Iceberg signatures and detection in SAR images in two test 1 regions of the Weddell Sea , Antarctica

A pixel-based methodology was established for automatic identification of icebergs 6 in satellite synthetic aperture radar (SAR) images, which were acquired during different seasons 7 and for different sea ice conditions. This includes in particular smaller icebergs (longitudinal axis 8 between 100 m and 18.5 km). Investigations were carried out for two test regions located in the 9 Weddell Sea, Antarctica, using images of the ENVISAT Advanced SAR (ASAR) at HH-polarization, 10 and of the ERS-2 SAR (VV-polarized). From the former, a sequence of Image Mode (IM) and Wide 11 SwathMode (WS) data were available for the whole year 2006. The ERS-data were acquired around 12 the tip of the Antarctic Peninsula in spring and summer months of the years 2000 to 2003. The 13 minimum size of icebergs that could be identified in the IM-mode images was less than 0.02 km2. 14 Radar backscattering coefficients of icebergs, sea ice and open water were determined separately. 15 It is demonstrated that the error in separating icebergs from their surroundings (sea ice or open 16 water) depends on meteorological, oceanographic, and sea ice conditions. Also the preprocessing of 17 the SAR images (e. g. speckle reduction) influences the iceberg recognition. Differences of detection 18 accuracy as a function of the season could not be substantiated for our test sites, but have in general 19 to be taken into account as results of other investigations indicate. 20