Decadal changes in two types of the western North Pacific subtropical high in boreal summer associated with Asian summer monsoon/El Niño–Southern Oscillation connections
Decadal changes in two types of the western North Pacific subtropical high in boreal summer associated with Asian summer monsoon/El Niño–Southern Oscillation connections
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DOI：
10.1029/2009jd013642
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发表时间：
2010-11
影响因子：
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通讯作者：
Jong-Yeon Park;J. Jhun;S. Yim;WonMoo Kim
中科院分区：
文献类型：
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作者：
Jong-Yeon Park;J. Jhun;S. Yim;WonMoo Kim
基于850 hPa水平风异常的经验正交函数，研究了与亚洲夏季风/厄尔尼诺-南方涛动相关的北太平洋副热带高压（WNPSH）的年代际变化。这两种类型的WNPSH与东亚-西北太平洋（EA-WNP）地区夏季平均降雨量变率与赤道太平洋海温（SST）变率之间的两个不同联系有关。每种类型对这些连接的贡献在20世纪90年代中期之后发生了变化。两种类型的西太平洋低气压主要与补偿赤道地区对流增强的局部沉降有关，并表现出2.5年和4-5年两个显著的周期。然而，第一种类型伴随着以东太平洋为中心的厄尔尼诺样变暖从冬季前期到夏季同期的快速衰减，而第二种类型的特征是持续的海温变暖转移到太平洋中部。20世纪90年代中期以后，1型降水的相对优势可能是导致东北亚地区8月降水增加的原因之一。此外，两种类型的WNPSH的时间变化都具有1年的滞后关系，这种滞后关系在20世纪90年代中期后显著减弱，这可能部分解释了EA与WNP夏季风关系的年代际变化。这一结果表明WNPSH和EA-WNP夏季风在长期变率上有着密切的联系。
[1] The decadal variability of boreal summertime western North Pacific subtropical high (WNPSH) associated with Asian summer monsoon/El Nino–Southern Oscillation is investigated through the two types of WNPSH that are identified from the empirical orthogonal function of 850 hPa horizontal wind anomalies. These two types of WNPSH are associated with two different connections between the summer mean rainfall variability over the East Asian–western North Pacific (EA-WNP) region and the sea surface temperature (SST) variability over the equatorial Pacific. The contribution of each type to these connections has been changed after the mid-1990s. Both types of WNPSH are predominantly associated with the local subsidence compensating the enhanced convection over equatorial regions and exhibit two significant periodicities, 2.5 and 4–5 years. However, the first type accompanies a fast decay of El Nino-like warming centered in the eastern Pacific from preceding winter to concurrent summer, while the second type features the persistent SST warming shifted to the central Pacific. The relative dominance of type 1 after the mid-1990s may be one of possible causes for the increase of August rainfall over northeast Asia. Moreover, temporal variations of two types of WNPSH are characterized by the 1 year lagged relationship, which has been significantly weakened after the mid-1990s, which may partly explain the decadal change in the relationship between EA and WNP summer monsoons. This result suggests the close linkage between WNPSH and EA-WNP summer monsoon on the long-term variability.