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This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides 22 years of comprehensive high-resolution mapping of grounding lines in Antarctica from 1992 to 2014. The data were derived using differential satellite synthetic aperture radar interferometry (DInSAR) measurements from the following platforms: Earth Remote Sensing Satellites 1 and 2 (ERS-1 and ERS-2), RADARSAT-1, RADARSAT-2, the Advanced Land Observing System Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR), Cosmo Skymed, and Copernicus Sentinel-1.
See Antarctic Ice Sheet Velocity and Mapping Data for related data.
This is the most recent version of these data.
In Version 2, the temporal coverage now includes 22 years from 1992 to 2014. In addition, the data format changed to shapefiles.
STANDARD Level of Service
Data: Data integrity and usability verified
Documentation: Key metadata and user guide available
User Support: Assistance with data access and usage; guidance on use of data in tools
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Geographic Coverage |
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.
Rignot, E., J. Mouginot, and B. Scheuchl. 2016. MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/IKBWW4RYHF1Q. [Date Accessed].As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.
Rignot, E., J. Mouginot, and B. Scheuchl. 2011. Antarctic Grounding Line Mapping from Differential Satellite Radar Interferometry, Geophyical Research Letters. 38. L10504. https://doi.org/10.1029/2011GL047109
Rignot, E., J. Mouginot, M. Morlighem, H. Seroussi, and B. Scheuchl. 2014. Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011, Geophysical Research Letters. 41. 3502-3509. https://doi.org/10.1002/2014GL060140
ESRI ArcGIS Shapefile:
.shp – main file that stores the feature geometry.shx – index file that stores the index of the feature geometry.dbf – dBASE table that stores the attribute information of features.prj – file that stores the coordinate system information.cpg – optional file that specifies the code page for identifying the character set to be usedThis data set also contains an XML file (.xml), which contains additional metadata.
Example file name:InSAR_GL_Antarctica_v02.shp
Files are named according to the following convention, which is described in Table 1:InSar_GL_Antarctica_v02.xxx
| Variable | Description |
|---|---|
InSAR |
SAR Interferometry |
GL |
Grounding Line |
Antarctica |
Geographic location |
v02 |
Data Set Version |
.xxx |
File type |
The character set code (.cpg) and projection (.prj) files are 1 KB each. The index file (.shx) is 2 KB, and the dBASE table is 29 KB. The shapefile (.shp) is 11,028 KB.
The total volume of the data set is approximately 10.8 MB.
The data cover roughly 75% of the Antarctic grounding line (the transition from grounded ice to floating ice sheet). The grounding lines of ice-covered offshore islands are partially covered. Lines are discontinuous, and in some areas multiple picks from different SAR missions and dates are shown. Most of the fast-flowing, large-flux outlet glaciers and ice streams are mapped. Spatial coverage for the data is shown in Figure 1 and is defined by the following boundaries:
Spatial Coverage Map
The data are provided in geographic latitude and longitude as defined by the WGS-84 datum.
Spatial resolution varies for each satellite/sensor. See Table 2 for the associated resolutions.
| Satellite/Sensor | Resolution |
|---|---|
| ERS-1, ERS-2 | ~50 m |
| RADARSAT-1 | ~35 m |
| RADARSAT-2 | ~46 m |
| ALOS PALSAR | ~120 m |
| COSMO SkyMed | ~25 m |
| Sentinel-1A | ~50 m |
07 February 1992 and 17 December 2014
The ata were obtained from multiple satellites during this time period. The satellites, collection years, and regions are listed in Table 4.
Detailed mappings of the geometric position of the Antarctic Ice Sheet grounding line, derived from satellite data, are provided. The parameter is comprised of latitude, longitude, satellite/sensor, and up to four orbits and acquisitions dates (see Table 3 for more information).
