Investigation of polythermal glacier on King George Island, Antarctica seen by ground penetrating radar

Abstract

Firn-ice transition zone and subglacial properties of polythermal glaciers on King George Island wereinvestigated by results of ground-penetrating radar (GPR). The northern 3.6-km NNW-SSE profile is along theboundary with the Doctors Icefall Glacier while the southern 3.4-km NE-SW profile is along the boundary of theMoczydlowski Glacier. Average profiling speeds were 3.17 m/s and 4.45 m/s, respectively. A center frequency of50-MHz unshielded GPR antenna with 59 ms radar pulse intervals and 4181 ns records was used. The firn line hasformed at 350 m altitude. Layers appeared on the radar sections are merged smoothly into the glacier surface andthicker at higher elevation. The upper 30 m layer of cold ice shows clear layering while the underlying warmer iceis characterized by strong scattering in the ablation zone. The accumulation of the ice mass in the profile 1 givesinsight to different inflow of ice mass from NNW and SSE to the gully direction. The ice mass was not enough andhad a discontinuity from the SSE. The basement is clearly imaged beneath a transparent layer of cold ice while somebasement is poorly imaged underlying warmer ice characterized by strong scattering. If GPR surveys are correlatedwith ice cores or snow pit data, GPR will be the most powerful tool for measuring snow and glacier distributions.