Vertical Strain at Siple Dome, Antarctica, 1999-2002

Summary

At the Siple Dome area of Antarctica, much of the ice flow is vertical, which causes vertical ice deformation. To measure this phenomenon, the investigators used a method known as vertical strain rate. This project was a part of the West Antarctic Ice Sheet Cores (WAISCORES) project for deep ice coring in West Antarctica. WAISCORES is supported by the Office of Polar Programs (OPP), National Science Foundation (NSF).

This data set consists of a table of long-term average strain rates measured between 1999 and 2002 at Siple Dome, Antarctica. The measurements were taken in hot-water boreholes by bridge gauges. Data are available in tab-delimited ASCII text format or PDF via FTP.

Citing These Data

Harrison, W. 2007. Vertical strain at Siple Dome, Antarctica, 1999-2002. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5HH6H00.

Overview Table

Category	Description
Data format	Tab-delimited ASCII text and PDF
Spatial coverage	Investigators collected data from two sites at Siple Dome, Antarctica. Site 1, located 500 m from the Polar Ice Coring Office (PICO) deep ice core site:     Southernmost Latitude: 81.655° S     Northernmost Latitude: 81.655° S     Westernmost Longitude: 148.822° W     Easternmost Longitude: 148.822° W Site 2, located 7 km to the northeast of Site 1:     Southernmost Latitude: 81.595° S     Northernmost Latitude: 81.595° S     Westernmost Longitude: 148.693° W     Easternmost Longitude: 148.693° W
Temporal coverage and resolution	05 December 1999 through 02 January 2002, 2-year average rates from hourly measurements
Data files	strain_rate.txt (1 KB) StrainRateNSIDC.pdf (112 KB)
Parameter	Average vertical strain rates
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. References and Related Publications
5. Document Information

1. Contacts and Acknowledgments

Investigators

William Harrison
Geophysical Institute
University of Alaska, Fairbanks
PO Box 757320
Fairbanks, Alaska 99775-7320
USA

John Morack
Geophysical Institute
University of Alaska, Fairbanks
PO Box 757320
Fairbanks, Alaska 99775-7320
USA

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

Erin Pettit
Department of Earth and Space Sciences
University of Washington
Box 351310
Seattle, Washington 98195-1310
USA

Mark Zumberge
Scripps Institution of Oceanography
University of California, San Diego
La Jolla, California 92093-0225
USA

Daniel Elsberg
Geophysical Institute
University of Alaska, Fairbanks
PO Box 757320
Fairbanks, Alaska 99775-7320
USA

Technical Contact

Acknowledgements

The investigator wishes to thank the following scientists: Eric Husmann and Daniel Elsberg of the University of Alaska, Fairbanks, Ed Waddington and Erin Pettit of the University of Washington, and Mark Zumberge of the Scripps Institution of Oceanography.

This grant was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) award OPP-9615502.

2. Detailed Data Description

Investigators measured the vertical strain rate as a function of depth at two sites on Siple Dome, Antarctica. One site was at the divide (ice divides separate areas with different flow patterns and directions) and one at the flank (side). Ice flow near a divide such as Siple Dome is predominantly vertical. As a consequence ice deformation is in the vertical direction, known as the "vertical strain rate." Measuring this rate is important for the calibration of dynamic models of ice flow. Investigators used two high-resolution systems for measuring strain rate in hot-water-drilled holes.

This data set consists of a table of long term average strain rates measured in 2000 and 2001 at Siple Dome, Antarctica. The Wheatstone bridge gauges were placed at various depths at two sites, one 500 m from the PICO deep ice core site, and the other 7 km to the northeast. The strain rates are averaged over the gauge length, approximately 1 m.

Resulting Ice Flow Model

The ice flow model resulting from the measurements and flow law determination is used to interpret the shapes of radar internal layering in terms of the dynamic history and accumulation patterns of Siple Dome over the past 10,000 years. This improved model can be applied to the interpretation of annual layer thicknesses used to produce annual accumulation rates and borehole temperatures from the ice core drilled at Siple Dome during the 1997/98 field season. This research is a collaborative project between the University of Alaska, the University of California, San Diego and the University of Washington.

Format

Data are provided in tab-delimited ASCII text format and PDF.

Spatial Coverage

The cores were taken from Siple Dome, Antarctica.

Site 1, located 500 m from the PICO deep ice core site:
    Southernmost Latitude: 81.655° S
    Northernmost Latitude: 81.655° S
    Westernmost Longitude: 148.822° W
    Easternmost Longitude: 148.822° W

Site 2, located 7 km to the northeast of Site 1:
    Southernmost Latitude: 81.595° S
    Northernmost Latitude: 81.595° S
    Westernmost Longitude: 148.693° W
    Easternmost Longitude: 148.693° W

Temporal Coverage

The study was conducted from 05 December 1999 to 02 January 2002.

Parameter

Investigators measured the average vertical strain rate at Siple Dome, Antarctica.

Units of Measurement

Strain rates are measured as micro-strain per year (parts-per-million strain per year). Depths are given in actual depth below the surface at the time of emplacement (January 1998), not ice equivalent units.

Data Record Format

The data show long-term-average strain rates as measured by the resistance wire gauges. An "X" indicates a nonfunctioning gauge. Where relevant, these strain rates have been corrected to remove the modeled effects of shear strain (on the deeper Flank gauges). The corrected rates are shown with the uncorrected values following in parentheses.

The data columns are:

1. Depth (m)
2. Strain rate (με a^-1)
3. Uncertainty (με a^-1)

Error Sources

Investigators believe that the rates are, on average, 15% too large (too negative) due to the coupling of the gauge anchors with the ice.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

Total volume of data files 111 KB.

Related Data Collections

• Compilation of Antarctic Radar Data, Siple Coast, 2000-2002
• Ice Motion and Topography Near Margin Areas of Kamb Ice Stream, Antarctica
• Ice Velocity Data from Ice Stream C, West Antarctica
• Siple Dome Glaciology and Ice Stream History 1994, 1996

4. References and Related Publications

Elsberg, D. H., W. D. Harrison, E. Husmann, J. L. Morack, E. C. Pettit, E. D. Waddington, and M. A. Zumberge. 2004. Depth- and time-dependent strain rates at Siple Dome, Antarctica. Journal of Glaciology 50 (171): 511-521.

5. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AGDC	Antarctic Glaciological Data Center
FTP	File Transfer Protocol
NSF	National Science Foundation
OPP	Office of Polar Programs
PDF	Portable Document Format
PICO	Polar Ice Coring Office
ppm	parts per million
WAISCORES	West Antarctic Ice Sheet Cores

Document Creation Date

February 2007

Document URL

http://nsidc.org/data/docs/agdc/nsidc0214_harrison/index.html