1959—2018年沈阳地区冻土时空变化特征

Temporal and spatial variation characteristics of frozen soil in Shenyang area from 1959 to 2018

利用1959年10月至2018年4月沈阳地区7个气象站逐日冻土观测资料、逐日平均气温、逐日平均地温及5 cm、10 cm、15 cm、20 cm、40 cm地温观测资料,分析了近60 a沈阳地区最大冻土深度的时空变化特征,并探讨了其对气候变暖的响应。结果表明:近60 a来沈阳地区冻土一般在10月开始出现,翌年4月消融。1959-2018年沈阳地区年平均月最大冻土深度在2月和3月最大,10月最小;年最大冻土深度以-4.8 cm/10 a的速度显著变浅,年代平均最大冻土深度也呈变浅趋势。相关分析表明,近60 a沈阳地区日最大冻土深度与日平均气温、地温呈显著负相关关系,相关系数分别为-0.60和-0.72。Mann-Kendall检验表明,7个气象站年平均最大冻土深度均有突变发生,突变点大多出现在20世纪80年代。近60 a沈阳地区最大冻土深度开始日期和结束日期分别呈延后和提前趋势,趋势率分别为1.0 d/10 a和-3.2 d/10 a。1959-2018年沈阳地区平均冻土持续时间为164 d,年变化呈缩短趋势,趋势率为-4.4 d/10 a。

Based on daily frozen soil observation data,daily average air and surface temperature,daily average ground temperature at the depth of 5 cm,10 cm,15 cm,20 cm and 40 cm from the seven meteorological stations in Shenyang area,the temporal and spatial variation characteristics of maximum frozen soil depth(MFSD)are analyzed and discussed.The results show that the frozen soil in Shenyang area generally appears in October and melts in April next year.The frozen soil depth is the largest in February-March and the smallest in October;and the MFSD decreases significantly at a rate of-4.8 cm/10 a.In addition,the interdecadal variation of the MFSD also shows a decreasing trend.Meanwhile,the daily MFSD has a significant negative correlation with the daily average temperature and the daily average ground temperature at the depth of 20-40 cm and their correlation coefficients are 0.60 and 0.72,respectively.Mann-Kendall test shows that the MFSD in the seven weather stations shows climatic abrupt change in 1980s.Moreover,the starting and ending dates of maximum frozen soil depth in recent 60 years are delayed and advanced with trend rates o`f 1 d/10 a and 3.2 d/10 a respectively,and the average duration of frozen soil is 164 d in Shenyang area and shows a shortening trend with a rate of 4.4 d/10 a.