摘要:前人在研究极端气温时，大多关注其长期变化趋势，而对其年代际变化的研究较少。本文利用1961～2016年全国839个台站的逐日最高气温、最低气温和日平均气温资料，重点分析了我国冬季极端低温指数的年代际变化特征。本文采用谐波分解提取了每个台站冬季极端低温指数前四波分量，将其作为年代际变化分量，并将其累计方差贡献大于25%的台站认为发生了明显的年代际变化的台站。结果表明：呈明显年代际变化的台站主要位于长江以北地区、新疆北部以及青藏高原东部地区。其中，长江以北地区及新疆北部地区的年代际变化在1979年后较为一致，据此可将1979年之后的时段大致划分为前冷期（1979～1986年）、暖期（1987～2007年）和后冷期（2008～2016年）三个时期。上述两个地区的冬季极端低温指数的年代际变化与东大西洋/西俄罗斯遥相关型联系在一起，该遥相关型的年代际变化对应着乌拉尔山阻塞型环流频次和东亚大槽强度的年代际变化。
关键词:极端气温指数/
年代际变化/
环流异常
Abstract:Although the long-term trend of extreme temperatures has been extensively explored in previous studies, few studies have addressed the interdecadal variation of extreme temperatures. Based on the daily maximum temperature, minimum temperature, and daily temperature at 839 stations in China from 1961 to 2016, the authors analyzed the interdecadal variations in the winter extreme-low-temperature index in China. The first four wave components of the extreme temperature at each station were extracted by harmonic decomposition, which is regarded as the interdecadal component. A station is regarded as having undergone an obvious interdecadal variation if the cumulative variance explained by the interdecadal component is greater than 25%. The results show that the stations with obvious interdecadal variation in their winter extreme-low-temperature index are mainly located north of the Yangtze River, in northern Xinjiang, and in eastern Qinghai–Tibet Plateau. The interdecadal variations north of the Yangtze River and in northern Xinjiang are basically consistent after 1979. The years after 1979 can be divided into three periods: previously cold period (1979–1986), warm period (1987–2007), and later-cold period (2008–2016). The interdecadal variation in the extreme temperature indices of the stations located in the abovementioned two areas might be modulated by the interdecadal variation in the East Atlantic/West Russia (EAWR) teleconnection pattern, which corresponds to the interdecadal variation in both the frequency of the blocking-like circulation over the Ural Mountains and the amplitude of the planetary trough over East Asia.
Key words:Extreme temperature index/
Interdecadal variation/
Circulation anomaly
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