South Polar in situ radio-frequency ice attenuation

Abstract

We have determined the in situ electric field attenuation length Lα, (defined as the length over which the signal amplitude diminishes by a factor 1/e) for radio-frequency signals broadcast vertically through South Polar ice and reflected off the underlying bed. Conservatively assuming a bedrock field reflectivity R = 1.0, we estimate Lα = 1450-150+300 m for f = 380 MHz, and T = -50°C; the errors incorporate uncertainties in R. This value is consistent with previous estimates that the radiofrequency attenuation length exceeds the attenuation length at optical frequencies by an order of magnitude.