Analysis of the Characteristics of Shallow Ground Temperature Changes in Hebei Province under the Background of Climate Change

To analyze the characteristics of shallow ground temperature response to climate change in Hebei Province, the province was divided into two zones: the northern zone (I) and the southern zone(II) based on latitude and altitude differences. Using monthly average ground temperature data from 0-40 cm at ground meteorological observation stations in Hebei Province from 1980 to 2022, linear trends, cumulative anomalies, signal-to-noise ratio, coefficient of variation, and other methods were used to analyze the climate change trends, abrupt changes, and interannual stability of annual and seasonal shallow ground temperature in Hebei Province. The spatial distribution of ground temperature in various layers of the province was plotted, and the correlation between major meteorological elements and ground temperature changes in each layer was analyzed using Person correlation. The results showed that: (1) The annual average ground temperature of each layer showed a significant upward trend, with a linear tendency rate of 0.495 ℃/10a (Zone I) and 0.396 ℃/10a (Zone II) for the increase in surface 0cm ground temperature, respectively. Taking 1996 and 2013 as abrupt change years, the overall trend in the past 40 years was "cold-flat-warm". From the perspective of seasonal changes, the temperature increase in spring is the largest, at 0.50 ℃/10a (Zone I) and 0.56 ℃/10a (Zone II), respectively, while in summer it is the smallest, at 0.27 ℃/10a (Zone I) and 0.23 ℃/10a (Zone II), respectively. (2) From the fluctuation of ground temperature changes, the highest ground temperature in each layer shows a significant upward trend, while the coefficient of variation of ground temperature in each layer shows a significant downward trend, and the average coefficient of variation in Zone I is higher than that in Zone II. (3) From the spatial distribution of stratified ground temperature, the average ground temperature of each stratum in the province varies within the range of 5.8-16.8 ℃, showing a latitudinal spatial distribution from north to south, with lower temperatures in the north and higher temperatures in the south. (4) From the correlation between ground temperature and meteorological conditions, the 0cm ground temperature is significantly positively correlated with temperature. While in most cities, the ground temperature is significantly negatively correlated with precipitation, relative humidity, and wind speed. The correlation with sunshine hours is not strong.