Abstract:
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.
Quality
Error in the measurements arises from three main sources: * the migration technique (See Processing Steps (http://nsidc.org/data/docs/agdc/nsidc0274_conway/index.html#process...).) * 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.
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
City:
Boulder
Province or State:
CO
Postal Code:
80309-0449
Country:
USA
Publications/References
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.