| Attribute | Description |
|---|---|
| Satellite/Sensor | Satellites/Sensors used for this product include:
|
| Orbit | Sensor orbits: unique identifiers for the data used to generate the grounding lines |
| Date | Data acquisition dates |
Grounding lines for the Antarctic Ice Sheet were derived using differential satellite synthetic aperture radar interferometry (DInSAR) data for the years 1992 to 2014 from the Earth Remote Sensing Satellites 1 and 2 (ERS-1 and ERS-2), RADARSAT and RADARSAT-2, the Advanced Land Observing System (ALOS) PALSAR, COSMO Skymed, and Sentinel-1A. Two interferograms are required to perform differential interferometry. This requires a minimum of three consecutive acquisitions from a single sensor. In some cases, two sets of two consecutive acquisitions were used to generate the grounding line. In the case of the ERS-1/ERS-2 Tandem mission, two Tandem interferograms (four acquisitions) were used for grounding line detection. A detailed description of the product and the methodology is provided in Rignot et al. (2011).
Data Sources
Table 4 lists the temporal and spatial coverages for each satellite sensor used in this data set.
| Parameter | ERS-1, ERS-2 | RADARSAT-1 | RADARSAT-2 | ALOS Palsar | COSMO SkyMed | Sentinel-1 |
|---|---|---|---|---|---|---|
| Temporal coverage | 1992, 1994-1996, 1999, 2000 | 2000 | 2009 | 2007, 2008 | 2013 | 2014 |
| Mode* | N/A | F1 | S5 | FBS | Himage Polarimetric | Interferometric Wide |
| Incidence Angle | 23° | 38.5° | 41.45° | 39° | 40.3° | 32.3° |
| Number of Range Looks (Interferogram) | 2 | 4 | 2 | 12 | 10 | 20 |
| Number of Azimuth Looks (Interferogram) | 10 | 5 | 6 | 30 | 10 | 2 |
| Range pixel spacing (resolution) | 8 (13.5 m) | 5.3 (5.9 m) | 11.8 (13.5 m) | 4.7 (7.5 m) | 3 (<3 m) | 3 (2.3 m) |
| Azimuth pixel spacing (resolution) | 4 (5 m) | 4.6 (6.9 m) | 5.3 (7.7 m) | 3.3 (4 m) | 3 (<3 m) | 22(17.4 m) |
*For more information on the modes of the different satellite sensors, see the following websites: RADARSAT-1, RADARSAT-2, ALOS PALSAR, COSM-SKMED, and Sentinel-1.
Quality Assessment
A detailed description of the product and its quality is provided in Rignot et al. (2011). Multiple mappings, instruments, and epochs were compared to estimate the positional accuracy. The standard error is ±100 m, with greater geolocation variations locally. In some cases, large (km) short-term and long-term migrations are present. The quality of the grounding line mapping depends on the satellite data used, the length of the interferometric baseline (short baselines yield more accurate positioning), the amplitude of the differential tides, phase coherence (high phase coherence means less noise), and the frequency of revisits. Short revisit times are most crucial in order to measure the grounding line in some regions of fast flow (e.g., Pine Island Glacier). See below for a list of satellites in order of accuracy, with the lowest accuracy listed first and the highest listed last.
For information about the SAR systems used to construct the mosaics from which this data set is derived, see the Canadian Space Agency's RADARSAT-1 web page, the European Space Agency's ERS-1/2 mission site, the Japan Aerospace Exploration Agency's About ALOS - PALSAR web page, the COSMO-Skymed website, and the European Space Agency's Copernicus Sentinel-1 web page.
Dr. Eric Rignot
University of California, Irvine
Department of Earth System Science
Croul Hall
Irvine, California 92697
USA
Dr. Jeremie Mouginot
University of California, Irvine
Department of Earth System Science
Croul Hall
Irvine, California 92697
USA
Dr. Bernd Scheuchl
University of California, Irvine
Department of Earth System Science
Croul Hall
Irvine, California 92697
USA
The data were generated through a grant from the NASA MEaSUREs program.
Spaceborne SAR acquisitions were provided through data grants from the following agencies:
The data set contains modified Copernicus Sentinel data (2014), acquired by the European Space Agency, distributed through the Alaska Satellite Facility, and processed by E. Rignot, J. Mouginot, and B. Scheuchl.
Data acquisitions between 2006 and 2009 are courtesy of the International Polar Year (IPY) Space Task group; thereafter, acquisitions were coordinated by the successor organization, the Polar Space Task Group.
October 2016
December 2018
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