Anomaly Trigger Dimension Scale 1 dim_scale 1 9 auxiliaryInformation Dimension scale indexing the short segment anomaly trigger array having nine elements. Index = 1 corresponds to coarse ht difference; Index = 2 corresponds to abnormal length; Index = 3 corresponds to histogram mode spread; Index = 4 corresponds to histogram mode count; Index = 5 corresponds to histogram mode intensity; Index = 6 corresponds to invalid long segment; Index = 7 corresponds to shore buffer designation; Index = 8 corresponds to insufficient signal phs; Index = 9 corresponds to unavailability of coarse water height against which to test. coarse_ht_difference abnormal_length histogram_mode_spread histogram_mode_count histogram_mode_intensity invalid_long_segment shore_buffer_designation insufficient_signal_phs coarse_water_height_unavailable 1 2 3 4 5 6 7 8 9 Segment Quality Dimension Scale 1 dim_scale 1 4 auxiliaryInformation Dimension scale indexing the short segment quality array. Index = 1 corresponds to nominal; Index = 2 corresponds to possible afterpulse; Index = 3 corresponds to possible impulse response; Index = 4 corresponds to possible TEP nominal possible_afterpulse possible_impulse_response possible_TEP 1 2 3 4 ATL13 L3A This data set (ATL13) contains along track surface heights of inland water bodies, including lakes, estuaries and rivers. Water surface slope and descriptive statistics are also provided. The data were acquired by the Advanced Topographic Laser Altimeter S CF-1.6 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) Instrument Engineer, Investigator, Principle Investigator, Data Producer, Data Producer UTC trajectory degrees_north degrees_east ATL13 http://dx.doi.org 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. http://dx.doi.org Horizontal CF-1.6 CCSDS UTC-A 2025-12-22T18:32:36.000000Z HDF5 1.14.4 2025-12-22T18:32:36.000000Z;c230515c-aaf1-3821-b287-d22fed4296fc;Created by PGE atlas_l3a_iw Version 4.1.1 c230515c-aaf1-3821-b287-d22fed4296fc 4.1 22630. 2025-09-12T01:34:36.000000Z 2025-09-11T19:17:26.000000Z -90. -180. 90. 180. NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center nsidc@nsidc.org http://nsidc.org/daac/ ATLAS/ICESat-2 L3A Along Track Inland Surface Water Data ATL13 doi:10.5067/ATLAS/ATL13.007 National Aeronautics and Space Administration (NASA) GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System The purpose of ATL13 is to provide along-track inland water surface heights and associated statistics. EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > SURFACE WATER FEATURES > NONE > NONE > NONE > NONE NASA/GCMD Science Keywords Cite these data in publications as follows: The data used in this study were produced by the ICESat-2 Science Project Office at NASA/GSFC. The data archive site is the NASA National Snow and Ice Data Center Distributed Active Archive Center. 3A http://nsidc.org/data/icesat2/data.html ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 ATLAS > Advanced Topographic Laser Altimeter System ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 Spacecraft Time of Last Spacecraft Orientation Change time seconds since 2018-01-01 POD/PPD referenceInformation 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. Ascending Node Crossing Time time seconds since 2018-01-01 POD/PPD referenceInformation 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. Orbit Number 1 Operations 1 65000 referenceInformation Unique identifying number for each planned ICESat-2 orbit. crossing_time Spacecraft Orientation 1 POD/PPD 0 2 referenceInformation 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. sc_orient_time backward forward transition 0 1 2 Reference Ground track 1 POD/PPD 1 1387 referenceInformation The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs. crossing_time Cycle Number 1 Operations 0 50 referenceInformation A count of the number of exact repeats of this reference orbit. crossing_time Ascending Node Longitude degrees_east POD/PPD -180. 180. referenceInformation Longitude at the ascending node crossing. crossing_time Contains orbit information. Varies. Data are only provided when one of the stored values (besides time) changes. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Longitude degrees_east geo_poly -180. 180. auxiliaryInformation Longitude values for a bounding polygon. Polygon Latitude degrees_north geo_poly -90. 90. auxiliaryInformation Latitude values for a bounding polygon. Contains the bounding polygons associated with the input ATL03s. ISO 19139 Dataset XML ISO 19139 Dataset XML ISO 19139 Series XML ISO 19139 Series XML ISO19115 Structured Metadata Represented within HDF5 10000 pps 532 nm ATLAS Laser Altimeter ATLAS on ICESat-2 determines the range between the satellite and the Earth's surface by measuring the two-way time delay of short pulses of laser light that it transmits in six beams. It is different from previous operational ice-sheet altimeters in that it is a photon-counting LIDAR. ATLAS records a set of arrival times for individual photons, which are then analyzed to derive surface, vegetation, and cloud properties. ATLAS has six beams arranged in three pairs, so that it samples each of three reference pair tracks with a pair of beams; ATLAS transmits pulses at 10 kHz, giving approximately one pulse every 0.7 m along track; ATLAS's expected pointing control will be better than 90 m RMS. Pre-Release 12/31/17 A document describing the ATLAS instrument will be provided by the ICESat-2 Project Science Office. ICESat-2 Ice, Cloud, and land Elevation Satellite-2 Spacecraft 31-Dec-16 31-Dec-16 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 NOT_SET directInternal TBD TBD TBD NOT_SET directInternal TBD TBD TBD NOT_SET ATL13_SDP utf8 eng Feb 2020 ICESat-2-SIPS-SPEC-4267 - ATLAS Science Algorithm Standard Data Product (SDP) Volume T12 (ATL13). Revision -. v3.3 asNeeded SET_BY_META 007 eng utf8 NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center ATLAS/ICESat-2 L3A Along Track Inland Surface Water Data ATL13 doi:10.5067/ATLAS/ATL13.007 2022-08-09 National Aeronautics and Space Administration (NASA) The ICESat-2 ATL13 standard data product contains along track surface height of inland water bodies. This product contains, for each beam, water surface height, slope, and rms aggregated into segments defined by approximately 100 signal photons. Also includes water surface slope and aspect between neighboring strong beams. The purpose of ATL13 is to provide along-track inland water surface heights and associated statistics. The software that generates the ATL13 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland. onGoing HDF 5 geoscientificInformation ICESat-2 > Ice, Cloud, and land Elevation Satellite-2 along-track 2025-12-22T18:32:36.000000Z c230515c-aaf1-3821-b287-d22fed4296fc ATL13_20250911191726_13452801_007_02.h5 007 eng utf8 ATL13 GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System The ICESat-2 ATL13 standard data product contains along track surface height of inland water bodies. This product contains, for each beam, water surface height, slope, and rms aggregated into segments defined by approximately 100 signal photons. Also includes water surface slope and aspect between neighboring strong beams. The purpose of ATL13 is to provide along-track inland water surface heights and associated statistics. The software that generates the ATL13 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland. onGoing geoscientificInformation 90. 