Northern Hemisphere summer monsoon intensified by mega-El Nino/southern oscillation and Atlantic multidecadal oscillation
Northern Hemisphere summer monsoon intensified by mega-El Nino/southern oscillation and Atlantic multidecadal oscillation
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DOI：
10.1073/pnas.1219405110
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发表时间：
2013-04-02
影响因子：
11.1
通讯作者：
Xiang, Baoqiang
中科院分区：
文献类型：
--
作者：
Wang, Bin;Liu, Jian;Xiang, Baoqiang
预测未来几十年的季风变化对于基础设施规划和可持续经济发展非常重要。年代际预测涉及自然年代际变化和人为强迫。迄今为止，北半球夏季风（NHSM）年代际变化的原因在很大程度上尚不清楚，因为亚洲、西非和北美的季风主要在区域基础上进行研究，无法识别连贯的年代际变化和对行星尺度的压倒性控制。在这里，我们表明，自 20 世纪 70 年代末以来全球变暖约 0.4 摄氏度期间，整个 NHSM 系统中出现了降水和环流的连贯十年变化。令人惊讶的是，NHSM 以及哈德利和沃克环流都表现出大幅增强，全球变暖每度 NHSM 降雨量显着增加 9.5%。这是最近 21 世纪的理论预测和模型预测所始料未及的。这种加剧主要归因于特大厄尔尼诺/南方涛动（全球海面温度年际至年代际变化的主导模式）和大西洋数十年涛动，并进一步受到半球不对称全球变暖的影响。这些驱动 NHSM 系统当前变化的因素有助于理解和预测未来的年代际变化，并确定复杂气候系统中人为影响和长期内部变率造成的气候变化比例。
Prediction of monsoon changes in the coming decades is important for infrastructure planning and sustainable economic development. The decadal prediction involves both natural decadal variability and anthropogenic forcing. Hitherto, the causes of the decadal variability of Northern Hemisphere summer monsoon (NHSM) are largely unknown because the monsoons over Asia, West Africa, and North America have been studied primarily on a regional basis, which is unable to identify coherent decadal changes and the overriding controls on planetary scales. Here, we show that, during the recent global warming of about 0.4 degrees C since the late 1970s, a coherent decadal change of precipitation and circulation emerges in the entirety of the NHSM system. Surprisingly, the NHSM as well as the Hadley and Walker circulations have all shown substantial intensification, with a striking increase of NHSM rainfall by 9.5% per degree of global warming. This is unexpected from recent theoretical prediction and model projections of the 21st century. The intensification is primarily attributed to a mega-El Nino/Southern Oscillation (a leading mode of interannual-to-interdecadal variation of global sea surface temperature) and the Atlantic Multidecadal Oscillation, and further influenced by hemispherical asymmetric global warming. These factors driving the present changes of the NHSM system are instrumental for understanding and predicting future decadal changes and determining the proportions of climate change that are attributable to anthropogenic effects and long-term internal variability in the complex climate system.