In a study recently published in the journal Atmosphere, ATMS graduate student Lina Rivelli-Zea leveraged disdrometer data collection in the Americas to compare the drop-size distributions and parameters across field campaigns for the first time. Prof. Steve Nesbitt and graduate student Alfonso Ladino Rincon contributed to this study. The data were collected at two sites in the mid-latitudes: the core site of the RELAMPAGO-CACTI campaign near Córdoba, Argentina, and the U.S. Southern Great Plains site in central Oklahoma. Additional data were collected at a site in central tropical Amazonia during the GoAmazon campaign. These are all areas where intense rain-producing systems contribute to most rainfall in the Americas’ largest river basins.

The distributions of physical parameters for the raindrop spectra without rainfall mode classification seemed similar, except for the much broader Nw (normalized droplet concentration) distributions in Córdoba. The raindrop spectra were then classified into a light precipitation mode and a precipitation mode using a cutoff at 0.5 mm h−1 based on previous studies that characterized the full drop size spectra. As a result, the co-variability between the physical parameters of the drop-size distributions indicates that the precipitation observed in Córdoba may confound existing methods of determining the rain type by using the drop size distribution.

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