180. -90. -180. 2025-09-11T19:17:26.000000Z 2025-09-12T01:34:36.000000Z 2025-12-22T20:49:02.000000Z 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 ATL13_20250911191726_13452801_007_02.qa 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. CTL_atlas_l3a_iw_021426055.ctl CNTL 1 ISO 19139 XML file containing DataSet-level metadata information. ANC38-13_20250523205159_007_01.xml ANC38-13 527a0d6a-3fbd-3a9c-833e-a76aa0c2fffa 007 ISO 19139 XML file containing Series-level metadata information. ANC36-13_20250523205158_007_01.xml ANC36-13 434d6e13-f24e-3081-aff7-e3893a2b8945 007 HDF5 template file that defines the organization and default content of the product metadata. atl13_metadata_template.h5 ANC26-13 92fd7663-ad71-378e-b85b-c7a1cc34b8ab 041 ICESat-2 ATLAS L2A Global Geolocated Photon data products. ATL03_20250911211241_13462804_007_01.h5 ATL03_20250911211750_13462805_007_01.h5 ATL03_20250911212316_13462806_007_01.h5 ATL03_20250911213146_13462807_007_01.h5 ATL03_20250911213848_13462808_007_01.h5 ATL03_20250911215933_13462811_007_01.h5 ATL03_20250911220516_13462812_007_01.h5 ATL03_20250911221257_13462813_007_01.h5 ATL03_20250911221859_13462814_007_01.h5 ATL03_20250911222602_13472801_007_01.h5 ATL03_20250911223304_13472802_007_01.h5 ATL03_20250911224134_13472803_007_01.h5 ATL03_20250911224659_13472804_007_01.h5 ATL03_20250911225208_13472805_007_01.h5 ATL03_20250911225733_13472806_007_01.h5 ATL03_20250911230604_13472807_007_01.h5 ATL03_20250911231305_13472808_007_01.h5 ATL03_20250911232008_13472809_007_01.h5 ATL03_20250911232610_13472810_007_01.h5 ATL03_20250911233351_13472811_007_01.h5 ATL03_20250911233934_13472812_007_01.h5 ATL03_20250911234715_13472813_007_01.h5 ATL03_20250911235317_13472814_007_01.h5 ATL03_20250912000018_13482801_007_01.h5 ATL03_20250912000720_13482802_007_01.h5 ATL03_20250912001551_13482803_007_01.h5 ATL03_20250912002116_13482804_007_01.h5 ATL03_20250912002625_13482805_007_01.h5 ATL03_20250912003150_13482806_007_01.h5 ATL03_20250912005425_13482809_007_01.h5 ATL03_20250912010027_13482810_007_01.h5 ATL03_20250912010807_13482811_007_01.h5 ATL03_20250912011351_13482812_007_01.h5 ATL03_20250912012131_13482813_007_01.h5 ATL03_20250912012733_13482814_007_01.h5 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 ATL03 707d300c-60bd-329e-99e2-d7e3997e2f15 125c826a-0b21-3ea6-8146-41b31c27cc8c 12866cae-c5ac-3227-84ce-80a82279f8d7 ae21a86b-afc1-3239-9295-ccc06efd7466 ed468c36-b3e3-3d21-81c4-da02d09c47b0 9c8dbb0b-b248-3d2a-bb1e-f8ce3e90e276 48418869-16c8-3a8d-85d6-59687bab0c38 728afbd2-bc61-3d4c-b6a7-57d9a6fcc622 2d485087-6018-35aa-bcec-a4ed8c83f21a b2c0be1f-07ac-3d17-8517-0a13282469c0 bd818098-4f97-3bd8-a9e8-d93af3bc584a b35f2a1b-b429-361a-81cb-914bb748e06f 4db49d0c-fe4a-3745-a983-3f44984c62c2 d793a62d-0c6b-32e8-999d-4060908e1d3e 97f561fc-3559-3d9f-b35e-e48e6bbd38ae 4161332a-b682-3187-bc50-4fee81770963 a0e5297f-40a2-300a-a983-52aef7c05a66 8c3fe7b6-0286-336f-8b76-6c9fa5672349 8db6d4ae-73a3-3e36-8653-bed590fe309b 1345c50e-0179-34fd-a3b5-f9fad0125d2b 9e25e992-3ed2-3e7b-9d00-e6ab5d3f29a4 a610cfa4-f481-32ea-9cee-2a4af231d36c 77e67e93-5a61-3322-b5ea-2f468cc7cc8a da41c3d9-a29f-3b21-b4fb-789547abf2dc 597eb9db-acc9-31fa-a200-c13986f428f0 209f638a-0bbf-3f4c-bf0d-a9f60fbb8f5a 367b60b6-b080-35a6-9ff5-af6a5ee0de58 52679700-2416-382c-ad96-195122d90e0f c1441ce1-bbbe-3b5e-b690-8b23132a4579 970f9765-eab9-3c2b-8a9b-748348d3ff87 7ded6457-91af-3e9a-9036-82f603d60b23 6e423d94-7801-39ae-8d52-061a3ad80e5e fd67730b-a158-386a-9e0f-83deaf66b928 76372cd9-939c-3e3a-b27e-1c34afa824ad 6b8d0071-c0ac-385f-9d3f-64c3a987d732 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 007 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 38996 38996 38996 38996 38996 38996 38996 38996 38996 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 38996 38996 38996 38996 38996 38996 38996 38996 38996 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38997 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 38998 1346 1346 1346 1346 1346 1346 1346 1346 1346 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 1346 1346 1346 1346 1346 1346 1346 1346 1346 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1347 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 1348 4 5 6 7 8 11 12 13 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2 3 4 5 6 9 10 11 12 13 14 4 5 6 7 8 11 12 13 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2 3 4 5 6 9 10 11 12 13 14 446047 555736 671060 852076 1001777 1443579 1565340 1728837 1857240 1 149699 330711 446034 555722 671047 852068 1001775 1151678 1280088 1443590 1565349 1728845 1857245 1 149696 330708 446033 555720 671049 1151688 1280098 1443599 1565353 1728847 1857246 555735 671059 852075 1001776 1151673 1565339 1728836 1857239 2007130 149698 330710 446033 555721 671046 852067 1001774 1151677 1280087 1443589 1565348 1728844 1857244 2007132 149695 330707 446032 555719 671048 852074 1280097 1443598 1565352 1728846 1857245 2007134 ICESat-2 ATLAS L3A atmosphere data products. ATL09_20250911205144_13462801_007_01.h5 ATL09_20250911222602_13472801_007_01.h5 ATL09_20250912000018_13482801_007_01.h5 ATL09 ATL09 ATL09 20800f06-ef53-305c-8ddb-7ef98589ae9a 4d1f8233-22da-38f2-be82-ae178b223964 5261c889-db07-308a-ade4-d4d9b8d7ccfc 007 007 007 28 28 28 28 28 28 38996 38997 38998 38996 38997 38998 1346 1347 1348 1346 1347 1348 1 1 1 14 14 14 551628 3 2 2007125 2007126 2007134 TAI to UTC leapsecond file retrieved from ftp://maia.usno.navy.mil/ser7/tai-utc.dat tai_utc_2017.dat ANC19 7c66d365-278a-31f7-8fe4-9c80e2f012e5 001 HDF5 template file that defines the organization and default content of the product. atl13_template.h5 ANC25-13 babdaeb6-b231-3658-9cd6-b4a60b095bd8 041 Water Basin shapefiles provided by the Inland Water ATBD lead. ATL13_Region_Mask_by_basins_20170201.dbf ANC20-01 9d332759-a01c-3a75-a4ae-0b4306924e52 20170201 Water Body shapefiles provided by the Inland Water ATBD lead. ATL13_Inland_Water_Body_Mask_v3_20191220.dbf ANC20-02 828c2c64-0165-3179-af17-fcc9721d4ceb 20191220 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. atlas_brw Version 3.1.3 Apr 8 2025 Creates ATLAS HDF5 browse files CTL_atlas_l3a_iw_021426055.ctl 2025-12-22T20:49:05.000000Z 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. atlas_meta Version 5.1.3 Apr 8 2025 Creates ATLAS XML metadata files CTL_atlas_l3a_iw_021426055.ctl 2025-12-22T20:51:30.000000Z 12/04/2019 Algorithm Theoretical Basis Document (ATBD) for Inland Water Data Products ATL13 v.3 Feb 2020 ATLAS Science Algorithm Software Design Description (SDD) - Volume 21 (atlas_l3a_iw) Computes along-track inland water surface height, slope, and roughness for each ATLAS beam, and also aspect and maximum slope (or gradient) of the planar surface between adjacent strong beams. atlas_l3a_iw Version 4.1.1 Jul 30 2025 ASAS L3A Inland Water PGE CTL_atlas_l3a_iw_021426055.ctl 2025-12-22T18:32:36.000000Z 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 atl13_qa_util Version 4.1 Apr 8 2025 ATL13 QA Utility CTL_atlas_l3a_iw_021426055.ctl 2025-12-22T20:49:02.000000Z 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce3 strong gt1r profile_1 5 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters. 