Iceberg Drift in the Western Weddell Sea Region: Observed and Modeled
Wesche, Christine1; Dierking, Wolfgang2; Rackow, Thomas2
1Alfred Wegener Institute, GERMANY; 2AWI, GERMANY

Ice shelves and glacier tongues cover almost 45% of Antarctica's coastline. They are the birthplaces of icebergs. Large tabular iceberg calve mainly from the large ice shelves (e.g. Ross or Filchner-Ronne Ice Shelf), but there are a variety of smaller ice shelves and glacier tongues, which produce smaller icebergs of different shapes (e.g. domed, drydocked, wedged). The drift of huge icebergs (length > 18.5km) is systematically tracked by the NIC (National Ice Center) using different satellite images. Smaller icebergs, however, are not systematically monitored. The iceberg drift is influenced by several forces, among which the wind velocity and the ocean currents are dominant. Volume forces (Coriolis force or sea surface tilt) become more important on huge icebergs. Lichey and Hellmer (2001) showed that the presence of sea ice has also a considerable influence on the drift of icebergs. If sea ice concentration is close to 10/10 and its strength resists the acceleration of the iceberg, the latter is captured in the sea ice and drifts along with it. We are investigating the western Weddell Sea region with a main focus on the region north of the Atka Bay and Ekstrom Ice Shelf where several icebergs drifted by, taking different paths. Since a landing place at the Ekstrom Ice Shelf is used for the supply of the German overwintering station Neumayer III and the South-African station Sanae IV, it is important to monitor the drifting route taken by the icebergs in this region. We use a series of ENVISAT WSM data to follow the iceberg D18 and some smaller ones through the western Weddell Sea region, In addition we have series of ENVISAT WSM data in the region of the Ekstrom Ice Shelf from the end of October 2009 to the beginning of March 2010. During that time, three huge icebergs (C19-c, B15-f and B15-k) drifted by the Ekstrom Ice Shelf. We investigate the main forces influencing the different drifting routes. Model simulations of the iceberg drift are carried out to get more detailed information about the relative influence of different forces on the iceberg drift in this region. In our presentation, we will provide an overview about the results. References: Lichey, C. & Hellmer, H. H. (2001), Modeling giant-iceberg drift under the influence of sea ice in the Weddell Sea, Antarctica, Journal of Glaciology, 47(158), pp. 452-460