Direct impact of El Niño on East Asian summer precipitation in the observation
Direct impact of El Niño on East Asian summer precipitation in the observation
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DOI：
10.1007/s00382-015-2605-2
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发表时间：
2014-05
期刊：
影响因子：
4.6
通讯作者：
Na Wen;Zhengyu Liu;Yinghui Liu
中科院分区：
文献类型：
--
作者：
Na Wen;Zhengyu Liu;Yinghui Liu
本文研究了热带太平洋厄尔尼诺对东亚夏季降水的直接影响。广义平衡反馈评估被用来隔离这种直接影响，从相互关联的海洋强迫的观测。结果表明，厄尔尼诺对我国东部夏季降水有显著的直接影响。降水响应呈现三极格局，东南部和东北地区异常偏湿，北方地区异常偏干。对1 °C厄尔尼诺强迫，我国东部大部分地区降水响应幅度约为总降水的20%，最大响应幅度可达30%/°C。这种三极降水响应是由厄尔尼诺引起的东北亚气旋性异常和西北太平洋反气旋性异常共同作用的结果。异常气旋使东亚大槽向西南方向加深，有利于东南、东北地区槽前气流上升，北方地区槽后气流下降。西北太平洋的异常反气旋加强了西北太平洋副热带高压的东北向，为我国东南部地区提供了充足的水汽。异常气旋和异常反气旋共同作用，形成华东地区的三极降水响应型。进一步的研究表明，这两个关键的异常环流是西北传播的Rossby波的一部分，这是由厄尔尼诺变暖引起的副热带太平洋中西部对流激发的。研究结果可为厄尔尼诺发展期和衰减期东亚降水的预测提供参考。
This study investigates the direct impact of El Niño in the tropical Pacific on the East Asian summer precipitation . Generalized equilibrium feedback assessment is used to isolate this direct impact from interrelated ocean forcings in the observations. Results indicate that the El Niño can directly influence the summer precipitation in East China significantly. The precipitation response presents a tri-pole pattern, with anomalous wet in the Southeast and the Northeast China and anomalous dry in the northern China. Amplitude of the precipitation response is around 20 % of the total precipitation for 1 °C El Niño forcing in most area of the East China, with maximal response up to 30 %/°C. The tri-pole precipitation response is attributed to an El Niño-induced cyclonic anomaly in the Northeast Asia and an anticyclonic anomaly in the western North Pacific (WNP). The anomalous cyclone deepens the East Asian trough southwestward, favoring an air ascending in front of the trough in the Southeast and the Northeast China, and an air descending at the rear of the trough in the northern China. The anomalous anticyclone in the WNP strengthens the WNP Subtropical High northeastward, providing adequate water vapor to the Southeast China. The anomalous cyclone and anomalous anticyclone work together to generate the tri-pole precipitation response pattern in the East China. Further investigation suggests that these two key anomalous circulations are part of a northwestward propagating Rossby wave, which is excited by the El Niño warming-induced convection over the subtropical west-central Pacific. This study can serve as a reference for the prediction of the East Asian precipitation in both the developing and decaying summer of El Niño.