Abstract:

The study of seasonal frozen soil change in Shanxi Province has important application value for revealing the response of seasonal frozen soil thawing to climate change and the direct impact of land degradation caused by frozen soil change on agricultural production, irrigation and water conservancy infrastructure and road construction in the Loess Plateau under the background of climate warming. Based on the frozen soil data from meteorological observation records at 108 stations in Shanxi Province from 1981 to 2018, this paper analyzed the spatiotemporal variation characteristics of the ground freezing date, thawing date, the number of frozen days and annual maximum depth of frozen soil, and the interannual and interdecadal variation characteristics of the annual maximum frozen soil depth, and the responses of the above factors to climate warming. Results showed that soil freezing in northern Shanxi began in September, and the frozen soil subsided in May at the latest. The depth and area of frozen soil reached the maximum at the end of winter and the beginning of spring. The date of ground freezing was postponed and the date of ground thawing was earlier, and the number of frozen days was reduced accordingly to various degrees in most parts of the province from 1981 to 2018. The annual maximum depth of frozen soil gradually decreased from north to south. The annual maximum depth of frozen soil decreased in the middle and southern parts of the province, and increased in the northern part, which might be related to the warming and wetting of winter climate in north Shanxi. Under climate warming, winter precipitation and 0 cm ground temperature had complex response relationship with the annual maximum depth of frozen soil. The annual maximum depth of frozen soil was negatively correlated with 0 cm ground temperature under the background of excessive winter precipitation. The decreasing trend of the maximum frozen soil depth was a direct response to the increase of the annual average temperature, and the response of the maximum frozen soil depth to the annual average temperature was more significant than that to the annual precipitation.

Key words: seasonal frozen soil, spatiotemporal distribution, evolution characteristics, climate warming, response, Shanxi