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CN 11-1768/O4

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亚洲夏季风30~60天季节内振荡对中国东部地区持续性极端降水的影响
作者:
作者单位:

1.南京信息工程大学气象灾害教育部重点实验室,南京210044;2.中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG),北京100029;3.中国地质大学(武汉),武汉430074

作者简介:

李健颖,女,1990年出生,副教授,主要从事大气低频振荡研究。E-mail: lijy@cug.edu.cn

通讯作者:

毛江玉,E-mail: mjy@lasg.iap.ac.cn

基金项目:

中国地质大学 武汉;气象灾害教育部重点实验室 南京信息工程大学国家自然科学基金项目91537103、41730963,全球变化与海气相互作用专项GASI-IPOVAI-03,中国科学院前沿科学重点研究项目 QYZDY-SSW-DQC018,中国地质大学(武汉)杰出人才培育基金CUG170643,气象灾害教育部重点实验室(南京信息工程大学)开放课题KLME1602


Impact of the Boreal Summer 30‒60-day Intraseasonal Oscillation over the Asian Summer Monsoon Region on Persistent Extreme Rainfall over Eastern China
Author:
Affiliation:

1.Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044;2.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;3.School of Environmental Studies, China University of Geosciences, Wuhan 430074

Fund Project:

National Natural Science Foundation of China NSFC 41730963;the SOA Program on Global Change and Air?Sea Interactions Grant GASI-IPOVAI-03;the Priority Research Program of the Chinese Academy of Sciences Grant QYZDY-SSW-DQC018;the China University of Geosciences (Wuhan) Grant CUG170643;Nanjing University of Information Science and Technology Grant KLME1602National Natural Science Foundation of China (NSFC) (Grants 91537103, 41730963), the SOA Program on Global Change and Air?Sea Interactions (Grant GASI-IPOVAI-03), the Priority Research Program of the Chinese Academy of Sciences (Grant QYZDY-SSW-DQC018), the Fundamental Research Funds for the Central Universities, the China University of Geosciences (Wuhan) (Grant CUG170643), the Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology (Grant KLME1602)

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    摘要:

    本文基于1979~2015年中国台站观测的格点化高分辨率降水和NCEP II大气再分析逐日资料,探讨了亚洲季风区夏季30~60天大气季节内振荡(ISO)与长江中下游地区持续性降水异常的关系,重点揭示了南亚和东亚子季风区ISO的相互作用及二者协同引起长江中下游持续性极端降水的物理机制。合成分析表明,南亚和东亚ISO是通过高层辐散环流发生相互作用。在ISO位相1~3(5~7),异常活跃(抑制)对流从赤道印度洋北传至孟加拉湾—印度次大陆区域,其伴随的高层异常辐散(辐合)环流通过补偿效应,引起南海—热带西北太平洋的异常高层辐合(辐散),加强了局地的异常下沉(上升)运动,有利于南海—西北太平洋的异常抑制(活跃)对流发展并维持。南海—西北太平洋的异常抑制(活跃)对流伴随着显著的斜压散度,并进一步激发出一个连接南海和长江中下游的经向垂直环流圈,引起长江中下游强烈的异常上升(下沉)运动和低层水汽辐合(辐散),使得降水持续性偏多(少),极端降水的发生概率持续地偏高(低),有利于(不利于)形成持续性极端降水事件。研究还表明,亚洲季风区ISO的强度存在显著的年际变化,并对长江中下游持续性极端降水的发生频次和持续时间具有调制作用。在ISO偏强(弱)年,长江中下游持续性极端降水的发生频次较高(低),且持续时间较长(短)。

    Abstract:

    The daily high-resolution gridded station-observed rainfall over China and NCEP-DOE AMIP-II atmospheric reanalysis datasets for the period 1979-2015 are used to investigate the impact of the 30-60-day atmospheric intraseasonal oscillation (ISO) over the Asian monsoon region on persistent anomalous rainfall over the middle and lower reaches of the Yangtze River (MLYR). The interaction between ISOs over two sub-monsoon areas of South Asia and East Asia as well as the physical mechanism for the ISOs to jointly influence persistent extreme rainfall over the MLYR are revealed. Composite analyses demonstrate that the ISO over the South Asian monsoon region interacts with its counterpart over the East Asian monsoon region through upper-level divergent flows. During phases 1‒3 (5‒7) of the ISO, active (inactive) convection anomalies propagate northward from the equatorial Indian Ocean to the Indian Subcontinent‒Bay of Bengal. The accompanied divergence (convergence) anomalies in the upper troposphere cause anomalous convergence (divergence) downstream over the South China Sea‒western North Pacific (SCS‒WNP) through compensation effect, leading to anomalous descents (ascents) locally over the SCS‒WNP, and therefore is favorable for the development and persistence of anomalous inactive (active) convection anomalies. Such inactive (active) convection anomalies are characterized by prominent baroclinic divergence structure and further trigger a meridional-vertical circulation cell between the SCS and the Yangtze Basin, resulting in anomalous ascents (descents) and low-level moisture convergence (divergence) over the MLYR. As a consequence, positive (negative) rainfall anomalies continuously arise over the MLYR with the occurrence probability of extreme rainfall significantly increasing (decreasing), favorable (unfavorable) for the occurrence of persistent extreme rainfall events. Moreover, the intensity of ISO over the Asian monsoon region exhibits strong interannual variations and further modulates the frequency and duration of persistent extreme rainfall events over the MLYR. In strong (weak) ISO years, more (fewer) persistent extreme rainfall events occur over the MLYR and the duration is longer (shorter).

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李健颖,毛江玉.亚洲夏季风30~60天季节内振荡对中国东部地区持续性极端降水的影响.大气科学,2019,43(4):796~812 .Impact of the Boreal Summer 30‒60-day Intraseasonal Oscillation over the Asian Summer Monsoon Region on Persistent Extreme Rainfall over Eastern China.Chinese Journal of Atmospheric Sciences (in Chinese),2019,43(4):796~812

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  • 收稿日期:2018-04-08
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  • 在线发布日期: 2019-08-08
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