4.0 2.0 ATL06_20250913142324_13722807_007_01.h5 /nasa-ngap/atl/tmpatl/ATL06_20250913142324_13722807_007_01.h5 short_name String ATL06 level String L3A description String This data set (ATL06) provides geolocated, land-ice surface heights (above the WGS 84 ellipsoid, ITRF2014 reference frame), plus ancillary parameters that can be used to interpret and assess the quality of the height estimates. The data were acquired by th Conventions String CF-1.6 contributor_name String Thomas A 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) contributor_role String Instrument Engineer, Investigator, Principle Investigator, Data Producer, Data Producer data_rate String Data within this group pertain to the granule in its entirety. date_type String UTC featureType String trajectory geospatial_lat_units String degrees_north geospatial_lon_units String degrees_east granule_type String ATL06 identifier_product_doi_authority String http://dx.doi.org license String 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. naming_authority String http://dx.doi.org spatial_coverage_type String Horizontal standard_name_vocabulary String CF-1.6 time_type String CCSDS UTC-A date_created String 2025-12-19T22:01:54.000000Z hdfversion String HDF5 1.14.4 history String 2025-12-19T22:01:54.000000Z;fe870c8f-7533-3a33-8c17-d667ecdd83b6;Created by PGE atlas_l3a_is Version 5.1 identifier_file_uuid String fe870c8f-7533-3a33-8c17-d667ecdd83b6 identifier_product_format_version String 5.1 time_coverage_duration Float64 422. time_coverage_end String 2025-09-13T14:30:26.000000Z time_coverage_start String 2025-09-13T14:23:24.000000Z geospatial_lat_min Float64 25.474481959584711 geospatial_lon_min Float64 -171.42912310348692 geospatial_lat_max Float64 25.51268125829365 geospatial_lon_max Float64 -171.42503689992421 publisher_name String NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center publisher_email String nsidc@nsidc.org publisher_url String http://nsidc.org/daac/ title String ATLAS/ICESat-2 L3A Land Ice Height identifier_product_type String ATL06 identifier_product_doi String doi:10.5067/ATLAS/ATL06.007 institution String National Aeronautics and Space Administration (NASA) creator_name String GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System summary String ATL06 provides estimates of the ice-sheet mean surface height relative to the WGS-84 ellipsoid, and ancillary parameters needed to interpret and assess the quality of these height estimates. keywords String EARTH SCIENCE > CRYOSPHERE > GLACIERS/ICE SHEETS > GLACIER ELEVATION/ICE SHEET ELEVATION > NONE > NONE > NONE keywords_vocabulary String NASA/GCMD Science Keywords citation String 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. processing_level String 3A references String http://nsidc.org/data/icesat2/data.html project String ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 instrument String ATLAS > Advanced Topographic Laser Altimeter System platform String ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 source String Spacecraft ancillary_data release 1 long_name String Release Number units String 1 source String Operations contentType String auxiliaryInformation description String Release number of the granule. The release number is incremented when the software or ancillary data used to create the granule has been changed. end_geoseg 1 long_name String Ending Geolocation Segment units String 1 source String Derived contentType String auxiliaryInformation description String 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. version 1 long_name String Version units String 1 source String Operations contentType String auxiliaryInformation description String 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. end_region 1 long_name String Ending Region units String 1 source String Derived contentType String auxiliaryInformation description String 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. atlas_sdp_gps_epoch 1 long_name String ATLAS Epoch Offset units String seconds since 1980-01-06T00:00:00.000000Z source String Operations contentType String auxiliaryInformation description String 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. end_rgt 1 long_name String Ending Reference Groundtrack units String 1 source String Derived valid_min Int32 1 valid_max Int32 1387 contentType String auxiliaryInformation description String 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. end_delta_time 1 long_name String ATLAS End Time (Actual) standard_name String time units String seconds since 2018-01-01 source String Derived contentType String auxiliaryInformation description String 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. end_orbit 1 long_name String Ending Orbit Number units String 1 source String Derived contentType String auxiliaryInformation description String 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. start_cycle 1 long_name String Starting Cycle units String 1 source String Derived valid_min Int32 0 valid_max Int32 99 contentType String auxiliaryInformation description String 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. data_end_utc 1 long_name String End UTC Time of Granule (CCSDS-A, Actual) units String 1 source String Derived contentType String auxiliaryInformation description String UTC (in CCSDS-A format) of the last data point within the granule. control 1 long_name String Control File units String 1 source String Operations contentType String auxiliaryInformation description String PGE-specific control file used to generate this granule. To re-use, replace breaks (BR) with linefeeds. start_gpssow 1 long_name String Start GPS SOW of Granule (Actual) units String seconds source String Derived contentType String auxiliaryInformation description String GPS seconds-of-week of the first data point in the granule. granule_end_utc 1 long_name String End UTC Time of Granule (CCSDS-A, Requested) units String 1 source String Derived contentType String auxiliaryInformation description String Requested end time (in UTC CCSDS-A) of this granule. end_cycle 1 long_name String Ending Cycle units String 1 source String Derived valid_min Int32 0 valid_max Int32 99 contentType String auxiliaryInformation description String 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. granule_start_utc 1 long_name String Start UTC Time of Granule (CCSDS-A, Requested) units String 1 source String Derived contentType String auxiliaryInformation description String Requested start time (in UTC CCSDS-A) of this granule. start_delta_time 1 long_name String ATLAS Start Time (Actual) standard_name String time units String seconds since 2018-01-01 source String Derived contentType String auxiliaryInformation description String 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. start_geoseg 1 long_name String Starting Geolocation Segment units String 1 source String Derived contentType String auxiliaryInformation description String 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. start_orbit 1 long_name String Starting Orbit Number units String 1 source String Derived contentType String auxiliaryInformation description String 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. data_start_utc 1 long_name String Start UTC Time of Granule (CCSDS-A, Actual) units String 1 source String Derived contentType String auxiliaryInformation description String UTC (in CCSDS-A format) of the first data point within the granule. end_gpsweek 1 long_name String Ending GPSWeek of Granule (Actual) contentType String auxiliaryInformation description String GPS week number of the last data point in the granule. units String weeks from 1980-01-06 source String Derived start_rgt 1 long_name String Starting Reference Groundtrack units String 1 source String Derived valid_min Int32 1 valid_max Int32 1387 contentType String auxiliaryInformation description String 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. end_gpssow 1 long_name String Ending GPS SOW of Granule (Actual) units String seconds source String Derived contentType String auxiliaryInformation description String GPS seconds-of-week of the last data point in the granule. qa_at_interval 1 long_name String QA Along-Track Interval units String seconds/cell source String control contentType String auxiliaryInformation description String Statistics time interval for along-track QA data. start_region 1 long_name String Starting Region units String 1 source String Derived contentType String auxiliaryInformation description String 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. start_gpsweek 1 long_name String Start GPSWeek of Granule (Actual) units String weeks from 1980-01-06 source String Derived contentType String auxiliaryInformation description String GPS week number of the first data point in the granule. data_rate String Data within this group pertain to the granule in its entirety. description String Contains information ancillary to the data product. This may include product characteristics, instrument characteristics and/or processing constants. land_ice rbin_width 1 long_name String Bin Size units String meters source String Operations contentType String auxiliaryInformation description String Residual histogram bin size sigma_beam 1 long_name String Sigma of Gaussian Footprint units String meters source String Operations contentType String auxiliaryInformation description String Spatial sigma of the Gaussian footprint (m) qs_lim_hsigma 1 long_name String Height Sigma QS Limit units String 1 source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing Height Sigma. fit_maxiter 1 long_name String Maximum Iterations of Fit units String 1 source String Operations contentType String auxiliaryInformation description String Maximum number of iterations in at_seg_fit txp_maxiter 1 long_name String Maximum Iterations units String counts source String Operations contentType String auxiliaryInformation description String Maximum number of iterations in tx_shape_corr qs_lim_hrs 1 long_name String Height Robust Spread QS Limit units String meters source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing Height Robust Spread. qs_lim_bsc 1 long_name String Blowing Snow Confidence QS Limit units String 1 source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing Blowing Snow Confidence. qs_lim_snr 1 long_name String SNR Significance QS Limit units String 1 source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing SNR Significance. n_hist 1 long_name String Number of Histogram Bins units String 1 source String Operations contentType String auxiliaryInformation description String Number of bins in a histogram min_gain_th 1 long_name String Minimum Gain Threshold units String 1 source String Operations contentType String auxiliaryInformation description String Minimum estimated gain threshold (3.1.6) qs_lim_sss 1 long_name String Signal Selection Source QS Limit units String 1 source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing Signal Selection Source. n_sigmas 1 long_name String Number of Sigmas units String 1 source String Operations contentType String auxiliaryInformation description String Multiplied by sigma_expected to get h_win dt_hist 1 long_name String Histogram Bin Size units String seconds source String Operations contentType String auxiliaryInformation description String Bin size for histograms (sec) sigma_tx 6 long_name String Sigma Tx units String seconds source String Operations contentType String auxiliaryInformation description String RDE of the Tx pulse in ATLAS Spot order (1-6). Calculated as half the difference between the 84th and 16th percentiles of the signal bins. min_signal_conf 1 long_name String Minimum Signal Confidence units String 1 source String Operations valid_min Int32 0 valid_max Int32 4 contentType String auxiliaryInformation description String Minimum signal confidence level for a photon to be considered valid. t_dead 6 long_name String Dead Time units String seconds source String Operations contentType String auxiliaryInformation description String Dead time, in ATLAS spot order (1-6). Calculated as the average of the CAL42 per-channel dead times, using the appropriate channels for strong and weak spots. qs_lim_msw 1 long_name String Multiple Scattering Warning QS Limit units String 1 source String Operations contentType String auxiliaryInformation description String atl06_quality_summary limit for testing Multiple Scattering Warning. min_n_sel 1 long_name String Mininum Number of Photons units String 1 source String Operations contentType String