Ice velocity from static GPS observations along the transect from Zhongshan station to Dome A, East Antarctica

Abstract

Dome A, the highest point on the Antarctic ice sheet at just over 4000 m a.s.l., is located near the centre of East Antarctica. Chinese National Antarctic Research Expeditions have studied ice-sheet dynamics and mass balance along a traverse route from Zhongshan station to Dome A during the austral summers from 1996/97 to 2004/05. Nineteen GPS sites were occupied on at least two occasions at approximately 50 km intervals. The purpose of the surveys was to provide accurate ice-dynamics data. A dual-frequency GPS receiver was used and each site was occupied for 1-12 hours. GPS data were processed using GAMIT/GLOBK software, and horizontal accuracies were within 0.1 m. Repeat GPS measurements provided ice velocities. The horizontal surface ice velocities increase from the summit of the ice sheet to the coast. In the Dome A area, the velocities are <10ma-1; in the plateau area, velocities range from 8 to 24 m a-1 and reach about 98.2 m a-1 at a site (LT980) near the coast. The flow directions are roughly pendicular to the ice-sheet surface elevation contours, primarily toward the Lambert Glacier basin.