Raindrop size distributions observed by the Fengyun satellite precipitation validation network in the southern coastal area of China

Abstract The raindrop size distribution (DSD) plays a significant role in the simulation of precipitation in numerical weather prediction models and estimating precipitation quantitatively from radar observations. This study analyzed the properties of precipitation by using the two-dimensional video disdrometer (2DVD) measurements at eight sites in the Fengyun satellite precipitation validation network in Guangdong Province, located in the southern coastal region of China. The comparison of the cumulative hourly rainfall from the 2DVD and surface rain gauge data at the eight sites suggests good agreement, with average correlation coefficient (CC), mean bias error (MBE) and root mean square error (RMSE) values of 0.98, −0.29 mm and 1.38 mm, respectively. The average mass-weighted mean diameter ( D m ), log 10 N w (generalized intercept parameter: N w ) and liquid water content ( LWC ) are 1.16 ± 0.45 mm, 3.72 ± 0.66 and 0.30 ± 0.75 g m −3 at the eight sites. The average fitted power law relationship of D m and the rain rate ( R ) is D m = 1.11 R 0.14 at the eight sites. For the radar-based rainfall estimation algorithms, the average power law Z − R relationship is Z = 720 R 1.14 at the eight sites. Rainfall estimation based on the radar reflectivity ( Z H ) and differential reflectivity ( Z DR ) pair is expressed as R = 1.92 × 10 − 3 Z H 0.94 Z DR − 1.41 at the eight sites. The average CC, MBE and RMSE between the estimations and 2DVD observations are 0.99, −0.15 mm and 0.91 mm, respectively, for the cumulative hourly rainfall. By establishing a regional DSD climatology and validating an optimized radar rainfall estimation algorithm, this study provides a methodological advancement for hydrological and meteorological communities operating in similar coastal and monsoon-influenced climatic zones.