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Ice Flow History of the Thwaites Glacier, West Antarctica

Summary

This data set contains past flow lines of Thwaites Glacier. The flow lines were identified using layer patterns tracked between parallel radar layers, from a radar profile of the Thwaites Glacier catchment. The radar data was run and processed by the University of Texas Institute for Geophysics. The flow lines were identified using internal layer patterns detected with radar. The patterns in the internal layers of glaciers were created upstream, and over time moved downstream.

Data are available via FTP in ASCII text (.txt) format.

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, data set title, publisher: NSIDC, and digital media.

Conway, H., G. Catania, and T. J. Fudge. 2010. Ice Flow History of the Thwaites Glacier, West Antarctica. Boulder, Colorado, USA: National Snow and Ice Data Center. Digital media.

Overview Table

Category Description
Data format Data are in ASCII text (.txt) format
Spatial coverage and resolution Southernmost Latitude: 79.7°S
Northernmost Latitude: 76°S
Westernmost Longitude: 99.5°W
Easternmost Longitude: 123°W
Temporal coverage and resolution Radar data were collected during the 2004 to 2005 Antarctic field season (October through February).
File naming convention paleo_flow_line_picks.txt
File size The data set consists of one 13 KB file.
Parameter(s) X and Y coordinates that define a glacier flow line.
Procedures for obtaining data Data are available via FTP.
Version Version 1.1: Added Figures 1 and 2 and a PDF of the Weak Bed Control of the Eastern Shear Margin of Thwaites Glacier, West Antarctica journal paper.

Table of Contents

  1. Contacts and Acknowledgments
  2. Detailed Data Description
  3. Data Access and Tools
  4. Data Acquisition and Processing
  5. References and Related Publications
  6. Document Information

1. Contacts and Acknowledgments

Investigators

Dr. Howard Conway
Department of Earth and Space Sciences
University of Washington
Johnson Hall Rm-070, Box 351310
4000 15th Avenue NE
Seattle, WA 98195
USA

Dr. Ginny Catania
University of Texas Institute of Geophysics
J.J. Pickle Research Campus, Bldg. 196
10100 Burnet Road (R2200)
Austin, TX 78758
USA

T. J. Fudge
Department of Earth and Space Sciences
University of Washington
Johnson Hall
4000 15th Avenue NE
Seattle, WA 98195
USA

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgements

This research was supported by NSF OPP grant 0739372.

2. Detailed Data Description

This data set contains past flow lines of Thwaites Glacier identified from distinct layer patterns tracked between parallel radar layers. Each row of data contains two pairs of x and y coordinates, which form one paleo flow line. Coordinates are in polar stereographic with units of km. The parallel of true scale is 71S.

Figure 1, adapted from Fudge et al. 2013, shows an InSAR velocity map (Joughin et al. 2009) overlain by radar lines (Holt et al. 2006). The purple lines indicate areas where radar-detected features were tracked. The yellow circles are shallow core locations from US-ITASE. The Red circle is the WAIS DIVIDE ice core site. Letters A through E are GPS locations.

InSAR velocity map

Figure 1. InSAR Velocity Map Overlain by Radar


Figure 2 displays radar-detected flow lines shown with black circles connected by thin black lines. X-Y coordinates for the paleo-flowlines are given in the file named paleo_flow-line_picks.txt. GPS velocities are shown with white arrows. InSAR velocities at GPS locations are shown with red arrows. Large black numbers are average direction diference (i) between radar-detected and InSAR ice flow directions. Small white numbers are direction difference between InSAR and GPS measurements. Small red numbers are direction difference between radar-detected and GPS. Background color is bedrock elevation.

Radar-detected Flow Lines

Figure 2. Radar-detected Flow Lines


Format

This data set consists of one data file in ASCII text (.txt) format.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/conway_nsidc_0463/ directory. The data set consists of one file, paleo_flow_line_picks.txt, which contains flow line data derived from a radar sounding of Thwaites Glacier in West Antarctica.

