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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, derived using differential satellite synthetic aperture radar interferometry (DInSAR) data from the 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 Sentinel-1 for years 1992 to 2014.

Note: These data are considered provisional pending a review by the MEaSUREs program. Once the data have been reviewed, this statement will be removed from this documentation.

Version Summary:

The data's temporal coverage increased to 22 years, 1992 - 2014, and the data format changed to shapefiles.

Geographic Coverage

Spatial Coverage:
  • N: -60, S: -90, E: 180, W: -180

Spatial Resolution:
  • 25 m to 120 m
Temporal Coverage:
  • 7 February 1992 to 17 December 2014
Temporal Resolution: 263 month
Parameter(s):
  • Glaciers/Ice Sheets > Ice Sheets > Grounding Line
Platform(s) ALOS, COSMO-SKYMED, ERS-1, ERS-2, RADARSAT-1, RADARSAT-2, SENTINEL-1A
Sensor(s): PALSAR, SAR
Data Format(s):
  • ESRI Shapefile
Version: V2
Data Contributor(s): Eric Rignot, Jeremie Mouginot, Bernd Scheuchl

Data Citation

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: http://dx.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. http://dx.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. http://dx.doi.org/10.1002/2014GL060140

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Detailed Data Description

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, derived using differential satellite synthetic aperture radar interferometry (DInSAR) data from the 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 Sentinel-1 for the years 1992 to 2014.

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
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File and Directory Structure

The data are available via FTP and HTTPS.

The directory contains the following files:

  • InSAR_GL_Antarctica_v2.cpg
  • InSAR_GL_Antarctica_v2.dbf
  • InSAR_GL_Antarctica_v2.prj
  • InSAR_GL_Antarctica_v2.shp
  • InSAR_GL_Antarctica_v2.shx
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File Naming Convention

Files are named according to the following convention (see Table 1).

Example:
InSAR_GL_Antarctica_v2.shp
Convention:
InSar_GL_Antarctica_v2.xxx

Where:

Variable Description
Table 1. Naming Convention for Shapefiles
InSAR SAR Interferometry
GL Grounding Line
Antarctica Geographic location
v2 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.

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Volume

The volume of the data set is 10.8 MB.

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Spatial Coverage

The data cover roughly 75 percent of the Antarctic grounding line (the transition from grounded ice to floating ice sheet) and partial coverage of the grounding line of ice-covered offshore islands. 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.

Southernmost Latitude: 90° S
Northernmost Latitude: 60° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

Spatial Coverage Map

Figure1. Delineation of Antarctic grounding lines with satellite radar interferometry (DInSAR) from ERS-1 and ERS-2 (red), RADARSAT-1 (purple), RADARSAT-2 (blue), ALOS PALSAR (green), Sentinel-1A (yellow), COSMO Skymed (cyan) overlaid on the Moderate Resolution Imaging Spectroradiometer (MODIS) mosaic of Antarctica.

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
Table 2. Spatial 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

Data were obtained from multiple satellites between 7 February 1992 and 17 December 2014. The satellites, year, and region of collection are listed below in the Data Sources section.

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Parameter or Variable

The data set provides detailed mappings of the geometric position of the Antarctic Ice Sheet grounding line, derived from satellite data. 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

Table 3. Parameter Attributes Description
Attribute Description
Satellite/Sensor Satellites/Sensors used for this product include:
ERS: European Space Agency Earth Remote Sensing Satellites 1 and 2
RSAT: RADARSAT-1 — Canadian Space Agency Synthetic Aperture Radar Satellite
R2: RADARSAT-2 — Canadian Space Agency Synthetic Aperture Radar Satellite
PALSAR: Japan Aerospace Exploration Agency Advanced Land Observing System (ALOS) Phased Array type L-band Synthetic Aperture Radar
COSMO SkyMed: Italian Space Agency Synthetic Aperture Radar Constellation
Sentinel-1A: European Union and European Space Agency Synthetic Aperture Radar Satellite
Orbit Sensor orbits: unique identifiers for the data used in the generation of the grounding line
Date Dates of data acquisitions
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Software and Tools

Shapefiles can be readily accessed using GIS software such as ArcGIS and QGIS.

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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 from the Earth Remote Sensing Satellites 1 and 2 (ERS-1 and -2), RADARSAT and RADARSAT-2, the Advanced Land Observing System (ALOS) PALSAR, COSMO Skymed, and Sentinel-1A for years 1992 to 2014. Two interferograms are required to perform differential interferometry. This requires a minimum of three consecutive acquisitions of 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) are 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
Table 4. Parameters by Source Satellite
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 these Web sites: 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. 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 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 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, the COSMO-Skymed Web site, and the European Agency's Sentinel-1 site.

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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

Acknowledgements: 

These 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: European Space Agency (ESA)
  • COSMO SkyMed: Italian Space Agency (ASI)

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

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