RELAMPAGO-CACTI drop size distribution observations and the implications for cloud and hydrologic studies

Comparisons of drop size distributions (DSD) properties and rainfall modes among three deep convective regions (the U.S. Southern Great Plains, in Córdoba Province in subtropical South America, and Manacapuru in central Amazonia) where heavy rain-producing systems contribute the majority of rainfall in the largest river basins of the Americas, are conducted. Measurements from two types of disdrometers sampled at two of the three sites were considered, and subsequently separated into a light precipitation mode and a precipitation mode using a cutoff at 0.5 mm hr-1. The distributions of physical parameters (such as rain rate R, mass-weighted mean diameter Dm, and normalized droplet concentration Nw) for the raindrop spectra without classification appear to be similar amongst the sites, except for much broader distributions of Nw at the Córdoba site. In the light precipitation and precipitation modes, the dominant higher observed frequency of Nw in both types of disdrometers, as well as the identification of shallow, light precipitation in vertically-pointing cloud radar data represent a unique characteristic of the Córdoba site relative to the other sites. As a result, the co-variability between DSD physical parameters indicates that the precipitation observed at Córdoba may confound existing drop size distribution methods of determining rain type