On July 8, 2013, a huge area of the ice shelf broke away from the Pine Island glacier¹, the longest and fastest flowing glacier in the Antarctic, and is now floating in the Amundsen Sea in the form of a very large iceberg². Scientists of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine³ Research have been following this natural spectacle via Earth observation satellites TerraSAR-X from the German Space Agency (DLR) and have documented it in many individual images. The data is intended to help solve the physical puzzle of this "calving（产犊，崩解）." Scientists from the American space agency NASA discovered the first crack in the glacier tongue on 14 October 2011 when flying over the area. At that time it was some 24 kilometres long and 50 metres wide. "As a result of these cracks, one giant iceberg broke away from the glacier tongue. It measures 720 square kilometres and is therefore almost as large as the city of Hamburg," reports Prof. Angelika Humbert, ice researcher at the Alfred Wegener Institute.

 

The glaciologist and her team used the high resolution radar⁴ images of the DLR earth observation satellite TerraSAR-X to observe the progress of the two cracks and to better understand the physical processes behind the glacier movements. The researchers were thus able to measure the widths of the gaps and calculate the flow speed of the ice. "Above the large crack, the glacier last flowed at a speed of twelve metres per day," reports Humbert's colleague Dr. Dana Floricioiu from DLR. And Nina Wilkens, PhD graduate in Prof. Humbert's team, adds: "Using the images we have been able to follow how the larger crack on the Pine Island glacier extended initially⁵ to a length of 28 kilometres. Shortly before the "birth" of the iceberg, the gap then widened bit by bit so that it measured around 540 metres at its widest point."

 

The scientists incorporate these and other TerraSAR-X satellite data in computer simulations using which they are able to model the break and flow mechanisms⁶ of the ice masses. "Glaciers⁷ are constantly in motion. They have their very own flow dynamics⁸. Their ice is exposed to permanent tensions and the calving of icebergs⁹ is still largely unresearched ," explains ice modeller Angelika Humbert.

 

The scientist and her team then compare their simulation results with current satellite data such as from TerraSAR-X. If the model agrees with reality, the scientists can conclude, for example, the gliding¹⁰（滑行的，流畅的） property of the ground beneath the glacier ice and how the ice flow could behave in the event of further global warming.

点击收听单词发音