Explaining the polarization signal from rain dichroic effects

Radiative transfer simulations for a dichroic medium consisting of horizontally oriented spheroid raindrops in a cloud have been performed to better understand the polarization properties of the radiation field in such kind of media. A successive order of scattering methodology is employed to obtain exact and approximate equations of the rain medium in order to evaluate the contribution of the different scattering orders to the polarization signal for a 1D geometry approximation at all cloud levels. Then a Monte Carlo technique is used to evaluate the impact of 3D effects in the polarization of the downwelling/upwelling radiation field at the bottom/top of the dichroic layer. An accurate analysis of the impact of the emission term onto the total polarization signal is carried out. The 3D effects seem to be more relevant in polarization signatures when the emission/absorption processes dominate. © 2006 Elsevier Ltd. All rights reserved.