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ISSN 1006-9895

CN 11-1768/O4

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中国东部夏季极端降水年代际变化特征及成因分析
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作者单位:

1.上海市气候中心;2.中国气象局国家气候中心开放实验室;3.常熟理工学院物理与电子工程学院

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基金项目:

重大灾害专项(2018YFA0606301)、国家自然科学基金项目(41875100和41875093)和上海市气象局科技开发项目(YJ201804)


Analysis of the Characteristics and Causes of the Interdecadal Changes of Summer Extreme Precipitation over Eastern China
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Affiliation:

College of Physics and Electronic Engineering, Changshu Institute of Technology

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    摘要:

    本研究利用逐日降水资料对中国东部夏季极端降水进行检测,并对转变前后的特征进行对比分析,进而从海、陆对增温的响应不同导致的环流调整给出成因分析。结果表明,(1)中国东部夏季极端降水在1990年前后出现显著的年代际转变,极端降水由偏少转为偏多。转折后与转折前相比,中国东部夏季极端降水落区南移,南方偶极子分布型加强,南方极端降水增加、北方极端降水减少,其中华南和华东地区,极端降水量和降水日数增加,对夏季降水的贡献率增大;华北地区,极端降水量和降水日数减少,对夏季降水的贡献率减小。(2)西太平洋暖池区异常升温造成的海陆温差减小是中国东部夏季极端降水1990年前后转变的重要驱动因素之一。它造成1990年之后低纬度季风强度减弱、西太平洋副热带高压增强并南移、南海副高增强,而中高纬度气旋性环流异常被破坏、东亚大槽增强,进而导致华北经向水汽输送减弱,下沉运动显著加强,极端降水量和降水日数减少。于此同时,华南和华东地区则水汽输送加强,上升运动显著,有利于降水偏多,并伴随极端降水量和降水日数有所增加。

    Abstract:

    Using daily precipitation data of eastern China, the interdecadal shift of summer extreme precipitation (SEP) are tested, and the characteristics before and after the climate shift are analyzed. Furthermore, the cause analysis is discussed from the perspective of different response to global warming between land and ocean, which leading to circulation adjustment. The result shows that the SEP in eastern China presents obvious interdecadal shift around 1990, which become positive anomaly after the shift. Compared with the SEP before the shift, the distributions of major modes shift to south, the intensity of SEP enhances and the contribution rate to summer precipitation increases in both South China and East China, while in North China all of the above factors are with opposite change. The change of temperature difference between land and ocean caused by strongly positive anomaly of sea surface temperature (SST) in western Pacific warm pool is one of the important driven factors to this shift, leading to interdecadal adjustment of East Asia summer monsoon system. In low-middle latitude, the intensity of summer monsoon weakens, West Pacific subtropical high (WPSH) strengthens and moves to south, and South China Sea high also enhances. While in middle-high latitude, the cyclonic anomaly is broken and the East Asia Trough strengthens. Under the influence of circulation adjustment, the water vapor decreases (increases) and vertical motion weakens (enhances) in North China (South China and East China). Thus, the SEP in North China decreases, and increases in South China and East China.

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历史
  • 收稿日期:2019-12-16
  • 最后修改日期:2020-06-18
  • 录用日期:2020-07-31
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