MONTE-CARLO RADIATIVE-TRANSFER IN THE MICROWAVE AND IN THE VISIBLE - BIASING TECHNIQUES

Two Monte Carlo methods for atmospheric radiative transfer are present ed. One is a backward three-dimensional code suitable for the visible region of the electromagnetic spectrum in which the source is consider ed to be a parallel flux incident on the upper boundary. The second is a forward plane-parallel code for the microwave region in which radia tion is given by thermal emission. The biasing techniques used to redu ce the computational time and keep the statistical oscillations relati vely small are described. The results are tested by comparison with th e results of equivalent codes, when available, and the speed of conver gence is analyzed. (C) 1997 Optical Society of America.