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高晶, 高辉. 副热带东南太平洋海温对东北夏季降水的影响及可能机制[J]. 大气科学, 2015, 39(5): 967-977. DOI: 10.3878/j.issn.1006-9895.1503.14246
引用本文: 高晶, 高辉. 副热带东南太平洋海温对东北夏季降水的影响及可能机制[J]. 大气科学, 2015, 39(5): 967-977. DOI: 10.3878/j.issn.1006-9895.1503.14246
GAO Jing, GAO Hui. Relationship between Summer Precipitation over Northeastern China and Sea Surface Temperature in the Southeastern Pacific and the Possible Underlying Mechanisms[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(5): 967-977. DOI: 10.3878/j.issn.1006-9895.1503.14246
Citation: GAO Jing, GAO Hui. Relationship between Summer Precipitation over Northeastern China and Sea Surface Temperature in the Southeastern Pacific and the Possible Underlying Mechanisms[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(5): 967-977. DOI: 10.3878/j.issn.1006-9895.1503.14246

副热带东南太平洋海温对东北夏季降水的影响及可能机制

Relationship between Summer Precipitation over Northeastern China and Sea Surface Temperature in the Southeastern Pacific and the Possible Underlying Mechanisms

  • 摘要: 诊断分析表明,前期副热带东南太平洋海温尤其是前春海温与东北夏季降水存在持续稳定的负相关关系。无论是在年际时间尺度还是年代际尺度上,冬、春、夏季海温演变趋势与降水均呈反位相。尺度分离结果显示,关键区海温与降水的显著负相关主要依赖于其年代际分量,但年际分量也起到较重要贡献。相关分析和合成分析结果都发现,当副热带东南太平洋海温偏低时,其上空可激发出反气旋式距平风场,而在关键区海域西北部激发出气旋式距平环流。同时在所罗门群岛和菲律宾南部分别出现反气旋式和气旋式距平环流。西太平洋副热带高压(副高)位置较常年偏西,副高区为反气旋式距平环流。在东北地区西侧则为气旋式距平环流。在这样的环流背景下,副高西侧的南风加强了源自南海和西太平洋的暖湿气流和北方冷空气在东北地区的交汇,从而使东北夏季多雨。反之,当东南太平洋海温偏高时,其激发的气旋及反气旋距平中心和偏低年刚好相反,副高位置偏东,其西侧的南方水汽输送偏弱,同时东北冷涡也偏弱,冷暖空气汇合形成的低空辐合弱,东北降水因此偏少。这表明,副热带东南太平洋海温异常时确实能激发出一个从关键海区到东北地区的跨越南北半球的气旋-反气旋交替波列,引发北半球中高纬度大气环流异常,从而影响东北夏季降水。

     

    Abstract: A stable negative relationship between boreal summer precipitation over northeastern China and the sea surface temperatures (SSTs) in previous seasons, especially in spring, in the subtropical southeastern Pacific (SSEP) is revealed in this paper. Scale separation results show that the SSTs and precipitation possess anti-phase variations at both the interannual (less than 7 years) and interdecadal (more than 7 years) timescales. This close relationship is mainly determined by the interdecadal components, though the interannual components play an important role. Correlation and composite analyses show that the lower SSTs in the SSEP cause an anticyclonic wind anomaly over the study region, and a cyclonic wind anomaly in its northwestern region. At the same time an anticyclonic and a cyclonic anomaly exist over the Solomon Islands and southern Philippines, respectively. Under this circulation situation, the western Pacific subtropical high (WPSH) is situated more westward and stronger compared to its climatology, and the northeastern cold vortex (NECV) is stronger than its norm too. Thus, the southerly anomaly in the west of the WPSH strengthens the warm and wet moisture transportation from the South China Sea and western Pacific. The cold air in the west of the NECV becomes more powerful. Together, these lead to stronger convergence and more precipitation over northeastern China. On the contrary, higher SSTs in the SSEP generate opposite anticyclonic and cyclonic wind anomalies over the study region. This opposite wave train leads to a weaker WPSH and NECV, weaker moisture convergence in the lower troposphere, and less rainfall in the region. The results indicate that the SSTs in the SSEP exert an alternate cyclonic-anticyclonic wave train from the Southern Hemisphere to the eastern Northern Hemisphere. This wave train can impact the general circulation in northeastern Asia and ultimately affect precipitation over northeastern China.

     

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