辽宁朝阳地区季节冻土最大冻土深度和持续冻结时间与气候变化的响应研究

Response of maximum seasonally frozen depth and duration of soil frozen to climate change in Chaoyang Prefecture of Liaoning Province

利用辽宁省朝阳市气象站1960-2015年的最大季节冻土深度、最长连续冻结时间的起始日和终止日数据,采用小波分析方法对朝阳地区季节性冻土的年际变化特征进行分析,并探讨影响季节性冻土发育的影响因素。结果表明:朝阳地区最大冻土冻结深度存在4种尺度上的周期震荡,其周期分别为23~32 a、16~22 a、10~15 a和4~9 a。冻土年际变化的转折期发生在20世纪90年代初,表明朝阳市冬季气候转暖的时间段也发生在90年代初。通过对气温与季节性冻土冻结深度以及冻结时间的相关性分析,得出气候变暖对朝阳市季节冻土影响显著,冬季平均气温和冬季最低气温是影响朝阳市季节冻土发育的重要因素,其中冬季气温日较差对其影响尤为明显。冬季最低气温与冻土主冻期时间关系最为密切,而影响主冻期结束时间的热力因子为冬季平均最高气温。

Using the data of the maximum seasonally frozen depth,the longest frozen duration and the start and end days of the longest continuous freezing time from the meteorological stations in Chaoyang Prefecture of Liaoning Province from 1960 through 2015,the interannual change characteristics of permafrost in the prefecture were analyzed,,together with the wavelet analysis in this paper,and further discussed the influence factors on the seasonally frozen ground development in the prefecture. The results show that there have been four cycles of the maximum frozen depth,i. e.,23 - 32 a,16 - 22 a,10 - 15 a and 4 - 9 a,respectively. There was a shift of the frozen ground depth in the early 1990 s,showing a winter temperature warming in the prefecture since the early1990 s. According to correlation analysis between the temperature and frozen ground depth and frozen duration of seasonally frozen soil,it can be concluded that climate warming has a significant impact on the seasonally frozen in the prefecture. Meanwhile,the average temperature in winter and the lowest temperature in winter are closely related to the seasonally frozen depth in the prefecture. The analysis also indicates that the daily range of temperature in winter particularly affects the seasonally frozen depth. The lowest temperature in winter has closely related with the main frozen duration; the thermal factor that affects the end day of the main frozen period is the average maximum temperature in winter.