Thin ice dynamics in the Storfjorden polynya (Svalbard) by means of digital image analysis of SAR data

• Main Author: Glaw, Lukas
• Format: Thesis
• Language: unknown
• Published: 2014
• Subjects: Svalbard; Sea ice; Storfjorden
• Online Access: https://oceanrep.geomar.de/id/eprint/26973/

Thin-ice thickness (TIT) in recurrent polynyas is an important parameter for calculating ice production and for modelling the production of Brine-enriched Shelf Water (BSW). As operations at high latitudes are hazardous and expensive, remote sensing has become an indispensable tool for this purpose. Previous studies have been successful in estimating ice production based on a combination of remote sensing data and different models, but none used the advantage of high-resolution Synthetic Aperture Radar (SAR) to determine ice thicknesses. The present thesis focuses on the Storfjorden polynya (Svalbard), a relatively small region with a high impact on the global thermohaline circulation. The dependency of SAR backscatter and texture parameters derived from backscatter on thin-ice thickness is tested by correlating SAR based parameters with TIT distribution maps which were generated on the basis of MODIS ice surface temperatures. The effects of speckle and different ice properties (dielectrical constant and surface roughness) on the processing were evaluated. Based on the correlation from 86 SAR scenes from the Environmental Satellite (ENVISAT), acquired between 2007 and 2012, and MODIS TIT distribution it can be concluded that parameters directly derived from SAR backscatter are inapplicable to derive ice thickness. Consequently it was not possible to calculate the ice production in the Storfjorden polynya. The main reasons that cause the not existing relationship between TIT and SAR derived parameters are the physical properties of sea ice, which cause an ambiguity in the SAR signal.