A NEW PARAMETRIZATION OF THE RAIN DROP SIZE DISTRIBUTION

This paper revisits the problem of finding a parametric form for the r ain drop size distribution (DSD) which 1) is an appropriate model for tropical rainfall, and 2) involves statistically independent parameter s, Using TOGA/COARE data, we derive a parametrization which meets thes e criteria, This new parametrization is an improvement on the one that was derived in [3], using TRMM ground truth data from Darwin, Austral ia, The new COARE data allows us to verify that the spatial variabilit y of the two ''shape'' parameters is relatively small, thus confirming that this parametrization should be particularly useful for remote se nsing applications, We also derive new DSD-based radar-reflectivity-ra in-rate power laws, whose coefficients are directly related to the sha pe parameters of the DSD, Perhaps most important, since the coefficien ts are independent of the rain-rate itself, and vary little spatially, the relations are ideally suited for rain retrieval algorithms, It sh ould also prove straightforward to extend this method to the problems of estimating cloud hydrometeors from remote-sensing measurements.