First Results Obtained in the OSIRIS Project

Kurzfassung

In the OSIRIS project funded by ESA a potential extension of the current level 2 ENVISAT ASAR wave mode product is investigated. The idea of the project which is still in its first phase is to complement the current product with a complete two dimensional ocean wave spectrum which results from a blending of the ASAR measurement with information from a numerical model. The estimate of the spectrum is based on a maximum a posteriori approach and is computed with the PARSA (Partition rescale and shift algorithm) developed by DLR. In the presentation first results obtained using a test data set of wave spectra from the WAM model and buoy data from the IFREMER co-location system are presented. The basic methodology of the inversion scheme is presented and different retrieval examples are presented. Triple co-locations of prototype products of the extended level-2 products with co-located buoy and WAM data are analyzed. Furthermore the project structure is explained and the coming activities are summarised. A statistical validation and assessment will be performed in terms of spectral parameters most often used in practise, e.g., zero upcrossing period, peak period, significant wave height, swell wave height, wind sea wave height and propagation directions. Furthermore more sophisticated parameters like the crest length, the wave power and the expected maximum wave height will be investigated. The first analysis will concentrate on the North Atlantic with particular focus on storm events. Other regions will be considered as well to get a representative picture of the algorithm performance, e.g., in swell dominated regions. An additional analysis will be performed using the empirical CWAVE algorithm which provides estimates of integral wave parameters like the significant wave height without a priori information.