File Size

The data file is 13 KB.

Spatial Coverage

The data were derived using radar sounding data collected from Thwaites Glacier in West Antarctica.

Southernmost Latitude: 79.7°S
Northernmost Latitude: 76°S
Westernmost Longitude: 99.5°W
Easternmost Longitude: 123°W

Temporal Coverage

The radar data that support this investigation were collected by the University of Texas Institute for Geophysics during the Antarctic field season (October through February) in 2004 to 2005.

Parameter or Variable

The data set contains a table of coordinates that define flow lines derived from a radar sounding of Thwaites Glacier in West Antarctica.

Parameter Description

Each row contains two pairs of x and y coordinates, which form one flow line. Coordinates are in polar stereographic with units of kilometers (km). The parallel of true scale is 71°S.

Sample Data Record

x1 y1 x2 y2
-1.3438309e+003 -5.8595677e+002 -1.3461408e+003 -5.7038227e+002
-1.3388820e+003 -5.8459680e+002 -1.3409560e+003 -5.6897531e+002
-1.3364551e+003 -5.8392782e+002 -1.3391090e+003 -5.6846833e+002

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The total volume of the data set is 13 KB.

Software and Tools

Data are accessible using spreadsheet software.

Related Data Collections

4. Data Acquisition and Processing

Theory of Measurements

Researchers identified past glacial flow lines for Thwaites Glacier in Antarctica using internal layer patterns detected with radar. The patterns in the internal layers of glaciers were created upstream, and over time moved downstream. By looking at the pattern between radar lines, researchers can discern the direction and timescale of past flow. The technique is described in more detail in Ng and Conway, 2004.

5. References and Related Publications

Fudge, T. J., H. Conway, G. Catania, D. D. Blankenship, K. Christianson, I. Joughin, B. Smith, S. D. Kempf, D. A. Young & S. Anandakrishnan. 2013. Identifying Flow Lines and Limitations of Flux Analyses in the Interior of Thwaites Glacier. Annals Glaciol. 55(167).

Holt, J. W., D. D. Blankenship, D. L. Morse, D. A. Young, M. E. Peters, S. D. Kempf, T. G. Richter, D. G. Vaughan, and H. F.J. Corr. 2006. New Boundary Conditions for the West Antarctic Ice Sheet: Subglacial Topography of the Thwaites and Smith Glacier Catchments. Geophysical Research Letters, Vol. 33, L09502, doi: 10.1029/2005GL025561.

Joughin, I., S. Tulaczyk, J. L. Bamber, D. Blankenship, J. W. Holt, T. Scambos and D. G. Vaughan, 2009. Basal Conditions for Pine Island and Thwaites Glaciers, West Antarctica, Determined Using Satellite and Airborne Data. J. Glaciol. 55(190): 245-257.

MacGregor, Joseph A., Ginny A. Catania, Howard Conway, Dustin M. Schroeder, Ian Joughin, Duncan A. Young, Scott D. Kempf, Donald D. Blankenship. 2013. Weak Bed Control of the Eastern Shear Margin of Thwaites Glacier, West Antarctica. Journal of Glaciology, Vol. 59, No. 217, doi:10.3189/2013JoG13J050. PDF

Ng, F. and H. Conway. 2004. Fast-Flow Signature in the Stagnated Kamb Ice Stream. Geological Society of America 32:6, p. 481-484, doi:10.1130/G20317.1.

Related Web Sites

Table 1. Related Web Sites
Document Description URL
Antarctic Glaciological Data Center Web site Data Center Web site http://nsidc.org/agdc/

6. Document Information

Acronyms

The acronyms used in this document are listed in Table 2.

Table 2. Acronyms and Abbreviations
Acronym Description
FTP File Transfer Protocol
NSIDC National Snow and Ice Data Center
URL Uniform Resource Locator

Document Creation Date

28 April 2010

Document Revision Date

March 2014

Document URL

http://nsidc.org/data/docs/nsidc0463_conway/index.html