Millimetre Wave Emission by Discrete Method in Sea-foam Layer at WindSat Frequencies

Abstract

Computation of millimetre wave scattering by sea foam is a significant query which contributes immensely to measurement of sea surface emissivity and brightness temperature by passive microwave radiometers. For efficient evaluation of scattering by foam covered sea surface and measurement of brightness temperatures in milli-Kelvins, a discrete based physical model of sea foam is developed to provide accurate estimate of the complex effective dielectric constant of sea foam. The sea foam layer is modelled as sequences of thin phase screens in two dimensional (2𝐷) slices of sea foam layer with equal depth 𝑑 (𝑚𝑚). Each layer comprised of random distribution of bubbles that follows a log-normal distribution pattern with geometrical and optical properties such as foam layer thickness, foam void fraction, foam volume fraction, sea surface temperature and sea surface salinity. Results of sea surface emissivity as a function of polarization, angle of incidence, WindSat frequencies and thickness of sea foam are presented. .