GPS determination of the velocity and strain-rate fields on Schirmacher Glacier, central Dronning Maud Land, Antarctica

Global positioning system (GPS) campaigns were conducted during the 2003 and 2004 austral summer seasons to obtain insight into the velocity and strain-rate distribution on Schirmacher Glacier, central Dronning Maud Land, East Antarctica. CPS data were collected at 21 sites and analyzed to estimate the site coordinates, baselines and velocities. The short-term precision of the base station, MAIT, is estimated from the daily coordinate repeatability solutions during the two years. All CPS points on the glacier were constrained with respect to MAIT and nearby International GPS Service stations. Horizontal velocities of the glacier sites lie between 1.89 +/- 0.01 and 10.88 +/- 0.01 m a(-1) to the north-northeast, with an average velocity of 6.21 +/- 0.01 m a(-1). The principal strain rates provide a quantitative measurement of extension rates, which range from (0.11 +/- 0.01) X 10(-3) to (1.48 +/- 0.85) x 10(-3) a(-1), and shortening rates, which range from (0.04 +/- 0.02) x 10(-3) to (0.96 +/- 0.16) X 10-3 a(-1). The velocity and strain-rate distributions across the GPS network in Schirmacher Glacier are spatially correlated with topography, subsurface undulations, fracture zones/crevasses and the partial blockage of the flow by nunataks and the Schirmacher Oasis.