the Earth's surface by measuring the two-way time delay of short pulses of laser light that it transmits in six beams. It is different from previous operational ice-sheet altimeters in that it is a photon-counting LIDAR. ATLAS records a set of arrival times for individual photons, which are then analyzed to derive surface, vegetation, and cloud properties. ATLAS has six beams arranged in three pairs, so that it samples each of three reference pair tracks with a pair of beams; ATLAS transmits pulses at 10 kHz, giving approximately one pulse every 0.7 m along track; ATLAS's expected pointing control will be better than 90 m RMS."; } /METADATA/AcquisitionInformation/lidarDocument/ { String HDF5_OBJ_FULLPATH "/METADATA/AcquisitionInformation/lidarDocument/"; String edition "Pre-Release"; String publicationDate "12/31/17"; String title "A document describing the ATLAS instrument will be provided by the ICESat-2 Project Science Office."; } /METADATA/AcquisitionInformation/platform/ { String HDF5_OBJ_FULLPATH "/METADATA/AcquisitionInformation/platform/"; String identifier "ICESat-2"; String description "Ice, Cloud, and land Elevation Satellite-2"; String type "Spacecraft"; } /METADATA/AcquisitionInformation/platformDocument/ { String HDF5_OBJ_FULLPATH "/METADATA/AcquisitionInformation/platformDocument/"; String edition "31-Dec-16"; String publicationDate "31-Dec-16"; String title "The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation. Thorsten Markus, Tom Neumann, Anthony Martino, Waleed Abdalati, Kelly Brunt, Beata Csatho, Sinead Farrell, Helen Fricker, Alex Gardner, David Harding, Michael Jasinski, Ron Kwok, Lori Magruder, Dan Lubin, Scott Luthcke, James Morison, Ross Nelson, Amy Neuenschwander, Stephen Palm, Sorin Popescu, CK Shum, Bob E. Schutz, Benjamin Smith, Yuekui Yang, Jay Zwally. http://dx.doi.org/10.1016/j.rse.2016.12.029"; } /METADATA/DataQuality/ { String HDF5_OBJ_FULLPATH "/METADATA/DataQuality/"; String scope "NOT_SET"; } /METADATA/DataQuality/CompletenessOmission/ { String HDF5_OBJ_FULLPATH "/METADATA/DataQuality/CompletenessOmission/"; String evaluationMethodType "directInternal"; String measureDescription "TBD"; String nameOfMeasure "TBD"; String unitofMeasure "TBD"; String value "NOT_SET"; } /METADATA/DataQuality/DomainConsistency/ { String HDF5_OBJ_FULLPATH "/METADATA/DataQuality/DomainConsistency/"; String evaluationMethodType "directInternal"; String measureDescription "TBD"; String nameOfMeasure "TBD"; String unitofMeasure "TBD"; String value "NOT_SET"; } /METADATA/ProductSpecificationDocument/ { String HDF5_OBJ_FULLPATH "/METADATA/ProductSpecificationDocument/"; String characterSet "utf8"; String edition "F"; String language "eng"; String publicationDate "07/2019"; String ShortName "ATL08_SDP"; String title "ICESat-2-SIPS-SPEC-4262 - ATLAS Science Algorithm Standard Data Product (SDP) Volume 7 (ATL08)."; } /METADATA/SeriesIdentification/ { String HDF5_OBJ_FULLPATH "/METADATA/SeriesIdentification/"; String maintenanceAndUpdateFrequency "asNeeded"; String maintenanceDate "SET_BY_META"; String VersionID "002"; String identifier_product_DOI "10.5067/ATLAS/ATL08.001"; String language "eng"; String characterSet "utf8"; String pointOfContact "NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center"; String longName "ATLAS/ICESat-2 L3A Land and Vegetation Height"; String shortName "ATL08"; String revisionDate "2016-06-09"; String resourceProviderOrganizationName "National Aeronautics and Space Administration (NASA)"; String abstract "The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance."; String purpose "The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics."; String credit "The software that generates the ATL08 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland."; String status "onGoing"; String format "HDF"; String formatVersion "5"; String topicCategory "geoscientificInformation"; String mission "ICESat-2 > Ice, Cloud, and land Elevation Satellite-2"; } /METADATA/DatasetIdentification/ { String HDF5_OBJ_FULLPATH "/METADATA/DatasetIdentification/"; String spatialRepresentationType "along-track"; String creationDate "2019-08-22T21:07:29.000000Z"; String uuid "58383667-e9b3-3639-a8de-168784ceb5e9"; String fileName "ATL08_20181016124656_02730110_002_01.h5"; String VersionID "002"; String language "eng"; String characterSet "utf8"; String shortName "ATL08"; String originatorOrganizationName "GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System"; String abstract "The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance."; String purpose "The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics."; String credit "The software that generates the ATL08 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland."; String status "onGoing"; String topicCategory "geoscientificInformation"; } /METADATA/Extent/ { String HDF5_OBJ_FULLPATH "/METADATA/Extent/"; Float64 northBoundLatitude -78.498235427544756; Float64 eastBoundLongitude -153.32549412458567; Float64 southBoundLatitude -78.804759009697463; Float64 westBoundLongitude -153.81953845733065; String rangeBeginningDateTime "2018-10-16T12:54:26.671899Z"; String rangeEndingDateTime "2018-10-16T12:54:31.250499Z"; } /METADATA/QADatasetIdentification/ { String HDF5_OBJ_FULLPATH "/METADATA/QADatasetIdentification/"; String abstract "An ASCII product that contains statistical information on data product results. These statistics enable data producers and users to assess the quality of the data in the data product granule"; String creationDate "2019-08-22T21:08:14.000000Z"; String fileName "ATL08_20181016124656_02730110_002_01.qa"; } /METADATA/Lineage/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/"; } /METADATA/Lineage/Control/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/Control/"; String description "Text-based keyword=value file generated automatically within the ICESat-2 data system that specifies all of the conditions required for each individual run of the software."; String fileName "CTL_atlas_l3a_ld_000081470.ctl"; String shortName "CNTL"; String version "1"; } /METADATA/Lineage/ANC28/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC28/"; String description "DTU Mean Sea Surface re-referenced to the WGS84 ellipsoid."; String fileName "dtu13_20180705_001_01.nc"; String shortName "ANC28"; String uuid "56f47040-a72e-3109-99c2-bc1658e6dda4"; String version "20180705"; } /METADATA/Lineage/ANC14/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC14/"; String description "Landsat Canopy Mask File"; String fileName ""; String shortName "ANC14"; String uuid ""; String version ""; } /METADATA/Lineage/ANC06-02/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC06-02/"; String description "ArcticDEM 32m Digital Elevation Model reformatted into HDF5."; String fileName "arcticdem32m_20190611_001_01.h5"; String shortName "ANC06-02"; String uuid "ce07ef72-0bf4-353b-8475-fb568b029905"; String version "20190611"; } /METADATA/Lineage/ANC06-03/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC06-03/"; String description "REMA Antarctica 100m Digital Elevation Model filled and reformatted into HDF5"; String fileName "atl06rema100m_20190628_001_01.h5"; String shortName "ANC06-03"; String uuid "3e0a81bd-bbd5-35fa-b868-3254f9355b7f"; String version "20190628"; } /METADATA/Lineage/ANC25-08/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC25-08/"; String description "HDF5 template file that defines the organization and default content of the product."; String fileName "atl08_template.h5"; String shortName "ANC25-08"; String uuid "1d66a513-7f12-3239-bbb1-09e62031feec"; String version "032"; } /METADATA/Lineage/ANC33/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC33/"; String description "Water Mask File"; String fileName "watermask_2000_20180301_001_global.h5"; String shortName "ANC33"; String uuid "1e7d3697-c576-308d-9197-21d827ac21db"; String version "20180301"; } /METADATA/Lineage/ANC18/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC18/"; String description "Modis Land Cover Mask File"; String fileName "glcc_2012_20180226_001_global.h5"; String shortName "ANC18"; String uuid "46e34ac9-892a-3a9d-ab7e-6a329e167a1a"; String version "20180226"; } /METADATA/Lineage/ANC38-08/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC38-08/"; String description "ISO 19139 XML file containing DataSet-level metadata information."; String fileName "ATL08.002.dataset.xml"; String shortName "ANC38-08"; String uuid "55e7a88e-6258-3bc1-844a-458ba3a595fc"; String version "002"; } /METADATA/Lineage/ANC34/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC34/"; String description "Urban Mask File"; String fileName "SET_BY_PGE"; String shortName "SET_BY_PGE"; String uuid "SET_BY_PGE"; String version "SET_BY_PGE"; } /METADATA/Lineage/ATL03/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ATL03/"; String description "ICESat-2 ATLAS L2A Global Geolocated Photon data products."; String fileName "ATL03_20181016124656_02730110_002_01.h5"; String shortName "ATL03"; String uuid "5afc3dc0-33ba-335b-b3bb-2cc34e7c4cd5"; String version "002"; Int32 start_cycle 1; Int32 end_cycle 1; Int32 start_orbit 474; Int32 end_orbit 474; Int32 start_rgt 273; Int32 end_rgt 273; Int32 start_region 10; Int32 end_region 10; Int32 start_geoseg 1280110; Int32 end_geoseg 1443604; } /METADATA/Lineage/ATL09/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ATL09/"; String description "ICESat-2 ATLAS L3A atmosphere data products."; String fileName "ATL09_20181016114648_02730101_002_01.h5"; String shortName "ATL09"; String uuid "0392edf6-cdc4-3c42-9ee7-12c7c38d14af"; String version "002"; Int32 start_cycle 1; Int32 end_cycle 1; Int32 start_orbit 474; Int32 end_orbit 474; Int32 start_rgt 273; Int32 end_rgt 273; Int32 start_region 1; Int32 end_region 14; Int32 start_geoseg 19; Int32 end_geoseg 2007126; } /METADATA/Lineage/ANC06-01/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC06-01/"; String description "GMTED 7.5 arcsec Digital Elevation Model reformatted into HDF5 and re-referenced to the WGS-84 ellipsoid."; String fileName "gmted75_20180705_001_01.h5"; String shortName "ANC06-01"; String uuid "a44debc8-29af-3744-860c-227b37a4da6f"; String version "20180705"; } /METADATA/Lineage/ANC26-08/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC26-08/"; String description "HDF5 template file that defines the organization and default content of the product metadata."; String fileName "atl08_metadata_template.h5"; String shortName "ANC26-08"; String uuid "f2d4b804-5f00-388c-80ba-9c45b0f9aecf"; String version "032"; } /METADATA/Lineage/ANC19/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC19/"; String description "TAI to UTC leapsecond file retrieved from ftp://maia.usno.navy.mil/ser7/tai-utc.dat"; String fileName "tai_utc_2017.dat"; String shortName "ANC19"; String uuid "a5c65112-d05e-3263-83cd-a36f1a81acdf"; String version "001"; } /METADATA/Lineage/ANC36-08/ { String HDF5_OBJ_FULLPATH "/METADATA/Lineage/ANC36-08/"; String description "ISO 19139 XML file containing Series-level metadata information."; String fileName "ATL08.002.series.xml"; String shortName "ANC36-08"; String uuid "87849aa9-407f-3fec-9f8b-46f45b818b5e"; String version "002"; } /METADATA/ProcessStep/ { String HDF5_OBJ_FULLPATH "/METADATA/ProcessStep/"; } /METADATA/ProcessStep/Browse/ { String HDF5_OBJ_FULLPATH "/METADATA/ProcessStep/Browse/"; String processDescription "Browse processing is performed for each granule SIPS produces. The browse utility reads data from the granule and produces browse images as defined in the respective product ATBD. The utility then embeds each browse image into the product within the /Browse group."; String identifier "atlas_brw"; String softwareVersion "Version 2.2"; String softwareDate "Jul 31 2019"; String softwareTitle "Creates ATLAS HDF5 browse files"; String runTimeParameters "CTL_atlas_l3a_ld_000081470.ctl"; String stepDateTime "2019-08-22T21:08:14.000000Z"; } /METADATA/ProcessStep/Metadata/ { String HDF5_OBJ_FULLPATH "/METADATA/ProcessStep/Metadata/"; String processDescription "Metadata information is processed by the metadata utility for each granule produced by SIPS. During PGE processing, dynamic metadata are written to the product. Additional static information is provided with the metadata template. The metadata utility reads ISO Dataset and Series metadata files and updates the product with static information from within those files. The utility then merges the static and dynamic metadata to creates output ISO19139 Dataset and Series XML files. Finally the utility reads the ISO19139 Dataset and Series XML files into memory and stores the textual representations as attributes attached to the /METADATA group."; String identifier "atlas_meta"; String softwareVersion "Version 4.2"; String softwareDate "Jul 31 2019"; String softwareTitle "Creates ATLAS XML metadata files"; String runTimeParameters "CTL_atlas_l3a_ld_000081470.ctl"; String stepDateTime "2019-08-22T21:08:21.000000Z"; } /METADATA/ProcessStep/PGE/ { String HDF5_OBJ_FULLPATH "/METADATA/ProcessStep/PGE/"; String ATBDDate "11/1/17"; String ATBDTitle "ICESat-2-SIPS-SPEC-1608 - SIPs: Land, Vegetation, and Inland Water L5 Specification Document"; String ATBDVersion "2017 November"; String documentation "ICESat-2-SIPS-SPEC-2331 - ATLAS Science Algorithm Software Design Description (SDD) Volume 12 (atlas_l3a_ld). Revision B."; String documentDate "12/1/17"; String processDescription "Determines heights of ground and canopy surface. Where data permits, includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect and apparent reflectance."; String identifier "atlas_l3a_ld"; String softwareVersion "Version 3.2"; String softwareDate "Jul 31 2019"; String softwareTitle "ASAS L3A Land PGE"; String runTimeParameters "CTL_atlas_l3a_ld_000081470.ctl"; String stepDateTime "2019-08-22T21:07:29.000000Z"; } /METADATA/ProcessStep/QA/ { String HDF5_OBJ_FULLPATH "/METADATA/ProcessStep/QA/"; String processDescription "QA processing is performed by an external utility on each granule produced by SIPS. The utility reads the granule, performs both generic and product-specific quality-assessment calculations, and writes a text-based quality assessment report. The name and creation data of this report are identified within the QADatasetIdentification metadata"; String identifier "atl08_qa_util"; String softwareVersion "Version 3.2"; String softwareDate "Jul 31 2019"; String softwareTitle "ATL08 QA Utility"; String runTimeParameters "CTL_atlas_l3a_ld_000081470.ctl"; String stepDateTime "2019-08-22T21:08:14.000000Z"; } /ds_metrics { String HDF5_OBJ_FULLPATH "/ds_metrics"; String units "1"; String contentType "referenceInformation"; String long_name "Metrics"; String description "Dimension scale for metrics."; String flag_meanings "metrics1 metrics2 metrics3 metrics4 metrics5 metrics6 metrics7 metrics8 metrics9"; Int16 flag_values 1, 2, 3, 4, 5, 6, 7, 8, 9; Int16 valid_min 1; Int16 valid_max 4; String CLASS "DIMENSION_SCALE"; } /gt1r/ { String HDF5_OBJ_FULLPATH "/gt1r/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce3"; String atlas_beam_type "strong"; String groundtrack_id "gt1r"; String atmosphere_profile "profile_1"; String atlas_spot_number "5"; String sc_orientation "Forward"; } /gt1r/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt1r/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt1r/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt1r/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt1r/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt1r/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt1r/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt1r/land_segments/ { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/"; String Description "Contains data categorized as land at 100 meter intervals."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1r/land_segments/segment_watermask { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/segment_watermask"; Int32 _FillValue 255; String units "1"; String long_name "segment watermask"; String description "Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution."; String source "ATBD section 2.4.15"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_water water"; Int32 flag_values 0, 1; Int32 valid_min 0; Int32 valid_max 1; } /gt1r/land_segments/delta_time_end { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/delta_time_end"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time end"; String description "Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/rgt { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/rgt"; String units "1"; String contentType "referenceInformation"; String long_name "reference ground track"; String description "The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs."; String source "Operations"; String coordinates "delta_time latitude longitude"; Int16 valid_min 1; Int16 valid_max 1387; } /gt1r/land_segments/dem_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/dem_flag"; Int16 _FillValue 127; String units "1"; String contentType "referenceInformation"; String long_name "dem source flag"; String description "Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic."; String source "Atmosphere ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "none arctic gmted mss antarctic"; Int16 flag_values 0, 1, 2, 3, 4; Int16 valid_min 0; Int16 valid_max 4; } /gt1r/land_segments/msw_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/msw_flag"; Int16 _FillValue 127; String units "1"; String long_name "multiple scattering warning flag"; String description "Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5"; Int16 flag_values -1, 0, 1, 2, 3, 4, 5; } /gt1r/land_segments/cloud_flag_atm { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/cloud_flag_atm"; Int16 _FillValue 127; String units "1"; String long_name "cloud flag atm"; String description "Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10."; String source "ATL09"; String coordinates "delta_time latitude longitude"; Int16 valid_min 0; Int16 valid_max 10; } /gt1r/land_segments/snr { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/snr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "signal to noise ratio"; String description "The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments."; String source "ATBD section 2.5.14"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/canopy/ { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/"; String Description "Contains height parameters based on the land algorithm."