[ACG38-P19] Influence of ocean bed geometry on the ice front variations of Bowdoin Glacier, northwestern Greenland
We measured the bed topography at the fjord in front of the Bowdoin glacier on July 29, 2016 by using a boat with a sonar and a transducer. The ice thickness at the glacier was measured using ice radar and the surface elevation of the glacier was measured by GPS kinematic survey at the same point. Surface elevation from 2001 to 2012 was also acquired from DEM (digital elevation model) created from images taken by optical sensors of artificial satellites Terra and ALOS. Then, we calculated the elevation of the bed topography under the glacier by subtracting the ice thickness from the surface elevation of the glacier.As a result, the depth in front of the glacier were 280 m in the west side and 180 m in the east side at maximum. The surface elevation of the glacier had declined at 2.8 m a-1 on average from 2001 to 2012. Comparing the surface elevation with the Flotation level, the glacial surface elevation in 2001 was more than 10 m higher than the Flotation level. However, the surface elevation was 0 - 10 m below the flotation level in the west side of the glacier in 2007. Therefore, the Bowdoin glacier has, reached a condition to float on water in a wide area on the west side of the glacier, and it might cause to greatly retreat the ice front.