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Compilation of Antarctic Radar Data, Siple Coast, 2000-2002

Summary

These data consist of ground-based, ice-penetrating radar profiles across satellite-detected lineations and terrains that were taken in the lower reaches of Ross Ice Stream C, also known as the Kamb Ice Stream (KIS); on Roosevelt Island; on the Siple Dome; and on the Shabtaie Ice Ridge. Researchers collected low frequency (2 MHz - 7 MHz) data during two separate deployments, 11 November through 7 December 2000 and 3 January through 28 January 2002. These radar data provide information on surface morphology and internal layer stratigraphy. The data are in the form of raw binary data files, accompanied by processed data files in JPEG format.

These data are from a study of the scar-like features that are well known from the Siple Coast ice stream system in West Antarctica. The objective of the field work was to identify the nature of several scars, and to further characterize previously-identified margin scars that have been poorly dated. Advanced Very High Resolution Radiometer (AVHRR) and Radarsat image data, which are not included in this data set, were used to locate and map the features, and place them in a regional context. The study describes the recent history of the Siple Coast glaciers and investigates the causes of their changes in configuration. The main investigative tools were ground penetrating radar (GPR) profiles used to image internal layers and measure the depths to buried crevasses or disrupted layering. This, coupled with accumulation rates determined from shallow ice cores, provides "shutdown" ages for the margin features. The field data provide input parameters for simple models of ice flow for margins and inter-ice stream ridges during active shearing and after shutdown. Such modeling will output an estimate of the initial elevation of scars and the corresponding ice stream elevation at the time of shutdown.

Citing These Data

Raymond, C., H. Conway, and G. Catania. 2006. Compilation of Antarctic radar data, Siple Coast, 2000-2002. Boulder, CO: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5736NTS.

We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.

Overview Table

Category Description
Data format The processed data are JPEG image files. Raw data are DAT binary files.
Spatial coverage Southernmost Latitude: 84° S
Northernmost Latitude: 81° S
Westernmost Longitude: 158° W
Easternmost Longitude: 134° W

An image showing the locations where the profiles were obtained is provided in the Study Area Location section below.

Temporal coverage and resolution Researchers collected low (2-7 MHz) frequency data between 11 November and 7 December 2000 and between 3 January and 28 January 2002.
Tools for accessing data The processed radar images are in JPEG format and are viewable with most image viewing software. The binary files can be viewed using MATLAB. See Processing Radar Data with MATLAB.
File naming convention Raw data file names follow the convention YYDDDnn, where YY is the year (00 or 01), DDD is the Julian day (001, 002...365), and nn is the file number for that day (01, 02...21). Processed data images are named according to the profile name specified in the table provided in Spatial Coverage section. For example, the SIS profile is titled "SIS.jpg."
File size

Raw data files range from 16 KB to 1.6 MB. The processed JPEG image files range from 226 KB to 397 KB.

Parameter(s) These radar data provide information on surface morphology and internal layer stratigraphy of the Kamb Ice Stream (KIS).
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

Howard Conway
Department of Earth and Space Sciences
University of Washington
1100 NE 45th St, Suite 300
Seattle, WA 98195

Charles Raymond
Geophysics Program
Box 351650
University of Washington
Seattle, WA 98195-1650

Ginny Catania
Institute for Geophysics
4412 Spicewood Springs Rd., Unit 600
University of Texas
Austin, TX 78759

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 the NSF grant OPP- 9909518, Office of Polar Programs award to Charles Raymond and Howard Conway.

The investigators would like to thank Maurice Conway and Tony Gades for their assistance in the field.

2. Detailed Data Description

Format

The processed data are JPEG image files. Raw data are DAT binary files.

Directory Structure and File Naming Conventions

The image files are coded by location. The north side of Kamb Ice Stream (KIS) includes an area called "Duckfoot," named for the splayed pattern of lineations that mark its surface. A similar area exists on the south side of KIS called "Goosefoot." The two regions consist of several different types of ice terrains, each with distinct characteristics.

Duck Duckfoot location
BC Engelhardt Ice Ridge formerly known as Ice Ridge BC
UPBC "up BC," the upper reaches of the Engelhardt Ice Ridge
DNBC "down BC," the lower reaches of the Engelhardt Ice Ridge
GLBC the "grounding line" of the Engelhardt Ice Ridge
Bumps the "Bumps line" of the Engelhardt Ice Ridge

See the Study Area Location section to view site names and locations. The profile names provided in the Spatial Coverage section correspond to the file names of the JPEG images.

Raw data file names follow the convention YYDDDnn, where YY is the year (00 or 01), DDD is the Julian day (001, 002...365), and nn is the file number for that day (01, 02...21).

"metadata" directory:

"processed_data" directory: This directory contains rendered images of the raw data.

"Duckfoot" subdirectory:

  • D_Duck.jpg (383 KB)
  • U_Duck.jpg (271 KB)
  • C_Duck.jpg (226 KB)
  • K_Duck.jpg (318 KB)

"Goosefoot" subdirectory:

  • A_DNBC.jpg (259 KB)
  • B_DNBC.jpg (370 KB)
  • E_GLBC.jpeg (319 KB)
  • F_GLBC.jpg (397 KB)
  • G_GLBC.jpeg (291 KB)
  • O_GLBC.jpeg (348 KB)
  • S_GLBC.jpg (323 KB)

"up_ER" subdirectory:

  • B_UPBC.jpg (274 KB)
  • Bumps.jpg (269 KB)
  • C_UPBC.jpg (294 KB)

"raw_data" directory:

This directory contains the raw binary data files containing the radar profile data. The file sizes range from 24 KB to 1.61 MB.

File Size

Raw data files range from 16 KB to 1.61 MB. The processed JPEG image files range from 226 KB to 397 KB.