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1r/land_segments/canopy/h_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "height canopy"; String description "98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/canopy_rh_conf { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/canopy_rh_conf"; String units "1"; String contentType "modelResult"; String long_name "canopy relative height confidence"; String description "Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground)."; String source "Land/Veg ATBD 13March2019, Section 2.2.21"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground"; Int16 flag_values 0, 1, 2; Int16 valid_min 0; Int16 valid_max 2; } /gt1r/land_segments/canopy/h_median_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_median_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment median canopy height"; String description "The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.6"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_min_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_min_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum canopy height"; String description "The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 2.2.10"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_mean_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_mean_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute mean canopy height"; String description "Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.4"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_median_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_median_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median canopy height"; String description "The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature."; String source "Land ATBD section 2.2.8"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment canopy height"; String description "The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.2"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/toc_roughness { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/toc_roughness"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "top of canopy roughness"; String description "Standard deviation of the relative heights of all photons classified as top of canopy within the segment"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_min_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_min_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute minimum canopy height"; String description "The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_dif_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_dif_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy diff to median height"; String description "Difference between h_canopy and h_median_canopy"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_canopy_quad { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_canopy_quad"; String long_name "canopy quadratic mean"; String description "The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1r/land_segments/canopy/n_ca_photons { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/n_ca_photons"; String units "1"; String long_name "number canopy photons"; String description "The number of photons classified as canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/centroid_height { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/centroid_height"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "centroid height"; String description "Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/canopy_h_metrics_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/canopy_h_metrics_abs"; String long_name "canopy absolute height metrics"; String description "Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1r/land_segments/canopy/landsat_perc { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/landsat_perc"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "landsat percentage canopy"; String description "Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment"; String source "Land ATBD section 2.2.24"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_mean_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_mean_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean canopy height"; String description "Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/canopy_h_metrics { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/canopy_h_metrics"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy height metrics"; String description "Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/n_toc_photons { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/n_toc_photons"; String units "1"; String long_name "number top of canopy photons"; String description "The number of photons classified as top of canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/canopy_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/canopy_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "canopy flag"; String description "Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "no_canopy_present canopy_present"; Int32 flag_values 0, 1; } /gt1r/land_segments/canopy/landsat_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/landsat_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "landsat flag"; String description "Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1."; String source "Land ATBD section 2.2.25"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "canopy_not_assumed_present canopy_assumed_present"; Int32 flag_values 0, 1; } /gt1r/land_segments/canopy/h_max_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_max_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute maximum canopy height"; String description "Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_canopy_uncertainty { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_canopy_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment canopy height uncertainty"; String description "Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD"; String source "Land ATBD section 1.5"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/canopy_openness { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/canopy_openness"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "canopy openness"; String description "Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/canopy/h_max_canopy { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/canopy/h_max_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum canopy height"; String description "Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature."; String source "Land ATBD section 2.2.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/sigma_across { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/sigma_across"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas y"; String description "Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/terrain/ { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/"; String Description "Contains terrain parameters at a 100m aggregation."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1r/land_segments/terrain/h_te_uncertainty { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "uncertainty of h_te_mean"; String description "Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4"; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_mean { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_mean"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean terrain height"; String description "The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_min { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_min"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum terrain height"; String description "The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_interp { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_interp"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "interpolated terrain surface height"; String description "Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment."; String source "Land ATBD section 4.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_max { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_max"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum terrain height"; String description "The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_skew { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_skew"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "skew of terrain heights"; String description "The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_median { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_median"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median terrain height"; String description "The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_best_fit { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_best_fit"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment terrain height best fit"; String description "The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment."; String source "Land ATBD section 2.1.15"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_std { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_std"; String long_name "segment terrain roughness"; String description "The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1r/land_segments/terrain/terrain_slope { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/terrain_slope"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "segment terrain slope"; String description "The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/n_te_photons { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/n_te_photons"; String units "1"; String long_name "number of ground photons"; String description "The number of the photons classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/terrain/h_te_mode { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain/h_te_mode"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mode of terrain heights"; String description "The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1r/land_segments/layer_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/layer_flag"; String contentType "modelResult"; String long_name "consolidated cloud flag"; String description "This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "likely_clear likely_cloudy"; Int16 flag_values 0, 1; } /gt1r/land_segments/segment_snowcover { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/segment_snowcover"; Int16 _FillValue 127; String units "1"; String long_name "segment snowcover"; String description "Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice."; String source "ATBD section 4.2.16"; String coordinates "delta_time latitude longitude"; String flag_meanings "ice_free_water snow_free_land snow ice"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt1r/land_segments/beam_azimuth { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/beam_azimuth"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam azimuth"; String description "Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/solar_azimuth { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/solar_azimuth"; String units "degrees_east"; String contentType "referenceInformation"; String long_name "solar azimuth"; String description "The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/psf_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/psf_flag"; String units "1"; String contentType "referenceInformation"; String long_name "point spread function flag"; String description "Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)"; String source "Land/Veg ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt1r/land_segments/longitude { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/longitude"; String units "degrees"; String long_name "longitude"; String standard_name "longitude"; String description "Longitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude"; Float32 valid_min -180.; Float32 valid_max 180.; } /gt1r/land_segments/latitude { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/latitude"; String units "degrees"; String long_name "latitude"; String standard_name "latitude"; String description "Latitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time longitude"; Float32 valid_min -90.; Float32 valid_max 90.; } /gt1r/land_segments/segment_id_end { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/segment_id_end"; String units "1"; String contentType "referenceInformation"; String long_name "end geolocation segment bin"; String description "Geolocation segment number of the last photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/surf_type { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/surf_type"; String units "1"; String contentType "referenceInformation"; String long_name "surface type"; String description "Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water."; String source "ATL03 ATBD, Section 4"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_type is_type"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt1r/land_segments/brightness_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/brightness_flag"; Int16 _FillValue 127; String units "1"; String long_name "brightness flag"; String description "Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)"; String source "Land ATBD section 2.4.21"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_bright_surface bright_surface"; Int16 flag_values 0, 1; } /gt1r/land_segments/segment_landcover { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/segment_landcover"; Int32 _FillValue 255; String units "1"; String long_name "segment landcover"; String description "IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution."; String source "ATBD section 2.4.14"; String coordinates "delta_time latitude longitude"; String flag_meanings "Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren"; Int32 flag_values 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16; Int32 valid_min 0; Int32 valid_max 16; } /gt1r/land_segments/ph_removal_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/ph_removal_flag"; String units "1"; String long_name "ph removal flag"; String description "Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests"; String source "ATBD section 4.13"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt1r/land_segments/asr { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/asr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "apparent surface reflectance"; String description "Apparent surface reflectance"; String source "ATL09"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/sigma_atlas_land { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/sigma_atlas_land"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas land"; String description "Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2."; String source "Land ATBD section 2.5.13"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/segment_id_beg { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/segment_id_beg"; String units "1"; String contentType "referenceInformation"; String long_name "begin geolocation segment bin"; String description "Geolocation segment number of the first photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/sigma_along { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/sigma_along"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas x"; String description "Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/dem_h { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/dem_h"; Float32 _FillValue 3.402823466e+38; String units "meters"; String contentType "referenceInformation"; String long_name "dem height"; String description "Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid."; String source "GIMP, GMTED,MSS"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/beam_coelev { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/beam_coelev"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam co-elevation"; String description "Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/sigma_topo { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/sigma_topo"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas topo"; String description "Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope."; String source "Land ATBD section 2.5.12"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/night_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/night_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "night flag"; String description "Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "day night"; Int32 flag_values 0, 1; } /gt1r/land_segments/delta_time_beg { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/delta_time_beg"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time begin"; String description "Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/sigma_h { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/sigma_h"; String contentType "referenceInformation"; String long_name "height uncertainty"; String description "Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; Float32 _FillValue 3.402823466e+38; String units "1"; } /gt1r/land_segments/last_seg_extend { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/last_seg_extend"; String units "kilometers"; String long_name "last segment extended"; String standard_name "last_seg_extend"; String description "The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment."; String source "Land ATBD 13March2019, Section 2.4.20"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/atlas_pa { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/atlas_pa"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "atlas pointing angle"; String description "Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/ph_ndx_beg { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/ph_ndx_beg"; String units "1"; String long_name "photon index begin"; String description "Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/solar_elevation { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/solar_elevation"; String units "degrees"; String contentType "referenceInformation"; String long_name "solar elevation"; String description "Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/delta_time { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/delta_time"; String units "seconds since 2018-01-01"; String long_name "mean_pass_time"; String standard_name "time"; String description "Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Land ATBD section 2.4"; String coordinates "latitude longitude"; String CLASS "DIMENSION_SCALE"; } /gt1r/land_segments/cloud_fold_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/cloud_fold_flag"; Int16 _FillValue 127; String contentType "modelResult"; String long_name "cloud folding flag"; String description "Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_folding goes5_indicates profile_indicates both_indicate"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt1r/land_segments/n_seg_ph { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/n_seg_ph"; String units "1"; String long_name "number of photons"; String description "Number of photons within each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt1r/land_segments/terrain_flg { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/terrain_flg"; Int32 _FillValue 2147483647; String units "1"; String long_name "terrain flag"; String description "Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int32 flag_values 0, 1; } /gt1r/land_segments/urban_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/urban_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "segment urban flag"; String description "The urban flag indicates that a segment is likely located over an urban area."; String source "Land ATBD section 2.4.17"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_urban urban"; Int32 flag_values 0, 1; } /gt1r/land_segments/dem_removal_flag { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/dem_removal_flag"; String units "1"; String long_name "dem removal flag"; String description "Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests"; String source "ATBD section 2.4.11"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt1r/land_segments/h_dif_ref { String HDF5_OBJ_FULLPATH "/gt1r/land_segments/h_dif_ref"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "h dif from reference"; String description "Difference between h_te_median and ref_DEM"; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude longitude"; } /gt2r/ { String HDF5_OBJ_FULLPATH "/gt2r/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce2"; String atlas_beam_type "strong"; String groundtrack_id "gt2r"; String atmosphere_profile "profile_2"; String atlas_spot_number "3"; String sc_orientation "Forward"; } /gt2r/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt2r/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt2r/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt2r/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt2r/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt2r/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt2r/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt2r/land_segments/ { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/"; String Description "Contains data categorized as land at 100 meter intervals."