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Scientists blog from Antarctica and provide a glimpse of what it's like to do research in the field. 
What's hot in the news around climate and sea ice and what are scientists talking about now? On Wednesday, February 19th between 9:00 am and 11:00 am MDT, the following data collections may not be available due to planned system maintenance: AMSR-E, Aquarius, ASO, High Mountain Asia, IceBridge, ICESat/GLAS, ICESat-2, MEaSUREs, MODIS, NISE, SMAP, SnowEx, and VIIRS.
Data Set ID:
NSIDC-0498
MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry, Version 2
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.
Version Summary:
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 |
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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.
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].Literature Citation
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
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Detailed Data Description
Format
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 used
This data set also contains an XML file (.xml), which contains additional metadata.
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File Naming Convention
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 |
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File Size
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.
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Spatial Coverage
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:
- Southernmost latitude: 90° S
- Northernmost latitude: 60° S
- Westernmost longitude: 180° W
- Easternmost longitude: 180° E
Spatial Coverage Map
Projection and Grid Description
The data are provided in geographic latitude and longitude as defined by the WGS-84 datum.
Spatial Resolution
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 |
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Temporal Coverage
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.
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Parameter or Variable
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).
Parameter Description
| 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 |
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Software and Tools
Data Acquisition and Processing
Data Acquisition Methods
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.
- Sentinel 1-A (scansar)
- ALOS PalSAR (P-band, lower frequency)
- ERS-1,-2, Radarsat-1,-2 (C band)
- COSMO Skymed (X band)
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Sensor or Instrument Description
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.
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References and Related Publications
Contacts and Acknowledgments
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
Acknowledgments:
The data were generated through a grant from the NASA MEaSUREs program.
Spaceborne SAR acquisitions were provided through data grants from the following agencies:
- ALOS PALSAR: Japan Aerospace Exploration Agency (JAXA)
- ERS-1, ERS-2: European Space Agency (ESA)
- RADARSAT, RADARSAT-2: Canadian Space Agency (CSA)
- Sentinel-1A: Copernicus/European Space Agency (ESA)
- COSMO SkyMed: Italian Space Agency (ASI)
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.
Document Information
Document Creation Date
October 2016
Document Revision Date
December 2018
No technical references available for this data set.
How To
Programmatically access data using spatial and temporal filters
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