双月刊

ISSN 1006-9895

CN 11-1768/O4

中国西南地区5月降水与阿拉伯海季风关系的年代际变化
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1.成都信息工程大学大气科学学院;2.中国科学院大气物理研究所竺可桢—南森国际研究中心

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Decadal variability in the relationship between May rainfall over Southwest China and Arabian Sea Monsoon
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Nansen-Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences

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    摘要:

    本文利用1960~2017年中国西南地区115个台站观测降水资料和日本气象厅发布的55年再分析资料集,研究了中国西南地区5月降水变异的主导模态及其与阿拉伯海季风的关系。结果显示,中国西南地区5月降水的第一主导模态主要表现为全区一致的变异特征;该模态与同期5月阿拉伯海季风强度异常关系密切,但两者的关系在20世纪70年代后期发生了显著的年代际变化。在1960~1976年,阿拉伯海季风异常所引起的低层大气环流和水汽输送异常主要集中在阿拉伯海到孟加拉湾一带;此时,阿拉伯海季风异常所引起的大气环流不能到达中国西南地区,因此它对中国西南地区5月降水的影响偏弱。但在1981~2017年,阿拉伯海季风异常可以导致整个北印度洋到南海地区的大气环流异常,进而引起中国西南地区水汽和垂直运动的变化,最终对该地区5月降水产生显著的影响。进一步的研究显示,阿拉伯海季风与中国西南地区5月降水关系的变化可能与季风自身的年代际变率有关。阿拉伯海季风在20世纪70年代末之前变率偏弱,其引起的环流异常也偏弱;相反在20世纪70年代末之后,其变率增强,它引起的大气环流异常也偏强可以延伸到中国西南地区,进而影响到西南地区的5月降水。因此,季风变率的强弱可能在其影响中起着非常重要的作用。

    Abstract:

    Based on the observed precipitation data at 115 stations in Southwest China over the period of 1960-2017 and Japanese 55-year reanalysis data, this study investigated the dominant mode of the May rainfall over Southwest China and its relationship with the Arabian Sea monsoon. The results show that the leading mode of the May rainfall over Southwest China exhibits consistent variability over the region. The variability of the leading mode shows a close relationship with the Arabian Sea monsoon, but the relationship experienced an interdecadal change around the late 1970s. Over the period of 1960-2017, the anomalous atmospheric circulations and water vapor transportation associated with the Arabian Sea monsoon are mainly over the Arabian Sea to Bay of Bengal, which cannot reach Southeast China; consequently the Arabian Sea monsoon has a weak influence on the May rainfall over Southeast China during the period. In contrast, over the period of 1981- 2017, the anomalous Arabian Sea monsoon is related to larger-scale atmospheric anomalies over the region from the northern Indian Ocean to South China Sea. Such atmospheric anomalies can lead to anomalous water vapor and vertical motion over Southeast China; therefore, the Arabian Sea monsoon can significantly influence the May rainfall over Southeast China during the period. Further preliminary analysis indicates that the change in the relationship between Arabian Sea monsoon and May rainfall over Southwest China could be related to the change in decadal variability of Arabian Sea monsoon. Over the period before the late 1970s, the variability of Arabian Sea monsoon is relatively weak and its related atmospheric circulations are also weak. On the contrary, the variability of Arabian Sea monsoon is stronger after the late 1970s. The stronger variability of Arabian Sea monsoon is related to stronger atmospheric circulations, which can extend to Southwest China, consequently favoring the influence of Arabian Sea monsoon on May rainfall over Southwest China during the period. This result indicates that the variability of monsoon could play an important role in its influence.

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  • 收稿日期:2020-08-25
  • 最后修改日期:2020-12-27
  • 录用日期:2020-12-31
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