Assimilation of satellite cloudy radiances: forward and adjoint radiative transfer modeling

Satellite sensor designs, data assimilation and retrievals of geophysical parameters all require a fast and accurate radiative transfer model. In general, Stokes vector can be derived from the differential and integral radiative transfer equation. The discrete ordinate method was developed to approximate the integral term so that the equation is linearized to a set of the ordinary differential equations that are then solved from the eigenvalue method. In this study, we further derives the radiance gradient (Jacobian) for a scattering and emission atmosphere, which is a crucial component in satellite data assimilation. In addition, we also review land and ocean surface emissivity models affecting both the forward and adjoint computations.

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