Response of the Baiu Rainband to Northwest Pacific SST Anomalies and Its Impact on Atmospheric Circulation
Response of the Baiu Rainband to Northwest Pacific SST Anomalies and Its Impact on Atmospheric Circulation
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DOI：
10.1175/jcli-d-15-0691.1
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发表时间：
2016-04-01
影响因子：
4.9
通讯作者：
Sato, Tomonori
中科院分区：
文献类型：
--
作者：
Matsumura, Shinji;Horinouchi, Takeshi;Sato, Tomonori
在厄尔尼诺衰减年夏季，太平洋-日本遥相关型导致副热带和东亚之间的经向降水偶极子。然而，观测分析和模式试验表明，在黑潮偏潮延伸区（KOE），海温升高，海温梯度向北下降，导致副热带急流使白降水向北移动，形成西北太平洋三极降水异常型。7月降水的主导经验正交函数（EOF）模式表现为副热带和白雨之间的经向偶极子，而EOF-2模式表现为白雨向北移动的雨带。PJ大气强迫增加了KOE海温，增强了副热带急流和白雨带的北移，导致KOE上的海洋强迫。在使用区域气候模式的试验中，副热带急流对KOE海温强迫的响应解释了控制试验中约20%的异常。北移的白质凝聚加热也增强了副热带急流的北移，并向东北延伸。在白雨带消失的8月，副热带急流的北移主要受KOE海温变率的增强。夏季，由于东太平洋海温的增加和北移的白球加热，鄂霍次克海的气旋异常增强，西北太平洋的反气旋异常增强，影响西太平洋副热带高压。结果表明，为了更好地理解西北太平洋夏季气候，必须考虑东纬线上空的海气相互作用。
The Pacific Japan (PJ) teleconnection pattern leads to a meridional precipitation dipole between the subtropics and East Asia in the summer of El Nino decaying years. However, observational analysis and model experiments indicate that increased sea surface temperature (SST) in the Kuroshio Oyashio Extension (KOE) region, where a strong northward-decreasing SST gradient occurs, induces a northward shift of baiu rainfall with the subtropical jet, forming a tripolar precipitation anomaly pattern over the northwest Pacific. In July, the leading empirical orthogonal function (EOF) mode for precipitation represents the meridional dipole between subtropical and baiu rainfalls, while EOF-2 features the northward-shifted baiu rainband. The PJ atmospheric forcing increases KOE SST, which enhances northward shifts in the subtropical jet and baiu rainband, resulting in oceanic forcing over the KOE. In experiments using a regional climate model the subtropical jet response to KOE SST forcing explains about 20% of the anomalies in the control experiment. The northward-shifted baiu condensational heating also enhances the northward shift of the subtropical jet with a northeastward extension. In August when the baiu rainband disappears, the northward shift of the subtropical jet is enhanced mainly by KOE SST variability. During the summer, as a result of increased KOE SST and the northward-shifted baiu heating, cyclonic anomalies intensify over the Sea of Okhotsk and anticyclonic anomalies intensify over the northwest Pacific, affecting the western Pacific subtropical high. The results suggest that air sea interaction over the KOE must be considered to better understand the summer northwest Pacific climate.