Study Area Location

location map thumbnail Click on the thumbnail to view the location map (JPEG file, 200 KB) for the radar profiles measured during this project.

Spatial Coverage

Southernmost Latitude: 84° S
Northernmost Latitude: 81° S
Westernmost Longitude: 158° W
Easternmost Longitude: 134° W

Below is a table of information including the profile name, start waypoint, end waypoint, raw data file name, and the radar frequency.

profile information

Temporal Coverage

Data were collected between 11 November and 7 December 2000 and between 3 January and 28 January 2002.

Temporal Resolution

Low frequency data were collected from the range of 2 MHz to 7 MHz.

Parameter or Variable

Parameter Description

These radar data provide information on surface morphology and internal layer stratigraphy of the Kamb Ice Stream (KIS).

Sample Data Image

D Duck profile thumbnail Click on the thumbnail to view the D Duck radar profile (JPEG file, 187 KB).

Error Sources

Error in the measurements arises from three main sources:

For these measurements the investigators estimate the uncertainty in ice thickness to be approximately 5 m.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The entire data set is approximately 74.2 MB.

Software and Tools

The processed radar images are in JPEG format and are viewable with most image viewing software. The binary files can be viewed using MATLAB.

Related Data Collections

4. Data Acquisition and Processing

Sensor or Instrument Description

The University of Washington radar system is based on a design described by Watts and Wright (1981). The transmitter used for these measurements is a lightweight (<0.25 kg) mono-pulse unit described by Jones et al. (1989). A Tektronix digital oscilloscope is used to record the two-way travel time and amplitude of reflections from within the ice. The internal stacking capacity of this oscilloscope is limited to 10,000 records, but waveforms are recorded with an average of 500 stacks. Power for the transmitter, oscilloscope, and computer was supplied by separate 12V, 100 ampere-hour batteries. Investigators used weighted dipole antennae ( f=300 W ) (Watts & Wright, 1981), threaded inside climbing webbing for protection, with center frequencies of 2 MHz and 5 MHz. One and a half full dipole antennae lengths separated the transmitter and receiver.

Data Acquisition Methods

Short-pulse radar systems were used to image deep internal layers, 100 m to 1,000 m. Investigators used a pressure transducer and a geodetic-quality global positioning system (GPS) receiver to measure surface topography and elevations.

Processing Steps

Interpreting isolated spot measurements of the amplitude and two-way travel time of reflections can be problematic, so investigators made a profile of contiguous measurements that were typically spaced approximately 10 m apart. For each profile image, all records were first band-pass filtered. In cases where the amplitude of the surface topography is on the order of the ice thickness, it was necessary to adjust the records for surface elevation before migrating the data. Two-way travel time was converted to ice thickness by correcting for geometry and assuming a wave speed of 168 m/µs in ice.

See Processing Radar Data with MATLAB.

5. References and Related Publications

Anandakrishnan, S., R. B. Alley, R. W. Jacobel, and H. Conway. 2000. The flow regime of Ice Stream C and hypotheses concerning its recent stagnation. Antarctic Research Series 77, 283-296.

Catania, G., H. Conway, C. Raymond, and T. Scambos. 2004. Surface morphology and internal layer stratigraphy in the downstream end of Kamb Ice Stream, West Antarctica. Journal of Glaciology. In press.

Catania, G., H. Conway, C. Raymond, and T. Scambos. 2004. Evidence for grounding-line fluctuations prior to the stagnation of Kamb Ice Stream, West Antarctica. Journal of Geophysical Research: Earth Surface. Submitted.

Catania, G., H. Conway, A. Gades, C. Raymond, and H. Engelhardt. 2003. Bed reflectivity beneath inactive ice streams in West Antarctica. Annals of Glaciology 36, 287-291.

Conway, H., G. Catania, C. Raymond, A. Gades, T. Scambos, and H. Engelhardt. 2002. Switch of flow direction of an Antarctic ice stream. Nature 419, 465-467.

Jones, F., B. Narod and G. K. C. Clarke. 1989. Design and operation of a portable, digital impulse radar. Journal of Glaciology 35(119), 143-148.

Ng, F. and H. Conway. 2004. Fast-flow signature in the stagnated Kamb Ice Stream, West Antarctica. Geology 32(6), 481-484. doi: 10.1130/G20317.1

Parizek, B., R .B. Alley, S. Anandakrishnan, and H. Conway. 2002. Sub-catchment melt and long-term stability of Ice Stream D, West Antarctica. Geophysical Research Letters doi: 10.1029/2001GL014240.

Waddington, E. D., H. Conway, E. Steig, R. B. Alley, E. J. Brook, K. C. Taylor, and J. W. C. White. 2005. Decoding the dipstick: thickness of Siple Dome, West Antarctica, at the last glacial maximum. Geology 33(4), 281-284.

Watts, R. D. and D. L. Wright. 1981. Systems for measuring thickness of temperate and polar ice from the ground or from the air. Journal of Glaciology 27(97), 459-469.

6. Document Information

List of Acronyms

The following acronyms are used in this document:

AVHRR: Advanced Very High Resolution Radiometer
DNBC: Down Ice Ridge BC
FTP: File Transfer Protocol
GLBC: Grounding Line Ice Ridge BC
GPS: Global Positioning System
GPR: Ground Penetrating Radar
JPEG: Joint Photographic Experts Group
KIS: Kamb Ice Stream
MATLAB: Matrix Laboratory
NSF: National Science Foundation
NSIDC: National Snow and Ice Data Center
OPP: Office of Polar Programs
SIS: Siple Ice Stream
UPBC: Up Ice Ridge BC
URL: Universal Resource Locator

Document Creation Date

February 2006

Document URL

http://nsidc.org/data/docs/agdc/nsidc0274_conway/index.html