auxiliaryInformation description String Minimum number of selected PEs in pe_select max_res_ids 1 long_name String Max Segments units String 1 source String Operations contentType String auxiliaryInformation description String Maximum number of segment ids in each residual_histogram proc_interval 1 long_name String Processing Interval units String seconds source String Operations contentType String auxiliaryInformation description String Processing interval in number of geolocation segments.. fpb_maxiter 1 long_name String Maximum Iterations for FPB units String 1 source String Operations contentType String auxiliaryInformation description String Maximum number of iterations in fpb_corr min_n_pe 1 long_name String Minimum Photons units String 1 source String Operations contentType String auxiliaryInformation description String Minimum # PEs for fit min_dist 1 long_name String Minimum Distance units String meters source String Operations contentType String auxiliaryInformation description String Min dist between first and last selected PEs nhist_bins 1 long_name String Number of Bins units String 1 source String Operations contentType String auxiliaryInformation description String Number of bins in residual histogram description String Contains land-ice-specific information ancillary to the data product. This may include product characteristics, instrument characteristics and/or processing constants. quality_assessment qa_granule_fail_reason 1 long_name String Granule Failure Reason units String 1 source String Operations valid_min Int32 0 valid_max Int32 5 contentType String qualityInformation description String 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. flag_meanings String no_failure PROCESS_ERROR INSUFFICIENT_OUTPUT failure_3 failure_4 OTHER_FAILURE flag_values Int32 0 1 2 3 4 5 qa_granule_pass_fail 1 long_name String Granule Pass Flag units String 1 source String Operations valid_min Int32 0 valid_max Int32 1 contentType String qualityInformation description String Flag indicating granule quality. 0=granule passes automatic QA. 1=granule fails automatic QA. flag_meanings String PASS FAIL flag_values Int32 0 1 description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt1r delta_time 0 lon_mean 0 long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean lat_mean 0 long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean delta_time /quality_assessment/gt1r/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean signal_selection_source_fraction_0 0 long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 0 long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 0 long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 0 long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt2r delta_time 0 lon_mean 0 long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean delta_time /quality_assessment/gt2r/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean lat_mean 0 long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean signal_selection_source_fraction_0 0 long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 0 long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 0 long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 0 long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt1l delta_time 0 lon_mean 0 long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean lat_mean 0 long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean delta_time /quality_assessment/gt1l/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean signal_selection_source_fraction_0 0 long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 0 long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 0 long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 0 long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt3l delta_time 22 lon_mean /quality_assessment/gt3l/delta_time long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean delta_time /quality_assessment/gt3l/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean lat_mean /quality_assessment/gt3l/delta_time long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean signal_selection_source_fraction_0 /quality_assessment/gt3l/delta_time long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 /quality_assessment/gt3l/delta_time long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 /quality_assessment/gt3l/delta_time long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 /quality_assessment/gt3l/delta_time long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt2l delta_time 0 lon_mean 0 long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean delta_time /quality_assessment/gt2l/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean lat_mean 0 long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean signal_selection_source_fraction_0 0 long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 0 long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 0 long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 0 long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. gt3r delta_time 22 lon_mean /quality_assessment/gt3r/delta_time long_name String Longitude Mean standard_name String longitude units String degrees_east source String Section 7.2, Q/A Statistics valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the 10km segment. coordinates String delta_time lat_mean delta_time /quality_assessment/gt3r/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String Section 7.2, Q/A Statistics contentType String referenceInformation description String Mean number of GPS seconds since the ATLAS SDP epoch for the 10km segment. 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. coordinates String lat_mean lon_mean lat_mean /quality_assessment/gt3r/delta_time long_name String Latitude Mean standard_name String latitude units String degrees_north source String Section 7.2, Q/A Statistics valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the 10km segment. coordinates String delta_time lon_mean signal_selection_source_fraction_0 /quality_assessment/gt3r/delta_time long_name String Signal Selection Source Fraction 0 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to zero. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_2 /quality_assessment/gt3r/delta_time long_name String Signal Selection Source Fraction 2 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 2. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_1 /quality_assessment/gt3r/delta_time long_name String Signal Selection Source Fraction 1 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 1. coordinates String delta_time lat_mean lon_mean signal_selection_source_fraction_3 /quality_assessment/gt3r/delta_time long_name String Signal Selection Source Fraction 3 units String 1 source String ATL06 ATBD - Q/A Statistics valid_min Float32 0. valid_max Float32 1. contentType String qualityInformation description String The fraction of 20m segments with signal_selection_source equal to 3. coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time description String Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. METADATA iso_19139_dataset_xml 1 long_name String ISO 19139 Dataset XML description String ISO 19139 Dataset XML iso_19139_series_xml 1 long_name String ISO 19139 Series XML description String ISO 19139 Series XML Description String ISO19115 Structured Metadata Represented within HDF5 AcquisitionInformation lidar pulse_rate String 10000 pps wavelength String 532 nm identifier String ATLAS type String Laser Altimeter description String 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. lidarDocument edition String Pre-Release publicationDate String 12/31/17 title String A document describing the ATLAS instrument will be provided by the ICESat-2 Project Science Office. platform identifier String ICESat-2 description String Ice, Cloud, and land Elevation Satellite-2 type String Spacecraft platformDocument edition String 31-Dec-16 publicationDate String 31-Dec-16 title String 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 DataQuality scope String NOT_SET CompletenessOmission evaluationMethodType String directInternal measureDescription String TBD nameOfMeasure String TBD unitofMeasure String TBD value String NOT_SET DomainConsistency evaluationMethodType String directInternal measureDescription String TBD nameOfMeasure String TBD unitofMeasure String TBD value String NOT_SET ProductSpecificationDocument ShortName String ATL06_SDP characterSet String utf8 language String eng publicationDate String Feb 2020 title String ICESat-2-SIPS-SPEC-4260 - ATLAS Science Algorithm Standard Data Product (SDP) Volume 5 (ATL06). edition String v4.3 SeriesIdentification maintenanceAndUpdateFrequency String asNeeded maintenanceDate String SET_BY_META VersionID String 007 language String eng characterSet String utf8 pointOfContact String NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center longName String ATLAS/ICESat-2 L3A Land Ice Height shortName String ATL06 identifier_product_DOI String doi:10.5067/ATLAS/ATL06.007 revisionDate String 2022-08-09 resourceProviderOrganizationName String National Aeronautics and Space Administration (NASA) abstract String ATL06 provides estimates of the ice-sheet mean surface height relative to the WGS-84 ellipsoid, and ancillary parameters needed to interpret and assess the quality of these height estimates. purpose String ATL06 provides estimates of the ice-sheet mean surface height relative to the WGS-84 ellipsoid, and ancillary parameters needed to interpret and assess the quality of these height estimates. credit String The software that generates the ATL06 product was designed and implemented at the NASA Wallops Flight Facility in Wallops Island, Virginia. status String onGoing format String HDF formatVersion String 5 topicCategory String geoscientificInformation mission String ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 DatasetIdentification spatialRepresentationType String along-track creationDate String 2025-12-19T22:01:54.000000Z uuid String fe870c8f-7533-3a33-8c17-d667ecdd83b6 fileName String ATL06_20250913142324_13722807_007_01.h5 VersionID String 007 language String eng characterSet String utf8 shortName String ATL06 originatorOrganizationName String GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System abstract String ATL06 provides estimates of the ice-sheet mean surface height relative to the WGS-84 ellipsoid, and ancillary parameters needed to interpret and assess the quality of these height estimates. purpose String ATL06 provides estimates of the ice-sheet mean surface height relative to the WGS-84 ellipsoid, and ancillary parameters needed to interpret and assess the quality of these height estimates. credit String The software that generates the ATL06 product was designed and implemented at the NASA Wallops Flight Facility in Wallops Island, Virginia. status String onGoing topicCategory String geoscientificInformation Extent northBoundLatitude Float64 25.51268125829365 eastBoundLongitude Float64 -171.42503689992421 southBoundLatitude Float64 25.474481959584711 westBoundLongitude Float64 -171.42912310348692 rangeBeginningDateTime String 2025-09-13T14:23:47.485874Z rangeEndingDateTime String 2025-09-13T14:23:48.254371Z QADatasetIdentification creationDate String 2025-12-19T22:01:57.000000Z abstract String 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 fileName String ATL06_20250913142324_13722807_007_01.qa Lineage ANC36-06 description String ISO 19139 XML file containing Series-level metadata information. fileName String ANC36-06_20250523205141_007_01.xml shortName String ANC36-06 uuid String f486c1c2-b893-34c1-b902-1a59f2688c66 version String 007 Control description String 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. fileName String CTL_atlas_l3a_is_021426921.ctl shortName String CNTL version String 1 ANC28 description String DTU Mean Sea Surface re-referenced to the WGS84 ellipsoid. fileName String dtu13_20180705_001_01.nc shortName String ANC28 uuid String 56f47040-a72e-3109-99c2-bc1658e6dda4 version String 20180705 ANC38-06 description String ISO 19139 XML file containing DataSet-level metadata information. fileName String ANC38-06_20250523205142_007_01.xml shortName String ANC38-06 uuid String f8d47ee3-4f43-3070-a6b0-f05ef6bd3cb2 version String 007 ANC06-02 description String ArcticDEM 32m Digital Elevation Model reformatted into HDF5. fileName String arcticdem32m_20190611_001_01.h5 shortName String ANC06-02 uuid String ce07ef72-0bf4-353b-8475-fb568b029905 version String 