Meteo-Marine Parameters for Highly Variable Environment in Coastal Regions from Satellite Radar Images

Abstract

A new empirical algorithm XWAVE_C (C=coastal) for estimation of significant wave height from X-band satellite-borne Synthetic Aperture Radar (SAR) data has been developed, adopted for coastal application using TerraSAR-X (TS-X) and Tandem-X (TD-X) satellites in German Bight of North Sea and implemented into the Sea Sate Processor (SSP) for fully automatic processing for Near Real Time (NRT) services. The algorithm is based on spectral analysis of subscenes and the model function uses integrated image spectra parameters as well as local wind information from the subscene analyzed. The algorithm is able to recognize and remove the influence of non-sea state produced signals in Wadden Sea areas like dry sandbars as well as nonlinear SAR image distortions produced by e.g. short wind waves and wave breaking. Also parameters of very short waves, which are not visible in SAR images and produce only unsystematic clutter, can be accurately estimated. SSP includes XWAVE_C, pre-filtering procedure for removing artefacts like ships, seamarks, buoys, offshore constructions and slicks and an additional procedure performing a check of results based on statistics of whole scene. The SSP allows an automatic processing of TS-X images with an error RMSE=25cm and Scatter Index SI=20% for significant wave height from sequences of TS-X StripMap images with a coverage of ~30km×300km across the German Bight. The SSP was tuned spatially with model data of the German Weather Service’s (DWD) CWAM (Coastal WAve Model) with 900m horizontal resolution and tuned in situ with 6 buoys located in DWD model domain in the German Bight. The collected, processed and analyzed data base for the German Bight consists of more than 60 TS-X StripMap scenes/overflights with more than 200 images since 2013