北京地区冻土时空分布特征

基于1981—2021年北京地区6个气象站的逐日最大冻土深度、平均气温、平均地表温度及5、10、15、20、40、80 cm地温等资料，分析了近40年北京地区最大冻土深度的时空分布特征及其与气温和地温的关系。结果表明：北京地区最大冻土深度总体呈变浅趋势，气候倾向率为-2.3 cm/10 a，各站点最大冻土深度变浅趋势从西到东呈逐渐减弱趋势。北京地区最大冻土深度与40、80 cm地温相关性最好，与地表温度相关性较差。选取2021至2022年北京地区冻土对比试验数据，评估测温式冻土自动观测仪观测精度，发现仪器安装至少一个冻融周期后与冻土人工观测吻合度更好，测温式冻土自动观测仪的观测精度与仪器安装位置的地下岩层、土质分布密切相关，需要在仪器稳定运行后根据当地实际优化算法和冻融阈值。

Research on the Characteristics of Spatial and Temporal Distribution of Frozen Soil in Beijing and the Data Quality Assessment of Temperature Measuring Type Frozen Soil Instrument

This paper examines the relationship between the spatial and temporal distribution characteristics of the maximum depth of frozen soil, air temperature and ground temperature in Beijing over the past 40 years. data from six meteorological observation stations in Beijing from 1981 to 2021 were collected, including daily maximum depth of frozen soil, average air temperature, average ground surface temperature and the ground temperature data at depths of 5, 10, 15, 20, 40 and 80 cm. The results indicate that the maximum depth of frozen soil generally becomes shallower from west to east across the meteorological observation stations, with a climate tendency rate of -2.3 cm/10 years. The maximum depth of frozen soil in Beijing shows a weak correlation with ground surface temperature and a stronger correlation with ground temperatures at depths of 40 and 80 cm. By selecting the comparative test data of frozen soil in Beijing from 2021 to 2022, this study evaluated the data quality of the temperature measuring type frozen soil automatic observation instrument. The findings reveal that the instrument demonstrates better agreement with manual observation of frozen soil after one freezing and thawing cycle. The data quality of the temperature measurement type frozen soil automatic observation equipment is directly influenced by the subterranean rock formations and soil distributions at the installation location. After the instrument has achieved stable operation, it is necessary to optimize the algorithm and the threshold value for freezing and thawing in accordance with the local conditions.