20190611 ANC06-03 description String REMA Antarctica 100m Digital Elevation Model filled and reformatted into HDF5 fileName String atl06rema100m_20190628_001_01.h5 shortName String ANC06-03 uuid String 3e0a81bd-bbd5-35fa-b868-3254f9355b7f version String 20190628 ANC25-06 description String HDF5 template file that defines the organization and default content of the product. fileName String ANC25-06_20250523205529_051_01.h5 shortName String ANC25-06 uuid String 45545701-8dcb-30dc-9f21-e2ee4e77fe87 version String 051 ANC17 description String Land Ice Height SNR Significance Table fileName String anc17_snr_f_20180626_001_01.h5 shortName String ANC17 uuid String 10e264bc-139a-3737-9f92-29e64e9b858c version String 20180626 ANC26-06 description String HDF5 template file that defines the organization and default content of the product metadata. fileName String ANC26-06_20250523205537_051_01.h5 shortName String ANC26-06 uuid String 438c292c-43ce-3b04-9c33-683805c75ca5 version String 051 ATL03 description String ICESat-2 ATLAS L2A Global Geolocated Photon data products. fileName String ATL03_20250913142324_13722807_007_01.h5 shortName String ATL03 uuid String c48e4feb-e9c5-3553-bdfe-a1a6e367be23 version String 007 start_cycle Int32 28 end_cycle Int32 28 start_orbit Int32 39022 end_orbit Int32 39022 start_rgt Int32 1372 end_rgt Int32 1372 start_region Int32 7 end_region Int32 7 start_geoseg Int32 852091 end_geoseg Int32 1001793 ATL09 description String ICESat-2 ATLAS L3A atmosphere data products. fileName String ATL09_20250913134322_13722801_007_01.h5 shortName String ATL09 uuid String 758cce16-d1d5-3c1c-819f-88e47f7c36e1 version String 007 start_cycle Int32 28 end_cycle Int32 28 start_orbit Int32 39022 end_orbit Int32 39022 start_rgt Int32 1372 end_rgt Int32 1372 start_region Int32 1 end_region Int32 14 start_geoseg Int32 2 end_geoseg Int32 2007136 ANC06-01 description String MERIT 3 arcsec Digital Elevation Model reformatted into HDF5 and re-referenced to the WGS-84 ellipsoid. fileName String merit_3as_20200617_001_01.h5 shortName String ANC06-01 uuid String 3db8ab65-d2ac-37c7-86db-17c762268673 version String 20200617 ANC19 description String TAI to UTC leapsecond file retrieved from ftp://maia.usno.navy.mil/ser7/tai-utc.dat fileName String tai_utc_2017.dat shortName String ANC19 uuid String 7c66d365-278a-31f7-8fe4-9c80e2f012e5 version String 001 ProcessStep Browse processDescription String 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. identifier String atlas_brw softwareVersion String Version 3.1.3 softwareDate String Apr 8 2025 softwareTitle String Creates ATLAS HDF5 browse files runTimeParameters String CTL_atlas_l3a_is_021426921.ctl stepDateTime String 2025-12-19T22:01:57.000000Z Metadata processDescription String 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. identifier String atlas_meta softwareVersion String Version 5.1.3 softwareDate String Apr 8 2025 softwareTitle String Creates ATLAS XML metadata files runTimeParameters String CTL_atlas_l3a_is_021426921.ctl stepDateTime String 2025-12-19T22:02:07.000000Z PGE ATBDDate String 12/04/2019 ATBDTitle String Algorithm Theoretical Basis Document (ATBD) For Land-Ice Along-Track Products Part 2: Land-ice H(t)/ATL11 ATBDVersion String N/A documentDate String Feb 2020 documentation String ATLAS Science Algorithm Software Design Description (SDD) - Volume 9 (atlas_l3a_is) processDescription String Computes surface heights for each beam, along and across-track slopes calculated for beam pairs. identifier String atlas_l3a_is softwareVersion String Version 5.1 softwareDate String Apr 8 2025 softwareTitle String ASAS L3A Icesheet PGE runTimeParameters String CTL_atlas_l3a_is_021426921.ctl stepDateTime String 2025-12-19T22:01:54.000000Z QA processDescription String 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 identifier String atl06_qa_util softwareVersion String Version 5.1 softwareDate String Apr 8 2025 softwareTitle String ATL06 QA Utility runTimeParameters String CTL_atlas_l3a_is_021426921.ctl stepDateTime String 2025-12-19T22:01:57.000000Z orbit_info crossing_time 1 sc_orient_time 1 crossing_time /orbit_info/crossing_time long_name String Ascending Node Crossing Time standard_name String time units String seconds since 2018-01-01 source String POD/PPD contentType String referenceInformation description String 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. sc_orient_time /orbit_info/sc_orient_time long_name String Time of Last Spacecraft Orientation Change standard_name String time units String seconds since 2018-01-01 source String POD/PPD contentType String referenceInformation description String 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. cycle_number /orbit_info/crossing_time long_name String Cycle Number units String counts source String POD/PPD valid_min Int8 0 valid_max Int8 50 contentType String referenceInformation description String Tracks the number of 91-day cycles in the mission, beginning with 01. A unique orbit number can be determined by subtracting 1 from the cycle_number, multiplying by 1387 and adding the rgt value. coordinates String crossing_time rgt /orbit_info/crossing_time long_name String Reference Ground track units String counts source String POD/PPD valid_min Int16 1 valid_max Int16 1387 contentType String referenceInformation description String 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 GT2L and GT2R. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs. coordinates String crossing_time lan /orbit_info/crossing_time long_name String Ascending Node Longitude units String degrees_east source String POD/PPD valid_min Float64 -180. valid_max Float64 180. contentType String referenceInformation description String Longitude at the ascending node crossing. coordinates String crossing_time bounding_polygon_lat1 5 long_name String Polygon1 Latitude units String degrees_north source String geo_poly valid_min Float64 -90. valid_max Float64 90. contentType String auxiliaryInformation description String Latitude values for the first out of two possible bounding polygons orbit_number /orbit_info/crossing_time long_name String Orbit Number units String 1 source String POD/PPD valid_min UInt16 1 valid_max UInt16 65000 contentType String referenceInformation description String Unique identifying number for each planned ICESat-2 orbit. coordinates String crossing_time bounding_polygon_lon1 5 long_name String Polygon1 Longitude units String degrees_east source String geo_poly valid_min Float64 -180. valid_max Float64 180. contentType String auxiliaryInformation description String Longitude values for the first out of two possible bounding polygons sc_orient /orbit_info/sc_orient_time long_name String Spacecraft Orientation units String 1 source String POD/PPD valid_min Int8 0 valid_max Int8 2 contentType String referenceInformation description String 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. coordinates String sc_orient_time flag_meanings String backward forward transition flag_values Int8 0 1 2 DODS_EXTRA Container Unlimited_Dimension String crossing_time sc_orient_time description String Contains data that are common among all beams for the granule. These parameters are constants for a given granule. data_rate String These parameters are constant for a given granule. gt3l description String Contains subgroups organized by Ground Track (gt1l, gt1r, gt2l, gt2r, gt3l and gt3r) atlas_pce String pce1 atlas_beam_type String weak groundtrack_id String gt3l atmosphere_profile String profile_3 atlas_spot_number String 2 sc_orientation String Forward land_ice_segments delta_time 188 latitude /gt3l/land_ice_segments/delta_time long_name String Latitude standard_name String latitude units String degrees_north source String ATL06 ATBD - Top Level Fitting Routine valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Latitude of segment center, WGS84, North=+, coordinates String delta_time longitude delta_time /gt3l/land_ice_segments/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - Top Level Fitting Routine contentType String referenceInformation description String 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. coordinates String latitude longitude longitude /gt3l/land_ice_segments/delta_time long_name String Longitude standard_name String longitude units String degrees_east source String ATL06 ATBD - Top Level Fitting Routine valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Longitude of segment center, , WGS84, East=+ coordinates String delta_time latitude sigma_geo_h /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Vertical Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Total vertical geolocation error due to PPD and POD, including the effects of horizontal geolocation error on the segment vertical error. coordinates String delta_time latitude longitude h_li /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Land Ice height units String meters source String ATL06 ATBD - Top Level Fitting Routine contentType String physicalMeasurement description String Standard land-ice segment height determined by land ice algorithm, corrected for first-photon bias, representing the median- based height of the selected PEs coordinates String delta_time latitude longitude atl06_quality_summary /gt3l/land_ice_segments/delta_time long_name String ATL06_Quality_Summary units String 1 source String ATL06 ATBD - Top Level Fitting Routine valid_min Int8 0 valid_max Int8 1 contentType String qualityInformation description String The ATL06_quality_summary parameter indicates the best-quality subset of all ATL06 data. A zero in this parameter implies that no data-quality tests have found a problem with the segment, a one implies that some potential problem has been found. Users who select only segments with zero values for this flag can be relatively certain of obtaining high-quality data, but will likely miss a significant fraction of usable data, particularly in cloudy, rough, or low-surface-reflectance conditions. coordinates String delta_time latitude longitude flag_meanings String best_quality potential_problem flag_values Int8 0 1 segment_id /gt3l/land_ice_segments/delta_time _FillValue Int32 0 long_name String Reference Point, m units String 1 source String ATL06 ATBD - Top Level Fitting Routine contentType String referenceInformation description String Segment number, counting from the equator. Equal to the segment_id for the second of the two 20m ATL03 segments included in the 40m ATL06 segment coordinates String delta_time latitude longitude h_li_sigma /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected RMS segment misfit units String meters source String ATL06 ATBD - Top Level Fitting Routine contentType String qualityInformation description String Propagated error due to sampling error and FPB correction from the land ice algorithm coordinates String delta_time latitude longitude fpb_warning_flag /gt3l/land_ice_segments/delta_time long_name String fpb_warning_flag units String 1 source String ATL06 ATBD - FPB Corrections valid_min Int8 0 valid_max Int8 1 contentType String qualityInformation description String To flag that segments have potentially erroneous FPB corrections, the ATL06 algorithm sets fpb_warning_flag to 1 if full_sat_fract is greater than 0.90 (strong beams) or greater than 0.40 (weak beams) for either of the two ATL03 20 m segments that are used as inputs to each ATL06 40 m segment. Otherwise, fpb_warning_flag is set to 0. coordinates String latitude longitude delta_time flag_meanings String best_quality potential_problem flag_values Int8 0 1 DODS_EXTRA Container Unlimited_Dimension String delta_time description String The land_ice_height group contains the primary set of derived ATL06 products. This includes geolocation, height, and standard error and quality measures for each segment. This group is sparse, meaning that parameters are provided only for pairs of segments for which at least one beam has a valid surface-height measurement. data_rate String Data within this group are sparse. Data values are provided only for those ICESat-2 20m segments where at least one beam has a valid land ice height measurement. fit_statistics h_mean /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Height Mean units String meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String modelResult description String Mean surface height, not corrected for first-photon bias or pulse truncation. coordinates String ../delta_time ../latitude ../longitude signal_selection_source /gt3l/land_ice_segments/delta_time long_name String Signal Selection Source units String 1 source String ATL06 ATBD - Signal Selection based on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates the last algorithm attempted to select the signal for ATL06 fitting. 