Iceberg signatures and detection in synthetic aperture radar (SAR) images in two test regions of the Weddell Sea, Antarctica

• Published in: Journal of Glaciology
• Main Authors: Wesche, Christine, Dierking, Wolfgang
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: INT GLACIOL SOC 2012
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Weddell Sea; Weddell; Asar; Antarc*; Antarctica; Antarctica Journal; Iceberg*; Journal of Glaciology; Sea ice
• Online Access: https://epic.awi.de/id/eprint/25912/; https://epic.awi.de/id/eprint/25912/1/11J020R1.pdf; https://hdl.handle.net/10013/epic.38879; https://hdl.handle.net/10013/epic.38879.d001

A pixel-based methodology has been established for automatic identification of icebergs in satellite synthetic aperture radar (SAR) images acquired during different seasons and for different seaice conditions. This includes, in particular, smaller icebergs (longitudinal axis 100m to 18.5 km). Investigations were carried out for two test regions located in theWeddell Sea, Antarctica, using images of the Envisat Advanced SAR (ASAR) at HH polarization and of the European Remote-sensing Satellite-2 (ERS-2) SAR (VV-polarized). From the former, a sequence of Image Mode and Wide Swath Mode data are available for the whole of 2006. The ERS data were acquired around the tip of the Antarctic Peninsula in spring and summer months of the years 2000–03. The minimum size of icebergs that could be identified in the IM images was <0.02km2. Radar backscattering coefficients of icebergs, sea ice and open water were determined separately.We demonstrate that the error in separating icebergs from their surroundings (sea ice or open water) depends on meteorological, oceanographic and sea-ice conditions. Also the pre-processing of the SAR images (e.g. speckle reduction) influences iceberg recognition. Differences in detection accuracy as a function of season could not be substantiated for our test sites, but have in general to be taken into account, as results of other investigations indicate.