Aerosol multiple-scanning code, ASCAT

The well-known theory of Dolin and Fante describing multiple scattering is applied to analyze the intensity and power received by a detector with a variable field of view. The multiple scattering problem for a finite slab geometry including the cases of converging and diverging beams is solved using the ASCAT code. The backscattering from randomly distributed scatterers is included in the theory by solving, to the first approximation, a coupled system of equations for the forward and backward specific intensities. When supplemented with least squares fitting subroutines allowing one to determine the width of the forward and backward peaks of the scattering phase function, the ASCAT computer code yields rapidly the information about the on-axis multiple scattering in transmissometer and lidar configurations.