0=Signal selection succeeded using ATL03 detected PE; 1=Signal selection failed using ATL03 detected PE but succeeded using all flagged ATL03 PE; 2=Signal selection failed using all flagged ATL03 PE, but succeeded using the backup algorithm; 3=All signal-finding strategies failed. coordinates String ../delta_time ../latitude ../longitude flag_meanings String succeeded_using_pe succeeded_using_flagged_pe succeeded_using_backup failed flag_values Int8 0 1 2 3 snr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String SNR units String 1 source String ATL06 ATBD - Iterative Least Squares Fitting Routine contentType String physicalMeasurement description String Signal-to-noise ratio in the final refined window coordinates String ../delta_time ../latitude ../longitude h_robust_sprd /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Robust Spread units String meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String referenceInformation description String RDE of misfit between PE heights and the along-track segment fit. coordinates String ../delta_time ../latitude ../longitude n_seg_pulses /gt3l/land_ice_segments/delta_time units String counts _FillValue Float32 3.402823466e+38 long_name String Number potential segment pulses source String ATL06 ATBD - Top-Level Fitting Routine contentType String referenceInformation description String The number of pulses potentially included in the segment coordinates String ../delta_time ../latitude ../longitude dh_fit_dx_sigma /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Sigma of Along Track Slope units String meters/meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String qualityInformation description String Propagated error in the along-track segment slope coordinates String ../delta_time ../latitude ../longitude snr_significance /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String SNR Significance units String 1 source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Probability that signal-finding routine would converge to at least the observed SNR for a random-noise input. Small values indicate a small likelihood of a surface-detection blunder. coordinates String ../delta_time ../latitude ../longitude h_expected_rms /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected RMS misfit units String meters source String ATL06 ATBD - Iterative ground-window refinement contentType String qualityInformation description String Expected RMS misfit between PE heights and along-track segment fit coordinates String ../delta_time ../latitude ../longitude dh_fit_dy /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Across Track Slope units String meters/meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Across track slope from segment fits to weak and strong beam; the same slope is reported for both laser beams in each pair coordinates String ../delta_time ../latitude ../longitude sigma_h_mean /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Height Error units String meters source String ATL06 ATBD - Propagated Height Errors contentType String qualityInformation description String Propagated height error due to PE-height sampling error for height from the along-track fit, not including geolocation-induced error coordinates String ../delta_time ../latitude ../longitude h_rms_misfit /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String RMS Misfit units String meters source String ATL06 ATBD -Iterative Least-Squares Fitting Routine contentType String qualityInformation description String RMS misfit between PE heights and along- track segment fit coordinates String ../delta_time ../latitude ../longitude signal_selection_source_status /gt3l/land_ice_segments/delta_time long_name String Signal Selection Source Status units String 1 source String ATL06 ATBD - Signal Selection based on ATL03 flags valid_min Int8 0 valid_max Int8 4 contentType String qualityInformation description String Indicates the status of the last signal selection algorithm attempted (see signal_selection_source). The definition of flag is different for each source and are defined in each of the signal_selection_status flags. (See Land Ice ATBD Table 3-2). coordinates String ../delta_time ../latitude ../longitude dh_fit_dx /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Along Track Slope units String meters/meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String physicalMeasurement description String Along-track slope from along-track segment fit coordinates String ../delta_time ../latitude ../longitude n_fit_photons /gt3l/land_ice_segments/delta_time _FillValue Int32 2147483647 long_name String Number of Photons in Fit units String 1 source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String physicalMeasurement description String Number of PEs used in determining h_li, after editing coordinates String ../delta_time ../latitude ../longitude w_surface_window_final /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Surface Window Width units String meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Width of the surface window, top to bottom coordinates String ../delta_time ../latitude ../longitude description String The fit_statistics subgroup contains a variety of parameters that might indicate the quality of the fitted segment data. Data in this group are sparse, with dimensions matching the land_ice_height group. data_rate String Data within this group are stored at the land_ice_height segment rate. ground_track sigma_geo_at /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Along Track Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Along-track component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude ref_azimuth /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Azimuth units String degrees source String ATL03 contentType String referenceInformation description String The direction, eastwards from north, of the laser beam vector as seen by an observer at the laser ground spot viewing toward the spacecraft (i.e., the vector from the ground to the spacecraft). coordinates String ../delta_time ../latitude ../longitude sigma_geo_r /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Radial Orbit Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Radial orbit component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude seg_azimuth /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Segment Azimuth units String degrees source String ATL03 contentType String referenceInformation description String Azimuth of the pair-track, east of local north. coordinates String ../delta_time ../latitude ../longitude sigma_geo_xt /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Across Track Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Across-track component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude ref_coelv /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Co-elevation units String degrees source String ATL03 contentType String referenceInformation description String Coelevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot. coordinates String ../delta_time ../latitude ../longitude x_atc /gt3l/land_ice_segments/delta_time _FillValue Float64 1.7976931348623157e+308 long_name String X Along Track units String meters source String ATL06 ATBD - Local Coordinate Systems contentType String referenceInformation description String The along-track x-coordinate of the segment, measured parallel to the RGT, measured from the ascending node of the equatorial crossing of a given RGT. coordinates String ../delta_time ../latitude ../longitude y_atc /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Y Along Track units String meters source String ATL06 ATBD - Local Coordinate Systems contentType String referenceInformation description String Along-track y coordinate of the segment, relative to the RGT, measured along the perpendicular to the RGT, positive to the right of the RGT. coordinates String ../delta_time ../latitude ../longitude description String The ground_track group contains parameters describing the GT and RGT for each land ice segment, as well as angular information about the beams. data_rate String Data within this group are stored at the land_ice_height segment rate. dem dem_flag /gt3l/land_ice_segments/delta_time long_name String DEM Source Flag units String 1 source String ATL03 valid_min Int8 0 valid_max Int8 4 contentType String referenceInformation description String Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. coordinates String ../delta_time ../latitude ../longitude flag_meanings String none arctic global mss antarctic flag_values Int8 0 1 2 3 4 geoid_free2mean /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Geoid Free-to-Mean conversion units String meters source String ATL03 contentType String modelResult description String Additive value to convert geoid heights from the tide-free system to the mean-tide system. (Add to geoid to get the geoid heights in the mean-tide system.) coordinates String ../delta_time ../latitude ../longitude dem_h /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String DEM Height units String meters source String ATL03 contentType String referenceInformation description String Height of the DEM, interpolated by cubic-spline interpolation in the DEM coordinate system to the PE location. (Best available DEM value in priority of Arctic/Antarctic/Global/MSS) coordinates String ../delta_time ../latitude ../longitude geoid_h /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Geoid Height units String meters source String ATL03 contentType String referenceInformation description String Geoid height above WGS-84 reference ellipsoid (range -107 to 86m) in the tide-free system. coordinates String ../delta_time ../latitude ../longitude description String Contains reference DEM and geoid heights. data_rate String Data within this group are stored at the land_ice segment rate. geophysical msw_flag /gt3l/land_ice_segments/delta_time _FillValue Int8 127 long_name String Multiple Scattering Warning Flag units String 1 source String ATL09 valid_min Int8 -1 valid_max Int8 5 contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude flag_meanings String 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 flag_values Int8 -1 0 1 2 3 4 5 layer_flag /gt3l/land_ice_segments/delta_time units String 1 source String ATL09 _FillValue Int8 127 long_name String Consolidated cloud flag valid_min Int8 0 valid_max Int8 1 contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude flag_meanings String likely_clear likely_cloudy flag_values Int8 0 1 bsnow_conf /gt3l/land_ice_segments/delta_time _FillValue Int8 127 long_name String Blowing Snow confidence units String 1 source String ATL09 contentType String referenceInformation description String Confidence flag for presence of blowing snow coordinates String ../delta_time ../latitude ../longitude bsnow_h /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Blowing Snow Layer Top Height units String meters source String ATL09 contentType String referenceInformation description String Blowing snow layer top height coordinates String ../delta_time ../latitude ../longitude tide_ocean /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Ocean Tide units String meters source String ATL03 contentType String referenceInformation description String Ocean Tides including diurnal and semi-diurnal (harmonic analysis), and longer period tides (dynamic and self-consistent equilibrium). coordinates String ../delta_time ../latitude ../longitude tide_earth /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Earth Tide units String meters source String ATL03 contentType String referenceInformation description String Solid earth tides in the tide-free system. coordinates String ../delta_time ../latitude ../longitude solar_azimuth /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String solar azimuth units String degrees_east source String ATL03 contentType String referenceInformation description String The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot. coordinates String ../delta_time ../latitude ../longitude r_eff /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Effective uncorrected reflectance units String 1 source String ATL06 ATBD - Top-Level Fitting Routine contentType String referenceInformation description String Effective