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce2 strong gt2r profile_2 3 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters. 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce3 weak gt1l profile_1 6 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters. Granule Failure Reason 1 Operations 0 5 qualityInformation Flag indicating granule failure reason. 0=no failure; 1=processing failure; 2=insufficient data; 3=TBD3; 4=TBD4; 5=TBD5 no_failure processing_failure insufficient_data TBD3 TBD4 TBD5 0 1 2 3 4 5 Granule Pass Flag 1 Operations 0 1 qualityInformation Flag indicating granule quality. 0=granule passes automatic QA. 1=granule fails automatic QA. PASS FAIL 0 1 Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data. 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce1 weak gt3l profile_3 2 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters. 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce2 weak gt2l profile_2 4 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters. Release Number 1 Operations auxiliaryInformation Release number of the granule. The release number is incremented when the software or ancillary data used to create the granule has been changed. Ending Geolocation Segment 1 Derived auxiliaryInformation 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 Operations auxiliaryInformation 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. Ending Region 1 Derived auxiliaryInformation 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 Epoch Offset seconds since 1980-01-06T00:00:00.000000Z Operations auxiliaryInformation 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. Ending Reference Groundtrack 1 Derived 1 1387 auxiliaryInformation 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. ATLAS End Time (Actual) time seconds since 2018-01-01 Derived auxiliaryInformation 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. Ending Orbit Number 1 Derived auxiliaryInformation 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. Starting Cycle 1 Derived 0 99 auxiliaryInformation 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. End UTC Time of Granule (CCSDS-A, Actual) 1 Derived auxiliaryInformation UTC (in CCSDS-A format) of the last data point within the granule. Control File 1 Operations auxiliaryInformation PGE-specific control file used to generate this granule. To re-use, replace breaks (BR) with linefeeds. Start GPS SOW of Granule (Actual) seconds Derived auxiliaryInformation GPS seconds-of-week of the first data point in the granule. End UTC Time of Granule (CCSDS-A, Requested) 1 Derived auxiliaryInformation Requested end time (in UTC CCSDS-A) of this granule. Ending Cycle 1 Derived 0 99 auxiliaryInformation 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. Start UTC Time of Granule (CCSDS-A, Requested) 1 Derived auxiliaryInformation Requested start time (in UTC CCSDS-A) of this granule. ATLAS Start Time (Actual) time seconds since 2018-01-01 Derived auxiliaryInformation 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. Starting Geolocation Segment 1 Derived auxiliaryInformation 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. Starting Orbit Number 1 Derived auxiliaryInformation 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. Start UTC Time of Granule (CCSDS-A, Actual) 1 Derived auxiliaryInformation UTC (in CCSDS-A format) of the first data point within the granule. Ending GPSWeek of Granule (Actual) auxiliaryInformation GPS week number of the last data point in the granule. weeks from 1980-01-06 Derived Starting Reference Groundtrack 1 Derived 1 1387 auxiliaryInformation 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. Ending GPS SOW of Granule (Actual) seconds Derived auxiliaryInformation GPS seconds-of-week of the last data point in the granule. Starting Region 1 Derived auxiliaryInformation 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 of Granule (Actual) weeks from 1980-01-06 Derived auxiliaryInformation GPS week number of the first data point in the granule. Data within this group pertain to the granule in its entirety. Contains information ancillary to the data product. This may include product characteristics, instrument characteristics and/or processing constants. 127 Number of coarse iterations 1 ATBD Table 5-2 auxiliaryInformation Number of coarse iteration steps for amplitude, mean height and standard deviation for surface iterated convolution. ATM Background Window Top meters ATBD Table 5-2 auxiliaryInformation Upper limit of height above coarse water surface height for atmospheric background count calculation. Small Segment Bin Size meters ATBD Table 5-2 auxiliaryInformation Bin size to be used for histogramming of each small segment. 2147483647 Short Segment Length 1 ATBD Table 5-2 1 500 auxiliaryInformation Short segment size, indicating the number of along track signal photons per segment, operationally used as unit length over which to identify water surface height anomalies such as islands, bridges, etc. Detrend Width 1 ATBD Table 5-2 auxiliaryInformation Number of standard deviations +/- mode to include in detrend band. Subsurf Max Vertical Profile meters ATBD Table 5-2 auxiliaryInformation Maximum vertical profile of water subsurface to include in estimation of subsurface characteristics bin count above apparent bottom height 1 ATBD Table 5-2 auxiliaryInformation Number of bins above the long segment derived apparent bottom height over which to include member photons in short segment scale bottom finding adjustment. 3.402823466e+38 threshold adjustment 1 ATL13 ATBD, Section 5.2, Table 5-2 auxiliaryInformation Based on water body type, an adjustment to the threshold tests that must be passed in order to be identified as subsurface. Subsurface parameters 1 ATBD Table 5-2 auxiliaryInformation Coefficient multiplier of unit exponential distribution and subsurface alpha_unit maximum values of iteration loops used in deconvolution, described in section 5.3.4 (A), based on water body type. 127 bathymetry identification method 1 ATL13 ATBD, Section 5.2, Table 5-2 0 2 auxiliaryInformation Based on water body type, the method by which to identify bathymetry in the subsurface. do_not_search_for_bathymetry do_not_apply_density_threshold_coupling apply_density_threshold_coupling 0 1 2 Reference Difference meters ATBD Table 5-2 auxiliaryInformation Maximum distance from a water body that a geosegment reference photon indicates the need for overlap testing each individual photon in the geosegment 127 geosegment edge buffer 1 ATL13 ATBD, Section 5.2, Table 5-2 0 5 auxiliaryInformation Number of geosegments to include in the water surface calculation that are outside of both water body edges, as identified by reference photon location comparison to water body shapes. buffer_0 buffer_1 buffer_2 buffer_3 buffer_4 buffer_5 0 1 2 3 4 5 minimum mirror count 1 ATL13 ATBD, Section 5.2, Table 5-1 auxiliaryInformation Minimum number of signal photons required in a fully-filled long or very segment (consisting of only full member short segments) in each step of mirroring approach to estimating observed surface mean and standard deviation, designated by water body type. Short Segment Mode Frequency Test 1 ATBD Table 5-2 auxiliaryInformation Threshold to test number of short segment histogram modes against for inclusion or exclusion of short segment. 