A Vector Radiative Transfer Model for Coupled Atmosphere and Ocean Systems Based on Successive Order of Scattering Method

A vector radiative transfer model has been developed for coupled atmosphere and ocean systems. The new model is based on the Successive Order of Scattering (SOS) Method. Each term in the SOS formulation has physical significances and the errors are very easy to be analyzed. To evaluate the source terms in the SOS method, the angular integration has to be done via quadrature techniques. It is a normal practice to use double Gaussian quadrature points in ocean as those in atmosphere to match the interface boundary condition in traditional radiative transfer models for coupled atmosphere and ocean systems. In this new model, the same Gaussian quadrature points have been used for the ocean and atmosphere. Both memory requirements and CPU time have been reduced by this implementation which are crucial for remote sensing applications. To implement this, the radiation contribution transmitted through the interface has been divided into two different parts, the direct contribution to the detector and the source term caused by the transmission. The two parts can be handled by interpolation methods at the two sides of the interface. There are two physical assumptions in this implementation. One is that the diffused light at the bottom of the atmosphere and the top of the ocean (without the presence of the ocean interface) is smooth. The second is that the phase matrices of the atmosphere layers and ocean layers are smooth. These two assumptions are generally satisfied by the atmosphere and ocean particulates. The diffused light in the ocean is integrated with the normal Gaussian quadrature points and weights. The validation is carefully done with the Monte Carlo method. This work is primarily of interest in ocean color remote sensing, the general circulation model development, and many other scientific disciplines.