reflectance, uncorrected for atmospheric effects. coordinates String ../delta_time ../latitude ../longitude dac /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Dynamic Atmosphere Correction units String meters source String ATL03 contentType String referenceInformation description String Dynamic Atmospheric Correction (DAC) includes inverted barometer (IB) effect. coordinates String ../delta_time ../latitude ../longitude tide_load /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Load Tide units String meters source String ATL03 contentType String referenceInformation description String Load Tide - Local displacement due to Ocean Loading (-6 to 0 cm). coordinates String ../delta_time ../latitude ../longitude tide_earth_free2mean /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Earth Tide Free-to-Mean conversion units String meters source String ATL03 contentType String referenceInformation description String Additive value to convert solid earth tide from the tide-free system to the mean tide system. (Add to tide_earth to get solid earth tides in the mean-tide system.) coordinates String ../delta_time ../latitude ../longitude bsnow_od /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Blowing snow OD units String 1 source String ATL09 contentType String modelResult description String Optical thickness of blowing snow layer. coordinates String ../delta_time ../latitude ../longitude tide_equilibrium /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Equilibrium Tide units String meters source String ATL03 contentType String referenceInformation description String Long period equilibrium tide self-consistent with the ocean tide model (+-0.04m). coordinates String ../delta_time ../latitude ../longitude cloud_flg_atm /gt3l/land_ice_segments/delta_time _FillValue Int8 127 long_name String Cloud Flag ATM units String 1 source String ATL09 valid_min Int8 0 valid_max Int8 10 contentType String referenceInformation description String Number of layers found from the backscatter profile using the DDA layer finder. coordinates String ../delta_time ../latitude ../longitude solar_elevation /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String solar elevation units String degrees source String ATL03 valid_min Float32 -90. valid_max Float32 90. contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude tide_pole /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Solid Earth Pole Tide units String meters source String ATL03 contentType String referenceInformation description String Solid Earth Pole Tide -Rotational deformation due to polar motion (-1.5 to 1.5 cm). coordinates String ../delta_time ../latitude ../longitude e_bckgrd /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected background count rate units String hz source String ATL06 ATBD - Background PE Rate contentType String referenceInformation description String Expected background count rate based on sun angle, surface slope, for unit surface reflectance coordinates String ../delta_time ../latitude ../longitude cloud_flg_asr /gt3l/land_ice_segments/delta_time _FillValue Int8 127 long_name String Cloud Flag ASR units String 1 source String ATL09 valid_min Int8 0 valid_max Int8 5 contentType String referenceInformation description String Cloud flag (probability) from apparent surface reflectance. 0=clear with high confidence; 1=clear with medium confidence; 2=clear with low confidence; 3=cloudy with low confidence; 4=cloudy with medium confidence; 5=cloudy with high confidence coordinates String ../delta_time ../latitude ../longitude flag_meanings String clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence flag_values Int8 0 1 2 3 4 5 bckgrd /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Background count rate units String hz source String ATL03 contentType String referenceInformation description String Background count rate, derived from the ATL03 50-shot-average, interpolated to the segment center. coordinates String ../delta_time ../latitude ../longitude neutat_delay_total /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Total Neutral Atmospheric Delay units String meters source String ATL03 contentType String referenceInformation description String Total neutral atmosphere delay correction (wet+dry). coordinates String ../delta_time ../latitude ../longitude description String The sun_and_clouds group contains parameters related to solar background and parameters indicative of the presence or absence of clouds. data_rate String Data within this group are stored at the land_ice_height segment rate. bias_correction fpb_mean_corr_sigma /gt3l/land_ice_segments/delta_time units String meters _FillValue Float32 3.402823466e+38 long_name String fpb mean corr sigma source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated error in fpb_mean_corr coordinates String ../delta_time ../latitude ../longitude fpb_med_corr_sigma /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb median corr sigma units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated error in fpb_med_corr coordinates String ../delta_time ../latitude ../longitude fpb_mean_corr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String first photon bias mean correction units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated first-photon bias (fpb) correction to mean segment height coordinates String ../delta_time ../latitude ../longitude med_r_fit /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String mean median residual units String meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String qualityInformation description String Difference between uncorrected mean and median of linear fit residuals coordinates String ../delta_time ../latitude ../longitude fpb_med_corr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb median corr units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String First-photon-bias correction giving the difference between the mean segment height and the corrected median height coordinates String ../delta_time ../latitude ../longitude tx_mean_corr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String tx shape mean correction units String meters source String ATL06 ATBD - Transmit-pulse shape correction contentType String qualityInformation description String Estimate of the difference between the mean of the full-waveform transmit-pulse and the mean of a broadened, truncated waveform consistent with the received pulse coordinates String ../delta_time ../latitude ../longitude fpb_n_corr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb number photons corr units String counts source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated window photon count after first-photon-bias correction coordinates String ../delta_time ../latitude ../longitude tx_med_corr /gt3l/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String tx shape median correction units String meters source String ATL06 ATBD - Transmit-pulse shape correction contentType String qualityInformation description String Estimate of the difference between the median of the full-waveform transmit-pulse mean and the median of a broadened, truncated waveform consistent with the received pulse coordinates String ../delta_time ../latitude ../longitude description String The bias_correction group contains information about the estimated first-photon bias, and the transmit-pulse-shape bias. data_rate String Data within this group are stored at the land_ice segment rate. residual_histogram delta_time 16 bin_top_h 748 ds_segment_id 10 ds_segment_id /gt3l/residual_histogram/ds_segment_id long_name String Segment ID Index units String 1 source String ATL06 ATBD - Residual_histogram calculation valid_min Int8 1 valid_max Int8 10 contentType String auxiliaryInformation description String Relative index of each segment_id used in the derivation of the histogram. lat_mean /gt3l/residual_histogram/delta_time long_name String Latitude Mean standard_name String latitude units String degrees_north source String ATL06 ATBD - Residual_histogram calculation valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the segments included in the histogram coordinates String delta_time lon_mean lon_mean /gt3l/residual_histogram/delta_time long_name String Longitude Mean standard_name String longitude units String degrees_east source String ATL06 ATBD - Residual_histogram calculation valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the segments included in the histogram coordinates String delta_time lat_mean delta_time /gt3l/residual_histogram/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - Residual_histogram calculation contentType String referenceInformation description String 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. coordinates String lat_mean lon_mean bin_top_h /gt3l/residual_histogram/bin_top_h long_name String Bin Top Height units String meters source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Height of the top of each histogram bin, listed in increasing order. The bottom of each bin is equal to the top of the next- lowest bin. coordinates String delta_time lat_mean lon_mean count /gt3l/residual_histogram/delta_time /gt3l/residual_histogram/bin_top_h _FillValue Int32 2147483647 long_name String Bin Counts units String counts source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Residual count falling with each histogram bin. The top height of each histogram bin may be found in the bin_top_h dataset. coordinates String delta_time lat_mean lon_mean pulse_count /gt3l/residual_histogram/delta_time long_name String Number of Histogram Segment Pulses units String counts source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Number of pulses potentially included in the histogram (pulses are counted if they are in the central 20 m of each segment, even if no PE from the pulse are selected). coordinates String delta_time lat_mean lon_mean x_atc_mean /gt3l/residual_histogram/delta_time long_name String Along Track Coordinate Mean units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Mean along-track coordinate of the segments included in the histogram. coordinates String delta_time lat_mean lon_mean segment_id_list /gt3l/residual_histogram/delta_time /gt3l/residual_histogram/ds_segment_id long_name String Segment ID List units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String referenceInformation description String Segments ids included in each column of the histogram coordinates String delta_time lat_mean lon_mean _FillValue Int32 2147483647 bckgrd_per_m /gt3l/residual_histogram/delta_time long_name String Expected background PEs units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Number of background PE expected for each vertical meter of the histogram based on the observed background rate (bckgrd). coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time data_rate String Data within this group are stored at the 200-meter along-track rate. description String This group contains histograms of the residuals between PE heights and the least-squares fit segment heights, at 200-meter along-track resolution. segment_quality delta_time 202 reference_pt_lat /gt3l/segment_quality/delta_time long_name String Latitude units String degrees_north source String ATL06 ATBD - segment_quality group valid_min Float64 -90. valid_max Float64 90. contentType String referenceInformation description String Latitude of the reference segment location on the RPT coordinates String delta_time reference_pt_lon standard_name String latitude reference_pt_lon /gt3l/segment_quality/delta_time long_name String Longitude units String degrees_east source String ATL06 ATBD - segment_quality group valid_min Float64 -180. valid_max Float64 180. contentType String referenceInformation description String Longitude of the reference segment location on the RPT coordinates String delta_time reference_pt_lat standard_name String longitude delta_time /gt3l/segment_quality/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String 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. coordinates String reference_pt_lat reference_pt_lon record_number /gt3l/segment_quality/delta_time long_name String Land Ice Height Index units String 1 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String For those segments that have adequate signal strength, this parameter gives the record for the pair within the other groups in the granule. coordinates String delta_time reference_pt_lat reference_pt_lon signal_selection_source /gt3l/segment_quality/delta_time long_name String Signal Selection Source units String 1 source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates the last algorithm attempted to select the signal for ATL06 fitting. 