1961~2010年呼和浩特市区地温及季节冻土的变化特征

Variation Characteristics of Ground Temperature and Seasonal Frozen Soil in Hohhot City during 1961-2010

摘要: 对呼和浩特市区50a (1961~2010年)地温及冻土气象观测资料整理和分析的基础上，研究了地温和冻土随时间的演变规律，探讨其基本事实、特征及变化原因。结果为：50年间呼和浩特市区地温升高显著(p < 0.05)、土壤封冻状态及最大冻土深度均发生较大变化，且不同年代变化幅度也不尽相同：90年代地温和土壤封冻状态迅速变化，10年代地温增温最为剧烈、土壤封冻状态变化最为显著；最大冻土深度则表现为由浅到深、再到浅的过程。地温与气温的变化不同步，地温的变化滞后于气温，春季地温升高幅度大于冬季。日最低平均地表温度和日最高平均地表温度较其它两类地温增温明显，气候倾向率分别为0.45/10a和0.43℃/10a；平均解冻日的大幅提前(基本表现为每10年提前7天左右)是引起封冻天数变化的直接原因；70~90年代为冻土深度最大的时段，最大冻土深度10年代较70~90年代约减少17 cm。

Abstract: Based on the collection and analysis of meteorological observation data of ground temperature and seasonal frozen soil in Hohhot City during 1961-2010, time-variations of ground temperature and seasonal frozen soil were studied, and the basic facts, characteristics and reasons were also discussed. The results showed that: the ground temperature rose remarkably (p < 0.05), and the soil frozen state and maximum depth of frozen ground changed greatly within the fifty years. Furthermore, their degrees of changing were different among ages. The ground temperature and soil frozen state changed rapidly in 1990s, and the most severe changes of them were occurred in the first ten years of twenty first century. The maximum depth of frozen ground represented the process as: from shallow to deep, then to shallow during 1961-2010. Changes in ground temperature and air temperature were not synchronized, and the change of ground temperature lagged behind the air temperature. The rise extent of ground temperature in spring was larger than that in winter. Daily minimum and maximum mean surface temperature were increased obviously than the other two ground temperatures, and their climate tendency rates were 0.45/10a and 0.43˚C/ 10a respectively. The substantial advance of average thawing day (about 7 days in advance every 10 years) directly affected the frozen days. 1970s to 1990s was the greatest period of maximum depth of frozen soil, and the maximum depth of frozen soil in the 10s was decreased by about 17 cm compared with the 70s-90s.