Objective Classification of Severe Convective Wind Environments across China

Abstract

Data from cloud-to-ground lightning networks, radar reflectivity mosaics, ERA5 reanalysis, and observations from 2,422 surface stations during 2010–2021 were used to classify severe convective wind gust (SCW; ≥25 m s −1 ) events across China. The events were classified into six subtypes within two categories: NR (without short-duration heavy rainfall: NR1, NR2, and NR3) and R (with short-duration heavy rainfall: R1, R2, and R3). The six subtypes correspond to four distinct environmental regimes. NR1 occurs in dry environments with weak buoyancy and the strongest deep-layer vertical wind shear. R1 develops under moderate instability with relatively strong deep-layer wind shear. NR2 and R2 both occur in high-instability, low-shear environments. NR3 and R3 are produced in the environments of deep moist layers, moderate instability, and enhanced low-level vertical wind shear. Overall, R events exhibit significantly greater buoyancy and moisture but weaker vertical wind shear than NR events. Geographically, NR1 occurs frequently in North China during spring and summer, whereas R1 prevails mainly in summer over the plains. NR2, R2, NR3, and R3 peak in south of the Yangtze River in spring and expand northward in summer. Diurnally, NR1, R1, and R2 peak in mid-afternoon and NR3 and R3 show elevated nocturnal frequencies. Storm morphology varies systematically: cellular systems dominate in mountainous regions, while plains feature comparable contributions from cellular and linear modes, with linear systems prominent in NR3 and R3. These findings refine the understanding of environmental conditions associated with SCWs in China and provide a climatological basis for forecasting.