127 Type to Process 1 ATL13 ATBD, Section 4.7.1.2, Table 5-4 0 1 auxiliaryInformation Water body types that are to be processed by the ATL13 algorithm. This parameter is a rank 1 array of extent 9, with the body type digits coinciding with the array subscripts 1 through 9. Array elements are binary values, if 0 then process body type, 1 otherwise. Water body types are described in ATL13 chapter 4.7.1.2 and in Table 5-4. process_type otherwise 0 1 Apply mirror scheme 1 ATL13 ATBD, Section 5.2, Table 5-2 0 1 auxiliaryInformation By water body type, designation as to whether or not to apply the multi-step mirroring scheme for surface estimation, where 0= do not apply mirroring and 1=process water body through mirroring steps. do_not_apply_mirroring process_through_mirroring 0 1 Signal Confidence Threshold 1 ATBD Table 5-2 auxiliaryInformation Minimum signal confidence required for photon to be included in analysis 127 Size to Process 1 ATL13 ATBD, Section 4.7.1.2, Table 5-4 0 1 auxiliaryInformation Water body sizes that are to be processed by the ATL13 algorithm for each water body type. This parameter is a rank 2 array of size 9x9, where array subscripts 1 through 9, coincide with body type digits along columns, and body size digits along rows. Array elements are binary values, if 0 then process body size for that type, 1 otherwise. Water body sizes are described in ATL13 chapter 4.7.1.2 and in Table 5-4. process_size otherwise 0 1 Subsurface parameters 1 ATBD Table 5-2 auxiliaryInformation Coefficient multiplier of unit exponential distribution and subsurface alpha_unit minimum values of iteration loops used in deconvolution, described in section 5.3.4 (A), based on water body type. 3.402823466e+38 bin count ratio 1 ATL13 ATBD, Section 5.2, Table 5-2 auxiliaryInformation Based on water body type, the required bin counts that must exist above and inclusive of a subsurface bin relative to the count of the entire column in order to qualify as possible bottom. Subsurface parameters 1 ATBD Table 5-2 auxiliaryInformation Iteration loop coefficient multiplier of unit exponential distribution and subsurface alpha_unit step increments used in deconvolution, described in section 5.3.4 (A), based on water body type. Gaussian Peak Threshold 1 ATBD Table 5-2 auxiliaryInformation Fraction of the peak amplitude above which Gaussian fit error analysis is executed (ie, calculate error on Gaussian only between the peak amplitude and gauss_pk_thres * peak) 127 Short segment mode count test 1 ATBD Table 5-2 7 10 referenceInformation Threshold to test number of values contained in short segment histogram multimodes against for inclusion or exclusion of short segment sseg_stdev_thres_1 sseg_stdev_thres_2 sseg_stdev_thres_3 sseg_stdev_thres_4 sseg_stdev_thres_5 sseg_stdev_thres_6 10 10 7 7 7 7 127 Shore buffer 1 ATL13 ATBD, Section 5.2, Table 5-2 0 1 auxiliaryInformation Number of near-shore short segments to ignore in analysis due to near-shore influences. buffer_0 buffer_1 0 1 Num Depth Bins C meters ATBD Table 5-2 auxiliaryInformation Number of bins over which to calculate moving average Background Threshold counts/sec ATBD Table 5-2 auxiliaryInformation Thresholds outside of which computed background is flagged (High, Low). refractive index of water 1 ATL13 ATBD Section 5.3.2 C auxiliaryInformation Refractive index of water for a processed water body. Minimum Distance Thres meters ATBD Table 5-2 auxiliaryInformation Minimum distance threshold between photons required for inclusion in algorithm. Max Geoseg Search Radius 1 ATBD Table 5-2 auxiliaryInformation Maximum number of geosegments in either direction to search for reported water surface heights 3.402823466e+38 Short Segment Length Test meters ATBD Table 5-2 1. 500. auxiliaryInformation Threshold by which to test the length of a short segment to determine anomalous or not anomalous, varying by water body type. Num Depth Bins A meters ATBD Table 5-2 auxiliaryInformation Number of depth bins over which to compute H_mavg_a Signal Window Bottom meters ATBD Table 5-2 auxiliaryInformation Lower limit below coarse water surface to include photons for analysis. 3.402823466e+38 iteration loop minimum values 1 ATBD Table 5-2 auxiliaryInformation Amplitude, mean, and sigma minimum values of iteration loops used in deconvolution described in section 5.3.4(B) Minimum photon count for downscaling bottom 1 ATBD Table 5-2 auxiliaryInformation Minimum number of photons required to calculate a valid mean while downscaling a found bottom into short segment rate output. 127 Skip factor for surface iterated convolution 1 ATBD Table 5-2 auxiliaryInformation Number of amplitude, mean height and standard deviation values skipped based on body type, within coarse iteration loops of amplitude, HM_unit and sigma_unit used in deconvolution described in section 5.3.4 (B), to determine an approximate error minimum location over the surface profile range. Fresnel Coeff 1 ATBD Table 5-2 auxiliaryInformation Fresnel specular reflection coefficient @ 532 nm Short Segment Mode Spread Test meters ATBD Table 5-2 auxiliaryInformation Threshold to test distance between short segment histogram multimodes against for inclusion or exclusion of short segment. Anomaly Test meters ATBD Table 5-2 auxiliaryInformation Array containing threshold values against which to test segments for heights that are anomalous to the rest of the water surface. The anmly_test value is selected based on the corresponding length of the water body crossing, calculated in the code as iw_bdy_xlen_flag. The mode of each segment histogram will be tested against ht_water_coarse and marked as anomalous if the difference is greater than the anomaly test value associated with the segment crossing length. Num Depth Bins B meters ATBD Table 5-2 auxiliaryInformation Number of depth bins over which to compute H_mavg_b Limit histogram depth analysis 1 ATL13 ATBD, Section 5.2, Table 5-2 0 1 auxiliaryInformation By water body type, designation as to whether or not to limit the initial short segment histogram depth analysis by range_hist_depth, where 0= do not limit depth range and 1= limit the depth range consideration by range_hist_depth. do_not_limit_depth_range limit_depth_range 0 1 Long Bin Size meters ATBD Table 5-2 auxiliaryInformation Bin size to be used by which to establish a histogram of long segments. 