中国东部夏季气候20世纪80年代后期的年代际转型及其可能成因

指出了中国东部夏季气候在20世纪80年代末出现了一次明显的年代际气候转型.伴随着这次年代际转型,80年代末以后中国东部南方地区降水明显增多,500 hPa西太平洋副热带高压西伸且南北范围变大,西北太平洋上空850 hPa反气旋增强.中国东部夏季80年代后期出现南方多雨的年代际转型与欧亚大陆春季积雪、西北太平洋夏季海面温度的年代际变化存在密切联系,它们也都在80年代末出现年代际转型.从80年代末以后,伴随着欧亚大陆春季积雪明显减少和西北太平洋夏季海面温度明显增高,中国夏季南方降水明显增加.文中分析了欧亚大陆春季积雪和西北太平洋夏季海面温度影响中国降水的物理过程,指出欧亚大陆春季积雪能够在500 hPa激发出大气中的遥相关波列,所激发出的波列可以从春季一直持续到夏季,造成中国北方为高压控制,南方为微弱低压控制,使得降水出现在中国南方.西北太平洋夏季海面温度的升高能够减小海陆热力差异,使得夏季风减弱,导致中国南方地区降水增多.     

北半球冬季阿留申低压－冰岛低压相关关系的年代际变化及其模拟

使用多种长期观测和再分析资料,分析了北半球冬季阿留申低压和冰岛低压相关关系的年代际变化。结果表明,两低压存在显著的负相关关系,使北太平洋和北大西洋海平面气压形成跷跷板式的变化(Aleutian Low-Icelandic Low Seesaw,AIS)。此外,AIS还存在显著的年代际变化,在1935~1949年和1980年后较为显著,其余时期并不显著。对1980年代的年代际转变分析表明,太平洋年代际振荡(Pacific Decadal Oscillation,PDO)在1970年代末的位相转变是AIS这次年代际转变的主要原因。PDO由负位相转变为正位相,使全球大部分大洋海表温度升高,而北太平洋海表温度降低,两低压显著变深,低压南部西风增强,从而通过Rossby波的频散效应使两低压强度形成显著负相关。1930年代中期的年代际转变与此类似,但强度较弱。同时,年代际背景的变化也影响到两低压的年际变化。在给定海表温度和海冰分布的驱动下,大气环流模式IAP AGCM4能基本模拟出AIS年代际转变的过程和机理,但仍存在一些偏差。     

CMIP5气候模式对中国东部夏季降水年代际变化的模拟性能评估

使用分类集合的方法评估了第五次耦合模式比较计划(CMIP5)多个耦合模式对中国东部夏季降水年代际变化的模拟性能.结果表明,在评估的38个模式中,仅有6个模式(第1类模式)可以成功再现1970年代末中国东部夏季降水年代际变化的主要特征,即长江流域降水偏多、而华北和华南偏少.这些模式模拟的成功归因于它们能较好再现1970年代末东亚夏季风的年代际减弱及相关的环流场的变化,包括东亚沿海的偏北风异常以及西太平洋副热带高压的偏向西南、强度增强等.而对降水年代际变化模拟很差的第2类模式,则模拟出不出东亚夏季风的这种减弱特征.进一步的分析表明,两类CMIP5模式对太平洋年代际振荡(PDO)空间分布特征都有较好的再现能力,但对PDO年代际转变特征的模拟能力则差异较大.第1类模式能很好地模拟出1970年代末热带海洋的增暖和相关的PDO位相由负到正的转换,而第2类模式所模拟的PDO位相转变与观测完全相反,且也不能模拟出热带中东太平洋海洋的年代际增暖及江淮流域夏季的变冷,因此导致该类模式对1970年代末东亚夏季风的减弱和中国东部夏季雨型的年代际转变没有模拟能力.由此也表明,对耦合模式来说,中国夏季降水年代际变化的模拟能力在很大程度上取决于模式对海洋年代际变化信号的模拟.     