0=Signal selection succeeded using ATL03 detected PE; 1=Signal selection failed using ATL03 detected PE but succeeded using all flagged ATL03 PE; 3=All signal-finding strategies failed. coordinates String delta_time reference_pt_lat reference_pt_lon flag_meanings String succeeded_using_pe succeeded_using_flagged_pe failed flag_values Int8 0 1 3 segment_id /gt3l/segment_quality/delta_time long_name String Reference Point, m units String 1 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String Segment number corresponding to the second of two ATL03 segments in the ATL06 segment, counted from the RGT equator crossing coordinates String delta_time reference_pt_lat reference_pt_lon DODS_EXTRA Container Unlimited_Dimension String delta_time data_rate String Data within this group are stored at the ICESat-2 20m segment rate. description String The segment_quality group contains a dense record (i.e. for every possible segment in the granule) of the success or failure of the surface-finding strategies, and gives the locations of the reference points on the RPTs. For segments with adequate data quality (i.e. with more than 10 PE) it also contains offsets into the data structures for the other groups that allow each segment to be efficiently located within the file. signal_selection_status signal_selection_status_all /gt3l/segment_quality/delta_time units String 1 long_name String Signal Selection Status Flag source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates confidence of the signal-selection algorithm using all ATL03-flagged PEs. 0=Signal selection succeeded using all ATL03-flagged PEs (or algorithm not attempted); 1=Signal selection using all ATL03-flagged PEs failed the 20-meter-spread test; 2=Signal selection using all ATL03-flagged PEs failed the 10-photon-count test; 3=Signal selection using all ATL03-flagged PEs failed both tests coordinates String ../delta_time ../reference_pt_lat ../reference_pt_lon flag_meanings String succeeded failed_20 failed_10 failed_both flag_values Int8 0 1 2 3 signal_selection_status_confident /gt3l/segment_quality/delta_time units String 1 long_name String Signal Selection Confident Flag source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates confidence of the signal-selection algorithm using low or better PEs. 0=Signal selection succeeded using ATL03 low-or-better confidence PEs; 1=Signal selection using ATL03 low-or-better confidence PEs failed the 20-meter-spread test; 2=Signal selection using ATL03 low-or-better confidence PEs failed the 10-photon-count test; 3=Signal selection using ATL03 low-or-better confidence PEs failed both tests coordinates String ../delta_time ../reference_pt_lat ../reference_pt_lon flag_meanings String succeeded failed_20 failed_10 failed_both flag_values Int8 0 1 2 3 description String The signal selection status subgroup contains the success or failure for each surface-finding strategies data_rate String Data within this group are stored at the ICESat-2 20m segment rate. gt3r description String Contains subgroups organized by Ground Track (gt1l, gt1r, gt2l, gt2r, gt3l and gt3r) atlas_pce String pce1 atlas_beam_type String strong groundtrack_id String gt3r atmosphere_profile String profile_3 atlas_spot_number String 1 sc_orientation String Forward land_ice_segments delta_time 188 latitude /gt3r/land_ice_segments/delta_time long_name String Latitude standard_name String latitude units String degrees_north source String ATL06 ATBD - Top Level Fitting Routine valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Latitude of segment center, WGS84, North=+, coordinates String delta_time longitude delta_time /gt3r/land_ice_segments/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - Top Level Fitting Routine contentType String referenceInformation description String 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. coordinates String latitude longitude longitude /gt3r/land_ice_segments/delta_time long_name String Longitude standard_name String longitude units String degrees_east source String ATL06 ATBD - Top Level Fitting Routine valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Longitude of segment center, , WGS84, East=+ coordinates String delta_time latitude sigma_geo_h /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Vertical Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Total vertical geolocation error due to PPD and POD, including the effects of horizontal geolocation error on the segment vertical error. coordinates String delta_time latitude longitude h_li /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Land Ice height units String meters source String ATL06 ATBD - Top Level Fitting Routine contentType String physicalMeasurement description String Standard land-ice segment height determined by land ice algorithm, corrected for first-photon bias, representing the median- based height of the selected PEs coordinates String delta_time latitude longitude atl06_quality_summary /gt3r/land_ice_segments/delta_time long_name String ATL06_Quality_Summary units String 1 source String ATL06 ATBD - Top Level Fitting Routine valid_min Int8 0 valid_max Int8 1 contentType String qualityInformation description String The ATL06_quality_summary parameter indicates the best-quality subset of all ATL06 data. A zero in this parameter implies that no data-quality tests have found a problem with the segment, a one implies that some potential problem has been found. Users who select only segments with zero values for this flag can be relatively certain of obtaining high-quality data, but will likely miss a significant fraction of usable data, particularly in cloudy, rough, or low-surface-reflectance conditions. coordinates String delta_time latitude longitude flag_meanings String best_quality potential_problem flag_values Int8 0 1 segment_id /gt3r/land_ice_segments/delta_time _FillValue Int32 0 long_name String Reference Point, m units String 1 source String ATL06 ATBD - Top Level Fitting Routine contentType String referenceInformation description String Segment number, counting from the equator. Equal to the segment_id for the second of the two 20m ATL03 segments included in the 40m ATL06 segment coordinates String delta_time latitude longitude h_li_sigma /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected RMS segment misfit units String meters source String ATL06 ATBD - Top Level Fitting Routine contentType String qualityInformation description String Propagated error due to sampling error and FPB correction from the land ice algorithm coordinates String delta_time latitude longitude fpb_warning_flag /gt3r/land_ice_segments/delta_time long_name String fpb_warning_flag units String 1 source String ATL06 ATBD - FPB Corrections valid_min Int8 0 valid_max Int8 1 contentType String qualityInformation description String To flag that segments have potentially erroneous FPB corrections, the ATL06 algorithm sets fpb_warning_flag to 1 if full_sat_fract is greater than 0.90 (strong beams) or greater than 0.40 (weak beams) for either of the two ATL03 20 m segments that are used as inputs to each ATL06 40 m segment. Otherwise, fpb_warning_flag is set to 0. coordinates String latitude longitude delta_time flag_meanings String best_quality potential_problem flag_values Int8 0 1 DODS_EXTRA Container Unlimited_Dimension String delta_time description String The land_ice_height group contains the primary set of derived ATL06 products. This includes geolocation, height, and standard error and quality measures for each segment. This group is sparse, meaning that parameters are provided only for pairs of segments for which at least one beam has a valid surface-height measurement. data_rate String Data within this group are sparse. Data values are provided only for those ICESat-2 20m segments where at least one beam has a valid land ice height measurement. fit_statistics h_mean /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Height Mean units String meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String modelResult description String Mean surface height, not corrected for first-photon bias or pulse truncation. coordinates String ../delta_time ../latitude ../longitude signal_selection_source /gt3r/land_ice_segments/delta_time long_name String Signal Selection Source units String 1 source String ATL06 ATBD - Signal Selection based on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates the last algorithm attempted to select the signal for ATL06 fitting. 0=Signal selection succeeded using ATL03 detected PE; 1=Signal selection failed using ATL03 detected PE but succeeded using all flagged ATL03 PE; 2=Signal selection failed using all flagged ATL03 PE, but succeeded using the backup algorithm; 3=All signal-finding strategies failed. coordinates String ../delta_time ../latitude ../longitude flag_meanings String succeeded_using_pe succeeded_using_flagged_pe succeeded_using_backup failed flag_values Int8 0 1 2 3 snr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String SNR units String 1 source String ATL06 ATBD - Iterative Least Squares Fitting Routine contentType String physicalMeasurement description String Signal-to-noise ratio in the final refined window coordinates String ../delta_time ../latitude ../longitude h_robust_sprd /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Robust Spread units String meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String referenceInformation description String RDE of misfit between PE heights and the along-track segment fit. coordinates String ../delta_time ../latitude ../longitude n_seg_pulses /gt3r/land_ice_segments/delta_time units String counts _FillValue Float32 3.402823466e+38 long_name String Number potential segment pulses source String ATL06 ATBD - Top-Level Fitting Routine contentType String referenceInformation description String The number of pulses potentially included in the segment coordinates String ../delta_time ../latitude ../longitude dh_fit_dx_sigma /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Sigma of Along Track Slope units String meters/meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String qualityInformation description String Propagated error in the along-track segment slope coordinates String ../delta_time ../latitude ../longitude snr_significance /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String SNR Significance units String 1 source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Probability that signal-finding routine would converge to at least the observed SNR for a random-noise input. Small values indicate a small likelihood of a surface-detection blunder. coordinates String ../delta_time ../latitude ../longitude h_expected_rms /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected RMS misfit units String meters source String ATL06 ATBD - Iterative ground-window refinement contentType String qualityInformation description String Expected RMS misfit between PE heights and along-track segment fit coordinates String ../delta_time ../latitude ../longitude dh_fit_dy /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Across Track Slope units String meters/meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Across track slope from segment fits to weak and strong beam; the same slope is reported for both laser beams in each pair coordinates String ../delta_time ../latitude ../longitude sigma_h_mean /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Height Error units String meters source String ATL06 ATBD - Propagated Height Errors contentType String qualityInformation description String Propagated height error due to PE-height sampling error for height from the along-track fit, not including geolocation-induced error coordinates String ../delta_time ../latitude ../longitude h_rms_misfit /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String RMS Misfit units String meters source String ATL06 ATBD -Iterative Least-Squares Fitting Routine contentType String qualityInformation description String RMS misfit between PE heights and along- track segment fit coordinates String ../delta_time ../latitude ../longitude signal_selection_source_status /gt3r/land_ice_segments/delta_time long_name String Signal Selection Source Status units String 1 source String ATL06 ATBD - Signal Selection based on ATL03 flags valid_min Int8 0 valid_max Int8 4 contentType String qualityInformation