Observed Characteristics of Hail Size in Four Regions in China during 1980–2005

Abstract

Abstract The climatology and long-term trend of hail size in four regions of China are documented for the period of 1980–2005 using the maximum hail diameter (MHD) data obtained from the Meteorological Administrations of Xinjiang Uygur Autonomous Region (XUAR), the Inner Mongolia Autonomous Region (IMAR), Guizhou Province, and Hebei Province. The reported MHD is mainly around 10 mm in the four regions. Guizhou (in southwestern China) has the largest proportion of severe hail (MHD greater than 15 mm) among the four regions. Severe hail in southwestern China mainly occurs between February and June, while in northern China it occurs in summer (from May to August) with the peak in June. During the period studied, the size of severe hail shows a slight downtrend in Guizhou and IMAR, whereas it shows an uptrend and a flat trend in Hebei and XUAR, respectively. However, none of the trends is statistically significant. Results from sensitivity experiments using a one-dimensional numerical model show that hail size is sensitive to the freezing level height, the maximum updraft, and column cloud liquid water—all working together to determine the geographic distribution and long-term trend of the observed hail size in China.