Investigating antarctic ice-sheet vulnerability to internal ice-sheet processes

Abstract

The Weddell Sea sector of West Antarctic Ice Sheet may be increasingly vulnerable to melting specifically close to the grounding line through atmospheric warming and modifications in ocean circulation. This project investigates the complexity of ice-sheet stability at and close to the grounding line in the Institute, Möller and Foundation Ice Streams using airborne radar data and satellite images. A new bed elevation model in the Weddell Sea sector is developed which updates the previous Bedmap2 bed product. While the gross form of the new bed elevation model is similar to Bedmap2, there are some notable differences. Ice-penetrating radar data show flow-parallel hard-bed landforms beneath the grounded ice, and channels incised upwards into the ice shelf, inherited from the landforms, beneath meandering surface features. Radar reveals the presence of subglacial water alongside the landforms, indicating a well-organised drainage system where water exits the ice-sheet as a point source. Both the Institute and Möller Ice Streams are also associated with the ice-shelf channels similar to Foundation Ice Stream. The location of the ice shelf channel coincides with the rough bed across the deep section of Robin Subglacial Basin upstream of Institute Ice Stream. Additionally, a deep subglacial embayment is discovered immediately inland of the Institute Ice Stream grounding line. For the Möller Ice Stream, subglacial water flows along the smooth basal trough. The trough moulds the ice-sheet base, such that at the point of flotation it is characterised by a notable downward-facing mound. The consistency between different grounding lines lineation is determined by the thickness of ice and the bed elevation. Results from model outputs is also compared with the geophysical data in the Weddell Sea sector. In general, the model is performing well in some areas, however, further improvement is needed for the model to accurately characterize the ice-sheet complexity.