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. ATLAS Epoch Offset Operations seconds since 1980-01-06T00:00:00.000000Z atlas_sdp_gps_epoch /ancillary_data/atlas_sdp_gps_epoch auxiliaryInformation UTC (in CCSDS-A format) of the last data point within the granule. End UTC Time of Granule (CCSDS-A, Actual) Derived 1 data_end_utc /ancillary_data/data_end_utc auxiliaryInformation UTC (in CCSDS-A format) of the first data point within the granule. Start UTC Time of Granule (CCSDS-A, Actual) Derived 1 data_start_utc /ancillary_data/data_start_utc auxiliaryInformation Derived 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. Ending Cycle 1 end_cycle /ancillary_data/end_cycle 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. ATLAS End Time (Actual) Derived seconds since 2018-01-01 time end_delta_time /ancillary_data/end_delta_time 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. Ending Geolocation Segment Derived 1 end_geoseg /ancillary_data/end_geoseg auxiliaryInformation GPS seconds-of-week of the last data point in the granule. Ending GPS SOW of Granule (Actual) Derived seconds end_gpssow /ancillary_data/end_gpssow auxiliaryInformation GPS week number of the last data point in the granule. Ending GPSWeek of Granule (Actual) Derived weeks from 1980-01-06 end_gpsweek /ancillary_data/end_gpsweek auxiliaryInformation Derived 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. Ending Orbit Number 1 end_orbit /ancillary_data/end_orbit 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. Ending Region Derived 1 end_region /ancillary_data/end_region auxiliaryInformation Derived 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. Ending Reference Groundtrack 1 end_rgt /ancillary_data/end_rgt auxiliaryInformation Requested end time (in UTC CCSDS-A) of this granule. End UTC Time of Granule (CCSDS-A, Requested) Derived 1 granule_end_utc /ancillary_data/granule_end_utc auxiliaryInformation Requested start time (in UTC CCSDS-A) of this granule. Derived Start UTC Time of Granule (CCSDS-A, Requested) 1 granule_start_utc /ancillary_data/granule_start_utc 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. Release Number Operations 1 release /ancillary_data/release auxiliaryInformation ATL03 granule used to produce this granule ATL03 Resource Operations 1 resource /ancillary_data/resource auxiliaryInformation Operations Git commit ID (https://github.com/SlideRuleEarth/sliderule.git) of SlideRule software used to generate this granule SlideRule Commit 1 sliderule_commit /ancillary_data/sliderule_commit auxiliaryInformation Git commit ID (https://github.com/SlideRuleEarth/sliderule.git) of SlideRule environment used to generate this granule SlideRule Environment Operations 1 sliderule_environment /ancillary_data/sliderule_environment auxiliaryInformation Version of SlideRule software used to generate this granule SlideRule Version Operations 1 sliderule_version /ancillary_data/sliderule_version 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. Starting Cycle Derived 1 start_cycle /ancillary_data/start_cycle auxiliaryInformation Derived 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. ATLAS Start Time (Actual) seconds since 2018-01-01 start_delta_time /ancillary_data/start_delta_time auxiliaryInformation Starting Geolocation Segment Derived 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. 1 start_geoseg /ancillary_data/start_geoseg auxiliaryInformation GPS seconds-of-week of the first data point in the granule. Start GPS SOW of Granule (Actual) Derived seconds start_gpssow /ancillary_data/start_gpssow auxiliaryInformation GPS week number of the first data point in the granule. Start GPSWeek of Granule (Actual) Derived weeks from 1980-01-06 start_gpsweek /ancillary_data/start_gpsweek 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. Starting Orbit Number Derived 1 start_orbit /ancillary_data/start_orbit auxiliaryInformation Derived 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. Starting Region 1 start_region /ancillary_data/start_region 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. Starting Reference Groundtrack Derived 1 start_rgt /ancillary_data/start_rgt 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. Version Operations 1 version /ancillary_data/version modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt1l/class_ph gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt1l/confidence gt1l_delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt1l/delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement Photon WGS84 height ATL03 meters Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. ellipse_h /gt1l/ellipse_h gt1l_delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt1l/index_ph gt1l_delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt1l/index_seg gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult Invalid Kd Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt1l/invalid_kd gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt1l/invalid_wind_speed gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult Latitude degrees_north latitude 90.000000000000000 -90.000000000000000 Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. ATL03 lat_ph /gt1l/lat_ph gt1l_delta_time gt1l_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt1l/lon_ph gt1l_delta_time gt1l_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry boolean Low confidence bathymetry flag false, true 0, 1 low_confidence_flag /gt1l/low_confidence_flag gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt1l/night_flag gt1l_delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt1l/ortho_h gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt1l/sensor_depth_exceeded gt1l_delta_time gt1l_lat_ph gt1l_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt1l/sigma_thu gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt1l/sigma_tvu gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt1l/surface_h gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt1l/x_atc gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt1l/y_atc gt1l_delta_time gt1l_lat_ph gt1l_lon_ph modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt1r/class_ph gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt1r/confidence gt1r_delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt1r/delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. Photon WGS84 height ATL03 meters ellipse_h /gt1r/ellipse_h gt1r_delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt1r/index_ph gt1r_delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt1r/index_seg gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon Invalid Kd VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt1r/invalid_kd gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt1r/invalid_wind_speed gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Latitude ATL03 degrees_north latitude 90.000000000000000 -90.000000000000000 lat_ph /gt1r/lat_ph gt1r_delta_time gt1r_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt1r/lon_ph gt1r_delta_time gt1r_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry Low confidence bathymetry flag boolean false, true 0, 1 low_confidence_flag /gt1r/low_confidence_flag gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt1r/night_flag gt1r_delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt1r/ortho_h gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt1r/sensor_depth_exceeded gt1r_delta_time gt1r_lat_ph gt1r_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt1r/sigma_thu gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt1r/sigma_tvu gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt1r/surface_h gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt1r/x_atc gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt1r/y_atc gt1r_delta_time gt1r_lat_ph gt1r_lon_ph modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt2l/class_ph gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt2l/confidence gt2l_delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt2l/delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. Photon WGS84 height ATL03 meters ellipse_h /gt2l/ellipse_h gt2l_delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt2l/index_ph gt2l_delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt2l/index_seg gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon Invalid Kd VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt2l/invalid_kd gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt2l/invalid_wind_speed gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Latitude ATL03 degrees_north latitude 90.000000000000000 -90.000000000000000 lat_ph /gt2l/lat_ph gt2l_delta_time gt2l_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt2l/lon_ph gt2l_delta_time gt2l_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry Low confidence bathymetry flag boolean false, true 0, 1 low_confidence_flag /gt2l/low_confidence_flag gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt2l/night_flag gt2l_delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt2l/ortho_h gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt2l/sensor_depth_exceeded gt2l_delta_time gt2l_lat_ph gt2l_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt2l/sigma_thu gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt2l/sigma_tvu gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt2l/surface_h gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt2l/x_atc gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt2l/y_atc gt2l_delta_time gt2l_lat_ph gt2l_lon_ph modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt2r/class_ph gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt2r/confidence gt2r_delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt2r/delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. Photon WGS84 height ATL03 meters ellipse_h /gt2r/ellipse_h gt2r_delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt2r/index_ph gt2r_delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt2r/index_seg gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon Invalid Kd VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt2r/invalid_kd gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt2r/invalid_wind_speed gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Latitude ATL03 degrees_north latitude 90.000000000000000 -90.000000000000000 lat_ph /gt2r/lat_ph gt2r_delta_time gt2r_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt2r/lon_ph gt2r_delta_time gt2r_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry Low confidence bathymetry flag boolean false, true 0, 1 low_confidence_flag /gt2r/low_confidence_flag gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt2r/night_flag gt2r_delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt2r/ortho_h gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt2r/sensor_depth_exceeded gt2r_delta_time gt2r_lat_ph gt2r_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt2r/sigma_thu gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt2r/sigma_tvu gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt2r/surface_h gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt2r/x_atc gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt2r/y_atc gt2r_delta_time gt2r_lat_ph gt2r_lon_ph modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt3l/class_ph gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt3l/confidence gt3l_delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt3l/delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. Photon WGS84 height ATL03 meters ellipse_h /gt3l/ellipse_h gt3l_delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt3l/index_ph gt3l_delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt3l/index_seg gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon Invalid Kd VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt3l/invalid_kd gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt3l/invalid_wind_speed gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Latitude ATL03 degrees_north latitude 90.000000000000000 -90.000000000000000 lat_ph /gt3l/lat_ph gt3l_delta_time gt3l_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt3l/lon_ph gt3l_delta_time gt3l_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry Low confidence bathymetry flag boolean false, true 0, 1 low_confidence_flag /gt3l/low_confidence_flag gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt3l/night_flag gt3l_delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt3l/ortho_h gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt3l/sensor_depth_exceeded gt3l_delta_time gt3l_lat_ph gt3l_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt3l/sigma_thu gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt3l/sigma_tvu gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt3l/surface_h gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt3l/x_atc gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt3l/y_atc gt3l_delta_time gt3l_lat_ph gt3l_lon_ph modelResults 0 - unclassified, 1 - other, 40 - bathymetry, 41 - sea surface Photon classification ATL03 scalar class_ph /gt3r/class_ph gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult ensemble confidence score from 0.0 to 1.0 where larger numbers represent higher confidence in classification Ensemble confidence ATL03 scalar confidence /gt3r/confidence gt3r_delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement The transmit time of a given photon, measured in seconds from the ATLAS Standard Data Product Epoch. Note that multiple received photons associated with a single transmit pulse will have the same delta_time. 