Single and multiple scattering contributions to circumsolar radiation.

Single and multiple scattering contributions to the circumsolar radiation along the almucantar and sun vertical have been computed by a Gauss-Seidel solution to the radiative transfer equation. In the near forward direction, the multiple scattering contributions are significant for optical depths of the order of 0.4. However, the shape of the angular distribution of almucantar radiance up to 10 degrees appears less sensitive to multiple scattering. The results have been compared against an existing radiative transfer code.