Ice Thickness and Internal Layer Depth Along the 2001 and 2002 US ITASE Traverses

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Summary

Ice thickness and internal layer depth data were collected with a ground-based, ice-penetrating radar study as part of the US International Trans Antarctic Scientific Expedition (US ITASE) traverse in West Antarctica from 01 November 2001 to 10 January 2003. Longitude, latitude, ice thickness, and depth to a prominent internal reflector were collected at approximately 12 m intervals. Ice thickness values are reported for approximately 90% of the traverse, and internal layer depth values are reported for approximately 80% of the traverse. Data are avaialble in ASCII and JPEG formats via FTP.

Citing These Data

Please cite these data as follows:

Jacobel, R.W., and B.C. Welch. 2005. Ice thickness and internal layer depth along the 2001 and 2002 US ITASE traverses. Boulder, CO: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5R20Z9T.

Overview Table

Category	Description
Data format	Tab-delimited ASCII text files and JPEG images
Spatial coverage	80°S, 120°W to 89°S, 76°W
Temporal coverage	Data were collected from 01 November 2001 to 10 January 2003.
Data File naming convention and size	ASCII files: jacobel_usitase_2001_01-6_ellsworth.txt jacobel_usitase_2001_byrd_01-6.txt jacobel_usitase_2001_info_table.txt jacobel_usitase_2002_byrd_spole.txt jacobel_usitase_2002_herc_dome.txt jacobel_usitase_2002_info_table.txt JPEG files: jacobel_usitase_2001_01-6_ellsworth_plot.jpg jacobel_usitase_2001_byrd_01-6_plot.jpg jacobel_usitase_2001_map.jpg jacobel_usitase_2001_RES_data_sample.jpg jacobel_usitase_2002_byrd_spole_plot.jpg jacobel_usitase_2002_herc_dome_plot.jpg jacobel_usitase_2002_map.jpg jacobel_usitase_2002_RES_data_sample.jpg File sizes range from 1 KB to 4 MB.
Parameter(s)	Ice thickness and depth to an internal layer in meters
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

Investigator(s) Name and Title

Robert Jacobel and Brian Welch
St. Olaf College
Department of Physics
Northfield, MN 55057 USA

Technical Contact:

Acknowledgements

This research was supported by NSF OPP award #9814574, "Radar Studies of Internal Stratigraphy and Bedrock Topography Along the US ITASE Traverse."

2. Detailed Data Description

Format

Four ASCII text files contain the data. Each file has columns for longitude and latitude in decimal degrees, ice thickness in meters, and depth to the prominent internal layer in meters. Data spacing along the traverse is approximately 12 m. For each year of the traverse (2001 and 2002), an "info_table.txt" table indicates where the core sites were located along the route as well as any turns (kinks) in the traverse.

Corresonding JPEG image files show graphical plots of the data. Each year of the traverse also has a small "data_sample.jpg" image of radar data and two "map.jpg" files showing maps of the routes each year.

File Naming Convention and File Size

ASCII files:
jacobel_usitase_2001_01-6_ellsworth.txt
jacobel_usitase_2001_byrd_01-6.txt
jacobel_usitase_2001_info_table.txt
jacobel_usitase_2002_byrd_spole.txt
jacobel_usitase_2002_herc_dome.txt
jacobel_usitase_2002_info_table.txt

JPEG files:
jacobel_usitase_2001_01-6_ellsworth_plot.jpg
jacobel_usitase_2001_byrd_01-6_plot.jpg
jacobel_usitase_2001_map.jpg
jacobel_usitase_2001_RES_data_sample.jpg
jacobel_usitase_2002_byrd_spole_plot.jpg
jacobel_usitase_2002_herc_dome_plot.jpg
jacobel_usitase_2002_map.jpg
jacobel_usitase_2002_RES_data_sample.jpg

File sizes range from 1 KB to 4 MB.

