Extinction cross sections of realistic raindrops: Data-bank established using T-matrix method and nonlinear fitting technique

Abstract

In this paper, a new computer program is developed based on T-Matrix method to generate a large number of total (extinction) cross sections (TCS) values of the realistic raindrops that are deformed due to a balance of the forces that act on a drop falling under gravity, and were described in shape by Pruppacher and Pitter. These data for various dimensions of the raindrops (mean effective radius from 0 to 3.25 mm), frequencies (10 to 80 GHz), (horizontal and vertical) polarizations, and temperatures (0, 10 and 20°C) are stored to establish a data bank. Furthermore, a curve fitting technique, i.e., interpolation of order 3, is implemented for the TCS values in the data bank. Therefore, the interpolated TCS results can be obtained readily from the interpolation process with negligible or even null computational time and efforts. Error analysis is carried out to show the high accuracy of the present analysis and applicability of the interpolation. At three operating frequencies of 15, 21.225, and 38 GHz locally used in Singapore, some new TCS values are obtained from the new fast and efficient interpolation with a good accuracy.