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Data Set ID:
NSIDC-0503

GPS-Measured Ice Velocities and Strain Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica, Version 1

This data set includes ice flow velocities and strain configurations, from GPS measurements on the West Antarctic Ice Sheet (WAIS) Divide. Ninety markers installed in the firn were measured during two consecutive field seasons running from 2005-2006 and 2006-2007. The markers were located in 150 by 60 km area, with smaller clusters of five markers located within about 10 km of each other. Consecutive GPS measurements were used to derive velocity for each marker. Strain configurations were estimated by differentiating a linear fit of the data at each marker cluster.

Data are available via FTP as ASCII text (.txt ) files in comma separated value format.

Geographic Coverage

Parameter(s):
  • Snow/Ice > Ice Velocity
Spatial Coverage:
  • N: -78.7489, S: -79.6401, E: -109.128, W: -115.457

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 November 2005 to 1 March 2006
  • 1 November 2006 to 1 March 2007
Temporal Resolution: Not specified
Data Format(s):
  • ASCII Text
Platform(s) FIELD INVESTIGATION, FIELD SURVEYS, GPS
Sensor(s): GPS
Version: V1
Data Contributor(s): Kenichi Matsuoka, Donovan Power, Al Rasmussen
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.

Matsuoka, K., D. Power, and A. Rasmussen. 2011. GPS-Measured Ice Velocities and Strain Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5222RQ8. [Date Accessed].

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Detailed Data Description

Format

Data are provided as ASCII text (.txt ) files in comma separated value format.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0503_matsuoka_V01/ directory. Within this directory, there are two data files:

  • WAISDivide_velocity.txt provides GPS velocity data.
  • WAISDivide_strain.txt provides strain configuration data
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Volume

Data volume is a total of 11KB.

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Spatial Coverage

Data were collected on the West Antarctic Ice Sheet.

Southernmost Latitude: 79.6401°S
Northernmost Latitude: 78.7489°S
Westernmost Longitude: 115.457°W
Easternmost Longitude: 109.128°W

Spatial Coverage Map

maps showing site locations
Figure 1. a. Map of the Antarctic Ice Sheet showing broad location of study area (b)
b. Regional surface topography (contours) and ice thickness (background color) in the WAIS Divide area: Gray rectangle indicates study area (c).Thick contours are drawn at 500 m intervals, and thin contours are drawn at 100 m. Byrd and WAIS Divide ice core sites are shown with white crosses. Surface topography is from Liu et al. 1999, and ice thickness is a composite of a continental BEDMAP model (Lythe et al., 2001) and a regional model by Support Office for Aerogeophysical Research (Morse et al., 2002). 
c. Local surface topography (contours) and ice thickness (background color) in the WAIS Divide area, along with site names. 
White circles show polarimetric radar measurement sites, and GPS ice-motion measurement sites are shown with blue circles. 
Ninety-eight GPS markers were installed for mass balance study in the vicinity of the flowline through WAIS Divide core site, shown with blue dots (Conway and Rasmussen, 2009). Airborne along-flow radar profiles used for englacial attenuation analysis are shown with gray curves (Matsuoka et al., 2010).

Spatial Resolution

GPS measurements were made in clusters of five, located within about 10 km of each other. In total the marker clusters span a 150 km by 60 km area including the WAIS Divide deep ice coring site.

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Temporal Coverage

Data were collected during two Antarctic field seasons from 2005-2006 and 2006-2007.

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Parameter or Variable

This data set provides GPS velocity and strain configuration data. Table 1 describes the parameters for velocity data. Table 2 describes the parameters for the strain configuration data, which were derived from the velocity data.

Parameter Description

Table 1. Parameter Description for the WAISDivide_velocity.txt File
Parameter Description
Site Name Name of site
Elevation Elevation in meters above WGS84 ellipsoid, measured in the first year
Latitude Latitude in decimal degree (WGS84) measured the first year
Longitude Longitude in decimal degree (WGS84) measured the first year
Azimuth Angle (in degrees) of flow vector measured counter-clockwise from true north
Speed Speed in meters per year

Table 2. Parameter Description for the WAISDivide_strain.txt File
Parameter Description
Site Name Name of marker cluster
Latitude Latitude in decimal degree (WGS84) of the center marker of each cluster, measured the first year
Longitude Longitude in decimal degree (WGS84) of the center marker of each cluster, measured the first year
Elevation Elevation (meters above WGS84 ellipsoid) of the central marker at each cluster
Strain Configurations 
(7 columns)
Strain configurations are derived in units of (year)-1: 
Divergence
Curl
Stretching
Shear
Deformation
Extension
Compression
Theta Angle (rad) of the stretching axis measured clockwise from local UTM X-positive axis

Sample Data Record

This sample data record shows the first 4 rows of the WAISDivide_velocity.txt file

Name Elevation Lattitude Longitude Azimuth Speed
CE1_A 1776.2 79.089102442S 111.932826069W 18.2 2.89
CE1_B 1779.08 79.130355900S 111.835434950W 16.9 2.2
CE1_C 1781.21 79.148821914S 112.054192125W 21.5 1.6
CE1_D 1779.53 79.107454058S 112.150893425W 22.2 2.07

This sample data record shows the first 4 rows of the WAISDivide_strain.txt file

site name Lattitude (degree) Longitude (degree) elevation (m) divergence (year-1) curl (year-1) stretching (year-1) shear (year-1) deformation (year-1) extension (year-1) compression (year-1) theta (rad)
CE1 79.118552239S 111.993470842W 1780.66 1.50E-04 -4.30E-05 1.62E-04 1.31E-04 2.09E-04 1.80E-04 -2.91E-05 0.3402
S-E30 79.071715000S 110.940295556W 1763.77 8.97E-05 -1.19E-04 2.75E-04 3.26E-04 4.26E-04 2.58E-04 -1.68E-04 0.4354
N-E15 78.834677472S 113.740722167W 1799.78 2.39E-04 -2.81E-05 -8.88E-05 6.31E-05 1.09E-04 1.74E-04 6.49E-05 1.2618
N-Div 78.928057139S 114.245306417W 1809.86 1.31E-04 1.10E-06 -7.37E-05 9.63E-05 1.21E-04 1.26E-04 5.10E-06 1.112
 
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Software and Tools

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Data Acquisition and Processing

Theory of Measurements

Ninety markers installed in the firn were measured twice, during two consecutive field seasons (2005-2006 and 2006-2007), using L1/L2 geodetic GPS receivers. The markers were installed in 18 clusters of 5 markers, located within about 10 km of each other.

Velocity was derived for each marker based on the two measurements. Strain configuration data were obtained by differentiating a linear fit of these data at each marker cluster.

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Sensor or Instrument Description

L1/L2 geodetic Global Positioning System (GPS) receivers

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Contacts and Acknowledgments

Dr. Kenichi Matsuoka 
Norwegian Polar Institute 
Fram Centre 
NO-9296 Tromsø
Norway

Donovan Power 
Department of Earth and Space Sciences 
Box 351310 
University of Washington 
Seattle, WA 98195 
USA

Dr. Al Rasmussen
Department of Earth and Space Sciences 
Box 351310 
University of Washington 
Seattle, WA 98195 
USA

Acknowledgments: 

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant number 0440847.

Document Information

Document Creation Date

29 August 2011

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