3.402823466e+38 iteration loop increments 1 ATBD Table 5-2 auxiliaryInformation Iteration loop amplitude, mean, and sigma step increments used in deconvolution described in section 5.3.4(B) Detrend Bin Size meters ATBD Table 5-2 auxiliaryInformation Bin size used to establish a band of heights over which to determine the detrending equation. ATM Background Window Bottom meters ATBD Table 5-2 auxiliaryInformation Lower limit of height above coarse water surface height for atmospheric background count calculation. Num Depth Bins D meters ATBD Table 5-2 auxiliaryInformation Number of depth bins over which to compute P_ht_long_subsurf_mavg array index for refractive index of water 1 ATL13 ATBD Section 5.3.2 C auxiliaryInformation Array indices denoting refractive index of water for a processed water body. 3.402823466e+38 iteration loop maximum values 1 ATBD Table 5-2 auxiliaryInformation Amplitude, mean, and sigma maximum values of iteration loops used in deconvolution described in section 5.3.4(B) 2147483647 Long Surface Segment Size 1 ATBD Table 5-2 10 5000 auxiliaryInformation Long segment size, operationally used as unit length over which to detrend the water surface, characterize the surface, and deconvolve the instrument pulse and subsurface effects from the water surface response. Signal Window Top meters ATBD Table 5-2 auxiliaryInformation Upper limit above coarse water surface to include photons for analysis. bin count below apparent bottom height 1 ATBD Table 5-2 auxiliaryInformation Number of bins below the long segment derived apparent bottom height over which to include member photons in short segment scale bottom finding adjustment. LSBR Threshold 1 ATBD Table 5-2 auxiliaryInformation Threshold at which the LSBR indicates a significant transition from signal photon richness to noise. 2147483647 Long subsurface segment size 1 ATBD Table 5-2 30 15000 auxiliaryInformation Long segment size, operationally used as unit length over which to characterize the subsurface, and deconvolve the instrument pulse and subsurface effects from the water surface response. Small Segment Height Bin Size meters ATBD Table 5-2 auxiliaryInformation Bin size to be used for histogramming of small segment heights. Shore buffer short segment length 1 ATL13 ATBD, Section 5.2, Table 5-2 auxiliaryInformation Maximum length of a short segment that can be marked as anomalous due to shore buffering. Limiting depth for histogram analysis 1 ATL13 ATBD, Section 5.2, Table 5-2 auxiliaryInformation Depth at which to limit the initial short segment histogram analysis, if utilized for the body type as designated by limit_hist_depth. Contains general ancillary parameters. 1.7976931348623157e+308 Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of reporting location for all short segment statistics. delta_time segment_lat Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of reporting location for all short segment statistics. delta_time segment_lon Delta Time time seconds since 2018-01-01 ATL03 physicalMeasurement 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. segment_lat segment_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. delta_time segment_lat segment_lon 1.7976931348623157e+308 Distance from equator to segment start Along-track distance meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Along-track distance from the equator to the first photon in the short segment. delta_time segment_lat segment_lon 127 Height Bias Fit Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The height bias fit flag is set based on the value of the goodness of fit bias estimated as the difference between the centroid elevations of the observed surface water histogram and fitted integrated water surface model histogram. The flag values are set as follows: = -3 if H_bias_fit < -0.10 (m); -2 if -0.10 <= H_bias_fit < -0.05;-1 when -0.05 <= H_bias_fit < -0.01; 0 if -0.01 <= H_bias_fit < 0.01 (m); 1 if 0.01 <= H_bias_fit < 0.05; 2 if 0.05 < H_bias_fit < 0.10; 3 if 0.10 <= H_bias_fit; 4 if H_bias_fit is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 equal_to_or_above_threshold6 invalid -3 -2 -1 0 1 2 3 4 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Mean longitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 127 Cloud Flag Atm 1 ATL13 ATBD, Section 5.3.5 (A) 0 10 modelResult Cloud flag from backscatter profile. delta_time segment_lat segment_lon 127 Ice Quality Flag 1 Inland Water ATBD 0 3 qualityInformation The quality flag for ice describes the likelihood of ice on the short water body surface segment. 0 for QF_Bckgrd<= 2; 1 for 2 < QF_Bckgrd<= 4; 2 for 4 < QF_Bckgrd; 3 for (4 < QF_Bckgrd and QF_Cloud=1) delta_time segment_lat segment_lon qf_bckgrd_le_2 qf_bckgrd_le_4 qf_bckgrd_gt_4 qf_bckgrd_w_cloud 0 1 2 3 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. delta_time segment_lat segment_lon 127 Body type 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Type of Inland Water Body, where 1=Lake, 2=Known Reservoir, 3=(Reserved for future use), 4=Ephemeral Water, 5=River, 6=Estuary or Bay, 7=Coastal Water, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon Lake Known_Reservoir Reserved_for_future_use Ephemeral_Water River Estuary_or_Bay Coastal_Water Reserved Reserved 1 2 3 4 5 6 7 8 9 2147483647 Body ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Identifying signature of an individual inland water body. Each body of water is represented by a unique numeric value. delta_time segment_lat segment_lon End longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 127 Subsurface attenuation quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface attenuation was constrained during deconvolution by the minimum (initial) limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the subsurface attenuation fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for subsurface attenuation is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 2147483647 Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP delta_time segment_lat segment_lon 3.402823466e+38 Segment Geoid meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Applicable mean-tide system geoid value at reporting location for all short segment statistics. (see geoid_free2mean to convert to the tide-free system.) delta_time segment_lat segment_lon 127 Short Segment Length flag 1 Inland Water ATBD 0 9 qualityInformation Length of short segments flag. The flag is set as follows: 0 if sseg_length < 10 (meters); 1 if 10 <= sseg_length < 20 (meters); 2 if 20 <= sseg_length < 30 (meters); 3 if 30 <= sseg_length < 50 (meters); 4 if 50 <= sseg_length < 75 (meters); 5 if 75 <= sseg_length < 100 (meters); 6 if 100 <= sseg_length < 150 (meters); 7 if 150 <= sseg_length < 200 (meters); 8 if 200 <= sseg_length < 300 (meters); 9 if 300 <= sseg_length. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 below_threshold9 equal_to_or_above_threshold9 0 1 2 3 4 5 6 7 8 9 Start longitude longitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Longitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 Segment Tide Equilibrium meters ATL03 auxiliaryInformation Long period equilibrium tide self-consistent with ocean tide model (+- 0.04 m). