Abstract
An algorithm to derive the effect of the land surface on the emergent radiation from the top of the atmosphere in the coastal zone is proposed. The surface is simulated by checkerboard type of terrain composing pixels, either land or ocean. The Look-Up-Table method is used for the atmosphere-surface correction, where two parameters based on the diffuse transmission and reflection function of the atmosphere are introduced to investigate the contribution of adjacent pixels. These parameters are independent of the surface reflection properties. The ocean surface is in accordance with the Cox and Munk model surface, whereas that of land is assumed to be Lambertian. The upwelling radiation emerging from the top of the atmosphere is expressed by a sum of radiative interactions between surface and atmosphere, and it is calculated using these interactions until the sum is converged.
An example of numerical simulation is shown at wavelength of 0.56μm, which corresponds to the center wavelength of the shortest channel of ASTER on EOS-AM 1. The dust like model is used for the aerosols, whereas the land surface albedo is 0.2 or 0.4. The ocean wind is 5 m/sec and the refractive index is 1.333. The effect of the land surface on the radiance over the ocean is stronger just off the coastal zone and decreases with the increase of distance away from the land exponentially. It depends upon the solar zenith angle and atmospheric condition as well. The present new version enable us quantitatively to discuss radiative transfer over the non-uniform composite surface including coastal zone.
