Abstract
In this paper, a multiple scattering analysis of the reflectance and linear polarization image data measured by the airborne POLDER sensor is done.
Assuming an atmosphere-ocean system with a Cox-Munk type reflecting sea surface, the theoretical reflectance and linear polarization are computed by the adding and doubling method for several different atmospheric models. The simulated reflectance and polarization images based on the multiple scattering computations are presented. By comparing the theoretical results with the observational data (Medimar data), we find that many conspicuous features in the observed reflectance and linear polarization images can be explained by the sea surface reflection, together with multiple scattering within the atmosphere. Our investigation discloses several important new findings as follows:
1) A conspicuous partial elliptical pattern found in the forward scattering direction in the measured reflectance image is mainly due to the specular reflection by the rough sea surface.
2) Two distinct local polarization minimum points, located symmetrically against the principal plane in the backward scattering direction in the measured polarization image, seem to be produced by an unknown kind of coupling effects between the atmosphere and the rough sea surface. It is shown that neither the rough ocean surface alone nor the atmospheric multiple scattering alone can explain such eye-ball like polarization minimum features.
3) We find the oceanic type aerosol model is not an appropriate aerosol model for Medimar data. On the other hand, the Junge type aerosol model with 3<v<5 is able to show similar polarization features as those in the observation.
