Seminarium "Modeling of Complex Systems"

This presentation will shortly introduce today’s interest for glaciers through the 1950s rebirth of Glaciology, i.e. the study of ice and snow, and the developments of the theory of ice flow by Glen and Nye from the University of Cambridge. Two research projects in Svalbard, Norway are then discussed which emphasize the importance of understanding glacier mechanics to predict glacier contribution to sea-level rise. The first presents velocity observations at the front of a glacier showing that iceberg break-off, also called "calving", can be predicted. Velocity time-series from a terrestrial radar interferometer 2-min scans identifies block accelerations prior to the calving of the blocks, hinting towards a relationship between block rotation, strain rates and crevasse opening. Our last story of the day will be on a dramatic glacier phenomena called “surges". In less than a few years, complex changes in basal friction leads to rapid glacier acceleration, sometimes ten-fold its normal velocity, drainage of the entire glacier accumulation basin and front advance in the fjords of sometimes several kilometres. This behaviour is illustrated at a glacier currently monitored by the Norwegian Polar Institute through a combination of remote sensing and GNSS observations measurements. A non-linear feedback explains this cyclic behaviour through changes in basal friction, acceleration, opening of crevasses providing meltwater access to the glacier bed before the glacier mass is drained into the fjord.