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中南半岛夏季逐月降水年际变化的差异性特征分析

Different characteristics of the interannual variation in summer monthly precipitation over the Indochina Peninsula

  • 摘要: 本文主要研究了1979-2019年中南半岛夏季(6-9月)逐月降水的年际变化,发现不同月份降水呈现出明显的相互独立性。尽管夏季各月降水均受到来自热带太平洋的东风异常和来自印度洋的西风异常的共同影响,但各月引起这些环流异常的因子却明显不同。结果表明,热带西印度洋海温异常显著影响中南半岛6月降水,它通过影响辐合辐散环流来调节中南半岛附近的垂直运动,从而导致中南半岛降水异常。7月中南半岛降水与前冬热带中东太平洋地区海温异常联系紧密,前冬海温通过影响西北太平洋副热带高压活动来调节中南半岛降水。而8月降水主要受到同期热带西太平洋和海洋性大陆附近东西偶极型海温异常的影响,这些海温异常会通过引起局地Hadley环流异常和Rossby波来调节中南半岛降水。相对而言,9月没有对应明显的热带大尺度海温信号,但中南半岛的降水主要受到台风活动的重要影响,尤其是其东部沿海地区。本研究有助于深入认识中南半岛夏季各月降水年际变率,为中南半岛夏季降水气候预测提供科学参考。

     

    Abstract: This study focuses on the interannual variation of monthly precipitation in summer (June to September) over the Indochina Peninsula from 1979 to 2019, and finds that the precipitation in different months is obviously independent of each other. Although the summer monthly precipitation is generally affected by the easterly anomalies from the tropical Pacific Ocean and the westerly anomalies from the Indian Ocean, the regulatory factors causing these circulation anomalies are obviously different. The results show that the tropical west Indian Ocean SST anomalies largely modulate the precipitation in June over the Indochina Peninsula. They regulate the vertical movement near the Indochina Peninsula by influencing the convergence and divergence circulation, and result in precipitation anomalies in the Indochina Peninsula. In July, the precipitation over the Indochina Peninsula is closely related to the SST anomalies in the tropical central and eastern Pacific region in the previous winter, which regulate the precipitation by influencing the northwest Pacific subtropical high activities. In addition, the precipitation in August is mainly affected by the simultaneous east-west dipole SST anomalies around the tropical western Pacific and Maritime Continent. These SST anomalies can regulate the precipitation in the Indochina Peninsula through local Hadley circulation anomalies and Rossby waves. Relatively, there isn’t a notably significant large-scale tropical SST signal related to precipitation in the Indochina Peninsula in September. However, it is significantly affected by typhoon activities, particularly along its eastern coastal areas. This study is helpful to further understand the interannual variation of summer monthly precipitation in the Indochina Peninsula, and provides scientific reference for the summer precipitation climate forecast in the Indochina Peninsula.

     

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