Space Geodesy as a tool for measuring ice surface velocity in the Dome C region and along the ITASE traverse

ABSTRACT Dome C was chosen by the European Project for Ice Coring in Antarctica (EPICA) as the site at which to drill a deep ice core. This paper presents results from geodetic surveys of ice velocities (absolute and relative) at Dome C and along a transect to Terra Nova Bay. The purpose of the surveys was to provide accurate data for the study of ice dynamics studies; particularly a strain network comprising 37 poles surveyed in 1995 and again in 1999. Data indicates that ice surface at the poles closest to the topographic summit move horizontally by up to a few mm a-1 in a direction consistent with downslope motion of the ice sheet, while those located 25 km away from the summit move up to 211 mm a-1. The EPICA drilling site yields an interpolated velocity of about 15±10 mm a-1 in N-NW direction. Analysis of the velocity field and surface topography reveals that the surface flow centre is nearly co-located with the dome summit, and that both are in a steady-state condition. The measured horizontal velocities are consistent with remote sensing result and provide accurate ground truth control for flow mapping. Seven snow-firn cores, up to 53 m deep, were drilled during the Terra Nova Bay - Dome C traverse. Submerged velocity systems were installed at the borehole and measured using GPS (Global Positioning System), first results show a steady state condition. Measured (horizontal) ice velocities increase from the summit of the ice sheet to the coast, reaching about 28 m a-1 at site GPS2A.