The effect of salinity and temperature on the electromagnetic field scattered by sea water

Measuring scattering depolarisation ratio of a surface is one powerful means from which randomly rough dielectric surfaces can be effectively detected. Until now, theoretical models available to deal with the surface scattering topic are treated as a scalar problem. However, it is possible to extend these methods to the vectorial case to obtain the polarimetric signature of the ocean surface. To do this one must compute the backscattered and bistatic scattering coefficient for a sea surface and it is necessary to provide the calculation of dispersion properties of the sea water complex dielectric permittivity and its dependence on physical parameters: temperature T and salinity S. In order to describe the scattering of an electromagnetic wave, an appropriate theory has to be chosen. Existing theories may be classified in two mains groups: Kirchhoff approximation, small-perturbation approximation. Numerical results, of the RCS for the two groups are presented. Salinity effects are only visible for low frequencies