Phase transition of the Pacific decadal oscillation and decadal variation of the East Asian summer monsoon in the 20th century

This paper focuses on the relationship between the phase transition of the Pacific decadal oscillation (PDO) and decadal variation of the East Asian summer monsoon (EASM) in the twentieth century. The first transition occurred in the 1940s, with an enhanced SST in the North Pacific and reduced SST in the tropical eastern Pacific and South Indian Ocean. In agreement with these SST changes, a higher SLP was found in most parts of the Pacific, while a lower SLP was found in the North Pacific and most parts of the Indian Ocean. In this case, the EASM was largely enhanced with a southerly anomaly in the lower troposphere along the east coast of China. Correspondingly, there was less rainfall in the Yangtze River valley and more rainfall in northern and southern China. An opposite change was found when the PDO reversed its phase in the late 1970s. In the tropical Indian Ocean and western Pacific, however, the SST was enhanced in both the 1940s and 1970s. As a result, the western Pacific subtropical high (WPSH) tended to extend westward with a larger magnitude in the 1970s. The major features were reasonably reproduced by an atmospheric general circulation model (IAP AGCM4.0) prescribed with observed SST and sea ice. On the other hand, the westward extension of the WPSH was exaggerated in the 1970s, while it was underestimated in the 1940s. Besides, the spatial pattern of the simulated summer rainfall in eastern China tended to shift southward compared with the observation.     

北太平洋冬季次表层热状况及其与中国东部夏季气候的关系

利用北太平洋次表层海温及热容量资料和我国160个台站1951-2002年夏季(6-8月)降水、气温资料,分析了北太平洋冬季次表层热状况的特征,研究了中国区域气候与热容量变化之间的关系,并用SVD方法研究了北太平洋热容量变化与中国东部夏季气候的耦合关系.结果表明:北太平洋冬季次表层海温按其特征可分为40 m和240 m两类,两者的年代际特征都很明显;北太平洋冬季热容量异常变化与其相似,并与中国东部夏季气候异常有较好的耦合关系,北太平洋中部偏北和东南部地区冬季热容量异常偏高时,中国华南和华北区夏季降水将会偏多,华南区夏季气温将会偏低;黑潮延续体及北太平洋中部偏东地区冬季热容量异常偏高和北美西海岸地区异常偏低时,中国东北和长江流域地区夏季降水将会偏少,东北和华北地区夏季气温将会偏低,其关系有着明显的年代际特征.     

Boreal summer continental monsoon rainfall and hydroclimate anomalies associated with the Asian-Pacific Oscillation

With the twentieth century analysis data (1901–2002) for atmospheric circulation, precipitation, Palmer drought severity index, and sea surface temperature (SST), we show that the Asian-Pacific Oscillation (APO) during boreal summer is a major mode of the earth climate variation linking to global atmospheric circulation and hydroclimate anomalies, especially the Northern Hemisphere (NH) summer land monsoon. Associated with a positive APO phase are the warm troposphere over the Eurasian land and the relatively cool troposphere over the North Pacific, the North Atlantic, and the Indian Ocean. Such an amplified land–ocean thermal contrast between the Eurasian land and its adjacent oceans signifies a stronger than normal NH summer monsoon, with the strengthened southerly or southwesterly monsoon prevailing over tropical Africa, South Asia, and East Asia. A positive APO implies an enhanced summer monsoon rainfall over all major NH land monsoon regions: West Africa, South Asia, East Asia, and Mexico. Thus, APO is a sensible measure of the NH land monsoon rainfall intensity. Meanwhile, reduced precipitation appears over the arid and semiarid regions of northern Africa, the Middle East, and West Asia, manifesting the monsoon-desert coupling. On the other hand, surrounded by the cool troposphere over the North Pacific and North Atlantic, the extratropical North America has weakened low-level continental low and upper-level ridge, hence a deficient summer rainfall. Corresponding to a high APO index, the African and South Asian monsoon regions are wet and cool, the East Asian monsoon region is wet and hot, and the extratropical North America is dry and hot. Wet and dry climates correspond to wet and dry soil conditions, respectively. The APO is also associated with significant variations of SST in the entire Pacific and the extratropical North Atlantic during boreal summer, which resembles the Interdecadal Pacific Oscillation in SST. Of note is that the Pacific SST anomalies are not present throughout the year, rather, mainly occur in late spring, peak at late summer, and are nearly absent during boreal winter. The season-dependent APO–SST relationship and the origin of the APO remain elusive.     