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. Elapsed GPS seconds ATL03 seconds since 2018-01-01 delta_time /gt3r/delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement Height of each received photon, relative to the WGS-84 ellipsoid including refraction correction. Note neither the geoid, ocean tide nor the dynamic atmosphere (DAC) corrections are applied to the ellipsoidal heights. Photon WGS84 height ATL03 meters ellipse_h /gt3r/ellipse_h gt3r_delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 heights group Photon index ATL03 scalar index_ph /gt3r/index_ph gt3r_delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement 0-based index of the photon in the ATL03 geolocation group Segment index ATL03 scalar index_seg /gt3r/index_seg gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult Indicates that no data was available in the VIIRS Kd490 8-day cycle dataset at the time and location of the photon Invalid Kd VIIRS Kd490 boolean false, true 0, 1 invalid_kd /gt3r/invalid_kd gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult Indicates that ATL09 data was not able to be read to determine wind speed Invalid wind speed ATL09 boolean false, true 0, 1 invalid_wind_speed /gt3r/invalid_wind_speed gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult Latitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Latitude ATL03 degrees_north latitude 90.000000000000000 -90.000000000000000 lat_ph /gt3r/lat_ph gt3r_delta_time gt3r_lon_ph modelResult Longitude of each received photon. Computed from the ECF Cartesian coordinates of the bounce point. Longitude ATL03 degrees_east longitude 180.00000000000000 -180.00000000000000 lon_ph /gt3r/lon_ph gt3r_delta_time gt3r_lat_ph modelResult ATL03 There is low confidence that the photon classified as bathymetry is actually bathymetry Low confidence bathymetry flag boolean false, true 0, 1 low_confidence_flag /gt3r/low_confidence_flag gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult The solar elevation was less than 5 degrees at the time and location of the photon Night flag ATL03 boolean false, true 0, 1 night_flag /gt3r/night_flag gt3r_delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement Height of each received photon, relative to the geoid. Orthometric height ATL03 meters ortho_h /gt3r/ortho_h gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult The subaqueous photon is below the maximum depth detectable by the ATLAS sensor given the Kd of the water column Sensor depth exceeded ATL03 boolean false, true 0, 1 sensor_depth_exceeded /gt3r/sensor_depth_exceeded gt3r_delta_time gt3r_lat_ph gt3r_lon_ph physicalMeasurement The combination of the aerial and subaqueous horizontal uncertainty for each received photon Total horizontal uncertainty ATL03 meters sigma_thu /gt3r/sigma_thu gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult The combination of the aerial and subaqueous vertical uncertainty for each received photon Total vertical uncertainty ATL03 meters sigma_tvu /gt3r/sigma_tvu gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult The geoid corrected height of the sea surface at the detected photon Sea surface orthometric height ATL03 meters surface_h /gt3r/surface_h gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult Along-track distance in a segment projected to the ellipsoid of the received photon, based on the Along-Track Segment algorithm. Total along track distance can be found by adding this value to the sum of segment lengths measured from the start of the most recent reference groundtrack. Distance from equator crossing ATL03 meters x_atc /gt3r/x_atc gt3r_delta_time gt3r_lat_ph gt3r_lon_ph modelResult Across-track distance projected to the ellipsoid of the received photon from the reference ground track. This is based on the Along-Track Segment algorithm described in Section 3.1 of the ATBD. Distance off RGT ATL03 meters y_atc /gt3r/y_atc gt3r_delta_time gt3r_lat_ph gt3r_lon_ph auxiliaryInformation atl24 algorithm versioning and build information ATL24 MetaData Derived json atl24 /metadata/atl24 auxiliaryInformation geospatial and temporal extents Query MetaData Derived json extent /metadata/extent auxiliaryInformation Derived sliderule server and request information SlideRule MetaData json sliderule /metadata/sliderule referenceInformation POD/PPD 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. Ascending Node Crossing Time seconds since 2018-01-01 time crossing_time /orbit_info/crossing_time 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 1387 and adding the rgt value. Cycle Number POD/PPD counts cycle_number /orbit_info/cycle_number referenceInformation Longitude at the ascending node crossing. Ascending Node Longitude POD/PPD degrees_east lan /orbit_info/lan referenceInformation Unique identifying number for each planned ICESat-2 orbit. Orbit Number Operations 1 orbit_number /orbit_info/orbit_number 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 1387 RGTs. Reference Ground Track POD/PPD counts rgt /orbit_info/rgt 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. Spacecraft Orientation POD/PPD 1 backward forward transition 0, 1, 2 sc_orient /orbit_info/sc_orient referenceInformation POD/PPD 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. Time of Last Spacecraft Orientation Change seconds since 2018-01-01 time sc_orient_time /orbit_info/sc_orient_time onGoing along-track 2025-09-27T04:46:59.000000Z 02edefa0-02ff-47fa-b2c5-3ad02bbfa856 ATL24_20241107234251_08052501_006_01_002_01.h5 002 eng utf8 ATL24 SlideRule ATL24 provides global along-track coastal and nearshore bathymetry, consisting of refraction corrected seafloor and sea surface heights (orthometric and ellipsoidal heights and instantaneous depths), as well as associated uncertainties. The purpose of ATL24 is to provide photon level classification of sea surface and seafloor for ATL03 data in coastal and nearshore regions. The ATL24 product was designed and implemented by a team led by Lori Magruder at the University of Texas at Austin, and Christopher Parrish at Oregon State University. geoscientificInformation /metadata/DatasetIdentification