Two-dimensional sea surface current fields derived from multi-sensor satellite data

We used multi-sensor satellite images to compute small-scale surface currents in the Northern Baltic Sea. The images were acquired by the Thematic Mapper (TM) aboard Landsat, by the Synthetic Aperture Radar (SAR) aboard ERS-2, and by the Wide-Field Scanner (WiFS) aboard IRS-1C within two hours on 15 July, 1997, over the Northern Baltic Proper. Most of them show manifestations of an ongoing algae bloom, which are driven by the local currents. Pairs of images acquired at either different electromagnetic frequencies (TM and SAR) or at the same electromagnetic bands (TM and WiFS) are used for applying cross-correlation or partial differentiation techniques, respectively. Our results are insofar promising as the computed two-dimensional surface current fields complement existing data from numerical models. However, limitations of the proposed method are due to the strong dependence of the visibility of algae bloom manifestations on local weather conditions and to the low availability of satellite data.