description String Indicates the status of the last signal selection algorithm attempted (see signal_selection_source). The definition of flag is different for each source and are defined in each of the signal_selection_status flags. (See Land Ice ATBD Table 3-2). coordinates String ../delta_time ../latitude ../longitude dh_fit_dx /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Along Track Slope units String meters/meters source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String physicalMeasurement description String Along-track slope from along-track segment fit coordinates String ../delta_time ../latitude ../longitude n_fit_photons /gt3r/land_ice_segments/delta_time _FillValue Int32 2147483647 long_name String Number of Photons in Fit units String 1 source String ATL06 ATBD - Iterative Least-Squares Fitting Routine contentType String physicalMeasurement description String Number of PEs used in determining h_li, after editing coordinates String ../delta_time ../latitude ../longitude w_surface_window_final /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Surface Window Width units String meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String physicalMeasurement description String Width of the surface window, top to bottom coordinates String ../delta_time ../latitude ../longitude description String The fit_statistics subgroup contains a variety of parameters that might indicate the quality of the fitted segment data. Data in this group are sparse, with dimensions matching the land_ice_height group. data_rate String Data within this group are stored at the land_ice_height segment rate. ground_track sigma_geo_at /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Along Track Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Along-track component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude ref_coelv /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Co-elevation units String degrees source String ATL03 contentType String referenceInformation description String Coelevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot. coordinates String ../delta_time ../latitude ../longitude sigma_geo_r /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Radial Orbit Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Radial orbit component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude seg_azimuth /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Segment Azimuth units String degrees source String ATL03 contentType String referenceInformation description String Azimuth of the pair-track, east of local north. coordinates String ../delta_time ../latitude ../longitude sigma_geo_xt /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Across Track Geolocation Error units String meters source String ATL06 ATBD - Segment Geolocation contentType String qualityInformation description String Across-track component of the geolocation error. coordinates String ../delta_time ../latitude ../longitude ref_azimuth /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Azimuth units String degrees source String ATL03 contentType String referenceInformation description String The direction, eastwards from north, of the laser beam vector as seen by an observer at the laser ground spot viewing toward the spacecraft (i.e., the vector from the ground to the spacecraft). coordinates String ../delta_time ../latitude ../longitude x_atc /gt3r/land_ice_segments/delta_time _FillValue Float64 1.7976931348623157e+308 long_name String X Along Track units String meters source String ATL06 ATBD - Local Coordinate Systems contentType String referenceInformation description String The along-track x-coordinate of the segment, measured parallel to the RGT, measured from the ascending node of the equatorial crossing of a given RGT. coordinates String ../delta_time ../latitude ../longitude y_atc /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Y Along Track units String meters source String ATL06 ATBD - Local Coordinate Systems contentType String referenceInformation description String Along-track y coordinate of the segment, relative to the RGT, measured along the perpendicular to the RGT, positive to the right of the RGT. coordinates String ../delta_time ../latitude ../longitude description String The ground_track group contains parameters describing the GT and RGT for each land ice segment, as well as angular information about the beams. data_rate String Data within this group are stored at the land_ice_height segment rate. dem dem_flag /gt3r/land_ice_segments/delta_time long_name String DEM Source Flag units String 1 source String ATL03 valid_min Int8 0 valid_max Int8 4 contentType String referenceInformation description String Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. coordinates String ../delta_time ../latitude ../longitude flag_meanings String none arctic global mss antarctic flag_values Int8 0 1 2 3 4 geoid_free2mean /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Geoid Free-to-Mean conversion units String meters source String ATL03 contentType String modelResult description String Additive value to convert geoid heights from the tide-free system to the mean-tide system. (Add to geoid to get the geoid heights in the mean-tide system.) coordinates String ../delta_time ../latitude ../longitude dem_h /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String DEM Height units String meters source String ATL03 contentType String referenceInformation description String Height of the DEM, interpolated by cubic-spline interpolation in the DEM coordinate system to the PE location. (Best available DEM value in priority of Arctic/Antarctic/Global/MSS) coordinates String ../delta_time ../latitude ../longitude geoid_h /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Geoid Height units String meters source String ATL03 contentType String referenceInformation description String Geoid height above WGS-84 reference ellipsoid (range -107 to 86m) in the tide-free system. coordinates String ../delta_time ../latitude ../longitude description String Contains reference DEM and geoid heights. data_rate String Data within this group are stored at the land_ice segment rate. geophysical msw_flag /gt3r/land_ice_segments/delta_time _FillValue Int8 127 long_name String Multiple Scattering Warning Flag units String 1 source String ATL09 valid_min Int8 -1 valid_max Int8 5 contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude flag_meanings String 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 flag_values Int8 -1 0 1 2 3 4 5 layer_flag /gt3r/land_ice_segments/delta_time units String 1 source String ATL09 _FillValue Int8 127 long_name String Consolidated cloud flag valid_min Int8 0 valid_max Int8 1 contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude flag_meanings String likely_clear likely_cloudy flag_values Int8 0 1 bsnow_conf /gt3r/land_ice_segments/delta_time _FillValue Int8 127 long_name String Blowing Snow confidence units String 1 source String ATL09 contentType String referenceInformation description String Confidence flag for presence of blowing snow coordinates String ../delta_time ../latitude ../longitude bsnow_h /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Blowing Snow Layer Top Height units String meters source String ATL09 contentType String referenceInformation description String Blowing snow layer top height coordinates String ../delta_time ../latitude ../longitude tide_ocean /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Ocean Tide units String meters source String ATL03 contentType String referenceInformation description String Ocean Tides including diurnal and semi-diurnal (harmonic analysis), and longer period tides (dynamic and self-consistent equilibrium). coordinates String ../delta_time ../latitude ../longitude tide_earth /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Earth Tide units String meters source String ATL03 contentType String referenceInformation description String Solid earth tides in the tide-free system. coordinates String ../delta_time ../latitude ../longitude solar_azimuth /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String solar azimuth units String degrees_east source String ATL03 contentType String referenceInformation description String The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot. coordinates String ../delta_time ../latitude ../longitude r_eff /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Effective uncorrected reflectance units String 1 source String ATL06 ATBD - Top-Level Fitting Routine contentType String referenceInformation description String Effective reflectance, uncorrected for atmospheric effects. coordinates String ../delta_time ../latitude ../longitude dac /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Dynamic Atmosphere Correction units String meters source String ATL03 contentType String referenceInformation description String Dynamic Atmospheric Correction (DAC) includes inverted barometer (IB) effect. coordinates String ../delta_time ../latitude ../longitude tide_load /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Load Tide units String meters source String ATL03 contentType String referenceInformation description String Load Tide - Local displacement due to Ocean Loading (-6 to 0 cm). coordinates String ../delta_time ../latitude ../longitude tide_earth_free2mean /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Earth Tide Free-to-Mean conversion units String meters source String ATL03 contentType String referenceInformation description String Additive value to convert solid earth tide from the tide-free system to the mean tide system. (Add to tide_earth to get solid earth tides in the mean-tide system.) coordinates String ../delta_time ../latitude ../longitude bsnow_od /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Blowing snow OD units String 1 source String ATL09 contentType String modelResult description String Optical thickness of blowing snow layer. coordinates String ../delta_time ../latitude ../longitude tide_equilibrium /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Equilibrium Tide units String meters source String ATL03 contentType String referenceInformation description String Long period equilibrium tide self-consistent with the ocean tide model (+-0.04m). coordinates String ../delta_time ../latitude ../longitude cloud_flg_atm /gt3r/land_ice_segments/delta_time _FillValue Int8 127 long_name String Cloud Flag ATM units String 1 source String ATL09 valid_min Int8 0 valid_max Int8 10 contentType String referenceInformation description String Number of layers found from the backscatter profile using the DDA layer finder. coordinates String ../delta_time ../latitude ../longitude solar_elevation /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String solar elevation units String degrees source String ATL03 valid_min Float32 -90. valid_max Float32 90. contentType String referenceInformation description String 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. coordinates String ../delta_time ../latitude ../longitude tide_pole /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Solid Earth Pole Tide units String meters source String ATL03 contentType String referenceInformation description String Solid Earth Pole Tide -Rotational deformation due to polar motion (-1.5 to 1.5 cm). coordinates String ../delta_time ../latitude ../longitude e_bckgrd /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Expected background count rate units String hz source String ATL06 ATBD - Background PE Rate contentType String referenceInformation description String Expected background count rate based on sun angle, surface slope, for unit surface reflectance coordinates String ../delta_time ../latitude ../longitude cloud_flg_asr /gt3r/land_ice_segments/delta_time _FillValue Int8 127 long_name String Cloud Flag ASR units String 1 source String ATL09 valid_min Int8 0 valid_max Int8 5 contentType String referenceInformation description String Cloud flag (probability) from apparent surface reflectance. 