AUTHOR=Sun Jing , Wan Rong , Zhou Yue 

TITLE=Effects of Relative Humidity on the Diurnal Variation of Raindrop Size Distribution in Southwest China

JOURNAL=Frontiers in Environmental Science

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2022.948318

DOI=10.3389/fenvs.2022.948318

ISSN=2296-665X

ABSTRACT=This study assessed the impacts of relative humidity (RH) on diurnal variation in the raindrop size distribution (RSD) within a region in China with a valley topography (Zigui region) from 2019 to 2020 based on a two-dimensional video disdrometer (2DVD), auto-weather station (AWS) data, and ERA5. The daytime RSD structure under an RH < 60% and ≥ 60% showed three peaks and a single peak, respectively. Nighttime RSD under RH ≥ 60% and < 60% showed a single peak and two peaks, respectively. The daytime RSDs of short-duration precipitation Amount(SPA) showed broader distributions than the nighttime RSDs, whereas the nighttime RSDs of long-duration precipitation Amount (LPA) exhibited the opposite trend. Higher ground RH changed the RSD shape by sorting raindrops, collision-coalescence and breakup due to the formation of large raindrops. Under a constant RH, the melting and collision-coalescence of large raindrops in the daytime of SPA exceeded those of LPA. This difference may be related to the near-surface wind filed and the intensity of convection.