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Data Set ID:
ATL04
ATLAS/ICESat-2 L2A Normalized Relative Backscatter Profiles, Version 3
ATL04 contains along-track normalized relative backscatter profiles of the atmosphere. The product includes full 532 nm (14 km) uncalibrated attenuated backscatter profiles at 25 times per second for vertical bins of approximately 30 meters. Calibration coefficient values derived from data within the polar regions are also included. 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:
- Implemented a new approach for calibration method 3 and added new constants. The new calibration method computes the calibration factor using the average normalized relative backscatter between 13 km and 11 km continuously for a complete orbit, both day and night, while screening out high values of NRB caused by clouds. This calibration method uses a number of adjustable parameters that are defined and changed by control.
- Implemented the scaling factor alpha (set to 0 in Version 2) for the molecular scattering folding correction as a function of solar angle and PCE (photon counting electronics). The changes to the molecular contribution to the received photon count can be computed from equation 3.15 in the ATBD for ATL04.
- Changed the cal_solar_elev_min and cal_solar_elev_max constants to cal_solar_elev_min = -7 and cal_solar_elev_max = -1. These changes re-define the twilight portion of the orbit for calibration method 3 and improve the data for twilight solar elevations.
- The following parameters were added to ancillary_data/atmosphere/. Each parameter is described in the file metadata and where applicable in the ATBD for ATL04: default_nrb_twilight, min_nrb_twilight, max_nrb_twilight, min_calib_twilight, max_calib_twilight, alpha_day_pce1, alpha_day_pce2, alpha_day_pce3, alpha_night_pce1, alpha_night_pce2, alpha_night_pce3, alpha_twilight_pce1, alpha_twilight_pce2, alpha_twilight_pce3.
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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Once you have logged in, you will be able to click and download files via a Web browser. There are also options for downloading via a command line or client. For more detailed instructions, please see Options Available for Bulk Downloading Data from HTTPS with Earthdata Login. Earthdata Search: This application allows you to search, visualize, and access data across thousands of Earth science data sets. Additional customization services are available for select data sets, including subsetting, reformatting, and reprojection. |
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. 2020. ATLAS/ICESat-2 L2A Normalized Relative Backscatter Profiles, Version 3. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/ATLAS/ATL04.003. [Date Accessed].How To
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