Temporal and spatial distribution characteristics of hail disaster events in China from 2010 to 2020

Based on the hail data of the China Meteorological Administration, the spatial and temporal distributions of hail disaster eents in China during 2010-2020 are studied by using the statistical method and GIS technology. The result is shown below. (1) The number of stations and the days of hails in China increase, while the number of severe hails decreases during 2010-2020. (2) The seasonal change is significant for the number of stations and the days of hails with the maximum in summer and the minimum in winter. In terms of monthly variation, hail occurs most often in June and least often in November. In southwest and central China, the monthly variation of the number of stations and the days of hails is bimodal. The monthly distribution of severe hail is similar to that of hail, but it occurs least often in December. The severe hail occurs most frequently in southwest China. (3) For diurnal variation, hail or severe hail mainly occurrs from afternoon to evening. The peak appears 1-hour later in northwest China than in other areas. (4) In terms of spatial distribution, the number of stations and the days of hail or severe disaster in Northwest, Southwest, and North China are significantly higher than those in the other regions, and the proportion of severe hail in Northeast and South China is higher than that in the other regions. The annual average days of hail or severe hail are distributed in multi-zone bands, and the multi-hail area extends along the mountains, with the largest value located in the Yunnan-Guizhou Plateau, followed by the mountains of Qinling, Yinshan, Daxing 'anling, and Tianshan. In addition, the low-incidence area of eastern China in spring has become a high-incidence area of hail. (5)From the elevation distribution, hail is most likely to occur at the altitude of 1.5-2 km, and severe hail is most likely to occur at the altitude of 1-1.5 km. In winter, hail is mainly below 2 km. With the rise of temperature, hail gradually increases in the high-altitude areas, and the proportion of hailstones in the high-altitude areas reaches the maximum in September.