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 127 Long Segment Length flag 1 Inland Water ATBD 0 3 qualityInformation The Long Segment Length flag is set based on the length of the long segment. The flag is set as follows: 0 if Lseg_length < 500 (meters); 1 if 50 <= Lseg_length < 1500 (meters); 2 if 150 <= Lseg_length < 3000 (meters); 3 if 3000 <= Lseg_length delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 above_threshold4 0 1 2 3 3.402823466e+38 SWH meters section 5.3.3 (C) physicalMeasurement Significant wave height delta_time segment_lat segment_lon 1.7976931348623157e+308 Bottom latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. delta_time segment_lat segment_lon 127 Subsurface backscatter amplitude quality flag 1 ATL13 ATBD, Section 5.3.4 (A) -2 2 qualityInformation Quality flag indicating whether or not the reported subsurface backscatter amplitude was constrained during deconvolution by the minimum limit in the possible range (QF=-1), the maximum limit in the possible range (QF = 1), or was allowed to settle on a solution within the possible range (QF=0). For analysis prior to deconvolution of the backscatter amplitude fit to the observations, the flag indicates whether the value determined by attempting to fit the observations was below (QF= -2), above (QF= 2), or within (QF=0) the possible range of expected values. When the default value for backscatter amplitude is chosen due to any condition other than those defined by an existing quality flag, QF=invalid. delta_time segment_lat segment_lon obs_fit_below_range initial_limit within_range maximum_limit obs_fit_above_range -2 -1 0 1 2 3.402823466e+38 Water depth meters ATL13 ATBD, Section 5.3.4 (A) referenceInformation Depth from the mean water surface to detected bottom. delta_time segment_lat segment_lon 127 EM Bias Quality Flag 1 Inland Water ATBD -3 4 qualityInformation The Electromagnetic Bias flag is set based on threshold checks for the estimated electromagnetic height bias. The flag is set as follows: -3 if H_bias_EM < -0.10 (m); -2 if -0.10 < H_bias_EM < -0.05; -1 if -0.05 <= H_bias_EM < -0.01; 0 if -0.01 <= H_bias_EM < 0.01 (m); 1 if 0.01 <= H_bias_EM < 0.05; 2 if 0.05 <= H_bias_EM < 0.10; 3 if 0.10 < H_bias_EM; 4 if H_bias_EM is invalid. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 above_threshold6 invalid -3 -2 -1 0 1 2 3 4 Last ATL03 Segment ID 1 ATL03 referenceInformation Last ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the very long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Apparent height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Apparent height of the short segment, before adjustments are made by the algorithm, based on an average of heights within a designated range of the short segment mode. delta_time segment_lat segment_lon 3.402823466e+38 Surface StDev meters section 5.3.3 (C) referenceInformation Derived standard deviation of water surface, calculated over long segments (when available) with result reported at each short segment location tag contained within. delta_time segment_lat segment_lon 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height from ATL09 input. delta_time segment_lat segment_lon 127 Inland Water Segment Processing Flag 1 Inland Water ATBD 1 7 qualityInformation Describes the level of processing the inland water algorithm was able to perform based on the data available, ranging from one to 7. delta_time segment_lat segment_lon 1_short_segment 2_short_segments 3_to_5_short_segments 6_to_7_short_segments 8_to_9_short_segments 10_to_29_short_segments at_least_30_short_segments 1 2 3 4 5 6 7 0 POD_PPD Flag 1 ATL02, ANC04, ANC05 0 7 referenceInformation Composite POD/PPD flag that indicates the quality of input geolocation products for the utilized ATL03 segments on an ATL13 short segment output basis. A non-zero value may indicate that geolocation solutions are degraded or that ATLAS is within a calibration scan period (CAL). The ATL03 sigma values should indicate the degree of uncertainty associated with the degradation. Possible non-CAL values are: 0=NOMINAL; 1=POD_DEGRADE; 2=PPD_DEGRADE; 3=PODPPD_DEGRADE; possible CAL values are: 4=CAL_NOMINAL; 5=CAL_POD_DEGRADE; 6=CAL_PPD_DEGRADE; 7=CAL_PODPPD_DEGRADE; delta_time nominal pod_degrade ppd_degrade podppd_degrade cal_nominal cal_pod_degrade cal_ppd_degrade cal_podppd_degrade 0 1 2 3 4 5 6 7 127 Height adjustment Quality Flag 1 ATL13 ATBD, Section 5.3.5 (C) -4 5 qualityInformation Flag representing the range of height, defined in 5.3.5 (C), which has been added to the apparent surface height due to frame of reference scaling during deconvolution analysis. delta_time segment_lat segment_lon below_threshold1 below_threshold2 below_threshold3 below_threshold4 below_threshold5 below_threshold6 below_threshold7 below_threshold8 equal_to_or_above_threshold8 invalid -4 -3 -2 -1 0 1 2 3 4 5 3.402823466e+38 Full Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be fully saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon First ATL03 Segment ID 1 ATL03 referenceInformation First ATL03 segment_id associated with the photons within this inland water segment. delta_time segment_lat segment_lon 127 Subsurface Anomaly Quality Flag 1 Inland Water ATBD 5.3.4(A) 1 3 qualityInformation Describes the likelihood that the bottom or other subsurface anomaly is bottom based on the threshold value at which an anomaly was found. 1 = Subsurface anomaly due to bottom likely; 2 = Subsurface signal may indicate bottom or other anomaly; 3 = Possible subsurface anomaly; invalid = No subsurface anomaly detected delta_time segment_lat segment_lon bottom_likely bottom_or_other_anomaly possible_subsurface_anomaly 1 2 3 3.402823466e+38 Subsurface Attenuation m^-1 Section 5.3.4 (A) physicalMeasurement Subsurface attenuation coefficient. delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL13 ATBD, Section 5.3.5 (A) 0 1 qualityInformation Consolidated cloud flag. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 2147483647 Body region 1 ATL13 ATBD, Section 5.3.1 (A) referenceInformation ATL13-created shapefile representing relevant bodies of water over which to implement the ATL13 water surface finding algorithm only within a region of processing interest. delta_time segment_lat segment_lon End latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -180. 180. referenceInformation Latitude at which the short segment ends. May be a signal or non-signal photon. delta_time segment_lat segment_lon 1 ATL13 ATBD, Section 5.3.5 (A) 0 5 modelResult Cloud probability from ASR. delta_time segment_lat segment_lon clear_with_high_confidence clear_with_medium_confidence clear_with_low_confidence cloudy_with_low_confidence cloudy_with_medium_confidence cloudy_with_high_confidence 0 1 2 3 4 5 127 Cloud Flag ASR 127 Ice Flag 1 ATL13 ATBD, section 5.2 0 1 qualityInformation Describes likelihood of ice on water surface short segment. delta_time segment_lat segment_lon no_ice ice 0 1 Start latitude latitude degrees ATL13 ATBD, Section 5.3.2 (C) -90. 90. referenceInformation Latitude at which the short segment begins. May be a signal or non-signal photon. delta_time segment_lat segment_lon 3.402823466e+38 elevation elevation radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation Elevation of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from east-north plane and positive towards up. delta_time segment_lat segment_lon 3.402823466e+38 Apparent StDev meters section 5.3.2 (C) referenceInformation Standard deviation of short segment photon height in the short segment with signal classification >= sig_threshold. delta_time segment_lat segment_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height EGM2008 converted from ellipsoidal height. delta_time segment_lat segment_lon 3.402823466e+38 Maximum likelihood alpha m^-1 Section 5.3.4 (A) physicalMeasurement Alpha calculated by maximum likelihood analysis of the subsurface profile range. delta_time segment_lat segment_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. delta_time segment_lat segment_lon 3.402823466e+38 Water surface height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Water surface height, reported for each short segment (default length = approximately 100 signal photons) with reference to WGS84 ellipsoid delta_time segment_lat segment_lon 3.402823466e+38 Near Saturation Fraction 1 ATL13 ATBD, Section 5.2 0. 