1961—2010年阿拉善左旗气温和地温的变化特征分析

关于气温变化特征已有大量研究，但关于地温变化及其与气温的关系研究还较少。该研究以干旱区为研究区域，利用1961—2010 年阿拉善左旗平均气温和0~80 cm各层平均地温的逐月资料，采用气候倾向率、累积距平、信噪比等气候统计方法研究了近50 a 阿拉善左旗气温和各层地温的年代和季节变化趋势、地气温差变化、气候突变和异常年份以及气温和地温关系。结果表明：气温与各层地温有很好的相关性；与年均气温相比，地温对气温的放大程度除0 cm外随土层深度增加呈增加趋势。年、季平均气温和各层平均地温均呈显著升高趋势，但气温和地温的升温速率不一致；年均气温的升温率和升温幅度高于除0 cm外的各层地温变化；气温、0 cm 和80 cm 地温在冬季的升温最大，5~40 cm 地温在春季升温最大；春、夏季，随土壤深度增加，地温呈减小趋势，气温介于各层地温之间；秋、冬季，随土壤深度增加，地温呈增加趋势，气温小于除0 cm外的各层地温增加；气候变暖背景下，年均、夏、秋和冬季的气温比地温的响应更快，而春季各层地温比气温的响应更迅速。近50 a 各层年均地温(0 cm除外)和气温的温差减小0.3~0.8℃；随土壤深度增加，地气温差的减小幅度降低。年均气温和各层地温的气候突变出现在1980 年代和1990 年代，而气温和地温在四季大多无气候突变现象。四季气温和各层地温的异常年存在一定的对应性，而年均气温和各层地温的异常年份一致性较差。

Characteristics of Air Temperature and Ground Temperature in Alxa Left Banner from 1961 to 2010

Lots of studies have focused on characteristics of air temperature, however, few studies have been done on characteristics of ground temperature and its relationship with air temperature. As a case study, the characteristics of ground temperature and its relationship with air temperature in arid region including variation trend, abrupt change, anomalous years of annual and seasonal mean air temperature and mean ground temperature are analyzed, based on the data of monthly mean air temperature and monthly mean ground temperature at 0-80 cm soil depths in Alxa weather station from 1961 to 2010, together with modern statistical diagnostic methods including the linear trend analysis, accumulated variance and signal-noise ratio. The results showed that there were good correlations between ground temperature at different depths and air temperature. Compared with annual mean temperature, annual ground temperature at 5-80 cm depths was higher and had a rising trend with the increase of the soil depth. The annual and seasonal mean air temperature and mean ground temperature displayed a significant increasing trend in recent 50 years, but the rise of mean air temperature and mean ground temperature was asymmetric. The ascending rate and range of annual mean air temperature were higher than changes of annual mean ground temperature at 5-80 cm depths. The ascending rates of air temperature, ground temperature at 0 cm and 80 cm were most obvious in winter, and the most significant increase of 5-40 cm ground temperature happened in spring. The mean ground temperature had a decreasing trend with the increase of the soil depth in both spring and summer. The air temperature was lower than 0-40 cm ground temperature and higher than 80 cm ground temperature in spring, and the air temperature was lower than 0-20 cm ground temperature and higher than 40-80 cm ground temperature in summer. The mean ground temperature had a rising trend with the increase of the soil depth in autumn and winter. The air temperature was lower than ground temperature at different depths in autumn, and the air temperature was higher than 0 cm ground temperature while lower than ground temperature at other layers in winter. Under global warming, the responses of annual, summer, autumn and winter air temperature to climate change were more significant than ground temperatures at different depths, while the responses of ground temperature at different depths to climate change were more significant than air temperature in spring. The difference between annual ground temperature at 5-80 cm depths and annual air temperature was reduced by 0.3-0.8℃ in recent 50 years, and the reducing amplitude of difference between annual mean ground temperature at 5-80 cm depths and annual mean air temperature decreased with the increase of the soil depth. The abrupt changes of annual mean air and ground temperatures at different depths occurred mainly in the 1980s and the 1990s, but no abrupt change in four seasons. The anomalous years of air temperature and ground temperatures at different depths were relatively consistent in four seasons, but there were less consistent of anomalous years between annual air and ground temperatures at different depths.