Recently an iceberg collided with the ice shelf, dislodging a chunk as well as causing extensive cracks of some distance in the ice shelf. Scientists of the Alfred Wegener Institute are expecting new and valuable insights with regard to ice physics.
The iceberg B15-K collided with the Ekstrom Ice Shelf in Atka Bay on the 11th February 2010, at 16:42 Universal Time. The iceberg, which is 54 kilometres long, five kilometres wide and 200 metres thick hit the ice shelf in the vicinity of Neumayer Station III of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. The event has called both logistic experts and scientist on the scene.
A unique interdisciplinary compilation of data obtained from remote sensing, geophysics, meteorology, oceanography and ocean acoustics now provides new insights into the mechanics of the ice and crack propagation in the ice shelf.
High-resolution images of the German TerraSAR-X satellite depict the moment of collision between the approximately 45 billion-ton B15-K iceberg and the Ekström Ice Shelf. Together with the on site observations by scientists and technicians, they enable the precise analyses of the newly created fissures in the ice shelf. The loud underwater sounds created by the impact and the response of seals and whales was recorded by the acoustic observatory PALAOA, supervised by Dr. Lars Kindermann from the Alfred Wegener Institute.
Additional records were obtained from the seismometers of the geophysical observatory at Neumayer Station III. Together, the data are used to reconstruct an overall picture of the processes: The impact of multiple collisions, within 9 hours, dislodged a 300-meter wide and 700-meter long chunk of ice from ice shelf. The energy of each impact was equivalent to that released by between about five to ten tons of explosives.
The Antarctic summer season began with the observation of an iceberg the size of Berlin, the C19-C (891 square kilometres) in October 2009. This iceberg came from the Ross Ice Shelf, collided with the ice shelf east of Atka Bay and broke off a nearly 30 kilometre long and seven kilometre wide new iceberg (A61) from the ice shelf. The more recent collision involved the B15-K, a fragment of the largest ever-observed iceberg, B15, which at the time it broke off from the Ross Ice Shelf in March 2000 had a surface area of 11,000 square kilometres. Another fragment of the B15, the B15-F also drifted past the ice shelf near the Neumayer Station III in mid January.
All three large icebergs that ended up at the Ekstrom Ice Shelf have come from the approximately 9000 kilometres distant Ross Ice Shelf, driven by the counter clockwise coastal current around the Antarctic. Radar satellites were used to track their trajectories. The ENVISAT (Environmental Satellite) of the European Space Agency provides regular images with a spatial resolution of 150 x 150 meters. Dr. Christine Wesche from the Earth Observation Group of the Alfred Wegener Institute evaluates the data. "In addition, we use image data from the TerraSAR-X background-mission Antarctica of the German Aerospace Center (DLR)," says Wesche. In close cooperation with Dr. Angelika Humbert (Climate Campus, University of Hamburg) and Robert Metzig (German Remote Sensing Data Center, DLR Oberpfaffenhofen), she has been following iceberg movements since the beginning of the Antarctic winter.Multimedia:
The Alfred Wegener Institute conducts research in the Arctic, Antarctic and oceans of the high and mid latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctic. The Alfred Wegener Institute is one of the sixteen research centres of the Helmholtz Association, the largest scientific organisation in Germany.
Margarete Pauls | idw
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