1. qualityInformation The fraction of pulses within the short segment determined to be nearly saturated based on ATL03 geosegment rate input. delta_time segment_lat segment_lon 1 3.402823466e+38 Height Error section 5.3.3 (C) qualityInformation Error included in heights reported in ht_water_surf. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of actual bottom location, based on the apparent bottom sseg_mean_lat / sseg_mean_lon location corrected for refraction effects. delta_time segment_lat segment_lon 3.402823466e+38 Goodness of fit bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Bias contribution from goodness of observation/system response fit. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id delta_time segment_lat segment_lon 127 Consolidated cloud flag 1 ATL09 0 1 qualityInformation 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. From the ATL09 data closest to the segment time. delta_time segment_lat segment_lon likely_clear likely_cloudy 0 1 127 Body source 1 ATL13 ATBD, Section 5.3.1 (C) 1 9 referenceInformation Source of Inland Water Body shape, where 1=HydroLAKES, 2=Global Lakes and Wetlands Database, 3=Named Marine Water Bodies, 4=GSHHG Shoreline, 5=Global River Widths from Landsat, 6=Reserved, 7=Reserved, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon HydroLAKES Global_Lakes_and_Wetlands_Database Named_Marine_Water_Bodies GSHHG_Shoreline Global_River_Widths_from_Landsat Reserved Reserved Reserved Reserved 1 2 3 4 5 6 7 8 9 1.7976931348623157e+308 Segment length Length meters ATL13 ATBD, Section 5.3.2 (C) referenceInformation Distance from the first to the last photon in the short segment. delta_time segment_lat segment_lon 3.402823466e+38 Earth Tide Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Segment rate value to convert solid earth tide from the tide-free system that was applied in ATL03 to photon heights to the ht_water_surf to the mean-tide system. Subtract value from ht_water_surf to reference it in the mean-tide system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 observed standard deviation quality flag 1 ATL13 ATBD, Section 5.3.5 0 9 qualityInformation Quality flag indicating the magnitude of standard deviation (SD) of observed detrended heights of the long segment to which the short segment belongs, where 0: SD < 0.5 (meters), 1: 0.5 <= SD < 1.5, 2: 1.5 <= SD < 2.5, 3: 2.5 <= SD < 3.5, 4: 3.5 <= SD < 4.5, 5: 4.5 <= SD < 5.5, 6: 5.5 <= SD < 6.5, 7: 6.5 <= SD < 7.5, 8: 7.5 <= SD < 8.5, 9: 8.5 <= SD. It is recommended that a user consider this flag in conjunction with the water body type and size to best determine if the observed surface standard deviation is reasonable or whether results should be considered questionable. delta_time segment_lat segment_lon SD_below_0.5 SD_below_1.5 SD_below_2.5 SD_below_3.5 SD_below_4.5 SD_below_5.5 SD_below_6.5 SD_below_7.5 SD_below_8.5 SD_greater_or_equal_to_8.5 0 1 2 3 4 5 6 7 8 9 1 ATL13 ATBD, Section 5.3.5 0 4 referenceInformation Flag equal to the source of the selected photon (in hierarchy of Arctic/Global/MSS/Antarctic). Values: 0=None, 1=Arctic, 2=Global, 3=MSS, 4=Antarctic. delta_time segment_lat segment_lon none arctic global mss antarctic 0 1 2 3 4 2147483647 dem source flag 1.7976931348623157e+308 First photon bias correction meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation First photon bias correction. May be applied at user disrection by subtracting from mean height produts ht_ortho and ht_water_surf. delta_time segment_lat segment_lon 3.402823466e+38 Azimuth azimuth radians ATL13 ATBD, Section 5.3.5 (A) auxiliaryInformation 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). When the spacecraft is precisely at the geodetic zenith, the value will be 99999 degrees. delta_time segment_lat segment_lon 127 Body size 1 ATL13 ATBD, Section 5.3.1 (C) 0 9 referenceInformation Size of Inland Water Body, A=area, where 0=Not_Assigned, 1=A>10,000 sq km, 2=10,000>A>=1,000, 3=1,000>A>=100, 4=100>A>=10, 5=10>A>=1, 6=1>A>=0.1, 7=0.01>A, 8=Reserved, 9=Reserved delta_time segment_lat segment_lon not_assigned area_gt_10000 10000_gt_area_ge_1000 1000_gt_area_ge_100 100_gt_area_ge_10 10_gt_area_ge_1 1_gt_area_ge_0.1 0.01_gt_area Reserved Reserved 0 1 2 3 4 5 6 7 8 9 3.402823466e+38 Wind speed magnitude at 10m Wind speed m/s ATL13 ATBD, Section 5.3.5 (A) referenceInformation Wind speed magnitude at 10m height, based on derived water surface wave height. delta_time segment_lat segment_lon 2147483647 Snow Ice Flag 1 ATL13 ATBD, Section 5.3.5 (A) modelResult NOAA snow/ice flag scaled by ATL09 (0=ice-free water, 1=snow-free land, 2=snow, 3=ice, 127=invalid) delta_time segment_lat segment_lon ice_free_water snow_free_land snow ice invalid 0 1 2 3 127 3.402823466e+38 Segment Tide Ocean meters ATL03 auxiliaryInformation Ocean tides including diurnal and semi-diurnal (harmonic analysis (+-4 m)). Although available at short segment rate for all water body types, value is provide mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon 3.402823466e+38 Slope Error 1 section 5.3.3 (C) qualityInformation Error included in segment_slope_trk_local. delta_time segment_lat segment_lon 3.402823466e+38 Water Body Slope m/m ATL13 ATBD, Section 5.3.5 (A) physicalMeasurement Along track water body surface slope, reported per short segment ID per water body. delta_time segment_lat segment_lon 1.7976931348623157e+308 Mean latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Mean latitude of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Geoid Free-to-Mean conversion meters ATL03 ATBD, Section 6.3.8 auxiliaryInformation Value to convert segment geoid heights from the mean-tide system to the tide-free system. Subtract this value from mean-tide system segment_geoid (on ATL13) to get geoid heights in the tide-free system. Applicable value at reporting location for all short segment statistics. delta_time segment_lat segment_lon 127 Spectral width Flag 1 ATL13 ATBD, Section 4.8.8 0 9 qualityInformation Spectral moments width flag. The flag is set as follows: 0 when spec_width is invalid; 1 when 0 <= spec_width <= 0.2; 2 when 0.2 < spec_width <= 0.3; 3 when 0.3 < spec_width <= 0.4; 4 when 0.4 < spec_width <= 0.5; 5 when 0.5 < spec_width <= 0.6; 6 when 0.6 < spec_width <= 0.7; 7 when 0.7 < spec_width <= 0.8; 8 when 0.8 < spec_width <= 0.9; 9 when 0.9 < spec_width. delta_time segment_lat segment_lon invalid 0<=spec_width<=0.2 0.2<spec_width<=0.3 0.3<spec_width<=0.4 0.4<spec_width<=0.5 0.5<spec_width<=0.6 0.6<spec_width<=0.7 0.7<spec_width<=0.8 0.8<spec_width<=0.9 0.9<spec_width 0 1 2 3 4 5 6 7 8 9 127 Background Quality Flag 1 Inland Water ATBD 0 6 qualityInformation Describes the degree of background photons present in each short