Modeling the infrared radiance of rough sea surface in the infrared windows: 3-5 μm and 8-12 μm

The general formulations for spectral directional emissivity and spectral bi-directional reflectivity are analyzed by using Fresnel's formula and Snell's law in rough sea surface which is simulated by wave facets, whose slopes are changing according to the isotropic Gaussian distribution with respect to surface wind. Then, shadowing effect is taken into account in both emission and reflection of sea surface. On this basis, the mathematic expression is obtained for spectral radiance of rough sea surface, in which the radiance of rough sea surface is considered as a composition of self-emission, reflection of sky and reflection of sun. Finally, calculations for infrared radiance of rough sea surface in bands of 3-5 μm and 8-12 μm are given to illustrate their significant different, which are caused mostly by the dispersion of sun radiation.