MICROWAVE ATTENUATION OF SPHERICAL RAINDROPS - AN EFFICIENT TCS FORMULA USING 3-D FITTING

In this work, the Mie scattering theory is implemented in the MATHEMAT ICA package, and a very compact program is developed. Also, exact valu es of the electromagnetic total scattering cross sections (TCS) for va rious cases have been obtained. It is found that, depending upon the f requency and raindrop sizes, the convergence of the summation may beco me very slow. To increase the computational speed, a three-dimensional (3-D) nonlinear least squares fitting has been carried out based on t hose exact results, and an asymptotic but efficient formula is obtaine d. It is found that the computational speed is increased more than ten times using the efficient formula generated by the 3-D fitting. (C) 1 998 John Wiley & Sons, Inc.