辽西季节性冻土特征及融化过程对气候变化的响应

Characteristics of Seasonally Frozen Soil and Its Response to Climate Changes in the Thawing Process in Western Liaoning Province

为了开展地温监测和冻土融化深度预报业务,利用辽宁西部气象观测资料,运用相关系数和线性回归等方法,分析冻土变化特征、冻土融化过程,以及气象要素对冻土深度变化的影响,并建立其地温与气温、冻土融化过程与正积温相关模型。结果表明,辽宁西部稳定冻土期在11月中旬至翌年3月下旬,冻土最大深度呈逐年变浅趋势,倾向率为-5.4 cm/10 a;结冻日期推后,倾向率为2.0 d/10 a;化通日期提前,倾向率为-1.5 d/10 a;冻土融化期在3月中旬至4月上旬,冻土融化速率在3.1~4.0 cm/d。冻土最大深度与气温、地面温度及降水量显著相关。11月至翌年2月气温每升高1℃冻土最大深度变浅5.7 cm。气温与地温、正积温与冻土融化深度具有显著的线性关系;其中,气温与10 cm地温线性方程历史回代拟合率在96%以上;正积温与冻土融化深度线性方程历史回代拟合率在94%以上。线性方程可作为模型预测预报春季地温、冻土融化深度。

To ensure the safety of spring sowing and road maintenance, it is necessary to monitor the ground temperature and forecast the thawing depth of frozen soil. By combining the correlation coefficient and linear regression method, meteorological observation data in western Liaoning province were used to analyze the change characteristics, the thawing process of frozen soil and the influence of meteorological factors on changing depth of frozen soil, and establish a model related to the ground temperature and air temperature, the thawing of frozen soil and cumulative positive temperature. The results suggested that the stable frozen soil period in western Liaoning Province ran throughout the middle of November to the late March of the next year. The largest depth of frozen soil was becoming shallow year by year, with an inclination rate of-5.4 cm/10 years. The freezing date was postponed, with an inclination rate of 2.0 d/10 years. The melting date was advanced, with an inclination rate of-1.5 d/10 years. The frozen soil thawing period ran throughout the middle of March to the early April, with a thawing rate of 3.1-4.0 cm/d. The maximum depth of frozen soil was significantly correlated with temperature, ground temperature and precipitation. From November to February of the next year, the maximum depth of frozen soil reduced by 5.7 cm as the temperature increased by 1 ℃. There was a significant linear relationship between the air temperature and the ground temperature, the cumulative positive temperature and the thawing depth of frozen soil. In the linear relationship, the fitting rate of linear equation between air temperature and 10 cm ground temperature was above 96%. The fitting rate of linear equation between cumulative positive temperature and thawing depth of frozen soil was above 94%. It was proved in this study that the linear equations can be used as a model to forecast the ground temperature and thawing depth of frozen soil in spring. It lays a theoretical foundation for the further researches on frozen soil.