Characteristics and Small-Scale Variations of Raindrop Size Distribution over the Yangtze River Delta in East China

Abstract

To understand rain microphysics at the scale of 100 km over the Yangtze River Delta in East China, the characteristics and small-scale variations of raindrop size distribution (DSD) are investigated using data from two-year observations by five OTT Parsivel disdrometers. The characteristics of DSD are quantified and compared for three rainfall classifications: convective, stratiform, and mixed rainfall. Localized μ−λ and Z-R relationships are further derived based on the quantified DSD. For overall DSD, convective rain shows significant dispersion between different stations, while there is no obvious difference in stratiform and mixed rainfall. The DSD parameter shows that the convective rainfall tends to be enhanced but the stratiform and mixed rainfalls tend to be weakened by urbanization. The convective rainfall has the largest variability in number density (Nw) and mass-weighted mean diameter (Dm) followed by mixed rainfall, and stratiform rainfall has the smallest dispersion. Besides, both the μ−λ and Z-R relationships vary with rainfall types. These findings not only help to better understand precipitation physics but also contribute to the quantitative precipitation estimation (QPE) of weather radar, hydrological modeling, and water resource assessment.