An evaluation of raindrop size distribution as a function of height using S-Pol polarimetric radar data from DYNAMO

S-Pol (NCAR's dual polarized research radar) collected data from 1 October 2011 to 15 January 2012 on the Addu Atoll in the Maldives during DYNAMO (Dynamics of the Maddan-Julian Oscillation). It is well known that rainrate estimates can be a function of height above the earth surface due to evaporation, collision and coalescence, and breakup. In this study various rainrate calculations from the entire DYNAMO data set are integrated as a function azimuth angle, range and height and compared. The data indicate that the drop size distribution shifts towards larger drops sizes as the precipitation falls to earth, which suggests that collision-coalescence is occurring and that an equilibrium distribution is never reached. The results have implications for estimating rainfall during DYNAMO.