利用内蒙古西部地区1958-2014年3个站点的日最高和最低气温资料,使用线性趋势法、距平及累积距平法、Mann-Kendall检验法、主成分分析和Morlet复数小波,对10种极端气温指数开展分析.结果表明,年极端最高气温、年极端最低气温、暖日、暖夜、夏日和热夜6个指数呈递增趋势, 冷日、冷夜、冰日和霜冻4个指数呈递减趋势;年极端最高气温、年极端最低气温、冷夜、暖夜和暖日5个指数均有7和17 a左右的周期,反映了这一地区极端天气变化的周期规律;主成分分析结果表明,第1主成分方差贡献率为5357%,高荷载的指数为暖夜、热夜和霜冻,表明这3个指数对这一地区气温的总体变化起主要作用;突变分析表明,极值指数突变发生在1980年左右,相对指数的突变时间基本发生在20世纪80年代到90年代末前后,绝对指数的突变时间主要发生在1987年前后.极端气温的变化导致该区易发生旱灾和草原沙漠化.%The daily highest and lowest temperature data accumulated during the period from 1958 to 2014 in the 3 meteorological stations in the western region of Inner Mongolia were cited for analysis of 10 extreme temperature indices, using the linear trend method, temperature departure and cumulative anormalies method, Mann-Kendall test, principal component analysis, and Morlet plural wavelet.Results show that: (1) Six of the 10 extreme temperature indices, i.e.annual extreme highest (lowest) temperature, warm day, warm night, summer day and hot night, displayed rising trends, while the other four, i.e., cold day, cold night, freezing day and frosting day, did declining trends; (2) Five indices in the selected study area all exhibited a cycle of 7 and 17 a or so, which reflects that the extreme weather in the region followed a certain rule of variation; (3) Principal component analysis shows that variance contribution rate of the primary principal components reached 5357%, and the indices, high in load included warm night, hot night and frosting day, which indicates that the three indices play important roles in overall climate change in the region; And (4) Saltation analysis shows that the abrupt changes in the index of extreme value occurred around 1980, while those of relative indices did basically during the period from the 1980s to the end of the 1990s, and those of the absolute indices did mainly in 1987.Extreme temperature changes would bring about droughts to the region and cause desertification of grasslands.
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