Radar Meteorological Equations For Polydispersed Rotating Spheroidal Raindrops Under Normal Distribution Of Their Rotatory Axes

In this paper, based on the derived average scattering and alleviating cross sections of the small rotating spheroid raindrop groups having different rotating orientations when their axial orientations are in normal distribution. Studies are made of the expression of radar backscattering cross section when the rotating axial orientations of the small spheroid raindrop groups are in random distribution. In combination of the cloud precipitation particle spectrum (by using the most common M-P distribution), different radar cross section are introduced for the spheroid raindrop groups having different oriented axes so as to establish different radar meteorological equations and define the corresponding radar reflectivity rate factors. In comparison with the radar reflectivity rate factors of the spherical raindrops of the same volume, the correction coefficient under different rain intensity and the relationship between weather radar measurement data and rain intensity are determined. It is hoped that this study can provide a theoretical criterion and method for data correction about the raindrop shape and distribution features observed from the new-generation Doppler weather radar and the improvement of the precipitation accuracy contributing to meteorological work.