Airborne GPR sounding of deep temperate glaciers — Examples from the Northern Patagonian Icefield

Airborne ground penetrating radar (GPR) measurements of temperate ice are a challenge because of absorption, internal scattering, and surface roughness. We found that at center frequencies of 30 MHz or below effects of scattering and roughness are sufficiently reduced to produce good quality radar data. The 30 MHz helicopter radar system BGR-P30 is able to penetrate temperate ice to more than 700 m depth. In 2010 about 220 km of GPR profiles were obtained by helicopter measurements performed on flight patterns over Nef and Colonia glaciers in Patagonia, Chile. We report the technique, processing, and results of these novel ice thickness measurements.