segment. bckgrd_dnsty_threshold1= 0.001 (counts per bi per Lseg); bckgrd_dnsty_threshold2= 0.01 (counts per bin per Lseg); bckgrd_dnsty_threshold3= 0.05 (counts per bin per Lseg); bckgrd_dnsty_threshold4= 0.1 (counts per bin per Lseg); bckgrd_dnsty_threshold5= 0.3 (counts per bin per Lseg); bckgrd_dnsty_threshold6= 0.5 (counts per bin per Lseg) delta_time segment_lat segment_lon equal_to_or_below_threshold1 equal_to_or_below_threshold2 equal_to_or_below_threshold3 equal_to_or_below_threshold4 equal_to_or_below_threshold5 equal_to_or_below_threshold6 above_threshold6 0 1 2 3 4 5 6 1.7976931348623157e+308 Mean time time Seconds since 2018-01-01 ATL13 ATBD, Section 5.3.5 (A) referenceInformation Mean time of the signal-qualified photons in a short segment. delta_time segment_lat segment_lon 3.402823466e+38 Surface temperature temperature K ATL13 ATBD, Section 5.3.5 (A) referenceInformation Surface (skin) temperature from ATL09. delta_time segment_lat segment_lon 1.7976931348623157e+308 Electromagnetic bias meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Electromagnetic bias. (Has been applied to ht_ortho and _ht_water_surf products) delta_time segment_lat segment_lon 3.402823466e+38 DEM Height meters ATL13 ATBD, Section 5.3.5 referenceInformation DEM height relative to WGS-84 ellipsoid, reported at the short segment rate. delta_time segment_lat segment_lon 3.402823466e+38 Subsurface backscatter amplitude 1 Section 5.3.4 (A) modelResult Subsurface backscatter amplitude, described in section 4.5.3, reported per long segment (default length = 10 short segments = approximately 1000 signal photons). delta_time segment_lat segment_lon 3.402823466e+38 Segment DAC meters ATBD Section 5.3.5A auxiliaryInformation Dynamic atmospheric correction (DAC) includes inverted barometer (IB) effect (+- 5 cm). Although available at short segment rate for all water body types, value is provided mainly for transitional tidal and coastal water (types 6 and 7) and the largest lakes of Type 1 (~> 10,000 km2) for user's discretion. delta_time segment_lat segment_lon delta_time Contains per-beam data products. Data within this group are stored at the inland water short segment rate (/ancillary_data/inland_water/s_seg2). pce1 strong gt3r profile_3 1 Forward Latitude latitude degrees ATL13 ATBD, Section 5.3.5 (A) -90. 90. referenceInformation Latitude of the short segment (mean of signal class >=2 ph Lats). anom_sseg_time anom_sseg_lon Delta Time time sec ATL13 ATBD, Table 5-4b physicalMeasurement Time of the short segment (mean of signal class >=2 ph time). anom_sseg_lat anom_sseg_lon Longitude longitude degrees ATL13 ATBD, Section 5.3.5 (A) -180. 180. referenceInformation Longitude of the short segment (mean of signal class >=2 ph Lons). anom_sseg_time anom_sseg_lat 127 Transect ID 1 ATL13 ATBD, Section 5.3.2 (C) referenceInformation Transect within a water body to which the short segment rate output belongs. anom_sseg_time anom_sseg_lat anom_sseg_lon Cycle Number counts ATL03 0 50 referenceInformation 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 1,387 and adding the RGT value. anom_sseg_time anom_sseg_lat anom_sseg_lon Reference Ground track 1 ATL03 1 1387 referenceInformation 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 1,387 RGTs. anom_sseg_time anom_sseg_lat anom_sseg_lon 9223372036854775807 Signal photon count 1 ATL13 ATBD, Section 5 1 500 referenceInformation Count of signal photons in short segment, full or partial. anom_sseg_time anom_sseg_lat anom_sseg_lon 127 Anomalous classification flag 1 ATL13 ATBD, Table 5-4b 0 1 qualityInformation Nine element array describing justification for short segment classification as anomalous, where for each element 0 = not triggered as anomalous and 1 = triggered as anomalous due to any of the following causes: [element 1=coarse ht difference, element 2=abnormal length, element 3= histogram mode spread, element 4=histogram mode count, element 5=histogram mode intensity, element 6=invalid long segment, element 7=shore buffer designation, element 8=insufficient signal phs, element 9=transect coarse water height unavailable against which to test short segment height] anom_sseg_time anom_sseg_lat anom_sseg_lon not_triggered_as_anomalous triggered_as_anomalous 0 1 3.402823466e+38 Segment standard deviation meters ATL13 ATBD, Table 5-4b referenceInformation Standard deviation of anomalous short segment photon height in the anomalous short segment with signal classification >= 2. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Height difference meters ATL13 ATBD, Table 5-4b referenceInformation Height difference between anom_sseg_mode of the anomalous short segment and the transect coarse_transect_ht. anom_sseg_time anom_sseg_lat anom_sseg_lon 1.7976931348623157e+308 Segment length meters ATL13 ATBD, Table 5-4b referenceInformation Length of the short segment, based on end points computed by the average of sseg_endpoint_avg_n signal photons. anom_sseg_time anom_sseg_lat anom_sseg_lon End longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation End longitude of the anomalous short segment, based on the average longitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Coarse water height meters ATL13 ATBD, Table 5-4b referenceInformation Coarse water height of transect. anom_sseg_time anom_sseg_lat anom_sseg_lon 0 ATL13 Reference ID 1 ATL13 ATBD, Section 5.3.1 (C) referenceInformation Unique aggregate reference number for each shape in the ATL13 Inland Water Body Mask, where digit 1 = type, digit 2 = size, digit 3 = source, and digits 4-10 = shape id. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Anomalous mode bin height meters ATL13 ATBD, Table 5-4b referenceInformation Height of anomalous short segment as determined by histogram bin mode. anom_sseg_time anom_sseg_lat anom_sseg_lon Segment quality group count 1 ATL13 ATBD, Table 5-4b referenceInformation Four-element array of describing, for each anomalous short segment n, the count of photons qualifying in each quality group. (n,1) = nominal, (n,2) = possible afterpulse, (n,3) = possible impulse response effect, (n,4) = possible TEP anom_sseg_time anom_sseg_lat anom_sseg_lon 2147483647 Start longitude longitude degrees ATL13 ATBD, Table 5-4b -180. 180. referenceInformation Start longitude of the anomalous short segment, based on the average longitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon 3.402823466e+38 Orthometric Height meters ATL13 ATBD, Section 5.3.5 (A) referenceInformation Orthometric height of anomalous short segment as determined by the mean of photon orthometric heights in the anomalous short segment with signal classification >2 anom_sseg_time anom_sseg_lat anom_sseg_lon Start latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation Start latitude of the anomalous short segment, based on the average latitude of the first sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon End latitude latitude degrees ATL13 ATBD, Table 5-4b -90. 90. referenceInformation End latitude of the anomalous short segment, based on the average latitude of the last sseg_endpoint_avg_n signal photons in the segment. anom_sseg_time anom_sseg_lat anom_sseg_lon anom_sseg_time Contains per-beam anomalous short segment output parameters.