Statistical Characteristics of Raindrop Size Distribution in the Meiyu Season Observed in Eastern China

Abstract

Characteristics of raindrop size distribution (DSD) during the Meiyu season are studied using ground-based disdrometer measurements carried out in eastern China (Nanjing) from 2009 to 2011. The observational spectra are divided into convective and stratiform types. The results show that the histograms of the logarithm of the generalized intercept parameter (log10NW) and mass-weighted mean diameter of raindrops (Dm) are negatively and positively skewed, respectively, for both convective and stratiform rain. The absolute value of the skewness coefficient is higher for convective rain than for stratiform rain, in particular for the log10NW distribution. The mean log10NW and Dm values are 3.80 and 1.71 mm for convective rain and 3.45 and 1.30 mm for stratiform rain, respectively. The shape (μ)—slope (Λ) relationship of the gamma distribution and the radar reflectivity (Z)—rain rate (R) relationship are also derived for convective rain. The Z-R relationship is found to be Z = 368R1.21. The interpretation of the statistical parameters obtained in this study and possible mechanisms that yield difference and similarity in comparison with those in previous studies are discussed.