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利用1961~2007年石羊河流域上游、中游、下游当地气象站的冬季最大冻土深度、气温、地温、日照时数、降水量、相对湿度、蒸发、积雪资料,分析了近47 a石羊河流域冬季最大冻土深度的空间分布以及时间变化特征,进而采用相关系数法进一步探讨了冬季最大冻土深度变化的原因。结果表明:在空间分布上,石羊河流域冬季最大冻土深度分布与本地地理位置、土壤类型和海拔高度密切相关。石羊河流域冬季最大冻土深度梯度呈南—北走向,最大值出现在南部古浪,最小值出现在北部民勤。时间变化上,近47 a,石羊河流域以及流域上、中游冬季最大冻土深度呈下降趋势,而下游民勤冬季最大冻土深度则呈上升趋势,石羊河流域冬季最大冻土深度在不同时段内存在明显的6~7 a和9~10 a的周期反映,除下游民勤外在20世纪90年代都发生了突变。相关系数法分析表明,影响石羊河流域冬季最大冻土深度的气象因子是主要是热力因子,热力因子中关联最强的是极端最低地温和气温;水分因子中蒸发和冬季最大冻土深度的关联最明显。
Based on the data of winter maximum frozen soil temperature, temperature, ground temperature, sunshine duration, precipitation, relative humidity, evaporation and snow accumulation in the upper, middle reaches and downstream of the Shiyang River Basin from 1961 to 2007, In winter, the spatial distribution of the maximum frozen soil depth in Yanghe River Basin and its temporal variation are analyzed. The correlation coefficient method is used to further explore the reasons for the change of winter maximum frozen soil depth. The results show that the spatial distribution of winter maximum frozen soil depth in Shiyang River Basin is closely related to the local geographical location, soil type and altitude. In winter, the depth gradient of the largest frozen soil in Shiyanghe River basin shows a south-north trend with the maximum occurring in Gulang in the south and the lowest in Minqin in the north. In the recent 47 years, the depth of the frozen soil in the Shiyang River Basin and the upper and middle reaches of the basin decreased in the past 47 years, while the depth of the frozen soil in the lower reaches of the Minqin increased in winter. The maximum frozen soil depth in Shiyang River Basin in winter There were obvious periods of 6 ~ 7 a and 9 ~ 10 a in different time periods, with the exception of downstream Minqin mutation in the 1990s. Correlation coefficient analysis shows that the meteorological factors that affect the winter maximum frozen soil depth in Shiyanghe River Basin are mainly thermodynamic factors, and the thermodynamic factors most strongly relate to the extreme lowest geothermal temperatures; the evaporation in water factors and the maximum frozen depth in winter The most obvious correlation.