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt2r/land_segments/segment_watermask { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/segment_watermask"; Int32 _FillValue 255; String units "1"; String long_name "segment watermask"; String description "Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution."; String source "ATBD section 2.4.15"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_water water"; Int32 flag_values 0, 1; Int32 valid_min 0; Int32 valid_max 1; } /gt2r/land_segments/delta_time_end { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/delta_time_end"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time end"; String description "Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/rgt { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/rgt"; String units "1"; String contentType "referenceInformation"; String long_name "reference ground track"; String description "The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs."; String source "Operations"; String coordinates "delta_time latitude longitude"; Int16 valid_min 1; Int16 valid_max 1387; } /gt2r/land_segments/dem_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/dem_flag"; Int16 _FillValue 127; String units "1"; String contentType "referenceInformation"; String long_name "dem source flag"; String description "Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic."; String source "Atmosphere ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "none arctic gmted mss antarctic"; Int16 flag_values 0, 1, 2, 3, 4; Int16 valid_min 0; Int16 valid_max 4; } /gt2r/land_segments/msw_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/msw_flag"; Int16 _FillValue 127; String units "1"; String long_name "multiple scattering warning flag"; String description "Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5"; Int16 flag_values -1, 0, 1, 2, 3, 4, 5; } /gt2r/land_segments/cloud_flag_atm { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/cloud_flag_atm"; Int16 _FillValue 127; String units "1"; String long_name "cloud flag atm"; String description "Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10."; String source "ATL09"; String coordinates "delta_time latitude longitude"; Int16 valid_min 0; Int16 valid_max 10; } /gt2r/land_segments/snr { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/snr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "signal to noise ratio"; String description "The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments."; String source "ATBD section 2.5.14"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/canopy/ { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/"; String Description "Contains height parameters based on the land algorithm."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt2r/land_segments/canopy/h_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "height canopy"; String description "98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/canopy_rh_conf { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/canopy_rh_conf"; String units "1"; String contentType "modelResult"; String long_name "canopy relative height confidence"; String description "Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground)."; String source "Land/Veg ATBD 13March2019, Section 2.2.21"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground"; Int16 flag_values 0, 1, 2; Int16 valid_min 0; Int16 valid_max 2; } /gt2r/land_segments/canopy/h_median_canopy_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_median_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment median canopy height"; String description "The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.6"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_min_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_min_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum canopy height"; String description "The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 2.2.10"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_mean_canopy_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_mean_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute mean canopy height"; String description "Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.4"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_median_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_median_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median canopy height"; String description "The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature."; String source "Land ATBD section 2.2.8"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_canopy_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment canopy height"; String description "The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.2"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/toc_roughness { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/toc_roughness"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "top of canopy roughness"; String description "Standard deviation of the relative heights of all photons classified as top of canopy within the segment"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_min_canopy_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_min_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute minimum canopy height"; String description "The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_dif_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_dif_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy diff to median height"; String description "Difference between h_canopy and h_median_canopy"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_canopy_quad { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_canopy_quad"; String long_name "canopy quadratic mean"; String description "The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt2r/land_segments/canopy/n_ca_photons { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/n_ca_photons"; String units "1"; String long_name "number canopy photons"; String description "The number of photons classified as canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/centroid_height { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/centroid_height"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "centroid height"; String description "Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/canopy_h_metrics_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/canopy_h_metrics_abs"; String long_name "canopy absolute height metrics"; String description "Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt2r/land_segments/canopy/landsat_perc { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/landsat_perc"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "landsat percentage canopy"; String description "Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment"; String source "Land ATBD section 2.2.24"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_mean_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_mean_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean canopy height"; String description "Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/canopy_h_metrics { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/canopy_h_metrics"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy height metrics"; String description "Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/n_toc_photons { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/n_toc_photons"; String units "1"; String long_name "number top of canopy photons"; String description "The number of photons classified as top of canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/canopy_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/canopy_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "canopy flag"; String description "Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "no_canopy_present canopy_present"; Int32 flag_values 0, 1; } /gt2r/land_segments/canopy/landsat_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/landsat_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "landsat flag"; String description "Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1."; String source "Land ATBD section 2.2.25"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "canopy_not_assumed_present canopy_assumed_present"; Int32 flag_values 0, 1; } /gt2r/land_segments/canopy/h_max_canopy_abs { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_max_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute maximum canopy height"; String description "Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_canopy_uncertainty { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_canopy_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment canopy height uncertainty"; String description "Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD"; String source "Land ATBD section 1.5"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/canopy_openness { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/canopy_openness"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "canopy openness"; String description "Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/canopy/h_max_canopy { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/canopy/h_max_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum canopy height"; String description "Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature."; String source "Land ATBD section 2.2.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/sigma_across { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/sigma_across"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas y"; String description "Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/terrain/ { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/"; String Description "Contains terrain parameters at a 100m aggregation."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt2r/land_segments/terrain/h_te_uncertainty { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "uncertainty of h_te_mean"; String description "Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4"; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_mean { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_mean"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean terrain height"; String description "The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_min { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_min"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum terrain height"; String description "The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_interp { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_interp"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "interpolated terrain surface height"; String description "Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment."; String source "Land ATBD section 4.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_max { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_max"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum terrain height"; String description "The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_skew { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_skew"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "skew of terrain heights"; String description "The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_median { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_median"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median terrain height"; String description "The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_best_fit { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_best_fit"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment terrain height best fit"; String description "The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment."; String source "Land ATBD section 2.1.15"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_std { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_std"; String long_name "segment terrain roughness"; String description "The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt2r/land_segments/terrain/terrain_slope { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/terrain_slope"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "segment terrain slope"; String description "The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/n_te_photons { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/n_te_photons"; String units "1"; String long_name "number of ground photons"; String description "The number of the photons classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/terrain/h_te_mode { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain/h_te_mode"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mode of terrain heights"; String description "The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt2r/land_segments/layer_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/layer_flag"; String contentType "modelResult"; String long_name "consolidated cloud flag"; String description "This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "likely_clear likely_cloudy"; Int16 flag_values 0, 1; } /gt2r/land_segments/segment_snowcover { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/segment_snowcover"; Int16 _FillValue 127; String units "1"; String long_name "segment snowcover"; String description "Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice."; String source "ATBD section 4.2.16"; String coordinates "delta_time latitude longitude"; String flag_meanings "ice_free_water snow_free_land snow ice"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt2r/land_segments/beam_azimuth { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/beam_azimuth"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam azimuth"; String description "Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/solar_azimuth { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/solar_azimuth"; String units "degrees_east"; String contentType "referenceInformation"; String long_name "solar azimuth"; String description "The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/psf_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/psf_flag"; String units "1"; String contentType "referenceInformation"; String long_name "point spread function flag"; String description "Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)"; String source "Land/Veg ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt2r/land_segments/longitude { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/longitude"; String units "degrees"; String long_name "longitude"; String standard_name "longitude"; String description "Longitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude"; Float32 valid_min -180.; Float32 valid_max 180.; } /gt2r/land_segments/latitude { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/latitude"; String units "degrees"; String long_name "latitude"; String standard_name "latitude"; String description "Latitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time longitude"; Float32 valid_min -90.; Float32 valid_max 90.; } /gt2r/land_segments/segment_id_end { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/segment_id_end"; String units "1"; String contentType "referenceInformation"; String long_name "end geolocation segment bin"; String description "Geolocation segment number of the last photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/surf_type { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/surf_type"; String units "1"; String contentType "referenceInformation"; String long_name "surface type"; String description "Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water."; String source "ATL03 ATBD, Section 4"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_type is_type"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt2r/land_segments/brightness_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/brightness_flag"; Int16 _FillValue 127; String units "1"; String long_name "brightness flag"; String description "Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)"; String source "Land ATBD section 2.4.21"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_bright_surface bright_surface"; Int16 flag_values 0, 1; } /gt2r/land_segments/segment_landcover { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/segment_landcover"; Int32 _FillValue 255; String units "1"; String long_name "segment landcover"; String description "IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution."; String source "ATBD section 2.4.14"; String coordinates "delta_time latitude longitude"; String flag_meanings "Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren"; Int32 flag_values 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16; Int32 valid_min 0; Int32 valid_max 16; } /gt2r/land_segments/ph_removal_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/ph_removal_flag"; String units "1"; String long_name "ph removal flag"; String description "Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests"; String source "ATBD section 4.13"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt2r/land_segments/asr { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/asr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "apparent surface reflectance"; String description "Apparent surface reflectance"; String source "ATL09"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/sigma_atlas_land { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/sigma_atlas_land"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas land"; String description "Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2."; String source "Land ATBD section 2.5.13"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/segment_id_beg { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/segment_id_beg"; String units "1"; String contentType "referenceInformation"; String long_name "begin geolocation segment bin"; String description "Geolocation segment number of the first photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/sigma_along { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/sigma_along"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas x"; String description "Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/dem_h { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/dem_h"; Float32 _FillValue 3.402823466e+38; String units "meters"; String contentType "referenceInformation"; String long_name "dem height"; String description "Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid."; String source "GIMP, GMTED,MSS"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/beam_coelev { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/beam_coelev"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam co-elevation"; String description "Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/sigma_topo { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/sigma_topo"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas topo"; String description "Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope."; String source "Land ATBD section 2.5.12"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/night_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/night_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "night flag"; String description "Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "day night"; Int32 flag_values 0, 1; } /gt2r/land_segments/delta_time_beg { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/delta_time_beg"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time begin"; String description "Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/sigma_h { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/sigma_h"; String contentType "referenceInformation"; String long_name "height uncertainty"; String description "Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; Float32 _FillValue 3.402823466e+38; String units "1"; } /gt2r/land_segments/last_seg_extend { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/last_seg_extend"; String units "kilometers"; String long_name "last segment extended"; String standard_name "last_seg_extend"; String description "The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment."; String source "Land ATBD 13March2019, Section 2.4.20"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/atlas_pa { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/atlas_pa"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "atlas pointing angle"; String description "Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/ph_ndx_beg { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/ph_ndx_beg"; String units "1"; String long_name "photon index begin"; String description "Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/solar_elevation { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/solar_elevation"; String units "degrees"; String contentType "referenceInformation"; String long_name "solar elevation"; String description "Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/delta_time { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/delta_time"; String units "seconds since 2018-01-01"; String long_name "mean_pass_time"; String standard_name "time"; String description "Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Land ATBD section 2.4"; String coordinates "latitude longitude"; String CLASS "DIMENSION_SCALE"; } /gt2r/land_segments/cloud_fold_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/cloud_fold_flag"; Int16 _FillValue 127; String contentType "modelResult"; String long_name "cloud folding flag"; String description "Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_folding goes5_indicates profile_indicates both_indicate"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt2r/land_segments/n_seg_ph { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/n_seg_ph"; String units "1"; String long_name "number of photons"; String description "Number of photons within each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt2r/land_segments/terrain_flg { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/terrain_flg"; Int32 _FillValue 2147483647; String units "1"; String long_name "terrain flag"; String description "Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int32 flag_values 0, 1; } /gt2r/land_segments/urban_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/urban_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "segment urban flag"; String description "The urban flag indicates that a segment is likely located over an urban area."; String source "Land ATBD section 2.4.17"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_urban urban"; Int32 flag_values 0, 1; } /gt2r/land_segments/dem_removal_flag { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/dem_removal_flag"; String units "1"; String long_name "dem removal flag"; String description "Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests"; String source "ATBD section 2.4.11"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt2r/land_segments/h_dif_ref { String HDF5_OBJ_FULLPATH "/gt2r/land_segments/h_dif_ref"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "h dif from reference"; String description "Difference between h_te_median and ref_DEM"; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude longitude"; } /gt1l/ { String HDF5_OBJ_FULLPATH "/gt1l/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce3"; String atlas_beam_type "weak"; String groundtrack_id "gt1l"; String atmosphere_profile "profile_1"; String atlas_spot_number "6"; String sc_orientation "Forward"; } /gt1l/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt1l/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt1l/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt1l/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt1l/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt1l/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt1l/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt1l/land_segments/ { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/"; String Description "Contains data categorized as land at 100 meter intervals."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1l/land_segments/segment_watermask { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/segment_watermask"; Int32 _FillValue 255; String units "1"; String long_name "segment watermask"; String description "Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution."; String source "ATBD section 2.4.15"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_water water"; Int32 flag_values 0, 1; Int32 valid_min 0; Int32 valid_max 1; } /gt1l/land_segments/delta_time_end { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/delta_time_end"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time end"; String description "Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/rgt { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/rgt"; String units "1"; String contentType "referenceInformation"; String long_name "reference ground track"; String description "The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs."; String source "Operations"; String coordinates "delta_time latitude longitude"; Int16 valid_min 1; Int16 valid_max 1387; } /gt1l/land_segments/dem_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/dem_flag"; Int16 _FillValue 127; String units "1"; String contentType "referenceInformation"; String long_name "dem source flag"; String description "Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic."; String source "Atmosphere ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "none arctic gmted mss antarctic"; Int16 flag_values 0, 1, 2, 3, 4; Int16 valid_min 0; Int16 valid_max 4; } /gt1l/land_segments/msw_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/msw_flag"; Int16 _FillValue 127; String units "1"; String long_name "multiple scattering warning flag"; String description "Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5"; Int16 flag_values -1, 0, 1, 2, 3, 4, 5; } /gt1l/land_segments/cloud_flag_atm { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/cloud_flag_atm"; Int16 _FillValue 127; String units "1"; String long_name "cloud flag atm"; String description "Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10."; String source "ATL09"; String coordinates "delta_time latitude longitude"; Int16 valid_min 0; Int16 valid_max 10; } /gt1l/land_segments/snr { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/snr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "signal to noise ratio"; String description "The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments."; String source "ATBD section 2.5.14"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/canopy/ { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/"; String Description "Contains height parameters based on the land algorithm."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1l/land_segments/canopy/h_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "height canopy"; String description "98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/canopy_rh_conf { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/canopy_rh_conf"; String units "1"; String contentType "modelResult"; String long_name "canopy relative height confidence"; String description "Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground)."; String source "Land/Veg ATBD 13March2019, Section 2.2.21"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground"; Int16 flag_values 0, 1, 2; Int16 valid_min 0; Int16 valid_max 2; } /gt1l/land_segments/canopy/h_median_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_median_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment median canopy height"; String description "The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.6"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_min_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_min_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum canopy height"; String description "The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 2.2.10"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_mean_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_mean_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute mean canopy height"; String description "Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.4"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_median_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_median_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median canopy height"; String description "The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature."; String source "Land ATBD section 2.2.8"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment canopy height"; String description "The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.2"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/toc_roughness { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/toc_roughness"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "top of canopy roughness"; String description "Standard deviation of the relative heights of all photons classified as top of canopy within the segment"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_min_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_min_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute minimum canopy height"; String description "The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_dif_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_dif_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy diff to median height"; String description "Difference between h_canopy and h_median_canopy"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_canopy_quad { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_canopy_quad"; String long_name "canopy quadratic mean"; String description "The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1l/land_segments/canopy/n_ca_photons { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/n_ca_photons"; String units "1"; String long_name "number canopy photons"; String description "The number of photons classified as canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/centroid_height { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/centroid_height"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "centroid height"; String description "Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/canopy_h_metrics_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/canopy_h_metrics_abs"; String long_name "canopy absolute height metrics"; String description "Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1l/land_segments/canopy/landsat_perc { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/landsat_perc"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "landsat percentage canopy"; String description "Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment"; String source "Land ATBD section 2.2.24"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_mean_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_mean_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean canopy height"; String description "Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/canopy_h_metrics { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/canopy_h_metrics"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy height metrics"; String description "Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/n_toc_photons { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/n_toc_photons"; String units "1"; String long_name "number top of canopy photons"; String description "The number of photons classified as top of canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/canopy_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/canopy_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "canopy flag"; String description "Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "no_canopy_present canopy_present"; Int32 flag_values 0, 1; } /gt1l/land_segments/canopy/landsat_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/landsat_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "landsat flag"; String description "Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1."; String source "Land ATBD section 2.2.25"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "canopy_not_assumed_present canopy_assumed_present"; Int32 flag_values 0, 1; } /gt1l/land_segments/canopy/h_max_canopy_abs { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_max_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute maximum canopy height"; String description "Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_canopy_uncertainty { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_canopy_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment canopy height uncertainty"; String description "Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD"; String source "Land ATBD section 1.5"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/canopy_openness { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/canopy_openness"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "canopy openness"; String description "Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/canopy/h_max_canopy { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/canopy/h_max_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum canopy height"; String description "Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature."; String source "Land ATBD section 2.2.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/sigma_across { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/sigma_across"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas y"; String description "Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/terrain/ { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/"; String Description "Contains terrain parameters at a 100m aggregation."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt1l/land_segments/terrain/h_te_uncertainty { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "uncertainty of h_te_mean"; String description "Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4"; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_mean { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_mean"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean terrain height"; String description "The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_min { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_min"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum terrain height"; String description "The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_interp { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_interp"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "interpolated terrain surface height"; String description "Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment."; String source "Land ATBD section 4.