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Margin Migration Rates and Dynamics: Siple Coast Ice Streams, Version 1
This product, based on prior data collected under NSF-OPP grant 8716604 (Echelmeyer and Harrison) and NSF-OPP grant 9117911 (Harrison), includes ice velocity data between stations S17 and UpB on the Upper Whillans Ice Stream, Siple Coast, West Antarctica, from January 1994 to January 1995. Velocities were measured using a total station, a surveying instrument that combines a digital theodolite and an Electronic Distance Measuring (EDM) device to measure horizontal and vertical angles, slope, and horizontal and vertical distances. Data are in ASCII and Excel formats, and are available via FTP.
Geographic Coverage
Parameter(s): |
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Spatial Coverage: |
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Spatial Resolution: | Not Specified |
Temporal Coverage: |
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Temporal Resolution: | Not specified |
Data Format(s): |
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Platform(s) | GROUND-BASED OBSERVATIONS |
Sensor(s): | SURVEYING TOOLS, THEODOLITE |
Version: | V1 |
Data Contributor(s): | Martin Truffer, Keith Echelmeyer |
Metadata XML: | View Metadata Record |
Detailed Data Description
Data are available as tab-delimited ASCII files and as Excel spreadsheets.
gpsvel.txt: 376 bytes
truffer_margin_velocities.txt: 670 bytes
margin_velocities.xls: 15872 bytes
Data were collected on the Whillans Ice Stream (83.57778°S, 138.14972°W), Siple Coast, West Antarctica.
Upper Left: | 83.54415° S | 134.9841° W |
Lower Left: | 83.21296° S | 137.7229° W |
Upper Right: | 83.85934° S | 138.0105° W |
Lower Right: | 83.51190° S | 140.7206° W |
Study Area Location Map
Following is a map of the study area with the stations labeled and the optical data track shown as a red line. The plot overlays a Moderate Resolution Imaging Spectroradiometer (MODIS) image of the upper Whillans Ice Stream area.
Data were collected between January 1994 and January 1995.
Unit of Measurement
Velocity measurements and errors are in meters per year (m/a).
Sample Data Record
The following sample shows the first five lines of "gpsvel.txt."
Station |
Latitude(DMS) |
Longitude(DMS) |
Velocity(m/a) |
Error |
Azimuth |
S17 |
83° 34' 40" S |
138° 8' 59" W |
2.76 |
0.10 |
N77W |
I21 |
83° 34' 44" S |
138° 5' 51"W |
2.04 |
0.10 |
N67W |
OutB |
83° 37' 1" S |
138° 3' 31" W |
0.52 |
0.12 |
N56W |
Fishhook |
83° 40' 46" S |
138° 22' 28" W |
1.60 |
0.16 |
S65W |
The following sample shows the first five lines of "truffer_margin_velocities.txt."
Distance (from center) |
Speed (m/a) |
1771 |
427.05 |
2610 |
423.40 |
3527 |
423.40 |
5100 |
419.97 |
Software and Tools
Data Acquisition and Processing
Error Sources
Estimated errors for the GPS data range from 0.10 to 0.30 m/a. Maximum estimated errors for the optical data are approximately 0.2 m/a.
Velocities were measured using a total station, a surveying instrument that combines a digital theodolite and an Electronic Distance Measuring (EDM) device to measure horizontal and vertical angles, slope, and horizontal and vertical distances. An EDM is a device mounted on the top of the total station that sends out a pulse of light. The EDM measures the time it takes for the light to travel from the EDM to a prism, bounce off of the prism, then return to the EDM. This measurement is displayed as distance, but it is really a measurement of time (U.S. Army Corps of Engineers 2002).
References and Related Publications
Contacts and Acknowledgments
Martin Truffer and Keith Echelmeyer
University of Alaska Fairbanks
Fairbanks, AK USA
This research was supported by NSF OPP award #0086997, Margin Migration Rates and Margin Dynamics of the Siple Coast Ice Streams.
Document Information
Document Creation Date
March 2005
Document Revision Date
March 2005
Document Review Date
March 2005
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