Global statistics of integrated ocean wave parameters extracted from ERS-1 SAR wave mode image spectra

Ocean wave height spectra are extracted routinely from ERS-1 synthetic aperture radar (SAR) wave mode image spectra since July 1, 1992 by applying a SAR inversion scheme based on Hasselmann´s closed nonlinear spectral integral transform. The scheme requires a first-guess wave height spectrum as regularization term obtained from the WAM wave prediction model. Global monthly statistics of integrated spectral wave parameters, such as significant wave height, mean wavenumber, mean wave direction and directional spread, are calculated from wave model and SAR extracted wave spectra. The general agreement between the mean spectral wave parameters is quite good. They have a correlation between 0.83 and 0.94. However, the SAR extracted mean wave height is 10-15% larger and the mean wavenumber is about 10% smaller than the wave model values. The results demonstrate the good performance and high accuracy of the SAR ocean wave inversion scheme