Characteristics of Raindrop Size Distribution in Seoul, South Korea According to Rain and Weather Types

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ORIGINAL ARTICLE

Characteristics of Raindrop Size Distribution in Seoul, South Korea According to Rain and Weather Types Minchae Jwa 1 & Han-Gyul Jin 1 & Joohyun Lee 1 & Sungju Moon 1 & Jong-Jin Baik 1 Received: 18 March 2020 / Revised: 15 July 2020 / Accepted: 24 August 2020 # Korean Meteorological Society and Springer Nature B.V. 2020

Abstract The raindrop size distribution (RSD) is useful in understanding various precipitation-related processes. Here, we analyze disdrometer data collected in Seoul, South Korea from May 2018 to July 2019 to characterize the RSD according to rain and weather types. Rain types are categorized into stratiform, mixed, and convective rain, and weather types into the Changma front (type CF) and low-pressure system (type L). The slope parameter Λ decreases and the intercept parameter N0 fluctuates with rain rate. Among the rain types, the RSD of stratiform (convective) rain shows the steepest (mildest) slope and the smallest (largest) mean diameter. The logarithm of generalized intercept parameter log10Nw and Λ for stratiform rain have considerably dispersed distributions, which may be attributed to the diversity within the stratiform rain type in Seoul. Mixed-type rain has a larger mean value of log10Nw compared to stratiform and convective rain. Regarding the weather types, the RSD of type CF exhibits a milder slope, a larger mass-weighted mean diameter, and a larger radar reflectivity than type L. These differences between the weather types can be explained by the larger convective proportion in type CF (33%) compared to type L (9%). Possible causes for the differences between the RSD characteristics of the two weather types are examined using reanalysis and satellite data. Type CF has a larger convective available potential energy, a higher cloud top, and more active ice microphysical processes than type L, which can lead to different RSD characteristics. Keywords Raindrop size distribution . Disdrometer . Rain type . Weather type . Seoul

1 Introduction The raindrop size distribution (RSD) provides important pieces of information about clouds and precipitation and is one of the properties that can be observed directly using instruments such as disdrometers. Characterizing the RSD for different environmental conditions constitutes an important part of cloud and precipitation research (Pruppacher and Klett 2010), and a detailed analysis of direct observation data can play a part in advancing our understanding of clouds and precipitation. The RSD characteristics are different depending on the rain type, namely stratiform and convective rain. Each type of rain is known to originate from different precipitating clouds and

Responsible Editor: Jinwon Kim. * Jong-Jin Baik [email protected] 1

School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea

may occur separately or together in a cloud complex (Houze 2014). Using ground-based disdrometers, many studies have shown that stratiform rain has high number conce