Abstract
This paper proposes a simplified geometric optics model for estimation of surface reflection of the sky radiation, assuming that the sea surface consists of small facets. This model enables the correction process of surface reflection to be much easier and less time-consuming, incorporating roughness sensitivity in reflective process. This paper also introduces a typical noncoherent scattering model by Wu and Fung in appendix. Finally, comparison of estimated reflection of the sky brightness temperature is made among above two models and Fresnel reflection model which does not take into account the roughness effect of the sea surface.
Noncoherent scattering model resulted in the largest estimation and Fresnel reflection model the lowest one. The defference of estimated reflection among these three models ranges from 3-6 K and larger differences are seen at higher incidence angles. However, no reasonable explanation are available for these differences at present, since the surface reflection is highly dependent not only on the specific reflective process in each model but also on sea surface state, sky brightness temperature pattern, dielectric properties of sea water, etc. Less one tenth of calculation time of noncoherent scattering model was attained in geometric optics model, and this model is of higher practical potential application to the correction of surface reflection, however, detailed comparison is still prerequisite among models.