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_max { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_max"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum terrain height"; String description "The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_skew { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_skew"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "skew of terrain heights"; String description "The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_median { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_median"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median terrain height"; String description "The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_best_fit { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_best_fit"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment terrain height best fit"; String description "The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment."; String source "Land ATBD section 2.1.15"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_std { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_std"; String long_name "segment terrain roughness"; String description "The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt1l/land_segments/terrain/terrain_slope { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/terrain_slope"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "segment terrain slope"; String description "The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/n_te_photons { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/n_te_photons"; String units "1"; String long_name "number of ground photons"; String description "The number of the photons classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/terrain/h_te_mode { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain/h_te_mode"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mode of terrain heights"; String description "The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt1l/land_segments/layer_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/layer_flag"; String contentType "modelResult"; String long_name "consolidated cloud flag"; String description "This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "likely_clear likely_cloudy"; Int16 flag_values 0, 1; } /gt1l/land_segments/segment_snowcover { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/segment_snowcover"; Int16 _FillValue 127; String units "1"; String long_name "segment snowcover"; String description "Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice."; String source "ATBD section 4.2.16"; String coordinates "delta_time latitude longitude"; String flag_meanings "ice_free_water snow_free_land snow ice"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt1l/land_segments/beam_azimuth { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/beam_azimuth"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam azimuth"; String description "Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/solar_azimuth { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/solar_azimuth"; String units "degrees_east"; String contentType "referenceInformation"; String long_name "solar azimuth"; String description "The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/psf_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/psf_flag"; String units "1"; String contentType "referenceInformation"; String long_name "point spread function flag"; String description "Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)"; String source "Land/Veg ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt1l/land_segments/longitude { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/longitude"; String units "degrees"; String long_name "longitude"; String standard_name "longitude"; String description "Longitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude"; Float32 valid_min -180.; Float32 valid_max 180.; } /gt1l/land_segments/latitude { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/latitude"; String units "degrees"; String long_name "latitude"; String standard_name "latitude"; String description "Latitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time longitude"; Float32 valid_min -90.; Float32 valid_max 90.; } /gt1l/land_segments/segment_id_end { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/segment_id_end"; String units "1"; String contentType "referenceInformation"; String long_name "end geolocation segment bin"; String description "Geolocation segment number of the last photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/surf_type { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/surf_type"; String units "1"; String contentType "referenceInformation"; String long_name "surface type"; String description "Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water."; String source "ATL03 ATBD, Section 4"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_type is_type"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt1l/land_segments/brightness_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/brightness_flag"; Int16 _FillValue 127; String units "1"; String long_name "brightness flag"; String description "Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)"; String source "Land ATBD section 2.4.21"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_bright_surface bright_surface"; Int16 flag_values 0, 1; } /gt1l/land_segments/segment_landcover { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/segment_landcover"; Int32 _FillValue 255; String units "1"; String long_name "segment landcover"; String description "IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution."; String source "ATBD section 2.4.14"; String coordinates "delta_time latitude longitude"; String flag_meanings "Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren"; Int32 flag_values 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16; Int32 valid_min 0; Int32 valid_max 16; } /gt1l/land_segments/ph_removal_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/ph_removal_flag"; String units "1"; String long_name "ph removal flag"; String description "Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests"; String source "ATBD section 4.13"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt1l/land_segments/asr { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/asr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "apparent surface reflectance"; String description "Apparent surface reflectance"; String source "ATL09"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/sigma_atlas_land { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/sigma_atlas_land"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas land"; String description "Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2."; String source "Land ATBD section 2.5.13"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/segment_id_beg { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/segment_id_beg"; String units "1"; String contentType "referenceInformation"; String long_name "begin geolocation segment bin"; String description "Geolocation segment number of the first photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/sigma_along { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/sigma_along"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas x"; String description "Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/dem_h { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/dem_h"; Float32 _FillValue 3.402823466e+38; String units "meters"; String contentType "referenceInformation"; String long_name "dem height"; String description "Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid."; String source "GIMP, GMTED,MSS"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/beam_coelev { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/beam_coelev"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam co-elevation"; String description "Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/sigma_topo { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/sigma_topo"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas topo"; String description "Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope."; String source "Land ATBD section 2.5.12"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/night_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/night_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "night flag"; String description "Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "day night"; Int32 flag_values 0, 1; } /gt1l/land_segments/delta_time_beg { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/delta_time_beg"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time begin"; String description "Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/sigma_h { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/sigma_h"; String contentType "referenceInformation"; String long_name "height uncertainty"; String description "Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; Float32 _FillValue 3.402823466e+38; String units "1"; } /gt1l/land_segments/last_seg_extend { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/last_seg_extend"; String units "kilometers"; String long_name "last segment extended"; String standard_name "last_seg_extend"; String description "The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment."; String source "Land ATBD 13March2019, Section 2.4.20"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/atlas_pa { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/atlas_pa"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "atlas pointing angle"; String description "Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/ph_ndx_beg { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/ph_ndx_beg"; String units "1"; String long_name "photon index begin"; String description "Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/solar_elevation { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/solar_elevation"; String units "degrees"; String contentType "referenceInformation"; String long_name "solar elevation"; String description "Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/delta_time { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/delta_time"; String units "seconds since 2018-01-01"; String long_name "mean_pass_time"; String standard_name "time"; String description "Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Land ATBD section 2.4"; String coordinates "latitude longitude"; String CLASS "DIMENSION_SCALE"; } /gt1l/land_segments/cloud_fold_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/cloud_fold_flag"; Int16 _FillValue 127; String contentType "modelResult"; String long_name "cloud folding flag"; String description "Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_folding goes5_indicates profile_indicates both_indicate"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt1l/land_segments/n_seg_ph { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/n_seg_ph"; String units "1"; String long_name "number of photons"; String description "Number of photons within each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt1l/land_segments/terrain_flg { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/terrain_flg"; Int32 _FillValue 2147483647; String units "1"; String long_name "terrain flag"; String description "Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int32 flag_values 0, 1; } /gt1l/land_segments/urban_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/urban_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "segment urban flag"; String description "The urban flag indicates that a segment is likely located over an urban area."; String source "Land ATBD section 2.4.17"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_urban urban"; Int32 flag_values 0, 1; } /gt1l/land_segments/dem_removal_flag { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/dem_removal_flag"; String units "1"; String long_name "dem removal flag"; String description "Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests"; String source "ATBD section 2.4.11"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt1l/land_segments/h_dif_ref { String HDF5_OBJ_FULLPATH "/gt1l/land_segments/h_dif_ref"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "h dif from reference"; String description "Difference between h_te_median and ref_DEM"; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude longitude"; } /ds_surf_type { String HDF5_OBJ_FULLPATH "/ds_surf_type"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Surface Type Dimension Scale"; String description "Dimension scale indexing the surface type array. Index=1 corresponds to Land; index = 2 corresponds to Ocean; Index = 3 corresponds to SeaIce; Index=4 corresponds to LandIce; Index=5 corresponds to InlandWater"; String flag_meanings "land ocean seaice landice inland_water"; Int32 flag_values 1, 2, 3, 4, 5; Int32 valid_min 1; Int32 valid_max 5; String CLASS "DIMENSION_SCALE"; String NAME "/ds_surf_type"; } /quality_assessment/ { String HDF5_OBJ_FULLPATH "/quality_assessment/"; String Description "Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data."; } /quality_assessment/qa_granule_fail_reason { String HDF5_OBJ_FULLPATH "/quality_assessment/qa_granule_fail_reason"; String units "1"; String contentType "qualityInformation"; String long_name "Granule Failure Reason"; String description "Flag indicating granule failure reason. 0=no failure; 1=processing error; 2=Insufficient output data was generated; 3=TBD Failure; 4=TBD_Failure; 5=other failure."; String source "Operations"; String flag_meanings "no_failure PROCESS_ERROR INSUFFICIENT_OUTPUT failure_3 failure_4 OTHER_FAILURE"; Int32 flag_values 0, 1, 2, 3, 4, 5; Int32 valid_min 0; Int32 valid_max 5; } /quality_assessment/qa_granule_pass_fail { String HDF5_OBJ_FULLPATH "/quality_assessment/qa_granule_pass_fail"; String units "1"; String contentType "qualityInformation"; String long_name "Granule Pass Flag"; String description "Flag indicating granule quality. 0=granule passes automatic QA. 1=granule fails automatic QA."; String source "Operations"; String flag_meanings "PASS FAIL"; Int32 flag_values 0, 1; Int32 valid_min 0; Int32 valid_max 1; } /gt3l/ { String HDF5_OBJ_FULLPATH "/gt3l/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce1"; String atlas_beam_type "weak"; String groundtrack_id "gt3l"; String atmosphere_profile "profile_3"; String atlas_spot_number "2"; String sc_orientation "Forward"; } /gt3l/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt3l/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt3l/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt3l/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt3l/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt3l/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt3l/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt2l/ { String HDF5_OBJ_FULLPATH "/gt2l/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce2"; String atlas_beam_type "weak"; String groundtrack_id "gt2l"; String atmosphere_profile "profile_2"; String atlas_spot_number "4"; String sc_orientation "Forward"; } /gt2l/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt2l/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt2l/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt2l/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt2l/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt2l/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt2l/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /ancillary_data/ { String HDF5_OBJ_FULLPATH "/ancillary_data/"; String Description "Contains information ancillary to the data product. This may include product characteristics, instrument characteristics and/or processing constants."; String data_rate "Data within this group pertain to the granule in its entirety."; } /ancillary_data/release { String HDF5_OBJ_FULLPATH "/ancillary_data/release"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Release Number"; String description "Release number of the granule. The release number is incremented when the software or ancillary data used to create the granule has been changed."; String source "Operations"; } /ancillary_data/end_geoseg { String HDF5_OBJ_FULLPATH "/ancillary_data/end_geoseg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Ending Geolocation Segment"; String description "The ending geolocation segment number associated with the data contained within this granule. ICESat granule geographic regions are further refined by geolocation segments. During the geolocation process, a geolocation segment is created approximately every 20m from the start of the orbit to the end. The geolocation segments help align the ATLAS strong a weak beams and provide a common segment length for the L2 and higher products. The geolocation segment indices differ slightly from orbit-to-orbit because of the irregular shape of the Earth. The geolocation segment indices on ATL01 and ATL02 are only approximate because beams have not been aligned at the time of their creation."; String source "Derived"; } /ancillary_data/version { String HDF5_OBJ_FULLPATH "/ancillary_data/version"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Version"; String description "Version number of this granule within the release. It is a sequential number corresponding to the number of times the granule has been reprocessed for the current release."; String source "Operations"; } /ancillary_data/end_region { String HDF5_OBJ_FULLPATH "/ancillary_data/end_region"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Ending Region"; String description "The ending product-specific region number associated with the data contained within this granule. ICESat-2 data products are separated by geographic regions. The data contained within a specific region are the same for ATL01 and ATL02. ATL03 regions differ slightly because of different geolocation segment locations caused by the irregular shape of the Earth. The region indices for other products are completely independent."; String source "Derived"; } /ancillary_data/atlas_sdp_gps_epoch { String HDF5_OBJ_FULLPATH "/ancillary_data/atlas_sdp_gps_epoch"; String units "seconds since 1980-01-06T00:00:00.000000Z"; String contentType "auxiliaryInformation"; String long_name "ATLAS Epoch Offset"; String description "Number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS Standard Data Product (SDP) epoch (2018-01-01:T00.00.00.000000 UTC). Add this value to delta time parameters to compute full gps_seconds (relative to the GPS epoch) for each data point."; String source "Operations"; } /ancillary_data/end_rgt { String HDF5_OBJ_FULLPATH "/ancillary_data/end_rgt"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Ending Reference Groundtrack"; String description "The ending reference groundtrack (RGT) number associated with the data contained within this granule. There are 1387 reference groundtrack in the ICESat-2 repeat orbit. The reference groundtrack increments each time the spacecraft completes a full orbit of the Earth and resets to 1 each time the spacecraft completes a full cycle."; String source "Derived"; Int32 valid_min 1; Int32 valid_max 1387; } /ancillary_data/end_delta_time { String HDF5_OBJ_FULLPATH "/ancillary_data/end_delta_time"; String units "seconds since 2018-01-01"; String contentType "auxiliaryInformation"; String long_name "ATLAS End Time (Actual)"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch at the last data point in the file. