Contribution of changes in atmospheric circulation patterns to extreme temperature trends
Contribution of changes in atmospheric circulation patterns to extreme temperature trends
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DOI：
10.1038/nature14550
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发表时间：
2015-06-25
期刊：
影响因子：
64.8
通讯作者：
Diffenbaugh, Noah S.
中科院分区：
文献类型：
--
作者：
Horton, Daniel E.;Johnson, Nathaniel C.;Diffenbaugh, Noah S.
地表天气状况受地球大气层大规模环流的密切控制。最近一些极端天气现象（1，2）发生的增加导致了多种机制假设，将大气环流的变化与极端事件（3-5）的可能性增加联系起来。然而，观测到的大气环流长期变化的证据仍然不确定（6-8）。在这里，我们确定统计上显着的趋势，在大气环流模式的发生，这部分解释了观测到的趋势，在地面温度极端超过七个中纬度地区的北方半球。使用自组织地图聚类分析（9-12），我们在卫星观测时代（1979-2013）和最近的北极海冰快速下降时期（1990-2013）检测到这些地区的一个子集的强大环流模式趋势。特别重要的影响包括反气旋环流的增加趋势对欧亚大陆和北美部分地区夏季和秋季极端高温的贡献，以及向北气流的增加趋势对中亚冬季极端寒冷的贡献。我们的研究结果表明，虽然观察到的极端温度发生的变化的很大一部分是由于区域和全球尺度的热力学变化，在某些地区的极端温度的风险也改变了最近的变化的频率，持久性和最大持续时间的区域环流模式。
Surface weather conditions are closely governed by the large-scale circulation of the Earth's atmosphere. Recent increases in the occurrence of some extreme weather phenomena(1,2) have led to multiple mechanistic hypotheses linking changes in atmospheric circulation to increasing probability of extreme events(3-5). However, observed evidence of long-term change in atmospheric circulation remains inconclusive(6-8). Here we identify statistically significant trends in the occurrence of atmospheric circulation patterns, which partially explain observed trends in surface temperature extremes over seven mid-latitude regions of the Northern Hemisphere. Using self-organizing map cluster analysis(9-12), we detect robust circulation pattern trends in a subset of these regions during both the satellite observation era (1979-2013) and the recent period of rapid Arctic sea-ice decline (1990-2013). Particularly substantial influences include the contribution of increasing trends in anticyclonic circulations to summer and autumn hot extremes over portions of Eurasia and North America, and the contribution of increasing trends in northerly flow to winter cold extremes over central Asia. Our results indicate that although a substantial portion of the observed change in extreme temperature occurrence has resulted from regional-and global-scale thermodynamic changes, the risk of extreme temperatures over some regions has also been altered by recent changes in the frequency, persistence and maximum duration of regional circulation patterns.