Spatial Coverage

The traverses fall within the following bounding coordinates:

Southernmost Latitude: 90°S
Northernmost Latitude: 80°S
Westernmost Longitude: 120°W
Easternmost Longitude: 76°W

Spatial Coverage Map

Above is a map of the 1999-2002 traverse routes for the U.S. portion of the International Transantarctic Scientific Expedition (US ITASE).

Spatial Resolution

Data spacing along the traverse is approximately 12 m. Surface elevations along the traverse are available from a companion data set by Hamilton et al. at U. of Maine.

Temporal Coverage

Data were collected from 01 November 2001 to 10 January 2003.

Parameter or Variable

Unit of Measurement

Data files contain ice thickness and depth to the prominent internal layer in meters. Thickness and depth data are accurate to ± 10 m, and position values are accurate to within 1 m.

Sample Data Record

The following sample shows the first several lines of "jacobel_usitase_2001_01-6_ellsworth.txt."

Latitude	Longitude	Distance-kilometers	17.5ka bed_depth
-76.1011	-89.0138	0 -9999	2131.305
-76.1012	-89.0138	0.010691 -9999	2125.425
-76.1014	-89.0137	0.026805 -9999	2125.425
-76.1014	-89.0137	0.035792 -9999	2127.945
-76.1015	-89.0136	0.046494 -9999	2125.425
-76.1016	-89.0136	0.057361 -9999	2125.425

3. Data Access

Data Access

Data are available via FTP.

Related Data Collections

Surface elevations along the traverse are available from a companion data set by Gordon Hamilton and Ian Whillans, University of Maine.

See a list of ice depth/thickness data sets that the Antarctic Glaciological Data Center (AGDC) at NSIDC distributes.

4. Data Acquisition and Processing

Sensor or Instrument Description

Data were collected with a ground-based impulse radar with a center frequency of approximately 3 MHz.

Data Acquisition Methods

A ground-based impulse radar was used to sound the ice. Approximately 1,500 traces were averaged (stacked) for each waveform and recorded at approximately 12 m intervals. Positions were acquired with a dual-frequency precision Global Positioning System (GPS) using kinematic survey mode and differential correction.

A bright, reflective layer from volcanic activity dated 17,500 years ago is visible in all of the major cores (Byrd, Siple, etc.)

5. References and Related Publications

Jacobel, R.W., and B.C. Welch. 2005. A time marker at 17.5 KYBP detected throughout West Antarctica. Annals of Glaciology 41. In Press.

Jacobel, R.W., B.C. Welch, E.J. Steig, and D.P. Schneider. 2005. Hercules Dome – an optimal site for deep ice core drilling. Journal of Geophysical Research 110: F01015. doi:10.1029/2004JF000188.

Siegert, M.J., B.C. Welch, A. Vieli, D.D. Blankenship, I.M. Joughin, E.C. King, G. Leysinger Vieli, A.J. Payne, and R.W. Jacobel. 2004. Ice flow direction change in interior West Antarctica revealed by internal ice sheet layer distortions. Science 305: 1948-1951. doi: 10.1126/science.1101072.

Welch, B.C., and R.W. Jacobel. 2005. Bedrock topography and wind erosion sites in East Antarctica, observations from the 2002 US ITASE traverse. Annals of Glaciology 41. In Press.

Welch, B.C., and R.W. Jacobel. 2003. Analysis of deep-penetrating radar surveys of West Antarctica, US ITASE 2001. Geophysical Research Letters 30(8): 1444. doi: 10:1029/2003GL017210.

6. Document Information

List of Acronyms

The following acronyms are used in this document:

AGDC: Antarctic Glaciological Data Center
ASCII: American Standard Code for Information Interchange
FTP: File Transfer Protocol
GPS: Global Positioning System
JPEG: Joint Photographic Experts Group
NSIDC: National Snow and Ice Data Center
US ITASE: US International Trans Antarctic Scientific Expedition

Document Creation Date

March 2005

Document Revision Date

April 2005

Document Review Date

April 2005

Document URL

http://nsidc.org/data/docs/agdc/nsidc0264_jacobel/index.html