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived"; } /ancillary_data/end_orbit { String HDF5_OBJ_FULLPATH "/ancillary_data/end_orbit"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Ending Orbit Number"; String description "The ending orbit number associated with the data contained within this granule. The orbit number increments each time the spacecraft completes a full orbit of the Earth."; String source "Derived"; } /ancillary_data/start_cycle { String HDF5_OBJ_FULLPATH "/ancillary_data/start_cycle"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Starting Cycle"; String description "The starting cycle number associated with the data contained within this granule. The cycle number is the counter of the number of 91-day repeat cycles completed by the mission."; String source "Derived"; Int32 valid_min 0; Int32 valid_max 99; } /ancillary_data/data_end_utc { String HDF5_OBJ_FULLPATH "/ancillary_data/data_end_utc"; String units "1"; String contentType "auxiliaryInformation"; String long_name "End UTC Time of Granule (CCSDS-A, Actual)"; String description "UTC (in CCSDS-A format) of the last data point within the granule."; String source "Derived"; } /ancillary_data/control { String HDF5_OBJ_FULLPATH "/ancillary_data/control"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Control File"; String description "PGE-specific control file used to generate this granule. To re-use, replace breaks (BR) with linefeeds."; String source "Operations"; } /ancillary_data/start_gpssow { String HDF5_OBJ_FULLPATH "/ancillary_data/start_gpssow"; String units "seconds"; String contentType "auxiliaryInformation"; String long_name "Start GPS SOW of Granule (Actual)"; String description "GPS seconds-of-week of the first data point in the granule."; String source "Derived"; } /ancillary_data/granule_end_utc { String HDF5_OBJ_FULLPATH "/ancillary_data/granule_end_utc"; String units "1"; String contentType "auxiliaryInformation"; String long_name "End UTC Time of Granule (CCSDS-A, Requested)"; String description "Requested end time (in UTC CCSDS-A) of this granule."; String source "Derived"; } /ancillary_data/end_cycle { String HDF5_OBJ_FULLPATH "/ancillary_data/end_cycle"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Ending Cycle"; String description "The ending cycle number associated with the data contained within this granule. The cycle number is the counter of the number of 91-day repeat cycles completed by the mission."; String source "Derived"; Int32 valid_min 0; Int32 valid_max 99; } /ancillary_data/granule_start_utc { String HDF5_OBJ_FULLPATH "/ancillary_data/granule_start_utc"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Start UTC Time of Granule (CCSDS-A, Requested)"; String description "Requested start time (in UTC CCSDS-A) of this granule."; String source "Derived"; } /ancillary_data/land/ { String HDF5_OBJ_FULLPATH "/ancillary_data/land/"; String Description "Constants used in the land_vegetation ATBD"; } /ancillary_data/land/ca_class { String HDF5_OBJ_FULLPATH "/ancillary_data/land/ca_class"; String units "1"; String contentType "auxiliaryInformation"; String description "Canopy classification flag value. (Default = 2)"; String source "ATBD section 4.12 step 1"; String long_name "Canopy class value"; } /ancillary_data/land/canopy_flag_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/canopy_flag_switch"; String units "1"; String contentType "auxiliaryInformation"; String description "Controls entrance to the canopy flag subroutine . (Default = 1)"; String source "ATBD section 4.3"; String long_name "canopy_flag switch"; } /ancillary_data/land/up_toc_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/up_toc_bnd"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Upper bound restricting the search of a top of canopy surface."; String description "Upper bound restricting the search of a top of canopy surface. (Default=1.0)"; String source "ATBD section 4.7 step 3 entered from section 4.8"; } /ancillary_data/land/fnlgnd_filter_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/fnlgnd_filter_switch"; String units "1"; String contentType "auxiliaryInformation"; String long_name "finalground filter switch"; String description "Controls filtering based on FINALGROUND. (Default = 1)"; String source "ATBD section 4.13 step 2"; } /ancillary_data/land/psf { String HDF5_OBJ_FULLPATH "/ancillary_data/land/psf"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Point Spread Function"; String description "Parameter controlling identification of photons around an interpolated surface. (Default = 0.5)"; String source "ATBD section 4.7 step 12"; } /ancillary_data/land/dem_removal_percent_limit { String HDF5_OBJ_FULLPATH "/ancillary_data/land/dem_removal_percent_limit"; String units "percent"; String contentType "auxiliaryInformation"; String long_name "dem_removal_flag set threshold"; String description "Percent of photons in land segment failing DEM test to set dem_removal_flag. (default = 20.0)"; String source "ATBD section 2.4.11"; } /ancillary_data/land/atl08_region { String HDF5_OBJ_FULLPATH "/ancillary_data/land/atl08_region"; String units "1"; String contentType "modelResult"; String long_name "atl08 region"; String standard_name "atl08_region"; String description "ATL08 region(s) encompassed by ATL03 granule being processed"; String source "Land ATBD 29March2019, Table 2.4"; } /ancillary_data/land/can_noise_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/can_noise_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold for reclassification of canopy as noise"; String description "Threshold, as a number of canopy photons in the CAN_FILT_SEG, used for the reclassification of canopy signal photons. (Default = 75)"; String source "ATBD section 4.11 step 6"; } /ancillary_data/land/relief_hbot { String HDF5_OBJ_FULLPATH "/ancillary_data/land/relief_hbot"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "lower relief percentile"; String description "The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.05)"; String source "ATBD (section 4.5 step 6)"; } /ancillary_data/land/dem_filter_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/dem_filter_switch"; String units "1"; String contentType "auxiliaryInformation"; String long_name "dem_filter switch"; String description "Controls filtering based on DEM. (Default = 1)"; String source "ATBD section 4.5 step 5"; } /ancillary_data/land/relief_htop { String HDF5_OBJ_FULLPATH "/ancillary_data/land/relief_htop"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Upper relief percentile"; String description "The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.95)"; String source "ATBD (section 4.5 step 6)"; } /ancillary_data/land/dseg_buf { String HDF5_OBJ_FULLPATH "/ancillary_data/land/dseg_buf"; String units "1"; String contentType "auxiliaryInformation"; String long_name "DRAGANN segment buffer size"; String description "DRAGANN segment buffer length in 20m geolocated segments along ground track. (Default=10)"; String source "ATBD section 4.2.1 step 1"; } /ancillary_data/land/night_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/night_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold for night"; String description "Solar elevation threshold for determining night time conditions. (Default =0.0)"; String source "ATBD section 2.4.9"; } /ancillary_data/land/h_canopy_perc { String HDF5_OBJ_FULLPATH "/ancillary_data/land/h_canopy_perc"; String units "1"; String contentType "auxiliaryInformation"; String long_name "h_canopy percentile"; String description "Percentile component of h_canopy parameter. (Default =0.95)"; String source "ATBD section 2.2.3"; } /ancillary_data/land/up_filt_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/up_filt_bnd"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons."; String description "Lower bound of the filter window size function. (Default = 46)"; String source "ATBD section 4.4 step 2"; } /ancillary_data/land/lw_filt_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lw_filt_bnd"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons."; String description "Lower bound of the filter window size function. (Default = 5)"; String source "ATBD section 4.4 step 2"; } /ancillary_data/land/ph_removal_percent_limit { String HDF5_OBJ_FULLPATH "/ancillary_data/land/ph_removal_percent_limit"; String units "percent"; String contentType "auxiliaryInformation"; String long_name "ph_removal_flag set threshold"; String description "Percent of photons in land segment removed to set ph_removal_flag. (default = 50.0)"; String source "ATBD section 4.13 step 4"; } /ancillary_data/land/canopy_seg { String HDF5_OBJ_FULLPATH "/ancillary_data/land/canopy_seg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "segment size in canopy filter"; String description "Segment in number of signal photons for filtering sparse canopy cover. (Default = 500)"; String source "ATBD section 4.11 step 6"; } /ancillary_data/land/max_try { String HDF5_OBJ_FULLPATH "/ancillary_data/land/max_try"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Maximum try count"; String description "Maximum number of tries to compute a P value in alternative DRAGANN"; String source "ATBD section 4.2.1 step 17"; } /ancillary_data/land/bin_size_n { String HDF5_OBJ_FULLPATH "/ancillary_data/land/bin_size_n"; String units "1"; String contentType "auxiliaryInformation"; String long_name "neighbor histogram bin size"; String description "Size of neighbor histogram bins in number of neighbors in DRAGANN. (Default = 1)"; String source "ATBD (section 4.2 step 4)"; } /ancillary_data/land/lw_gnd_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lw_gnd_bnd"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Lower bound restricting the search of a ground surface in canopy cases."; String description "Lower bound restricting the search of a ground surface in canopy cases. (Default = -4.0)"; String source "ATBD section 4.7 step 3"; } /ancillary_data/land/del_mu { String HDF5_OBJ_FULLPATH "/ancillary_data/land/del_mu"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Step size for optimizing the mean parameter of Gaussian function."; String description "Step size for optimizing the mean parameter of Gaussian function. (Default = 0.2)"; String source "ATBD section 4.2 step 7"; } /ancillary_data/land/lw_toc_cut { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lw_toc_cut"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Lower cutoff for top of canopy"; String description "Lower cutoff for top of canopy surface. (Default = 2.0)"; String source "ATBD section 4.8 step 10"; } /ancillary_data/land/class_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/class_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold flag value for classification of photons as signal via input from ATL03"; String description "Threshold flag value for classification of photons as signal via input from ATL03. (Default =3)"; String source "ATBD section 4.2 step 17"; } /ancillary_data/land/lseg_buf { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lseg_buf"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Long segment buffer size"; String description "Overlapping long segment buffer size in 20m geosegments along ground track. (Default=10)"; String source "ATBD section 4.1 step 2"; } /ancillary_data/land/lw_toc_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lw_toc_bnd"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Lower bound restricting the search of a top of canopy surface."; String description "Lower bound restricting the search of a top of canopy surface. (Default = -4.0)"; String source "section 4.7 step 3 entered from section 4.8"; } /ancillary_data/land/up_toc_cut { String HDF5_OBJ_FULLPATH "/ancillary_data/land/up_toc_cut"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "upper cutoff of top of canopy surface."; String description "Upper cutoff for top of canopy surface. (Default = 150.0)"; String source "ATBD section 4.8 step 10"; } /ancillary_data/land/gnd_stat_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/gnd_stat_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold for terrain statistics"; String description "Minimum percentage of terrain photons to compute statistics upon. (Default =0.05)"; String source "ATBD section 4.13 step 2"; } /ancillary_data/land/iter_max { String HDF5_OBJ_FULLPATH "/ancillary_data/land/iter_max"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram."; String description "Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram. (Default = 10)"; String source "ATBD section 4.2 step 7"; } /ancillary_data/land/gthresh_factor { String HDF5_OBJ_FULLPATH "/ancillary_data/land/gthresh_factor"; String units "1"; String contentType "auxiliaryInformation"; String long_name "threshold for Gaussian Elimination"; String description "Controls threshold for Gaussian Elimination. (Default = 0.1)"; String source "ATBD sGaussian Rejection section of Appendix A"; } /ancillary_data/land/bright_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/bright_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "brightness flag average ph per shot"; String description "Threshold to set brightness_flag, average ground photons per shot. (Default = 3.0)"; String source "ATBD section 2.4.21"; } /ancillary_data/land/dseg { String HDF5_OBJ_FULLPATH "/ancillary_data/land/dseg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "DRAGANN segment size"; String description "DRAGANN segment length in 20m geolocated segments along ground track. (Default=170)"; String source "ATBD section 4.2.1 step 1"; } /ancillary_data/land/bin_size_h { String HDF5_OBJ_FULLPATH "/ancillary_data/land/bin_size_h"; String units "1"; String contentType "auxiliaryInformation"; String long_name "neighbor histogram bin size"; String description "Histogram bin size for the alternative DRAGANN algorithm. (Default = 1.0)"; String source "ATBD (section 4.2.1 step 3)"; } /ancillary_data/land/up_gnd_bnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/up_gnd_bnd"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Upper bound restricting the search of a ground surface in canopy cases."; String description "Upper bound restricting the search of a ground surface in canopy cases. (Default = 1.0)"; String source "ATBD (section 4.7 step 3)"; } /ancillary_data/land/min_nphs { String HDF5_OBJ_FULLPATH "/ancillary_data/land/min_nphs"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Minimum input photons"; String description "Minimum number of input photons from ATL03 to process. (default=1)"; String source "Operations"; } /ancillary_data/land/tc_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/tc_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Canopy Flag threshold"; String description "Percentage threshold for average L-km segment tree cover to be considered canopy. (Default = 5.0)"; String source "ATBD section 4.3 steps 6 and 7"; } /ancillary_data/land/te_class { String HDF5_OBJ_FULLPATH "/ancillary_data/land/te_class"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Terrain class value"; String description "Terrain classification flag value. (Default = 1)"; String source "ATBD section 4.12 step 1"; } /ancillary_data/land/toc_class { String HDF5_OBJ_FULLPATH "/ancillary_data/land/toc_class"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Top of canopy class value"; String description "Top of canopy classification flag value. (Default = 3)"; String source "ATBD section 4.12 step 1"; } /ancillary_data/land/iter_gnd { String HDF5_OBJ_FULLPATH "/ancillary_data/land/iter_gnd"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Iterations of smoothing of interpolated ground surface for ground estimate."; String description "Iterations of smoothing of interpolated ground surface for refinement. (Default = 10)"; String source "ATBD section 4.10 step 1"; } /ancillary_data/land/max_atl03files { String HDF5_OBJ_FULLPATH "/ancillary_data/land/max_atl03files"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Maximum number of input ATL03s"; String description "Maximum number of input ATL03 files. (Default = 200)"; String source "Operations"; } /ancillary_data/land/noise_class { String HDF5_OBJ_FULLPATH "/ancillary_data/land/noise_class"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Noise class value"; String description "Noise classification flag value. (Default = 0)"; String source "ATBD section 4.12 step 1"; } /ancillary_data/land/outlier_filter_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/outlier_filter_switch"; String units "1"; String contentType "auxiliaryInformation"; String long_name "outlier_filter switch"; String description "Controls entrance to the outlier filter subroutine. (Default = 1)"; String source "ATBD section 4.6"; } /ancillary_data/land/dragann_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/dragann_switch"; String units "1"; String contentType "auxiliaryInformation"; String long_name "DRAGANN switch"; String description "Controls entrance to the DRAGANN subroutine. (Default =1)"; String source "ATBD section 4.2"; } /ancillary_data/land/proc_geoseg { String HDF5_OBJ_FULLPATH "/ancillary_data/land/proc_geoseg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Geosegment process interval length"; String description "Geosegment process interval length. This controls the amount read from ATL03 and ATL09 at a time. (Default = 500000)."; String source "Operations"; } /ancillary_data/land/can_stat_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/can_stat_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold for canopy statistics"; String description "Minimum percentage of canopy photons to compute statistics upon. (Default =0.05)"; String source "ATBD section 4.14.1 step 1"; } /ancillary_data/land/lseg { String HDF5_OBJ_FULLPATH "/ancillary_data/land/lseg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Long segment size"; String description "Long segment size in number of 20 meter segments along ground track. (Default=500)"; String source "ATBD section 4.1 step 1"; } /ancillary_data/land/max_atl09files { String HDF5_OBJ_FULLPATH "/ancillary_data/land/max_atl09files"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Maximum number of input ATL09s"; String description "Maximum number of input ATL09 files. (Default = 200)"; String source "Operations"; } /ancillary_data/land/ref_dem_limit { String HDF5_OBJ_FULLPATH "/ancillary_data/land/ref_dem_limit"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "DEM threshold"; String description "Reference DEM limit used to reclassify signal as noise. (default = 120.0)"; String source "ATBD section 4.5 step 4"; } /ancillary_data/land/max_peaks { String HDF5_OBJ_FULLPATH "/ancillary_data/land/max_peaks"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Maximum number of Gaussian peaks to fit in the data set"; String description "Maximum number of Gaussian peaks to fit in the data set in DRAGANN. (Default =10)"; String source "ATBD section 4.2 step 9"; } /ancillary_data/land/stat_thresh { String HDF5_OBJ_FULLPATH "/ancillary_data/land/stat_thresh"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Threshold for land statistics"; String description "Minimum number of photons to compute statistics upon. (Default =50)"; String source "ATBD section 2 intro paragraph"; } /ancillary_data/land/sig_rsq_search { String HDF5_OBJ_FULLPATH "/ancillary_data/land/sig_rsq_search"; String units "meters^2"; String contentType "auxiliaryInformation"; String long_name "Square Radius of filter for canopy"; String description "Top of canopy refinement square search radius. (Default = 225.0)"; String source "ATBD section 4.8 step 6"; } /ancillary_data/land/del_amp { String HDF5_OBJ_FULLPATH "/ancillary_data/land/del_amp"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Step Gaussian Amplitude optimization"; String description "Step size for optimizing the amplitude variable of Gaussian function. (Default = 1.0)"; String source "ATBD section 4.2 step 7"; } /ancillary_data/land/sseg { String HDF5_OBJ_FULLPATH "/ancillary_data/land/sseg"; String units "meters"; String contentType "auxiliaryInformation"; String long_name "Short Segment Length"; String description "Short segment length in meters. (Default = 100.0)"; String source "ATBD section 4.13 step 1"; } /ancillary_data/land/shp_param { String HDF5_OBJ_FULLPATH "/ancillary_data/land/shp_param"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Exponential coefficient for controlling the exponential decay of the filter window size as a function of number of signal photons."; String description "Exponential coefficient of the filter window size as a function. (Default = 21.0E-06)"; String source "ATBD section 4.4 step 2"; } /ancillary_data/land/del_sigma { String HDF5_OBJ_FULLPATH "/ancillary_data/land/del_sigma"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Step size for optimizing the standard deviation parameter of Gaussian function."; String description "Step size for optimizing the standard deviation parameter of Gaussian function. (Default = 0.5)"; String source "ATBD section 4.2 step 7"; } /ancillary_data/land/cloud_filter_switch { String HDF5_OBJ_FULLPATH "/ancillary_data/land/cloud_filter_switch"; String units "1"; String contentType "auxiliaryInformation"; String long_name "cloud_filter switch"; String description "Controls entrance to the cloud_filter subroutine. (Default = 0)"; String source "ATBD section 4.1.1"; } /ancillary_data/land/n_dec_mode { String HDF5_OBJ_FULLPATH "/ancillary_data/land/n_dec_mode"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Mode decimal parameter"; String description "Number of decimal places to consider in mode computation. (Default =1)"; String source "ATBD needed for section 4.13 step 3(h_te_mode)"; } /ancillary_data/land/ref_finalground_limit { String HDF5_OBJ_FULLPATH "/ancillary_data/land/ref_finalground_limit"; String units "meters"; String contentType "auxiliaryInformation"; String description "Reference finalground limit used to reclassify signal as noise. (default = 150.0)"; String source "ATBD section 4.13 step 2"; String long_name "finalground threshold"; } /ancillary_data/land/p_static { String HDF5_OBJ_FULLPATH "/ancillary_data/land/p_static"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Dragann Parameter"; String description "Parameter for controlling the search radius in nearest neighbor search in DRAGANN. (Default = 20)"; String source "ATBD section 4.2 step 1"; } /ancillary_data/start_delta_time { String HDF5_OBJ_FULLPATH "/ancillary_data/start_delta_time"; String units "seconds since 2018-01-01"; String contentType "auxiliaryInformation"; String long_name "ATLAS Start Time (Actual)"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch at the first data point in the file. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived"; } /ancillary_data/start_geoseg { String HDF5_OBJ_FULLPATH "/ancillary_data/start_geoseg"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Starting Geolocation Segment"; String description "The starting geolocation segment number associated with the data contained within this granule. ICESat granule geographic regions are further refined by geolocation segments. During the geolocation process, a geolocation segment is created approximately every 20m from the start of the orbit to the end. The geolocation segments help align the ATLAS strong a weak beams and provide a common segment length for the L2 and higher products. The geolocation segment indices differ slightly from orbit-to-orbit because of the irregular shape of the Earth. The geolocation segment indices on ATL01 and ATL02 are only approximate because beams have not been aligned at the time of their creation."; String source "Derived"; } /ancillary_data/start_orbit { String HDF5_OBJ_FULLPATH "/ancillary_data/start_orbit"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Starting Orbit Number"; String description "The starting orbit number associated with the data contained within this granule. The orbit number increments each time the spacecraft completes a full orbit of the Earth."; String source "Derived"; } /ancillary_data/data_start_utc { String HDF5_OBJ_FULLPATH "/ancillary_data/data_start_utc"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Start UTC Time of Granule (CCSDS-A, Actual)"; String description "UTC (in CCSDS-A format) of the first data point within the granule."; String source "Derived"; } /ancillary_data/end_gpsweek { String HDF5_OBJ_FULLPATH "/ancillary_data/end_gpsweek"; String units "weeks from 1980-01-06"; String contentType "auxiliaryInformation"; String long_name "Ending GPSWeek of Granule (Actual)"; String description "GPS week number of the last data point in the granule."; String source "Derived"; } /ancillary_data/start_rgt { String HDF5_OBJ_FULLPATH "/ancillary_data/start_rgt"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Starting Reference Groundtrack"; String description "The starting reference groundtrack (RGT) number associated with the data contained within this granule. There are 1387 reference groundtrack in the ICESat-2 repeat orbit. The reference groundtrack increments each time the spacecraft completes a full orbit of the Earth and resets to 1 each time the spacecraft completes a full cycle."; String source "Derived"; Int32 valid_min 1; Int32 valid_max 1387; } /ancillary_data/end_gpssow { String HDF5_OBJ_FULLPATH "/ancillary_data/end_gpssow"; String units "seconds"; String contentType "auxiliaryInformation"; String long_name "Ending GPS SOW of Granule (Actual)"; String description "GPS seconds-of-week of the last data point in the granule."; String source "Derived"; } /ancillary_data/qa_at_interval { String HDF5_OBJ_FULLPATH "/ancillary_data/qa_at_interval"; String units "1"; String contentType "auxiliaryInformation"; String long_name "QA Along-Track Interval"; String description "Statistics time interval for along-track QA data."; String source "control"; } /ancillary_data/start_region { String HDF5_OBJ_FULLPATH "/ancillary_data/start_region"; String units "1"; String contentType "auxiliaryInformation"; String long_name "Starting Region"; String description "The starting product-specific region number associated with the data contained within this granule. ICESat-2 data products are separated by geographic regions. The data contained within a specific region are the same for ATL01 and ATL02. ATL03 regions differ slightly because of different geolocation segment locations caused by the irregular shape of the Earth. The region indices for other products are completely independent."; String source "Derived"; } /ancillary_data/start_gpsweek { String HDF5_OBJ_FULLPATH "/ancillary_data/start_gpsweek"; String units "weeks from 1980-01-06"; String contentType "auxiliaryInformation"; String long_name "Start GPSWeek of Granule (Actual)"; String description "GPS week number of the first data point in the granule."; String source "Derived"; } /gt3r/ { String HDF5_OBJ_FULLPATH "/gt3r/"; String Description "Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams."; String atlas_pce "pce1"; String atlas_beam_type "strong"; String groundtrack_id "gt3r"; String atmosphere_profile "profile_3"; String atlas_spot_number "1"; String sc_orientation "Forward"; } /gt3r/signal_photons/ { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/"; String Description "Contains parameters related to individual photons."; String data_rate "Data are stored at the signal-photon classification rate."; } /gt3r/signal_photons/classed_pc_flag { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/classed_pc_flag"; String units "1"; String long_name "photon land atbd classification"; String description "Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy."; String source "Land ATBD section 4.10"; String coordinates "delta_time"; String flag_meanings "noise ground canopy top_of_canopy"; Int16 flag_values 0, 1, 2, 3; } /gt3r/signal_photons/classed_pc_indx { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/classed_pc_indx"; String units "1"; String contentType "referenceInformation"; String long_name "indicies of classed photons"; String description "Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt3r/signal_photons/delta_time { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/delta_time"; String units "seconds since 2018-01-01"; String long_name "delta time"; String standard_name "time"; String description "Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "ATL03"; String CLASS "DIMENSION_SCALE"; } /gt3r/signal_photons/d_flag { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/d_flag"; String units "1"; String long_name "dragann flag"; String description "Flag indicating the labeling of DRAGANN noise filtering for a given photon."; String source "Land ATBD section 2.3.5"; String coordinates "delta_time"; String flag_meanings "noise signal"; Int16 flag_values 0, 1; } /gt3r/signal_photons/ph_segment_id { String HDF5_OBJ_FULLPATH "/gt3r/signal_photons/ph_segment_id"; String units "1"; String contentType "referenceInformation"; String long_name "segment id of photon"; String description "Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group."; String source "Retained from prior a_alt_science_ph packet"; String coordinates "delta_time"; } /gt3r/land_segments/ { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/"; String Description "Contains data categorized as land at 100 meter intervals."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt3r/land_segments/segment_watermask { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/segment_watermask"; Int32 _FillValue 255; String units "1"; String long_name "segment watermask"; String description "Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution."; String source "ATBD section 2.4.15"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_water water"; Int32 flag_values 0, 1; Int32 valid_min 0; Int32 valid_max 1; } /gt3r/land_segments/delta_time_end { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/delta_time_end"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time end"; String description "Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/rgt { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/rgt"; String units "1"; String contentType "referenceInformation"; String long_name "reference ground track"; String description "The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs."; String source "Operations"; String coordinates "delta_time latitude longitude"; Int16 valid_min 1; Int16 valid_max 1387; } /gt3r/land_segments/dem_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/dem_flag"; Int16 _FillValue 127; String units "1"; String contentType "referenceInformation"; String long_name "dem source flag"; String description "Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic."; String source "Atmosphere ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "none arctic gmted mss antarctic"; Int16 flag_values 0, 1, 2, 3, 4; Int16 valid_min 0; Int16 valid_max 4; } /gt3r/land_segments/msw_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/msw_flag"; Int16 _FillValue 127; String units "1"; String long_name "multiple scattering warning flag"; String description "Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5"; Int16 flag_values -1, 0, 1, 2, 3, 4, 5; } /gt3r/land_segments/cloud_flag_atm { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/cloud_flag_atm"; Int16 _FillValue 127; String units "1"; String long_name "cloud flag atm"; String description "Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10."; String source "ATL09"; String coordinates "delta_time latitude longitude"; Int16 valid_min 0; Int16 valid_max 10; } /gt3r/land_segments/snr { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/snr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "signal to noise ratio"; String description "The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments."; String source "ATBD section 2.5.14"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/canopy/ { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/"; String Description "Contains height parameters based on the land algorithm."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt3r/land_segments/canopy/h_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "height canopy"; String description "98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/canopy_rh_conf { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/canopy_rh_conf"; String units "1"; String contentType "modelResult"; String long_name "canopy relative height confidence"; String description "Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground)."; String source "Land/Veg ATBD 13March2019, Section 2.2.21"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground"; Int16 flag_values 0, 1, 2; Int16 valid_min 0; Int16 valid_max 2; } /gt3r/land_segments/canopy/h_median_canopy_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_median_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment median canopy height"; String description "The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.6"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_min_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_min_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum canopy height"; String description "The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 2.2.10"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_mean_canopy_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_mean_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute mean canopy height"; String description "Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.4"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_median_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_median_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median canopy height"; String description "The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature."; String source "Land ATBD section 2.2.8"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_canopy_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute segment canopy height"; String description "The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.2"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/toc_roughness { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/toc_roughness"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "top of canopy roughness"; String description "Standard deviation of the relative heights of all photons classified as top of canopy within the segment"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_min_canopy_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_min_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute minimum canopy height"; String description "The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid."; String source "Land ATBD section 2.2.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_dif_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_dif_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy diff to median height"; String description "Difference between h_canopy and h_median_canopy"; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_canopy_quad { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_canopy_quad"; String long_name "canopy quadratic mean"; String description "The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt3r/land_segments/canopy/n_ca_photons { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/n_ca_photons"; String units "1"; String long_name "number canopy photons"; String description "The number of photons classified as canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/centroid_height { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/centroid_height"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "centroid height"; String description "Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/canopy_h_metrics_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/canopy_h_metrics_abs"; String long_name "canopy absolute height metrics"; String description "Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt3r/land_segments/canopy/landsat_perc { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/landsat_perc"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "landsat percentage canopy"; String description "Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment"; String source "Land ATBD section 2.2.24"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_mean_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_mean_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean canopy height"; String description "Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/canopy_h_metrics { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/canopy_h_metrics"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "canopy height metrics"; String description "Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%."; String source "Land ATBD section 2.2.3"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/n_toc_photons { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/n_toc_photons"; String units "1"; String long_name "number top of canopy photons"; String description "The number of photons classified as top of canopy within the segment."