Polarized infrared emissivity of 2D sea surfaces with one surface reflection

Sea surface infrared emissivity is an important parameter in oceanic remote sensing. This article derives the infrared emissivity of two-dimensional (2D) sea surfaces with an analytical model, where one surface reflection (surface-emitted surface-reflected) is considered. Polarization is studied, and the surface slope probability density function is Gaussian and then non-Gaussian to study the skewness and the kurtosis effects. It is shown that sea surface infrared emissivity is sensitive to the zenith observation angle and the wind direction, and the skewness and the kurtosis effects are significant for grazing directions (with zenith angle > 80°). For Gaussian surfaces, surface emissivity for grazing zenith angles reaches maxima in the up-wind and down-wind directions, whereas minima are found in the cross-wind direction. After taking into account the skewness and the kurtosis effects, the surface emissivity has the largest value in the down-wind direction. The analytical results are then compared with measurements, which shows that considering one surface reflection significantly improves the agreement for large zenith angles.

► We model analytically the polarized infrared emissivity of two-dimensional sea surfaces. ► Shadowing and surface reflections are considered. ► Skewness and peakedness effects are considered. ► Good agreements with measurements are obtained.