东亚季风区夏季降水受季风影响显著， 不同季风配置通过影响区域水汽输送， 在东亚季风区形成不同的降水格局， 降水格局的变化容易引起旱涝灾害的发生。本文基于经验正交函数（EOF）分析， 利用全球降水气候中心（GPCC）降水资料、 美国国家环境预测中心/大气研究中心（NCEP/NCAR）再分析资料和不同夏季风指数， 分析了1951 -2020年东亚季风区夏季降水格局， 进一步结合相关分析、 水汽通量分析等， 研究了4种夏季风强弱不同配置对东亚季风区夏季降水的影响。结果表明： （1）1951 -2020年东亚季风区降水经历了先减少后增加的变化。EOF分析较好地展现了东亚季风区夏季降水的时空分布， 东亚季风区夏季降水主要表现为南北向“-、 ＋、 -”的三极型分布与南北方降水反相变化的偶极型特征； 东亚季风区夏季降水异常主要发生在三极型降水结构的相位转换上， 其次是偶极型的相位转换； （2）东亚季风区夏季降水异常是东亚季风、 南亚季风、 西风环流以及西太平洋季风等系统共同作用的结果。导致东亚季风区降水异常增加（减少）的季风配置主要为配置1： 西太平洋季风强， 东亚季风和西风弱（配置2： 西风强， 东亚季风和南亚季风弱）； （3）配置1时， 西太副高偏南偏西， 中高纬形成西风槽， 季风区南方季风较强， 容易通过切变线以及抬升作用在季风区中部形成降水， 导致异常降水增加， 配置2时， 西风强劲， 南方水汽动力不足， 无法深入大陆， 造成异常降水减少。本文研究结果为气候变化背景下， 探究东亚季风区异常降水机理提供理论基础， 也为应对区域极端降水事件以及旱涝灾害防治工作提供重要的科学参考依据。

Summer precipitation in the East Asian monsoon region is significantly affected by monsoon variations.Different monsoon configurations form distinct precipitation patterns in the East Asian monsoon region by affecting regional water vapor transport.Further， the phase changes in precipitation patterns are prone to the occurrence of abnormal precipitation events， which in turn induce droughts and floods.Based on the EOF analysis， the GPCC precipitation， NCEP/NCAR reanalysis data and different monsoon indices were used to study the spatial and temporal distribution of summer precipitation in the East Asian monsoon region.The effects of four different configurations of summer monsoon on summer precipitation patterns in the East Asian monsoon region were further investigated by combining correlation analysis and water vapor flux analysis.The results show that： （1） Precipitation in the East Asian monsoon region experienced a decrease followed by an increase from 1951 to 2020.The increase in precipitation anomalies after 2010， as well as the rapid fluctuations in precipitation series， indicate a decline in regional climate stability.The EOF successfully presents the distribution of summer precipitation over the East Asian monsoon region.It mainly exhibits as the three-pole structure of north-south "-， +， -"， followed by the dipolar-type structure with north-south reversed-phase variations.Precipitation anomalies occur in the phase transition of precipitation structure， mainly tripolar type followed by dipole type.（2） The combined influence of the East Asian， South Asian， West Pacific， and westerly circulation monsoon systems results in the summer precipitation anomaly in the East Asian monsoon region.The monsoon configurations leading to anomalous increase and decrease in precipitation are Configuration 1 （WNPMI strong， EASMI and AZCI weak） and Configuration 2 （AZCI strong， EASMI and SASMI weak） respectively.（3） At Configuration 1， the subtropical high is located in the southwest， the westerly trough appears at 40°N， and the southern monsoon is strong.These combine to form precipitation in the central part of the monsoon region through shear lines as well as uplift， leading to an increase in anomalous precipitation.In Configuration 2， the westerlies are strong and the southern water vapor dynamics are too weak to penetrate deep into the continent， resulting in an anomalous decrease in precipitation.The results of this study provide a theoretical framework for investigating the mechanisms behind precipitation anomalies in the East Asian monsoon region in the context of climate change.They also provide critical scientific references for managing the region's extreme precipitation occurrences， as well as preventing and controlling floods and droughts.