吉林省冻土的统计特征

The Statistical Characteristics of Frozen Soil in Jilin Province

本文根据吉林省42个气象台站1954—1980年冻土观测资料,系统地分析了不同冻土深度的地理分布状况和随时间的变化规律、最大冻土深度与12月平均地面最低温度的关系。同时分析了土壤稳定冻结和稳定融冻的起讫时间,反映出本省冻土有明显的季节性。还分析了土壤冻结速度,看出其上部为直线型,下部为曲线型的变化特征。

The observed data (1954-1980) of frozen soil from 42 meteorological stations over Jilin Province are used in this statistical analysis. In Jilin Province, all kinds of frozen soil are seasonal. The freezing period begins in November and ends in next May. The maximum depth of frozen occurs in March. Which is the same time of the stable passage of 0℃ air temperature. It increases from south and south east to north and north west. Its maximum value 250 cm, appears in Baicheng, a plain region in north west. The minimum value of frost depth, 101 cm, appears in Donggang, a mountainous region in south east. The maximum depth of frozen soil is mainly related to latitude, the depth of snow cover and duration. By the statistics, we find that the annual maximum depth of frozen soil can be well related to the minimum surficial ground temperature in December. It will takes about five monthes to reach the maximum depth of frozen soil in a year, and only more than two monthes for thawing of the frozen soil. The time distribution of the stable freezing depth of soil at 10, 30 and 50 cm is similar to latitude. The freezing depth at 100 cm is not the result of the difference of the soil structure, but well related to latitude.