Effective droplet number and droplet spectra parameters that determine the radar backscatter from clouds and rain

Abstract

Using the "slice" approach to the weather radar equation, it was found that, in general, for an imperfect rectangular probing pulse envelope and non-Poisson, small-scale fluctuations of particle concentration, the mean backscatter is governed by the effective droplet number and the first three moments of the cloud-rain particle size distribution function. We propose an approach to computing the effective spatial duration of a probing pulse used to estimate the effective number of scattering particles within a radar volume. We also assessed the difference between methods for estimating mean backscatter, first taking into account the factors listed above and then comparing the result to classical estimations attained through the sixth moment of the droplet spectra and a rectangular probing pulse.