doi:  10.3878/j.issn.1006-9895.1808.18164
东亚夏季环流多齿轮耦合特征及其对中国夏季降水异常的影响分析

The characteristics of coupling wheels in the East Asian Summer Monsoon circulation and its impacts on abnormal precipitation of China
摘要点击 574  全文点击 78  投稿时间:2018-05-17  修订日期:2018-08-01
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基金:  国家自然科学基金,高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金
中文关键词:  多齿轮耦合,东亚夏季风,夏季降水异常,时间稳定性
英文关键词:  Coupling wheels, East Asian Summer Monsoon, Summer abnormal rainfall, Time stability
     
作者中文名作者英文名单位
庞轶舒PangYishu四川省气候中心
祝从文ZhuCongwen中国气象科学研究院
引用:庞轶舒,祝从文.2019.东亚夏季环流多齿轮耦合特征及其对中国夏季降水异常的影响分析[J].大气科学
Citation:PangYishu,ZhuCongwen.2019.The characteristics of coupling wheels in the East Asian Summer Monsoon circulation and its impacts on abnormal precipitation of China[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文利用MV-EOF等方法诊断分析了东亚夏季风多齿轮耦合的变化特征、耦合机制、时间稳定性及其对中国夏季降水的影响机制,并在此基础上构建了典型多齿轮耦合形态影响夏季降水的概念模型。结果表明,多齿轮耦合受到垂直温、压场的强迫和青藏高原大地形的影响,主要表现在年际变化上(周期为2-6年)。其前两个模态稳定地反映了东亚夏季风成员典型联动作用。在第一模态中,北方蒙古气旋系统为正压系统,当其增强时,高层南侧的偏西气流增强,联动南亚高压增强,同时加强了中纬东部地区的下沉辐散气流,使西太副高偏强偏大,低层冷空气南压,西太副高位置偏南。在这种多齿轮耦合的作用下中国夏季降水自北向南“+,-,+,-”分布。在第二模态中,中高纬地区气旋活动增强,其高层南侧的西风气流增强,使东亚副热带西风急流增强,南亚高压位置偏北。同时气旋东南侧的偏南气流增强,使西北太平洋高、低层反气旋式环流增强,并加强了西太副高北侧的偏东气流,使副热带高压强度减弱,面积减小。在这种多齿轮耦合的作用下,中国黄河以北降水偏多,以南降水偏少。
Abstract:
      In this paper, variation features, mechanism and time stability of the coupling wheels, as well as its impacts on China abnormal precipitation, in the East Asian Summer Monsoon (EASM), were diagnosed and analyzed by MV-EOF and other methods. On that basis, conceptual models were constructed of the typical coupling wheels in EASM and its impacts on summer rainfall. As shown in results, the coupling wheels was forced by vertical temperature and pressure fields, so as the large terrain of the Tibet Plateau, and manifested in interannual variation (the period of about 2-6 years). Its first two modes are time stable for reflecting the typical linkages of the EASM members. In the first mode, enhancement of Mongolia Cyclone (MC) strengthened westerly in its southern side in the upper layer, which leaded enhancement of South Asian High, so as the downward divergent airflow in the eastern part of middle latitude. As a result, West Pacific Subtropical High enlarged and heightened. Meanwhile, for the positive structure of MC, abnormal northerly airflow in its lower layer pushed WPSH southward. Under action of such coupling wheels, summer rainfall in China is distributed from north to South with a shape of ‘ +,-,+,- ’ . In the second mode, intensification of cyclone in the middle and high latitude, leaded abnormal westerly airflow in its southern side in upper layer. So that, the East Asian Subtropical Westerly Jet increased and the South Asian High pressure moved northward. Meanwhile, abnormal southerly wind in the southeastern side of cyclone enhanced anticyclonic circulation in the whole troposphere over Northwest Pacific, which made abnormal eastward flow in the northern side of WPSH. Therefore, WPSH weakened correspondingly. Under such a situation, more rainfall in the north area of Yellow River, while less in its South.
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