Ice-Motion Determination by Means of Satellite Positioning Systems

Abstract

The satellite positioning systems, NNSS or Transit system and NAVSTAR-GPS, are used successfully for the determination of ice motion. The ice motion is derived from the change in the coordinates of a station between at least two measurement epochs. Simultaneous satellite observations on solid-ground-based and on ice stations yield precise relative or local coordinates between the stations. The ice motion can be determined very accurately from the variation in these coordinates. The field observations and post-processing steps, which differ slightly for the two positioning systems, are outlined. Results for several examples are presented. Ice-motion solutions are discussed for data from Anvers Island (NNSS), from Filchner-Ronne Ice Shelf (NNSS, GPS), and from Ekström Ice Shelf (NNSS, GPS). Slow velocities of a few dm/d could be estimated in the course of one field season and the velocity values found are confirmed by annual station displacements.