Regional differences in raindrop size distribution observed from disdrometers in South Korea and their possible causes

Abstract

In this study, we examine the regional differences in the characteristics of raindrop size distribution (RSD) among three cities (Seoul, Chuncheon, and Jincheon) in South Korea using disdrometer data for the period from 25 July 2018 to 31 July 2021 and investigate possible causes for the differences. Jincheon, the least populated and southernmost city among the three cities, is characterized by the smallest mean rainfall intensity and a relatively high frequency of light rain. These precipitation characteristics are related to the mass-weighted mean diameter D-m that is smallest and the logarithm of generalized intercept parameter log(10)N(w) that is largest in this city. In contrast, Chuncheon, a medium-sized city located in a basin, is characterized by the largest mean rainfall intensity and a relatively high frequency of heavy rain, which is related to the largest D-m and smallest log(10)N(w). Relatively small (large) convective available potential energy, low (high) cloud top, and high (low) cloud base in Jincheon (Chuncheon) can be responsible for the contrasts in RSD characteristics between the two cities. Seoul, the most populated city, is characterized by the intermediate mean rainfall intensity related to the intermediate D-m and log(10)N(w) between those in Jincheon and Chuncheon. Seoul exhibits the most frequent occurrence of extreme rainfall events and relatively large D-m for very heavy rain, which can be associated with the most frequent occurrence of large convective available potential energy.