Evolution of Dropsize Distributions in Liquid Precipitation Observed by Ground-Based Doppler Radar

Abstract

A technique is described for using ground-based Doppler radars to monitor the development of the drop-size spectra of number density, liquid-water density, and liquid flux, in time and height. It is shown how such observations reveal the height-time location of rapid growth zones and how drop-size growth rates can be remotely sensed in an important subrange of the number-density spectrum. A model that balances convergence of accretional growth in the size domain with convergence of vertical flux of drop number in the height domain reproduces major features of the observations. These include change in number density with height, shifts toward larger sizes with decreasing altitude in the cloud, and multiple peaks in the drop-size spectrum of precipitation particles.