Error analysis of Envisat ASAR level 2 algorithm based on simulation technique

In ESA's Envisat ASAR level 2 algorithm, it is assumed that the synthetic aperture radar (SAR) image cross spectra of mixed ocean waves were the summation of SAR image cross spectra of wind waves and that of swells. But our previous studies show that in addition to this, the cross spectra of mixed waves consist of an extra term (see the companion paper submited to this symposium). Just this term leads to an inherent error of this algorithm which has not been considered yet. This paper presents an error analysis of Envisat ASAR level 2 algorithm for ocean wave spectra retrieval in different significant wave height, wavelength, wave direction and wave component conditions based on simulation technique. It shows that the inherent errors (1) change with above parameters, and are always positive which mean the retrieved ocean wave height are overestimated; (2) increase for larger significant wave height; (3) increase for smaller wavelength; (4) increases for smaller propagation angle respect to azimuth direction. (5) increase for more wind wave component. Therefore, Envisat ASAR level 2 algorithm only works in small wave height, or large wavelength, or large propagation angle, or few wind wave component conditions.