The NAO, the AO, and global warming: How closely related?
The NAO, the AO, and global warming: How closely related?
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DOI：
10.1175/jcli3530.1
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发表时间：
2005-11-01
影响因子：
4.9
通讯作者：
Barlow, M
中科院分区：
文献类型：
--
作者：
Cohen, J;Barlow, M
北大西洋涛动（NAO）和密切相关的北极涛动（AO）强烈影响北方半球（NH）的表面温度与模式报告类似的全球变暖趋势。NAO和AO在20世纪70年代和80年代的大部分时间里都处于积极的趋势，在20世纪90年代初达到历史最高水平，有人认为它们对全球变暖信号做出了重大贡献。研究了1950-2004年12 - 2月AO、NAO和NH平均地表温度的标准指数的变化趋势，以及地表温度异常的相关模式。分析了北大西洋海温、印度洋-太平洋暖池海温、平流层环流和欧亚雪盖等与NAO、AO有关的因子及其正趋势。如果将这些数据包括在内，过去30年的总体趋势很弱，甚至不存在，而且在很大程度上取决于开始和结束日期的选择。在明显的区别，冬季半球变暖的趋势一直是有力的和一致的整个时期。当考虑整个半球时，NAO/AO模式也可以与趋势模式区分开来。因此，12月至2月的变暖趋势可能与AO和NAO的强度，一致性和趋势模式相区别。这些结果对索引或数据集的选择不敏感。虽然NAO和AO可能有助于半球和区域变暖多年的时间，这些差异表明，在过去的30年全球变暖趋势的大尺度特征是无关的AO和NAO。相关因子也可以清楚地区分，暖池SST与变暖趋势有关，而其他因子则与NAO和AO有关。
The North Atlantic Oscillation (NAO) and the closely related Arctic Oscillation (AO) strongly affect Northern Hemisphere (NH) surface temperatures with patterns reported similar to the global warming trend. The NAO and AO were in a positive trend for much of the 1970s and 1980s with historic highs in the early 1990s, and it has been suggested that they contributed significantly to the global warming signal. The trends in standard indices of the AO, NAO, and NH average surface temperature for December-February, 1950-2004, and the associated patterns in surface temperature anomalies are examined. Also analyzed are factors previously identified as relating to the NAO, AO, and their positive trend: North Atlantic sea surface temperatures (SSTs), Indo-Pacific warm pool SSTs, stratospheric circulation, and Eurasian snow cover.Recently, the NAO and AO indices have been decreasing; when these data are included, the overall trends for the past 30 years are weak to nonexistent and are strongly dependent on the choice of start and end date. In clear distinction, the wintertime hemispheric warming trend has been vigorous and consistent throughout the entire period. When considered for the whole hemisphere, the NAO/AO patterns can also be distinguished from the trend pattern. Thus the December-February warming trend may be distinguished from the AO and NAO in terms of the strength, consistency, and pattern of the trend. These results are insensitive to choice of index or dataset. While the NAO and AO may contribute to hemispheric and regional warming for multiyear periods, these differences suggest that the large-scale features of the global warming trend over the last 30 years are unrelated to the AO and NAO. The related factors may also be clearly distinguished, with warm pool SSTs linked to the warming trend, while the others are linked to the NAO and AO.