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Data Set ID:
NSIDC-0263

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):
  • Snow/Ice > Ice Velocity
Spatial Coverage:

  • N: -83.2, S: -83.9, E: -134.9, W: -140.7
Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 January 1994 to 31 January 1995
Temporal Resolution: Not specified
Data Format(s):
  • Microsoft Excel
  • ASCII Text
Platform(s) GROUND-BASED OBSERVATIONS
Sensor(s): SURVEYING TOOLS, THEODOLITE
Version: V1
Data Contributor(s): Martin Truffer, Keith Echelmeyer
Metadata XML: View Metadata Record
Please contact the data provider for the correct Data Citation for this data set.

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Detailed Data Description

Format

Data are available as tab-delimited ASCII files and as Excel spreadsheets.

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File Size

gpsvel.txt: 376 bytes
truffer_margin_velocities.txt: 670 bytes
margin_velocities.xls: 15872 bytes

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Spatial Coverage

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.

Map: Location of Siple Dome study site

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Temporal Coverage

Data were collected between January 1994 and January 1995.

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Parameter or Variable

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
 
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Software and Tools

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Data Acquisition and Processing

Derivation Techniques and Algorithms

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.

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Sensor or Instrument Description

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).

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References and Related Publications

Echelmeyer, K.A., W.D. Harrison, C. Larsen, and J.E. Mitchell. 1994. The role of the margins in the dynamics of an active ice stream. Journal of Glaciology 40(136): 527-538.

Echelmeyer, K.A. and W.D. Harrison. 1999. Ongoing margin migration of Ice Stream B, Antarctica. Journal of Glaciology 45(150): 361-369.

Harrison, W.D, K.A. Echelmeyer, and C.F. Larsen. 1998. Measurement of temperature in a margin of Ice Stream B, Antarctica: implications for margin migration and lateral drag. Journal of Glaciology 44(148): 615-624.

Truffer, M. and K.A. Echelmeyer. 2003. Of icestreams and isbrae. Annals of Glaciology 36: 67-72.

U.S. Army Corps of Engineers. 2002. "Angle and Distance Observations - Total Stations and EDM." In Structural Deformation Surveying. Engineer Manual 1110-2-1009.

Contacts and Acknowledgments

Martin Truffer and Keith Echelmeyer 
University of Alaska Fairbanks 
Fairbanks, AK     USA

Acknowledgments: 

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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