Interdecadal seesaw of precipitation variability between North China and the Southwest US
Interdecadal seesaw of precipitation variability between North China and the Southwest US
复制标题
华北与美国西南部降水变化的年代际跷跷板
DOI：
10.1175/jcli-d-18-0082.1
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发表时间：
2019
影响因子：
4.9
通讯作者：
Lixia Zhang
中科院分区：
文献类型：
--
作者：
Qing Yang;Zhuguo Ma;Peili Wu;Nicholas P.Klingaman;Lixia Zhang
本文报道了中国北部和美国西南部降水年代际变化之间的一致翘板关系，这种关系可以在几个模式的观测和模拟中找到。理想化模式模拟表明，翘翘板可能主要由年代际太平洋振荡(IPO)驱动，通过占据整个北太平洋的大尺度环流异常来驱动，而大西洋数十年振荡(AMO)的贡献相对较小。当AMO处于相反相时，IPO对沉淀的调制作用增强，而当AMO处于同相时，IPO对沉淀的调制作用减弱。IPO暖期与北太平洋北部的异常气旋有关；因此，异常的西南风为美国西南部带来了更多的水汽和降水，而西北风异常主导了中国北部，并伴随着负降雨异常。当环流异常在冷IPO阶段变为反气旋时，降水异常的东西拉锯反转。与IPO相关的热带海温异常影响北太平洋及邻近地区的经向温度梯度和平均经向环流。在北太平洋北部，大气对IPO强迫的响应在整个对流层中施加了相当的正压结构。这项研究的一个重要意义是，随着我们对IPO和AMO的理解和预测的进展，这些干旱和半干旱地区与干旱有关的水分胁迫的潜在可预测性。
This paper reports a consistent seesaw relationship between interdecadal precipitation variability over North China and the Southwest United States, which can be found in observations and simulations with several models. Idealized model simulations suggest the seesaw could be mainly driven by the interdecadal Pacific oscillation (IPO), through a large-scale circulation anomaly occupying the entire northern North Pacific, while the Atlantic multidecadal oscillation (AMO) contributes oppositely and less. Modulation of precipitation by the IPO tends to be intensified when the AMO is in the opposite phase, but weakened when the AMO is in the same phase. The warm IPO phase is associated with an anomalous cyclone over the northern North Pacific; consequently, anomalous southwesterly winds bring more moisture and rainfall to the Southwest United States, while northwesterly wind anomalies prevail over North China with negative rainfall anomalies. The east–west seesaw of rainfall anomalies reverses sign when the circulation anomaly becomes anticyclonic during the cold IPO phase. The IPO-related tropical SST anomalies affect the meridional temperature gradient over the North Pacific and adjacent regions and the mean meridional circulation. In the northern North Pacific, the atmospheric response to IPO forcing imposes an equivalent barotropic structure throughout the troposphere. An important implication from this study is the potential predictability of drought-related water stresses over these arid and semiarid regions, with the progress of our understanding and prediction of the IPO and AMO.