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Data Set ID:
NSIDC-0106

Ice Velocity Data from Ice Stream C, West Antarctica, Version 1

Ice velocity data from ice stream C, including the body of the ice stream and its area of onset, are available. The investigator calculated velocities from precise ice displacement measurements made with a geodetic-quality Global Positioning System (GPS). These ice displacement measurements accompanied seismic experiments aimed at understanding controls on the flow of ice streams in west Antarctica. An understanding of ice stream flow is essential to predicting the response of the West Antarctic Ice Sheet to future climate change.

Data are available in ASCII format via ftp.

Geographic Coverage

Spatial Coverage:
  • N: -82.2764, S: -82.362, E: -120.018, W: -121.644

  • N: -81.8039, S: -82.8113, E: -124.987, W: -152.598

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 November 1995 to 31 January 1996
Temporal Resolution: Not specified
Parameter(s):
  • Glaciers/Ice Sheets > Glacier Motion/Ice Sheet Motion
  • Snow/Ice > Ice Motion
  • Glaciers/Ice Sheets > Ice Sheets > Ice Stream
  • Snow/Ice > Ice Velocity
Platform(s) GROUND-BASED OBSERVATIONS
Sensor(s): GPS, GPS RECEIVERS
Data Format(s):
  • Microsoft Excel
  • ASCII Text
Version: V1
Data Contributor(s): Sridhar Anandakrishnan

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.

Anandakrishnan, S. 2001. Ice Velocity Data from Ice Stream C, West Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5CZ3539. [Date Accessed].

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Detailed Data Description

Ice velocity data from ice stream C, including the body of the ice stream and its area of onset, are available. The investigator calculated velocities from precise ice displacement measurements made with a geodetic-quality Global Positioning System (GPS). These ice displacement measurements accompanied seismic experiments aimed at understanding controls on the flow of ice streams in west Antarctica. An understanding of ice stream flow is essential to predicting the response of the West Antarctic Ice Sheet to future climate change.

Format

Data are available in two ASCII files:

  • "CWA-GPS-velocities.txt" and "CWA-GPS-velocities.xls" contain data from near the CWA camp at the onset of ice stream C.
  • "ISC-GPS-velocities.txt" and "ISC-GPS-velocities.xls" contain data from along the body of ice stream C.
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File Size

ASCII files are 0.2 KB and 1 KB, and Excel files are 14 KB and 16 KB each.

Sample Data Record:

Files are structured as follows:

         "Longitude, Latitude, Velocity (vector direction in degrees ccw of east, magnitude in m/a)"

         -120.018    -82.362   189.321   18.178
         -120.075    -82.3591  189.375   16.983
         -120.131    -82.3563  188.823   16.020
         -120.188    -82.3534  188.242   15.185
         -120.301    -82.3477  187.54    13.614
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Spatial Coverage

Measurement stations were located at the onset of ice stream C (near the CWA camp) and along the body of ice stream C of the West Antarctic Ice Sheet.

Study Area Location Map:

The dark gray box on the map below outlines the approximate area of ice stream C. Crosshairs mark the location of the South Pole.

Figure 1. Study Area Location Map
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Temporal Coverage

Data were collected in November and December 1995 and January 1996.

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Parameter or Variable

Velocities are given as vector directions in degrees counter-clockwise (ccw) of east and magnitudes in meters per annum (m/a).

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Software and Tools

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Data Acquisition and Processing

The investigator acquired measurements at six stations along the length of ice stream C using a dual-frequency geodetic-quality Trimble 4000 GPS receiver operating in static mode. Measurements were collected in November 1995 and 50 days later in January 1996. The receiver operated for a minimum of 24 hours, and data were processed in baseline mode to both a quasi-fixed station at Upstream C camp (actual velocity 24 m/a) and a fixed station at McMurdo. Data were also processed in Precise Point Positioning mode with precise orbits. The two methods yielded very similar results.

The investigator took measurements at the onset of ice stream C (near the CWA camp) along the Antalith seismic line at 300m intervals. These measurements (in 1995) and remeasurements (in 1996) employed a dual-frequency Trimble 4000 GPS receiver operating in Kinematic mode with a fixed base station. The maximum separation between base station and roving receiver was 9 km. The fixed base station position was calculated with a long baseline to MCM4 (McMurdo) and has low accuracy (2 m horizontal and 4 m vertical); however, the relative precision of the kinematic stations was 2 cm horizontal and 4 cm vertical. Although the absolute position of these stations is poorly resolved, their relative positions (and calculated velocities) are very precise.

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References and Related Publications

Contacts and Acknowledgments

Sridhar Anandakrishnan
Department of Geology
University of Alabama
Tuscaloosa, AL     USA

Acknowledgements: 

This research was supported by NSF OPP awards #9318121Microearthquake Monitoring of Ice Stream C, West Antarctica: A Sensor for Sticky Spots, and #9222121,Collaborative Research: Seismic Traverse of the Byrd Subglacial Basin-Field Test (i.e., the "Antalith" seismic experiment).

Document Information

DOCUMENT CREATION DATE

30 November 2001

DOCUMENT REVISION DATE

10 January 2002

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