双月刊

ISSN 1006-9895

CN 11-1768/O4

SR型与EAP型“结合模态”对2020年江淮入梅初期强降水的影响
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南京信息工程大学

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国家自然科学基金


The impact of the “combined modality” of SR and EAP on the heavy precipitation in the early stage of Meiyu in the Yangtze-Huai River region in 2020
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Nanjing University of Information Science and Technology

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    摘要:

    利用ERA5逐日再分析资料和中国气象局提供的逐日站点降水资料,分析了丝绸之路型(Silk-Road, SR)与东亚-太平洋型(East Asia-Pacific, EAP)遥相关的“结合模态”对2020年江淮梅雨入梅的影响,结果表明“结合模态”可以触发江淮流域的持续性降水。2020年6月初,负SR型(Silk-Road)和正EAP型(East Asia-Pacific)同时出现,并且位相差达到6月份最大值,二者协同作用下导致2020年入梅时间异常偏早。主要表现为:(1)负SR型引起西风急流加速,促使急流入口区南侧的江淮流域上空出现强的高层辐散。(2)负SR型有利于南亚高压东移,正EAP型有利于西太平洋副热带高压西移,二者相向而行。负SR型和正EAP型于6月9日位相差达最大,此时南亚高压和西太副高重叠于120°E左右,有利于江淮流域持续性降水。(3)低层东亚中、低纬度有一对与正EAP型相关的异常“气旋-反气旋”环流,使低空(20~35°N, 100~125°E)盛行强西南气流,中纬度的偏北气流有利于干冷空气向南输送,与西南暖湿气流汇合于江淮流域上空,带来强烈的水汽辐合,也使得大气的局地上升运动更为强烈。

    Abstract:

    Using the daily reanalysis data of ERA5 and the daily stations data of precipitation provided by the China Meteorological Administration, the influence of the “combined modality” of the Silk-Road Pattern(SR) and the East Asia-Pacific Pattern(EAP) teleconnection on the heavy precipitation in the early stage of Meiyu in the Yangtze-Huai River region in 2020 is analyzed, it shows that the “combined modality” can trigger continuous precipitation in the Yangtze-Huai River region. At the beginning of June 2020, the negative-phases SR(Silk-Road) and the positive-phases EAP(East Asia-Pacific) appeared at the same time, and the phase difference reached the maximum value in June. The synergy of the two lead to an abnormally early time for the Meiyu in 2020. The main manifestations are as follows: (1) The negative-phases SR causes the acceleration of the westerly jet, which promotes strong high-level divergence over the Yangtze-Huai River region on the south side of the jet stream entrance area. (2) The negative-phases SR is conducive to the eastward movement of the South Asian High, and the positive-phases EAP is conducive to the westward movement of the Western Pacific Subtropical High, and the two move towards each other. The negative-phases SR and the positive-phases EAP had the largest difference on June 9. At this time, the South Asian High and the West Pacific Subtropical High overlapped at about 120°E, which is conducive to continuous precipitation in the Yangtze-Huai River region. (3) There is a pair of anomalous “cyclone-anticyclone” circulations related to the positive-phases EAP in the middle and low latitudes of low-level East Asia, which makes the low altitude (20~35°N, 100~125°E) prevailing strong southwest airflow. The northerly airflow at mid-latitudes is conducive to the transportation of dry and cold air to the south. It merges with the warm and humid southwest airflow over the Yangtze-Huai River region, bringing about strong water vapor convergence and making the local upward movement of the atmosphere more intense.

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历史
  • 收稿日期:2021-11-16
  • 最后修改日期:2022-02-22
  • 录用日期:2022-04-07
  • 在线发布日期: 2022-04-14
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