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.
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Compilation of Antarctic Radar Data, Siple Coast, 2000-2002, Version 1
|Spatial Resolution:||Not Specified|
|Temporal Resolution:||Not specified|
|Data Contributor(s):||Charles Raymond, Howard Conway, Ginny Catania|
|Metadata XML:||View Metadata Record|
As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.Raymond, C., H. Conway, and G. Catania. 2005. Compilation of Antarctic Radar Data, Siple Coast, 2000-2002, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5736NTS. [Date Accessed].
Detailed Data Description
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.
The processed data are JPEG image files. Raw data are DAT binary files.
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.
||Engelhardt Ice Ridge formerly known as Ice Ridge BC|
||"up BC," the upper reaches of the Engelhardt Ice Ridge|
||"down BC," the lower reaches of the Engelhardt Ice Ridge|
||the "grounding line" of the Engelhardt Ice Ridge|
||the "Bumps line" of the Engelhardt Ice Ridge|
Raw data file names follow the convention
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.doc (5.61 MB)
- metadata.pdf (5.17 MB)
processed_data directory: This directory contains rendered images of the raw data.
- sis.jpg (312 KB)
- D_Duck.jpg (383 KB)
- U_Duck.jpg (271 KB)
- C_Duck.jpg (226 KB)
- K_Duck.jpg (318 KB)
- 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)
- B_UPBC.jpg (274 KB)
- Bumps.jpg (269 KB)
- C_UPBC.jpg (294 KB)
This directory contains the raw binary data files containing the radar profile data. The file sizes range from 24 KB to 1.61 MB.
Raw data files range from 16 KB to 1.61 MB. The processed JPEG image files range from 226 KB to 397 KB.
Data were collected between 11 November and 7 December 2000 and between 3 January and 28 January 2002.
Low frequency data were collected from the range of 2 MHz to 7 MHz.
These radar data provide information on surface morphology and internal layer stratigraphy of the Kamb Ice Stream (KIS).
Sample Data Image
Error in the measurements arises from three main sources:
- the migration technique (Refer to the Processing Steps section.)
- uncertainty picking the location of the bed reflection
- uncertainty in the radio wave velocity within the glacier.
For these measurements the investigators estimate the uncertainty in ice thickness to be approximately 5 m.
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.
The entire data set is approximately 74.2 MB.
Data Acquisition and Processing
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.
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.
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.
References and Related Publications
Contacts and Acknowledgments
University of Washington
1100 NE 45th St, Suite 300
Seattle, WA 98195
University of Washington
Seattle, WA 98195-1650
Institute for Geophysics
4412 Spicewood Springs Rd., Unit 600
University of Texas
Austin, TX 78759
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.
DOCUMENT CREATION DATE