The largest loss term in Antarctic mass balance is iceberg calving from the ice shelves and to estimate the amount of the loss, it is necessary to observe icebergs in every size. Because current mass loss calculations only include icebergs with an edge length of > 10 km, we focus on smaller icebergs (0.1 to 10 km edge length) in a test region north of Berkner Island in the Weddell Sea. Images of the ENVISAT ASAR at different imaging modes are used to analyse the backscattering coefficients of icebergs depending on the season. To detect icebergs in SAR images we need to find differences to the surrounding sea ice. Therefore, the backscattering coefficients of the sea ice are analysed for seasonal variations as well.Statistical analyses of the backscattering of icebergs and sea ice in ASAR image mode data show varying backscatter coefficients over the period of one year. The radar intensity contrast between icebergs and sea ice is smallest in the summer months and highest in winter and spring. The iceberg and sea-ice backscattering is investigated for seasonality in medium and low resolution ASAR images as well and compared to the results derived from image mode data. We will also include other frequency bands from other sensors to achieve a complete view of iceberg signature in radar images and their contrast to the surrounding. These statistics will improve the automatic extraction of icebergs from SAR images. As a next step, the extracted iceberg positions will be used to calculate the drift.
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic > WP 1.1: Role of Ice Sheets in the Earth System