Antarctic ice velocities from GPS locations logged by seismic stations

In 2007-08, seismologists began deploying passive seismic stations over much of the Antarctic ice sheet. These stations routinely log their position by navigation-grade global positioning system (GPS) receivers. This location data can be used to track the stations situated on moving ice. For stations along the traverse from Zhongshan station to Dome A in East Antarctica and at the West Antarctic Ice Sheet divide the estimated velocities of the ice surface based on positions recorded by navigation-grade GPS are consistent with those obtained by high-accuracy geodetic GPS. Most of the estimated velocities have an angle difference of <28° with the steepest downhill vector of the ice surface slope at the stations. These results indicate that navigation-grade GPS measurements over several months provide reliable information on ice sheet movement of ≥1 m yr^-1. With an uncertainty of ~0.3-1 m yr^-1, this method is able to resolve both very slow ice velocities near Dome A and velocities of >100 m yr^-1 on Thwaites Glacier. Information on ice velocity at three locations for which no data from satellite-based interferometric synthetic aperture radar are available have also been provided using this method.