Short-wave ocean wave slope models for use in remote sensing data analysis

Recent developments in the directionality of sea waves are reviewed and adapted into a working model for radiometric remote sensing. There is a weight of evidence, both theoretical and observational, that a bimodality exists in the directional wave spectrum for sea surface gravity waves at wavenumbers greater than the value at the peak of the spectrum. We develop a model for the directional splitting which is consistent with observations but which extrapolates in a credible manner to the omnidirectionality observed at wavelengths around 0.3 m. At shorter wavelengths the directional spectrum becomes unimodal and has an approximately constant shape across the gravity-capillary wave regime. A working model is suggested for the directionality of the wave spectrum to improve the analysis of radiometric sea surface data. The model will also be useful for other analyses including active radar techniques which use Bragg scatter. Index Terms--Bimodal wave spectra, directional wave spectra, gravity-capillary waves, wave slopes.