Abstract
A new method is adopted for the evaluation of the upwelling radiation emerging grom the atmosphere bounded by non-iniform terrain, which is assumed to be composed of "n" uniform regions (each regions may be different from each other). The atmosphere is assumed to be horizontally homogeneous, but it may be vertically inhomogeneous. It is composed of aerosol, molecules and absorbent gases. Numerical simulations are undertaken for the model aerosols of the oceanic and water soluble types.
In the computational procedure an iterative doubling-adding equation is expanded into a series of the radiative interaction modes between atmosphere and surface. A probability of contribution of respective regions in the radiation field is calculated based on the assumption of single scattering in the atmosphere. Then on the basis of this probability, the emergent radiation at the top of the atmosphere is calculated approximately by considering the radiative interactions with surfaces to be twice as large. Here, the effect of the multiple scattering in the atmosphere is fully undertaken in the computational procedures. Therefore, the present new version enable us to quantitavely discuss the upwelling radiation over the non-uniform surfaces even if the optical thickness (τ-2) is large and (or) surface albedo is great (A-0.7).
