Seabed Morphology Retrieval in Coastal Areas from ALOS and COSMO-Skymed SAR Data

SAR4BAT project (SAR data fusion for bathymetric data retrieval of sea bottom in coastal areas) is funded by Italian Space Agency and it is focused on development of SAR-based bathymetric products for coastal area by processing SAR data from ALOS and COSMO-SkyMed satellites. Since Synthetic Aperture Radar (SAR) signals are unable to penetrate sea surface and reach seabed, indirect processes with sea floor morphology sensed through its effects on sea surface must be used. Promising techniques for SAR-based bathymetry have been studied in the last years but they still need additional research to be effectively used. Improvement of these techniques could provide up-to-date bathymetric maps for coastal regions with appropriate resolution to monitor geological processes. The performed research has focused on the two different indirect processes which have been identified up to the present to relate the sea surface features visible on SAR images to seabed morphology and water depth: the indirect process based on swell waves and the one based on sea surface currents. Both the methods have been deeply studied and proper mathematical expressions have been identified to retrieve bathymetric data from SAR images. Implementation of the developed algorithms has been performed in the Gulf of Naples, Italy, by using SAR images from ALOS and COSMO-SkyMed. Bathymetric data have been retrieved by using both the two indirect processes. Comparison with the values reported on the Nautical Chart provided by the Italian Navy Hydrographic Institute have been performed.