Influence of variations in extratropical wintertime teleconnections on Northern Hemisphere temperature
Influence of variations in extratropical wintertime teleconnections on Northern Hemisphere temperature
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DOI：
10.1029/96gl00459
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发表时间：
1996-03-15
影响因子：
5.2
通讯作者：
Hurrell, JW
中科院分区：
文献类型：
--
作者：
Hurrell, JW
自20世纪70年代中期以来，北半球海洋盆地的冬季大气环流发生了显著变化，这些变化对地表温度产生了深远的影响。北大西洋的变化与北大西洋涛动（NAG）的变化有关，而北太平洋的变化与热带有关，并涉及阿留申低压的变化与北美下游的遥相关。多元线性回归表明，自20世纪70年代中期以来，西北大西洋的变冷和欧亚大陆及其下游地区的变暖几乎都是由NAG的变化引起的，NAO在过去50个冬季的半球年际变化中占31%。在太平洋盆地和北美，温度异常部分是由与厄尔尼诺-南方涛动现象相关的热带强迫造成的，但在温带地区也有重要的反馈。过去二十年来环流的变化导致了陆地表面温度偏高而海洋表面温度偏低的异常模式。由于与陆地和海洋的相互作用，这种温度变化模式放大了观测到的半球平均变暖；与海洋相比，陆地的温度变化更大，因为前者的热容量较小。
Pronounced changes in the wintertime atmospheric circulation have occurred since the mid-1970s over the ocean basins of the Northern Hemisphere, and these changes have had a profound effect on surface temperatures. The variations over the North Atlantic are related to changes in the North Atlantic Oscillation (NAG), while the changes over the North Pacific are linked to the tropics and involve variations in the Aleutian low with teleconnections downstream over North America. Multivariate linear regression is used to show that nearly all of the cooling in the northwest Atlantic and the warming across Europe and downstream over Eurasia since the mid-1970s results from the changes in the NAG, and the NAO accounts for 31% of the hemispheric in terannual variance over the past 50 winters. Over the Pacific basin and North America, the temperature anomalies result in part from tropical forcing associated with the El Nino-Southern Oscillation phenomenon but with important feedbacks in the extratropics. The changes in circulation over the past two decades have resulted in a surface temperature anomaly pattern of warmth over the continents and coolness over the oceans. This pattern of temperature change has amplified the observed hemispheric-averaged warming because of its interaction with land and ocean; temperature changes are larger over land compared to the oceans because of the small heat capacity of the former.