Differences in spatiotemporal variation and risk zoning of four types of extreme cold events in Jiangsu province

Based on observations collected at 70 stations in Jiangsu province from 1961 to 2020, spatial and temporal variations of four types of cold events are investigated first. A total of 14 evaluation indicators related to cold damages are selected to build the dangerousness index. Using the population and GDP data, the dangerous level and risk-zoning of cold events are then assessed. The results are as follows: (1) Cold air outbreaks, frost events and cold-rainy events frequently occur in Jiangsu province during 1961—2020, while the frozen events have a small total number of occurrence days. Cold air outbreaks and frost events have the maximum number of occurrence days during 1961—1980, while cold-rainy events and frozen events reach the maximum occurrence in 2001—2020. (2) Cold air outbreaks occur frequently in central and southern Jiangsu province during 1961—2020. Correspondingly, frost events occur more frequently over the northern areas than over the southern part of Jiangsu province. The number of days with cold-rainy events shows a decreasing tendency from southwest to northeast of Jiangsu province. Frozen events frequently occur in the southwest and northwest of Jiangsu province, where frozen events have a spatial distribution similar to that of precipitation. (3) High level of danger for cold air outbreak and frost events is located in the north of Jiangsu province, while the high level of danger for cold-rainy events is found in the southwestern areas of Jiangsu province. The high level of danger for frozen events appears in both south and north of Jiangsu province. The composite dangerousness of the four types of cold events shows that the high level of danger is located in the north and southwest of Jiangsu province and the low level appears in central and southeastern areas. (4) There exist notable differences in the spatial distribution and area of high risk between the population and GDP, which are mainly resulted from the spatially discontinuous hazard-bearing body under the condition of a similar meteorological environment in Jiangsu province.