全球变暖背景下新疆地区近45a来最大冻土深度变化及其突变分析

Variation and Abrupt Change of Maximum Depth of Frozen Soil over Xinjiang Under the Background of Global Warming,1961-2005

利用覆盖新疆大部分地区资料完整的93个站点资料,对1961-2005年新疆地区最大冻土深度进行了分析.结果表明:新疆地区月最大冻土深度有明显的季节变化,低海拔区域(海拔<1 800m)最大值出现在1月份,而高海拔区域(海拔≥1 800m)的最大值出现在2月份,比低海拔区域要滞后.新疆地区最大冻土深度的地理分布特征表现为北疆深于南疆,山区深于平原,且与气温的分布有很好的一致性.全年和冬、春季最大冻土深度与气温场的空间相关系数分别为-0.795、-0.736和-0.848.年际变化表明,近45a来的最大冻土深度出现了较为明显的下降.高海拔区域与低海拔区域年最大冻土深度的倾向率分别为-15.65cm·(10a)-1和-9.48cm·(10a)-1,且与气温的相关系数分别为-0.51和-0.69,均通过了0.001的信度检验.同时发现,高海拔区域冬季下降多,而低海拔区域春季下降多.新疆地区年最大冻土深度在近45a有明显的突变现象,高海拔区域和低海拔区域突变发生年份分别为1996/1997年度和1978/1979年度,说明新疆地区高海拔区域的年最大冻土深度对气温变化的响应比低海拔区域要滞后.突变年后高海拔区域与低海拔区域年最大冻土深度比突变年前的平均值分别降低了61.12cm和26.67cm.

A data set observed from 93stations of Xinjiang Uygur Autonomous Region is used to analyze the spatial distribution and temporal change of the maximum depth of frozen soil.The results showed that：（1）Monthly maximum depth of frozen soil in Xinjiang has obvious seasonal variation, with the maximum in areas with lower altitude presented in January,but in areas with higher altitude presented in February;（2）the maximum depth of frozen soil in north of the region is higher than that in south of the region,and those in mountain areas are greater than those in plains; the distribution of maximum depth of frozen soil was similar to that of air temperature;the spatial correlation coefficients between the maximum depth of frozen soil and air temperature are-0.795,-0.736and-0.848for all year round, winter and spring,respectively;（3）There had a distinct decreasing during the 45years in Xinjiang, with regression coefficients of areas with higher and lower altitude of-15.65cm·（10a）-1 and-9.48cm·（10a）-1,and their correlation coefficients with air temperature are-0.51and-0.69, which had all past 0.001significance level.Otherwise,the decreasing in winter shows that in Region a1the decreasing was sharper than that in Region a2,but in spring,the decreasing in Region a2 was sharper than that in Region a1;（4）There was an abrupt change of the maximum depth of frozen soil during the 45years in the autonomous region; the years of mutation in the areas with higher altitude and lower altitude were 1996/1997and 1978/ 1979,respectively,which can also prove that impact from air temperature in areas with higher altitude was latter than that in areas with lower altitude.The reductions of yearly maximum depth of frozen soil in areas with higher altitude and lower altitude were 61.12cm and 26.67cm,respectively.