PARAMETERIZING THE RAINDROP SIZE DISTRIBUTION

This paper addresses the problem of finding a parametric form for the raindrop size distribution (DSD) that 1) is an appropriate model for t ropical rainfall, and 2) involves statistically independent parameters . Such a parameterization is derived in this paper. One of the resulti ng three ''canonical'' parameters turns out to vary relatively little, thus making the parameterization particularly useful for remote sensi ng applications. In fact, a new set of Gamma drop-size-distribution-ba sed Z-R and k-R relations is obtained. Only slightly more complex than power laws, they are very good approximations to the exact radar rela tions one would obtain using Mie scattering. The coefficients of the n ew relations are directly related to the shape parameters of the parti cular DSD that one starts with. Perhaps most important, since the coef ficients are independent of the rain rate itself, the relations are id eally suited for rain retrieval algorithms.