ATLAS/ICESat-2 L3A Sea Ice Freeboard, Version 5 (ATL10)
Data set:
ATL10
This is the most recent version of these data.
Version Summary
Version Summary
Changes for this version include:
- The ATL10 QA check for insufficient output failure was updated. The code now checks for the number of valid freeboard ice segments and number of valid, un-interpolated, reference surfaces. Previously, the total number of freeboard ice segments written (valid and invalid) were counted, and the number of reference surfaces was not considered. A new controllable parameter, min_refsurf_count, was added to control the minimum reference surface count threshold (l3a_fb_cont_mod).
- The description of the reference surface interpolation flag has been updated to match the procedure in the atlas_l3a_fb code A controllable parameter used in the reference surface interpolation flag was also added to replace a hard coded value (max pad time).
- The height segment inverted barometer variable was moved to the geophysical group from the height segments group (it was already in the geophysical group in ATL07).
- The computation of the reference surface height has been updated to better match the description in the ATBD (essentially a minor bug fix).
- The MMS, Geoid, and the two free-to-mean parameters have been calculated at the reference surface-scale (e.g. 10 km, weighted by lead group size) and added to ATL10.
- The along track distance has been calculated at the beam reference surface and lead group scale.
- The reference surface time and location has been updated to be set to the center of the reference surface. Previously, the location was found by simply averaging data from all the segments within the 10 km sections which caused some odd behavior (skewed locations towards the sides of the sections). The reference surface lat/lon/time is now determined using interpolation. For reference surfaces set where there are no sea ice segments for a given beam, a filling procedure is used to estimate the reference surface lat/lon. The filling procedure uses a distance routine to find the lat/lon for a point a given distance from a known point, in a known direction.
- The new PODPPD flag, and updated segment_type flag, are read from ATL07 and used in filtering which sea ice segments are used in freeboard processing. Now, if there is a calibration scan maneuver occurring, the freeboard segment in ATL10 is invalidated. A new pointing angle variable is also calculated (from the co_elev variables) and is used to further filter the freeboard segments (currently default of 1 degree from nadir).
- An error in the computation of reference surface sigma values let to missing sigma variables for individual freeboard segments. The error was corrected by simply interpolating from nearby reference surface sigma values. Future work will look to update this approach. Note: The missing reference surface sigmas were only present for reference surfaces with an interpolation flag value of 3. Reference surfaces where the height is interpolated also uses an interpolated sigma value. The value of sigma for an interpolated reference surface may be re-visited in the future.
- Modified the integration test scripts to generate browse products and check for the presence of default 1 and default 2 plots.
- The ATLAS browse plot for ATL10 reference surface and freeboard heights has been corrected.
- New parameters of mean ocean sea level pressure dynamic inverted barometer effect from ATL07 and written to ATL10. The new parameters are: /ancillary_data/freeboard_estimation/mean_ocean_slp: Mean ocean sea level pressure computed in ATL07 and /gtx/freeboard_beam_segment/geophysical/height_segment_dynib: Dynamic inverted barometer effect computed in ATL07.These are not currently applied to the heights but could be in future releases.
Overview
This data set (ATL10) contains estimates of sea ice freeboard, calculated using three different approaches. Sea ice leads used to establish the reference sea surface and descriptive statistics used in the height estimates are also provided. 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):
FREEBOARD
Platform(s):
ICESat-2
Sensor(s):
ATLAS
Data Format(s):
HDF5
Temporal Coverage:
14 October 2018 to present
Temporal Resolution:
91 day
Spatial Resolution:
Varies
Spatial Reference System(s):
WGS 84
EPSG:4326
Spatial Coverage:
N:
90
S:
-90
E:
180
W:
-180
Yellow areas on the map below indicate the spatial coverage for this data set.
Data Access & Tools
A free NASA Earthdata Login account is required to access these data. Learn More
Documentation
User Guide
ATBDs
General Resources
Product Specification Documents
Help Articles
How To
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.
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).
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.
Getting started
This article covers frequently asked questions about the NASA NSIDC DAAC's Earthdata cloud migration project and what it means to data users.
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.
This short article describes the customization services available for ICESat-2 data using Earthdata Search.