Retrieval of sea ice drift from SAR doppler shift

TitleRetrieval of sea ice drift from SAR doppler shift
Publication TypeConference Proceedings
Year of Publication2010
AuthorsHansen, MW, Kloster, K, Dagestad, K-F, Sandven, S, Johannessen, JA
Refereed DesignationUnknown
Conference NameESA Living Planet Symposium
Conference Location and DateBergen, June 28 - July 2, 2010
KeywordsASAR, Doppler shift, Fram Strait, Sea ice drift

The Doppler shift of single antenna Synthetic Aperture Radar (SAR) signals is related to the line-of-sight ve- locity of the moving ocean surface. In this paper, the Doppler shift is applied to measurements of sea ice drift. This is performed over a sea ice eddy in the Skagerrak Sea from February 2010, and a sea ice eddy in the Fram Strait from November 2008. Cross-eddy velocity varia- tions are detected at about 1 m/s. A number of SAR images over the Fram Strait have been studied to re- trieve ice drift velocities across 79◦ North. In many cases, it is very challenging to properly calibrate the SAR Doppler shifts. However, 115 images of Doppler shift derived range oriented sea ice drift velocities have been compared to ice drift velocities based on feature tracking in SAR backscatter images. During winter, the comparison is promising with regards to this usage of the Doppler method. The summer season, however, is more difficult to monitor, probably because of high water con- tent in the ice and large open water areas. This causes the measurements to be mainly influenced by wind gen- erated (ocean) surface waves.

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