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Article
Modeling Englacial Radar Attenuation at Siple Dome, West Antarctica, Using Ice Chemistry and Temperature Data
Journal of Geophysical Research-Earth Surface
  • Joseph A. MacGregor
  • Dale P. Winebrenner
  • Howard Conway
  • Kenichi Matsuoka
  • Paul Andrew Mayewski, University of Maine - Main
  • Gary D. Clow
Document Type
Article
Publication Date
7-27-2007
Publication Number
F03008
Disciplines
Abstract/ Summary

The radar reflectivity of an ice-sheet bed is a primary measurement for discriminating between thawed and frozen beds. Uncertainty in englacial radar attenuation and its spatial variation introduces corresponding uncertainty in estimates of basal reflectivity. Radar attenuation is proportional to ice conductivity, which depends on the concentrations of acid and sea-salt chloride and the temperature of the ice. We synthesize published conductivity measurements to specify an ice-conductivity model and find that some of the dielectric properties of ice at radar frequencies are not yet well constrained. Using depth profiles of ice-core chemistry and borehole temperature and an average of the experimental values for the dielectric properties, we calculate an attenuation rate profile for Siple Dome, West Antarctica. The depth-averaged modeled attenuation rate at Siple Dome (20.0 +/- 5.7 dB km(-1)) is somewhat lower than the value derived from radar profiles (25.3 +/- 1.1 dB km(-1)). Pending more experimental data on the dielectric properties of ice, we can match the modeled and radar-derived attenuation rates by an adjustment to the value for the pure ice conductivity that is within the range of reported values. Alternatively, using the pure ice dielectric properties derived from the most extensive single data set, the modeled depth-averaged attenuation rate is 24.0 +/- 2.2 dB km(-1). This work shows how to calculate englacial radar attenuation using ice chemistry and temperature data and establishes a basis for mapping spatial variations in radar attenuation across an ice sheet.

Citation/Publisher Attribution
Macgregor, JA, Winebrenner, DP, Conway, H, Matsuoka, K, Mayewski, PA, and Clow, GD, 2007, Modeling Englacial Radar Attenuation at Siple Dome, West Antarctica, Using Ice Chemistry and Temperature Data: Journal of Geophysical Research-Earth Surface, v. 112, F03008. To view the published open abstract, go to http://dx.doi.org and enter the DOI.
Publisher Statement
© Copyright 2007 American Geophysical Union
DOI
10.1029/2006JF000717
Version
publisher's version of the published document
Citation Information
Joseph A. MacGregor, Dale P. Winebrenner, Howard Conway, Kenichi Matsuoka, et al.. "Modeling Englacial Radar Attenuation at Siple Dome, West Antarctica, Using Ice Chemistry and Temperature Data" Journal of Geophysical Research-Earth Surface Vol. 112 (2007)
Available at: http://works.bepress.com/paul_mayewski/30/