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/canopy_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/canopy_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "canopy flag"; String description "Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present."; String source "Land ATBD section 2.2.22"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "no_canopy_present canopy_present"; Int32 flag_values 0, 1; } /gt3r/land_segments/canopy/landsat_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/landsat_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "landsat flag"; String description "Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1."; String source "Land ATBD section 2.2.25"; String coordinates "../delta_time ../latitude ../longitude"; String flag_meanings "canopy_not_assumed_present canopy_assumed_present"; Int32 flag_values 0, 1; } /gt3r/land_segments/canopy/h_max_canopy_abs { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_max_canopy_abs"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "absolute maximum canopy height"; String description "Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid."; String source "Land ATBD section 2.2.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_canopy_uncertainty { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_canopy_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment canopy height uncertainty"; String description "Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD"; String source "Land ATBD section 1.5"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/canopy_openness { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/canopy_openness"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "canopy openness"; String description "Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness."; String source "Land ATBD section 4.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/canopy/h_max_canopy { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/canopy/h_max_canopy"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum canopy height"; String description "Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature."; String source "Land ATBD section 2.2.12"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/sigma_across { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/sigma_across"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas y"; String description "Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/terrain/ { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/"; String Description "Contains terrain parameters at a 100m aggregation."; String data_rate "Data are stored as aggregates of 100 meters."; } /gt3r/land_segments/terrain/h_te_uncertainty { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_uncertainty"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "uncertainty of h_te_mean"; String description "Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4"; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_mean { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_mean"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mean terrain height"; String description "The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_min { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_min"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "minimum terrain height"; String description "The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_interp { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_interp"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "interpolated terrain surface height"; String description "Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment."; String source "Land ATBD section 4.9"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_max { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_max"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "maximum terrain height"; String description "The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_skew { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_skew"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "skew of terrain heights"; String description "The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_median { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_median"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "median terrain height"; String description "The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_best_fit { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_best_fit"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "segment terrain height best fit"; String description "The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment."; String source "Land ATBD section 2.1.15"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_std { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_std"; String long_name "segment terrain roughness"; String description "The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; Float32 _FillValue 3.402823466e+38; String units "meters"; } /gt3r/land_segments/terrain/terrain_slope { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/terrain_slope"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "segment terrain slope"; String description "The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/n_te_photons { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/n_te_photons"; String units "1"; String long_name "number of ground photons"; String description "The number of the photons classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/terrain/h_te_mode { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain/h_te_mode"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "mode of terrain heights"; String description "The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment."; String source "Land ATBD section 4.11"; String coordinates "../delta_time ../latitude ../longitude"; } /gt3r/land_segments/layer_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/layer_flag"; String contentType "modelResult"; String long_name "consolidated cloud flag"; String description "This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "likely_clear likely_cloudy"; Int16 flag_values 0, 1; } /gt3r/land_segments/segment_snowcover { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/segment_snowcover"; Int16 _FillValue 127; String units "1"; String long_name "segment snowcover"; String description "Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice."; String source "ATBD section 4.2.16"; String coordinates "delta_time latitude longitude"; String flag_meanings "ice_free_water snow_free_land snow ice"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt3r/land_segments/beam_azimuth { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/beam_azimuth"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam azimuth"; String description "Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/solar_azimuth { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/solar_azimuth"; String units "degrees_east"; String contentType "referenceInformation"; String long_name "solar azimuth"; String description "The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/psf_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/psf_flag"; String units "1"; String contentType "referenceInformation"; String long_name "point spread function flag"; String description "Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)"; String source "Land/Veg ATBD"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt3r/land_segments/longitude { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/longitude"; String units "degrees"; String long_name "longitude"; String standard_name "longitude"; String description "Longitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude"; Float32 valid_min -180.; Float32 valid_max 180.; } /gt3r/land_segments/latitude { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/latitude"; String units "degrees"; String long_name "latitude"; String standard_name "latitude"; String description "Latitude of the center-most signal photon within each segment."; String source "Land ATBD section 2.4"; String coordinates "delta_time longitude"; Float32 valid_min -90.; Float32 valid_max 90.; } /gt3r/land_segments/segment_id_end { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/segment_id_end"; String units "1"; String contentType "referenceInformation"; String long_name "end geolocation segment bin"; String description "Geolocation segment number of the last photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/surf_type { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/surf_type"; String units "1"; String contentType "referenceInformation"; String long_name "surface type"; String description "Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water."; String source "ATL03 ATBD, Section 4"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_type is_type"; Int16 flag_values 0, 1; Int16 valid_min 0; Int16 valid_max 1; } /gt3r/land_segments/brightness_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/brightness_flag"; Int16 _FillValue 127; String units "1"; String long_name "brightness flag"; String description "Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)"; String source "Land ATBD section 2.4.21"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_bright_surface bright_surface"; Int16 flag_values 0, 1; } /gt3r/land_segments/segment_landcover { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/segment_landcover"; Int32 _FillValue 255; String units "1"; String long_name "segment landcover"; String description "IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution."; String source "ATBD section 2.4.14"; String coordinates "delta_time latitude longitude"; String flag_meanings "Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren"; Int32 flag_values 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16; Int32 valid_min 0; Int32 valid_max 16; } /gt3r/land_segments/ph_removal_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/ph_removal_flag"; String units "1"; String long_name "ph removal flag"; String description "Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests"; String source "ATBD section 4.13"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt3r/land_segments/asr { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/asr"; Float32 _FillValue 3.402823466e+38; String units "1"; String long_name "apparent surface reflectance"; String description "Apparent surface reflectance"; String source "ATL09"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/sigma_atlas_land { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/sigma_atlas_land"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas land"; String description "Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2."; String source "Land ATBD section 2.5.13"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/segment_id_beg { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/segment_id_beg"; String units "1"; String contentType "referenceInformation"; String long_name "begin geolocation segment bin"; String description "Geolocation segment number of the first photon in the land segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/sigma_along { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/sigma_along"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas x"; String description "Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/dem_h { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/dem_h"; Float32 _FillValue 3.402823466e+38; String units "meters"; String contentType "referenceInformation"; String long_name "dem height"; String description "Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid."; String source "GIMP, GMTED,MSS"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/beam_coelev { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/beam_coelev"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "beam co-elevation"; String description "Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/sigma_topo { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/sigma_topo"; Float32 _FillValue 3.402823466e+38; String units "1"; String contentType "referenceInformation"; String long_name "sigma atlas topo"; String description "Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope."; String source "Land ATBD section 2.5.12"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/night_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/night_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "night flag"; String description "Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "day night"; Int32 flag_values 0, 1; } /gt3r/land_segments/delta_time_beg { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/delta_time_beg"; String units "seconds since 2018-01-01"; String contentType "referenceInformation"; String long_name "delta time begin"; String description "Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Derived (gps_seconds-gps_sec_offset)"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/sigma_h { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/sigma_h"; String contentType "referenceInformation"; String long_name "height uncertainty"; String description "Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment."; String source "ATL03"; String coordinates "delta_time latitude longitude"; Float32 _FillValue 3.402823466e+38; String units "1"; } /gt3r/land_segments/last_seg_extend { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/last_seg_extend"; String units "kilometers"; String long_name "last segment extended"; String standard_name "last_seg_extend"; String description "The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment."; String source "Land ATBD 13March2019, Section 2.4.20"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/atlas_pa { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/atlas_pa"; Float32 _FillValue 3.402823466e+38; String units "radians"; String contentType "referenceInformation"; String long_name "atlas pointing angle"; String description "Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev."; String source "ATL03"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/ph_ndx_beg { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/ph_ndx_beg"; String units "1"; String long_name "photon index begin"; String description "Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/solar_elevation { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/solar_elevation"; String units "degrees"; String contentType "referenceInformation"; String long_name "solar elevation"; String description "Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy."; String source "ATL03g ATBD"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/delta_time { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/delta_time"; String units "seconds since 2018-01-01"; String long_name "mean_pass_time"; String standard_name "time"; String description "Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed."; String source "Land ATBD section 2.4"; String coordinates "latitude longitude"; String CLASS "DIMENSION_SCALE"; } /gt3r/land_segments/cloud_fold_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/cloud_fold_flag"; Int16 _FillValue 127; String contentType "modelResult"; String long_name "cloud folding flag"; String description "Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings."; String source "ATL09"; String coordinates "delta_time latitude longitude"; String flag_meanings "no_folding goes5_indicates profile_indicates both_indicate"; Int16 flag_values 0, 1, 2, 3; Int16 valid_min 0; Int16 valid_max 3; } /gt3r/land_segments/n_seg_ph { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/n_seg_ph"; String units "1"; String long_name "number of photons"; String description "Number of photons within each land segment."; String source "Derived"; String coordinates "delta_time latitude longitude"; } /gt3r/land_segments/terrain_flg { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/terrain_flg"; Int32 _FillValue 2147483647; String units "1"; String long_name "terrain flag"; String description "Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product."; String source "Land ATBD section 2.4.8"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int32 flag_values 0, 1; } /gt3r/land_segments/urban_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/urban_flag"; Int32 _FillValue 2147483647; String units "1"; String long_name "segment urban flag"; String description "The urban flag indicates that a segment is likely located over an urban area."; String source "Land ATBD section 2.4.17"; String coordinates "delta_time latitude longitude"; String flag_meanings "not_urban urban"; Int32 flag_values 0, 1; } /gt3r/land_segments/dem_removal_flag { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/dem_removal_flag"; String units "1"; String long_name "dem removal flag"; String description "Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests"; String source "ATBD section 2.4.11"; String coordinates "delta_time latitude longitude"; String flag_meanings "below_threshold above_threshold"; Int16 flag_values 0, 1; } /gt3r/land_segments/h_dif_ref { String HDF5_OBJ_FULLPATH "/gt3r/land_segments/h_dif_ref"; Float32 _FillValue 3.402823466e+38; String units "meters"; String long_name "h dif from reference"; String description "Difference between h_te_median and ref_DEM"; String source "Land ATBD section 2.4"; String coordinates "delta_time latitude longitude"; } }