FINITE-ELEMENT ALGORITHM FOR RADIATIVE-TRANSFER IN VERTICALLY INHOMOGENEOUS-MEDIA - NUMERICAL SCHEME AND APPLICATIONS

The recently developed finite-element method for solution of the radia tive transfer equation has been extended to compute the full azimuthal dependence of the radiance in a vertically inhomogeneous plane-parall el medium. The physical processes that are included in the algorithm a re multiple scattering and bottom boundary bidirectional reflectivity. The incident radiation is a parallel flux on the top boundary that is characteristic for illumination of the atmosphere by the Sun in the U V, visible, and near-infrared regions of the electromagnetic spectrum. The theoretical basis is presented together with a number of applicat ions to realistic atmospheres. The method is shown to be accurate even with a low number of grid points for most of the considered situation s. The FORTRAN code for this algorithm is developed and is available f or applications. (C) 1995 Optical Society of America