Coupled stratosphere-troposphere-Atlantic multidecadal oscillation and its importance for near-future climate projection
Coupled stratosphere-troposphere-Atlantic multidecadal oscillation and its importance for near-future climate projection
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DOI：
10.1038/s41612-022-00275-1
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发表时间：
2022-07
影响因子：
9
通讯作者：
N. Omrani;N. Keenlyside;K. Matthes;Lina Boljka;D. Zanchettin;J. Jungclaus;Sandro W. Lubis
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作者：
N. Omrani;N. Keenlyside;K. Matthes;Lina Boljka;D. Zanchettin;J. Jungclaus;Sandro W. Lubis
北半球（NH）气候在平流层、对流层、海洋和冰冻圈中经历了各种连贯的冬季数十年气候趋势。然而，连接这些趋势的总体机制框架尚未建立。在这里，我们表明，使用长期瞬态强制耦合气候模拟，可以在阻尼耦合平流层/对流层/海洋振荡框架内理解大部分相干的北半球数十年变化。波浪引起的向下传播的正平流层/对流层耦合的北环模（NAM）和相关的平流层冷却启动了大西洋翻转环流和温带大西洋环流的延迟温盐强化。这些增加了向极地的海洋热传输，导致北极海冰融化、北极变暖放大和大规模大西洋变暖，进而引发波浪引起的向下传播的负NAM和平流层变暖，从而逆转振荡相位。这种耦合的变异性提高了统计模型的性能，该模型预测北大西洋涛动、北大西洋变冷以及冬季北大西洋-北极海冰和全球表面温度的中断将进一步减弱，就像 20 世纪 50 年代至 1970 年代一样。
Northern Hemisphere (NH) climate has experienced various coherent wintertime multidecadal climate trends in stratosphere, troposphere, ocean, and cryosphere. However, the overall mechanistic framework linking these trends is not well established. Here we show, using long-term transient forced coupled climate simulation, that large parts of the coherent NH-multidecadal changes can be understood within a damped coupled stratosphere/troposphere/ocean-oscillation framework. Wave-induced downward propagating positive stratosphere/troposphere-coupled Northern Annular Mode (NAM) and associated stratospheric cooling initiate delayed thermohaline strengthening of Atlantic overturning circulation and extratropical Atlantic-gyres. These increase the poleward oceanic heat transport leading to Arctic sea-ice melting, Arctic warming amplification, and large-scale Atlantic warming, which in turn initiates wave-induced downward propagating negative NAM and stratospheric warming and therefore reverse the oscillation phase. This coupled variability improves the performance of statistical models, which project further weakening of North Atlantic Oscillation, North Atlantic cooling and hiatus in wintertime North Atlantic-Arctic sea-ice and global surface temperature just like the 1950s–1970s.