Antarctic ice shelves play a vital role in the global climate, producing significant water masses that drive ocean circulation and buttressing the rate at which inland ice sheets drain into the ocean. A recent study [RD06] suggests that the Filchner Ice Shelf region in Antarctica might soon experience a wholesale change in oceanographic regime with potentially dramatic consequences for the ice shelf and its tributary ice streams.
A newly initiated large-scale study will use glaciological and oceanographic measurements to improve and validate a set of regional models to predict the regions contribution to 21st Century sea level rise. The lack of the ability to predict these changes was highlighted in the latest IPCC report [RD07] noting the risk of “Abrupt and irreversible ice loss from a potential instability of marine-based sectors of the Antarctic Ice Sheet”.
The observational inputs to this study are wide ranging, but will include satellite observations of ice stream surface velocities to be validated by in situ GPS units. Satellite derived data provide important details of spatial and temporal variation in ice sheet and ice stream velocity.
[Figure 4: Filchner Ice Shelf study area showing surface ice sheet and ice stream velocities.]
Role of the Polar TEP
Derivation of ice sheet and ice stream surface velocities is a computationally intensive process that requires large volumes of satellite SAR imagery. To cover the required area and time periods, data from a number of different satellite sensors will be involved. This raises the issue of inter-comparison of velocity data derived from SAR sensors with different characteristics (e.g., how do velocities derived from C-band Radarsat2 data compare with data from X-band TerraSAR-X data?) and using different techniques (e.g., how do velocities derived from interferometry compare with velocities from feature tracking?).
The P-TEP will provide capabilities to answer a number of the issues involved.
(a) The P-TEP will provide access to multi-sensor SAR data archives and processing capacity which will allow testing and running of large processing jobs to simplify the effort involved in generating the required velocity fields.
(b) Capabilities in the P-TEP will allow inter-comparison of velocity fields derived from different SAR sensors and the publication of resulting statistics.
(c) Validation of surface velocity data is a critical step. The P-TEP will allow easy integration of in situ GPS data to validate the derived velocity data.