First results obtained in the OSIRIS project
Johannes Schulz-Stellenfleth(1), Susanne Lehner(1) and Xiao Ming Li(1)
(1) DLR, Oberpfaffenhofen, 82234 Wessling, Germany
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. Triple co-locations of prototype products of the extended level-2 products with co-located buoy and WAM data are analysed. The comparison is performed in terms of spectral parameters most often used in practize, 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 are 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 is performed using the empirical CWAVE algorithm which provides estimates of integral wave parameters like the significant wave height without a priori information.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,