ATLAS/ICESat-2 L3A Calibrated Backscatter Profiles and Atmospheric Layer Characteristics, Version 3
Data set id:
ATL09
DOI: 10.5067/ATLAS/ATL09.003
There is a more recent version of these data.
Version Summary
Version Summary
Changes for this version include:
- A new parameter was added to the equation used to compute blowing snow. The algorithm detects blowing snow at two rates -- high (25 Hz) and low (1 Hz) -- however, the optimal threshold for low rate detection was found to be different (lower) than for high rate detection. The new parameter (ancillary_data/atmosphere/lr_bsnow_fac) adjusts the low rate detection threshold and improves retrievals. The new parameter's nominal value of 0.5 is adjustable.
- Low-rate blowing snow height (profile_[x]/low_rate/bsnow_h) is now computed as defined in the ATBD for ATL04 (section 4.5.1 | Blowing Snow layer Height).
- The value for the high rate blowing snow threshold constant (ancillary_data/atmosphere/bs_thresh_scale) was changed from 10.0 to 20.0 to reduce blowing snow detections.
- A new parameter for blowing snow intensity (profile_[x]/high_rate/bsnow_intensity) was added to the product; it is defined as the average scattering ratio within the blowing snow layer multiplied by the 10 m level wind speed.
- ATL09 was updated to accommodate the new pass-through constant (alpha) added to ATL04.
- The single scaling constant phi, used to define a threshold in the apparent surface reflectance (ASR) cloud detection algorithm, was replaced by two constants, phi_land and phi_ocean. These new scaling parameters allow for different thresholds over land and ocean to address analyses that indicate the algorithm was reporting too many clouds over land and too few over ocean.
- Areas masked out in ATL04 due to dense clouds were not being properly masked out in ATL09. This bug was corrected.
- The ancillary_data/atmosphere/cloud_det_layer_thick parameter was no longer needed and removed.
Overview
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.
Parameter(s):
CLOUD PROPERTIESLIDAR BACKSCATTER
Platform(s):
ICESat-2
Sensor(s):
ATLAS
Data Format(s):
HDF5
Temporal Coverage:
13 October 2018 to 11 November 2020
Temporal Resolution:
- 91 day
Spatial Resolution:
- Not Specified
Spatial Reference System(s):
WGS 84
EPSG:4326
Spatial Coverage:
N:
90
S:
-90
E:
180
W:
-180
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.
Data Access & Tools
This data set has been retired. There is a more recent version of these data.
Documentation
User Guide
ATBDs
General Resources
Product Specification Documents
Help Articles
General Questions & FAQs
This article covers frequently asked questions about the NASA NSIDC DAAC's Earthdata cloud migration project and what it means to data users.
This short article describes the customization services available for ICESat-2 data using Earthdata Search.
How to Articles
Many NSIDC DAAC data sets can be accessed using the NSIDC DAAC's Data Access Tool. This tool provides the ability to search and filter data with spatial and temporal constraints using a map-based interface.Users have the option to
To convert HDF5 files into binary format you will need to use the h5dump utility, which is part of the HDF5 distribution available from the HDF Group. How you install HDF5 depends on your operating system.
This guide will provide an overview of the altimetry measurements and data sets across the missions, as well as a guide for accessing the data through NASA Earthdata Search and programmatically using an Application Programming Interface (API).
The NASA Earthdata Cloud is the NASA cloud-based archive of Earth observations. It is hosted by Amazon Web Services (AWS). Learn how to find and access NSIDC DAAC data directly in the cloud.
All data from the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) can be accessed directly from our HTTPS file system, using wget or curl. Basic command line instructions are provided in the article below.
NASA Earthdata Search is a map-based interface where a user can search for Earth science data, filter results based on spatial and temporal constraints, and order data with customizations including re-formatting, re-projecting, and spatial and parameter subsetting.
This webinar introduces the ICESat-2 mission and shows you how to explore, access and customize ICESat-2 data with the OpenAltimetry application, using NSIDC DAAC tools, and shows you how to subset, reformat and analyze the data using Python.