Analysis of the variation law of shallow ground temperature during the freezing-thawing period in Shenmu City

Shallow ground temperature is a key indicator for research on climate change and prevention of freeze-thaw disasters. This study takes Shenmu City as an example. Based on the monitoring data of air temperature and ground temperature from Shenmu National Meteorological Station from 2010 to 2024, the variation characteristics of shallow ground temperature at different time scales were analyzed. According to the variation of daily ground temperature, the freezing and thawing stages were divided. In addition, a quantitative study on the freezing depth during the freeze-thaw period was conducted based on negative accumulated temperature (ANT). The results showed that in terms of interannual variation, the annual average ground temperature at depths of 5 cm and 10 cm in the study area showed an overall upward trend, while the opposite was true from 20 cm to 160 cm. During the freeze-thaw period, the annual average ground temperature in various layers showed a weak upward trend. The freeze-thaw period within the year could be divided into five stages: unfrozen period, alternating freezing period, frozen period, alternating thawing period, and thawing period. There was a significant linear relationship between the minimum negative accumulated temperature and the maximum freezing depth. The maximum freezing depth during the freeze-thaw period was estimated to be 147 cm within the monitoring range of the research area. The research results can provide theoretical support for the prevention and control of regional freeze-thaw geological disasters.