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Data Set ID: 
ATL09

ATLAS/ICESat-2 L3A Calibrated Backscatter Profiles and Atmospheric Layer Characteristics, Version 5

This data set (ATL09) contains calibrated, attenuated backscatter profiles, layer integrated attenuated backscatter, and other parameters including cloud layer height and atmospheric characteristics obtained from the data. The data were acquired by the Advanced Topographic Laser Altimeter System (ATLAS) instrument on board the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) observatory.

This is the most recent version of these data.

Version Summary: 

Changes for this version include:

  • Added new routine process_blow_snow_dens to compute blowing snow height and diamond dust heights based on methods defined in the Density Dimension Algorithm (DDA) ATBD. bsnow_h_dens now has valid values when the DDA detects blowing snow.
  • Added constants bs_quartile, bs_gap, bs_bin_thresh, dd_min_top_bin, dd_bin_thresh, bs_thresh_sens, bs_thresh_bias, bs_downsample, bs_thresh_seg_len to ATL09.
  • Added parameters bsnow_dens_flag, ddust_htop_dens, ddust_hbot_dens to ATL09.
  • Added parameter podppd_flag to ATL09. podppd_flag provides identification of ATLAS data in nominal geolocation quality status or a degraded quality. podppd_flag =0 means geolocation is in reference ground track pointing with normal quality. podppd_flag =4 means geolocation is in around-the-world scan or ocean scan with normal quality. Other values are degraded quality.
  • Set Fill Value to 127 for snow_ice on ATL09.
  • Density Dimension Algorithm (DDA) processing is now done on same solar elevation sub-chunks (day, night, twilight) rather than using the first solar elevation per processing chunk.
  • Added check on invalid aclr_true and raised limit of aclr_clim to prevent errors.
  • Changed dead time correction algorithm used to correct the surface signal magnitude. This should improve the accuracy of the parameter surface_sig. This improved Apparent Surface Reflectivity (ASR) accuracy.
  • Replaced ANC32 surface reflectance map based on GOME with one generated from actual ICESat-2 ASR measurements in clear (no cloud or aerosol layers) conditions. This should increase the accuracy of ASR-based cloud detection and column optical depth measurements.

COMPREHENSIVE Level of Service

Data: Data integrity and usability verified; data customization services available for select data

Documentation: Key metadata and comprehensive user guide available

User Support: Assistance with data access and usage; guidance on use of data in tools and data customization services

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Parameter(s):
  • CLOUDS > CLOUD PROPERTIES
  • LIDAR > LIDAR BACKSCATTER
Data Format(s):
  • HDF5
Spatial Coverage:
N: 90, 
S: -90, 
E: 180, 
W: -180
Platform(s):ICESat-2
Spatial Resolution:
  • 280 m
Sensor(s):ATLAS
Temporal Coverage:
  • 13 October 2018
Version(s):V5
Temporal Resolution91 dayMetadata XML:View Metadata Record
Data Contributor(s):Steve Palm, Yeukui Yang, Ute Herzfeld, David Hancock, Kristine Barbieri, et al

Geographic Coverage

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As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Palm, S. P., Y. Yang, U. C. Herzfeld, D. Hancock, K. A. Barbieri, J. Wimert, and the ICESat-2 Science Team. 2021. ATLAS/ICESat-2 L3A Calibrated Backscatter Profiles and Atmospheric Layer Characteristics, Version 5. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/ATLAS/ATL09.005. [Date Accessed].

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