Millennially Averaged Accumulation Rates for Lake Vostok

Summary

This data set consists of inferred accumulation rates from three radar layers (26, 35 and 41 thousand years old) in the Vostok Subglacial Lake region. Accumulation rates were inferred using Local-Layer Approximation (LLA), which assumes that the strain-rate history of a particle traveling through the ice sheet can be approximated by the vertical strain-rate profile at the current position of the particle, which the researchers assume to be uniform. Parameters include location, in latitude and longitude, polar stereographic coordinates, and local grid X and Y coordinates, along with layer age, in thousands of years (ka), and inferred accumulation rate (cm/a). The data cover a 150 by 350 km area.

Data are available via FTP, as a text file (.txt) with columns in comma separated value 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.

MacGregor, J., K. Matsuoka, M. Studinger, E. Waddington, and D. Winebrenner. 2011. Millennially Averaged Accumulation Rates for the Lake Vostok Region. Boulder, Colorado, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5F769HV.

Overview Table

Category	Description
Data format	Comma-separated value format, text (.txt) files
Spatial coverage and resolution	Southernmost Latitude: 79.1°S Northernmost Latitude: 75.7°S Westernmost Longitude: 68.4°E Easternmost Longitude: 80.5°E
Temporal coverage and resolution	Radar data were collected during the field season running 2000 to 2001. Data span three time periods, approximately 26,000, 35,000 and 41,000 years old.
File naming convention	vostok_accum.txt
File size	3.6 MB
Parameters	Latitude/Longitude Polar Stereographic Coordinates Grid X and Y Coordinates Accumulation (cm/a)
Procedures for obtaining data	Data are available via FTP.

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. Joseph A. MacGregor
University of Texas at Austin
10100 Burnet Road, Bldg. 196
Austin, TX 78758
USA

Dr. Kenichi Matsuoka
Department of Earth and Space Sciences
University of Washington
Department of Earth and Space Sciences
Seattle, WA 98105
USA

Dr. Michael Studinger
Lamont-Doherty Earth Observatory
61 Route 9W
Palisades, NY 10964
USA

Dr. Edwin D. Waddington
University of Washington
Department of Earth and Space Sciences
Box 351310
Seattle, WA 98195-1310
USA

Dr. Dale Winebrenner
University of Washington
Applied Physics Laboratory
Gerberding Hall, Rm. 280
PO. Box 351
Seattle, WA 98195
USA

Technical Contact

Acknowledgements

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant number 0538674.

2. Detailed Data Description

Format

Text file (.txt) with columns in comma separated value format

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0500_macgregor_V01/ directory. The data set consists of one data file, vostok_accum.txt.

File Naming Convention

The data file, vostok_accum.txt , contains data on inferred accumulation rates for radar layers in the Lake Vostok region of Antarctica

File Size

3.6 MB

Spatial Coverage

These data span a 150 km by 350 km area in the Lake Vostok region of Antarctica.

Southernmost Latitude: 79.1°S
Northernmost Latitude: 75.7°S
Westernmost Longitude: 68.4°E
Easternmost Longitude: 80.5°E

Spatial Resolution

1.5 km

Projection

Locations are provided in latitude/longitude, polar stereographic, as well as a local grid X, Y projection.

Grid Description

The local northing/easting grid was developed by M. Studinger specifically for the Lake Vostok region and is oriented along the long axis of the lake. The grid (229 points in local grid Y, 112 points in local grid X) is repeated three times here, once for each of the three layers (26.2, 34.8 and 41.0 ka) for which accumulation rates were inferred.

Temporal Coverage

Radar data were collected during the Antarctic field season from 2000 to 2001. The radar layers span three time periods, approximately 26, 35 and 41 thousand years old.

Parameter or Variable

Parameter Description

Table 1. Parameter Description

Parameter	Description
Latitude	Longitude in decimal degrees S
Longitude	Latitude in decimal degrees W
Polar Sterographic X	Polar stereographic X coordinates (km)
Polar Sterographic X	Polar stereographic Y coordinates (km)
Grid X	Local grid X (km)
Grid Y	Local grid Y (km)
Layer Age	Layer Age in thousands of years (ka)
Accumulation Rate	Accumulation rate in centimeters per year (cm/a), inferred using local-layer approximation (LLA)

Sample Data Record

-79.072	104.86	1151	-305.47	-6	-6	26.2	NaN
-79.059	104.83	1152.5	-305.21	-6	-4.5	26.2	NaN
-79.047	104.8	1154	-304.95	-6	-3	26.2	NaN

Note. Not-a-number (NaN) values for accumulation rate occur when the layer was not traced in the vicinity of that particular grid point, and therefore was not interpolated onto it.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The data file is 3705 KB.

Software and Tools

Data can be accessed using spreadsheet software.

Related Data Collections

• Englacial Layers and Attenuation Rates across the Ross and Amundsen Sea Ice-Flow Divide (WAIS Divide), West Antarctica

4. Data Acquisition and Processing

Data Source

60 MHz airborne ice-pentrating radar data were collected by the US Support Office for Aerogeophysical Research (SOAR) at the University of Texas Institute for Geophysics in 2000-2001.

Derivation Techniques and Algorithms

The depths of radar-detected internal layers can be used to infer the spatial variability of accumulation rates. For this data set, researchers inferred accumulation rates from three radar layers, 26, 35 and 41 thousand years (ka) old, in the Vostok Subglacial Lake region using the LLA over a 150 km by 350 km area. The LLA assumes that the strain-rate history of a particle traveling through the ice sheet can be approximated by the vertical strain-rate profile at the current position of the particle, which is further assumed to be uniform. The LLA accumulation-rate map shows higher values in the northwestern corner of our study area and lower values near the downstream shoreline of the lake. The LLA-inferred accumulation-rate patterns over the three time periods are all similar, suggesting that the regional pattern did not change significantly between the start of the Holocene and the last ~20 ka of the last Glacial Period. For more details on methods, see MacGregor, et. al., 2009.

5. References and Related Publications

MacGregor, Joseph A., Kenichi Matsuoka, Michelle R. Koutnik, Edwin D. Waddington, Micheal Studinger and Dale P. Winebrenner. 2009. Millennially Averaged Accumulation Rates for the Vostok Subglacial Lake Region Inferred from Deep Internal Layers, Annals of Glaciology, 50(51) 25-34.

The following related documents are available online:

Table 2. Related Documents

Document	Description	URL
SOAR Projects and Data Distribution	University of Texas Institute for Geophysics Support Office for Aerogeophysical Research (SOAR)	http://www.ig.utexas.edu/research/projects/soar/SOAR_datanprojects.htm
AGDC Home Page	Data center home page	http://nsidc.org/agdc

6. Document Information

Acronyms

The following acronyms are used in this document.

Table 3. Acronyms and Abbreviations

Acronym	Description
FTP	File Transfer Protocol
ka	Thousands of years
LLA	Local-Layer Approximation
NSIDC	National Snow and Ice Data Center
SOAR	Support Office for Aerogeophysical Research/td>
URL	Uniform Resource Locator

Document Creation Date

5 August 2011

Document URL

http://nsidc.org/data/docs/agdc/nsidc0500_macgregor/index.html