Characteristics of Raindrop Size Distributions in Chongqing Observed by a Dense Network of Disdrometers

摘要

This study investigates the characteristics of raindrop size distribution (RSD) including the temporal and spatial variabilities and the summer rain RSD features using 34 Parsivel disdrometers data from Jan. 2015 to Jan. 2016 in Chongqing, an inland municipality in Southwest China. The observed RSDs are fitted with the gamma distribution (N(D) = N_0D~μe~(-λD)) in this study. Rainfall in summer differs greatly from winter with larger rain rate, rain water content and variabilities. From winter to summer, raindrop sizes increase as the frequency of convective rain increases, and the diurnal variabilities of raindrop sizes are greatly enlarged. The spatial variabilities of N_0, λ and μ are relatively weak and change little in summer. The summer rainfall RSD characteristics and parameter relationships in Chongqing are different from other regions (Nanjing, Beijing, Zhuhai and Daocheng) in China. A novel diagnosed relation between the shape parameter of the gamma distribution (μ) and the mean volume diameter (D_v) is proposed based on the large amount of observations, which allows for a wider range of the mean volume diameter of raindrops compared to traditional μ - λ relations in microphysics parameterizations.