0=clear with high confidence; 1=clear with medium confidence; 2=clear with low confidence; 3=cloudy with low confidence; 4=cloudy with medium confidence; 5=cloudy with high confidence coordinates String ../delta_time ../latitude ../longitude flag_meanings String clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence flag_values Int8 0 1 2 3 4 5 bckgrd /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Background count rate units String hz source String ATL03 contentType String referenceInformation description String Background count rate, derived from the ATL03 50-shot-average, interpolated to the segment center. coordinates String ../delta_time ../latitude ../longitude neutat_delay_total /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String Total Neutral Atmospheric Delay units String meters source String ATL03 contentType String referenceInformation description String Total neutral atmosphere delay correction (wet+dry). coordinates String ../delta_time ../latitude ../longitude description String The sun_and_clouds group contains parameters related to solar background and parameters indicative of the presence or absence of clouds. data_rate String Data within this group are stored at the land_ice_height segment rate. bias_correction fpb_mean_corr_sigma /gt3r/land_ice_segments/delta_time units String meters _FillValue Float32 3.402823466e+38 long_name String fpb mean corr sigma source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated error in fpb_mean_corr coordinates String ../delta_time ../latitude ../longitude fpb_med_corr_sigma /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb median corr sigma units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated error in fpb_med_corr coordinates String ../delta_time ../latitude ../longitude fpb_mean_corr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String first photon bias mean correction units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated first-photon bias (fpb) correction to mean segment height coordinates String ../delta_time ../latitude ../longitude med_r_fit /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String mean median residual units String meters source String ATL06 ATBD - Top-Level Fitting Routine contentType String qualityInformation description String Difference between uncorrected mean and median of linear fit residuals coordinates String ../delta_time ../latitude ../longitude fpb_med_corr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb median corr units String meters source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String First-photon-bias correction giving the difference between the mean segment height and the corrected median height coordinates String ../delta_time ../latitude ../longitude tx_mean_corr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String tx shape mean correction units String meters source String ATL06 ATBD - Transmit-pulse shape correction contentType String qualityInformation description String Estimate of the difference between the mean of the full-waveform transmit-pulse and the mean of a broadened, truncated waveform consistent with the received pulse coordinates String ../delta_time ../latitude ../longitude fpb_n_corr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String fpb number photons corr units String counts source String ATL06 ATBD - First-Photon Bias Correction contentType String qualityInformation description String Estimated window photon count after first-photon-bias correction coordinates String ../delta_time ../latitude ../longitude tx_med_corr /gt3r/land_ice_segments/delta_time _FillValue Float32 3.402823466e+38 long_name String tx shape median correction units String meters source String ATL06 ATBD - Transmit-pulse shape correction contentType String qualityInformation description String Estimate of the difference between the median of the full-waveform transmit-pulse mean and the median of a broadened, truncated waveform consistent with the received pulse coordinates String ../delta_time ../latitude ../longitude description String The bias_correction group contains information about the estimated first-photon bias, and the transmit-pulse-shape bias. data_rate String Data within this group are stored at the land_ice segment rate. residual_histogram delta_time 22 bin_top_h 748 ds_segment_id 10 ds_segment_id /gt3r/residual_histogram/ds_segment_id long_name String Segment ID Index units String 1 source String ATL06 ATBD - Residual_histogram calculation valid_min Int8 1 valid_max Int8 10 contentType String auxiliaryInformation description String Relative index of each segment_id used in the derivation of the histogram. lat_mean /gt3r/residual_histogram/delta_time long_name String Latitude Mean standard_name String latitude units String degrees_north source String ATL06 ATBD - Residual_histogram calculation valid_min Float64 -90. valid_max Float64 90. contentType String physicalMeasurement description String Mean latitude of the segments included in the histogram coordinates String delta_time lon_mean lon_mean /gt3r/residual_histogram/delta_time long_name String Longitude Mean standard_name String longitude units String degrees_east source String ATL06 ATBD - Residual_histogram calculation valid_min Float64 -180. valid_max Float64 180. contentType String physicalMeasurement description String Mean longitude of the segments included in the histogram coordinates String delta_time lat_mean delta_time /gt3r/residual_histogram/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - Residual_histogram calculation contentType String referenceInformation description String 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. coordinates String lat_mean lon_mean bin_top_h /gt3r/residual_histogram/bin_top_h long_name String Bin Top Height units String meters source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Height of the top of each histogram bin, listed in increasing order. The bottom of each bin is equal to the top of the next- lowest bin. coordinates String delta_time lat_mean lon_mean count /gt3r/residual_histogram/delta_time /gt3r/residual_histogram/bin_top_h _FillValue Int32 2147483647 long_name String Bin Counts units String counts source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Residual count falling with each histogram bin. The top height of each histogram bin may be found in the bin_top_h dataset. coordinates String delta_time lat_mean lon_mean pulse_count /gt3r/residual_histogram/delta_time long_name String Number of Histogram Segment Pulses units String counts source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Number of pulses potentially included in the histogram (pulses are counted if they are in the central 20 m of each segment, even if no PE from the pulse are selected). coordinates String delta_time lat_mean lon_mean x_atc_mean /gt3r/residual_histogram/delta_time long_name String Along Track Coordinate Mean units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Mean along-track coordinate of the segments included in the histogram. coordinates String delta_time lat_mean lon_mean segment_id_list /gt3r/residual_histogram/delta_time /gt3r/residual_histogram/ds_segment_id long_name String Segment ID List units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String referenceInformation description String Segments ids included in each column of the histogram coordinates String delta_time lat_mean lon_mean _FillValue Int32 2147483647 bckgrd_per_m /gt3r/residual_histogram/delta_time long_name String Expected background PEs units String 1 source String ATL06 ATBD - Residual_histogram calculation contentType String physicalMeasurement description String Number of background PE expected for each vertical meter of the histogram based on the observed background rate (bckgrd). coordinates String delta_time lat_mean lon_mean DODS_EXTRA Container Unlimited_Dimension String delta_time data_rate String Data within this group are stored at the 200-meter along-track rate. description String This group contains histograms of the residuals between PE heights and the least-squares fit segment heights, at 200-meter along-track resolution. segment_quality delta_time 202 reference_pt_lat /gt3r/segment_quality/delta_time long_name String Latitude units String degrees_north source String ATL06 ATBD - segment_quality group valid_min Float64 -90. valid_max Float64 90. contentType String referenceInformation description String Latitude of the reference segment location on the RPT coordinates String delta_time reference_pt_lon standard_name String latitude reference_pt_lon /gt3r/segment_quality/delta_time long_name String Longitude units String degrees_east source String ATL06 ATBD - segment_quality group valid_min Float64 -180. valid_max Float64 180. contentType String referenceInformation description String Longitude of the reference segment location on the RPT coordinates String delta_time reference_pt_lat standard_name String longitude delta_time /gt3r/segment_quality/delta_time long_name String Elapsed GPS seconds standard_name String time units String seconds since 2018-01-01 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String 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. coordinates String reference_pt_lat reference_pt_lon record_number /gt3r/segment_quality/delta_time long_name String Land Ice Height Index units String 1 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String For those segments that have adequate signal strength, this parameter gives the record for the pair within the other groups in the granule. coordinates String delta_time reference_pt_lat reference_pt_lon signal_selection_source /gt3r/segment_quality/delta_time long_name String Signal Selection Source units String 1 source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates the last algorithm attempted to select the signal for ATL06 fitting. 0=Signal selection succeeded using ATL03 detected PE; 1=Signal selection failed using ATL03 detected PE but succeeded using all flagged ATL03 PE; 3=All signal-finding strategies failed. coordinates String delta_time reference_pt_lat reference_pt_lon flag_meanings String succeeded_using_pe succeeded_using_flagged_pe failed flag_values Int8 0 1 3 segment_id /gt3r/segment_quality/delta_time long_name String Reference Point, m units String 1 source String ATL06 ATBD - segment_quality group contentType String referenceInformation description String Segment number corresponding to the second of two ATL03 segments in the ATL06 segment, counted from the RGT equator crossing coordinates String delta_time reference_pt_lat reference_pt_lon DODS_EXTRA Container Unlimited_Dimension String delta_time data_rate String Data within this group are stored at the ICESat-2 20m segment rate. description String The segment_quality group contains a dense record (i.e. for every possible segment in the granule) of the success or failure of the surface-finding strategies, and gives the locations of the reference points on the RPTs. For segments with adequate data quality (i.e. with more than 10 PE) it also contains offsets into the data structures for the other groups that allow each segment to be efficiently located within the file. signal_selection_status signal_selection_status_all /gt3r/segment_quality/delta_time units String 1 long_name String Signal Selection Status Flag source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates confidence of the signal-selection algorithm using all ATL03-flagged PEs. 0=Signal selection succeeded using all ATL03-flagged PEs (or algorithm not attempted); 1=Signal selection using all ATL03-flagged PEs failed the 20-meter-spread test; 2=Signal selection using all ATL03-flagged PEs failed the 10-photon-count test; 3=Signal selection using all ATL03-flagged PEs failed both tests coordinates String ../delta_time ../reference_pt_lat ../reference_pt_lon flag_meanings String succeeded failed_20 failed_10 failed_both flag_values Int8 0 1 2 3 signal_selection_status_confident /gt3r/segment_quality/delta_time units String 1 long_name String Signal Selection Confident Flag source String ATL06 ATBD - Signal selection base on ATL03 flags valid_min Int8 0 valid_max Int8 3 contentType String qualityInformation description String Indicates confidence of the signal-selection algorithm using low or better PEs. 0=Signal selection succeeded using ATL03 low-or-better confidence PEs; 1=Signal selection using ATL03 low-or-better confidence PEs failed the 20-meter-spread test; 2=Signal selection using ATL03 low-or-better confidence PEs failed the 10-photon-count test; 3=Signal selection using ATL03 low-or-better confidence PEs failed both tests coordinates String ../delta_time ../reference_pt_lat ../reference_pt_lon flag_meanings String succeeded failed_20 failed_10 failed_both flag_values Int8 0 1 2 3 description String The signal selection status subgroup contains the success or failure for each surface-finding strategies data_rate String Data within this group are stored at the ICESat-2 20m segment rate.