Work

Hundred‐Meter‐Scale In Situ Observations Reveal Joint Impact of Humidity and Wind on Raindrop Microphysics

Year: 2025

Type: article

Abstract: The mechanisms linking raindrop size distributions (DSDs) to environmental conditions remain poorly understood, limiting their practical application. We develop a unique fine‐scale vertical in situ data set to reveal the evolution of near‐surface DSDs and quantify how environmental factors modulate raindrop microphysics. Near‐surface raindrop breakup is identified as a common feature during the East Asian summer, with an average threshold diameter of 1.16 mm for breakup initialization. Further analysis reveals that relative humidity and wind speed exert opposing influences on raindrop microphysical processes, with coalescence favored in humid monsoon environments and breakup intensified within typhoon outer rainbands. By incorporating empirical relationships between these two environmental factors and microphysical processes, we derive observational constraints that significantly reduce biases in near‐surface rainfall estimates. For heavy rainfall cases the bias is reduced by up to 75%. These findings improve understanding of raindrop microphysics in boundary layer and help improve quantitative precipitation estimation.

Source: Geophysical Research Letters

DOI: 10.1029/2025gl116977