Decadal/interdecadal variations of the ocean temperature and its impacts on climate

Decadal/interdecadal climate variability is an important research focus of the CLIVAR Program and has been paid more attention. Over recent years, a lot of studies in relation to interdecadal climate variations have been also completed by Chinese scientists. This paper presents an overview of some advances in the study of decadal/interdecadal variations of the ocean temperature and its climate impacts, which includes interdecadal climate variability in China, the interdecadal modes of sea surface temperature (SST) anomalies in the North Pacific, and in particular, the impacts of interdecadal SST variations on the Asian monsoon rainfall. As summarized in this paper, some results have been achieved by using climate diagnostic studies of historical climatic datasets. Two fundamental interdecadal SST variability modes (7– 10-years mode and 25–35-years mode) have been identified over the North Pacific associated with different anomalous patterns of atmospheric circulation. The southern Indian Ocean dipole (SIOD) shows a major feature of interdecadal variation, with a positive (negative) phase favoring a weakened (enhanced) Asian summer monsoon in the following summer. It is also found that the China monsoon rainfall exhibits interdecadal variations with more wet (dry) monsoon years in the Yangtze River (South China and North China) before 1976, but vice versa after 1976. The weakened relationship between the Indian summer rainfall and ENSO is a feature of interdecadal variations, suggesting an important role of the interdecadal variation of the SIOD in the climate over the south Asia and southeast Asia. In addition, evidence indicates that the climate shift in the 1960s may be related to the anomalies of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO). Overall, the present research has improved our understanding of the decadal/interdecadal variations of SST and their impacts on the Asian monsoon rainfall. However, the research also highlights a number of problems for future research, in particular the mechanisms responsible for the monsoon long-term predictability, which is a great challenge in climate research.     

20世纪90年代初东亚夏季风的年代际转型

利用1979—2009年JRA-25和NCEP/NCAR再分析资料,通过复矢量经验正交方法揭示了东亚地区夏季850 hPa风场变率的优势模态。结果表明:两套再分析资料所揭示的东亚夏季风在20世纪90年代初均发生了年代际转型,与我国夏季降水的年代际转型时间一致。伴随着东亚夏季风的年代际转型,我国北方大部分地区夏季降水减少,尤其是我国东北北部和长江、黄河之间105°E附近区域显著减少,而华南地区和淮河流域降水显著增加。从动力上解释我国夏季降水年代际转型特征,夏季500 hPa高度场两个时段 (1993—2009年和1979—1992年) 的差值分布显示为欧亚大陆北部准纬向遥相关波列,夏季850 hPa风场差值分布表现为贝加尔湖东南侧和日本以南地区存在两个异常反气旋式环流,而我国南方地区和鄂霍次克海附近均为异常气旋式环流。夏季西北太平洋、北印度洋以及部分中高纬度海洋的海温和春季欧亚大陆积雪在20世纪90年代初出现显著变化,春季北极海冰的年代际转型发生在20世纪90年代初,都可能成为东亚夏季风年代际转型的原因。     

A Numerical Simulation of the Impact of Tropical Western Pacific SST Anomalies on the Decadal Shift of the Meiyu Belt

The sea surface temperature (SST) of the tropical western Pacific Ocean (TWPO) showed a pronounced warming in the late 1990s. Using numerical experiments of a regional climate model (RegCM), we analyzed the impact of this warming on rainfall over the Yangtze-Huaihe River valley of China during the Meiyu period (June-July). The model results revealed that the observed decadal changes in Meiyu rainfall since the late 1990s can be reproduced by a control experiment forced by the observed SST. Additionally, the sensitivity experiments suggested that the warming trend in the TWPO played a substantial role in the northward shift of the Meiyu belt in the late 1990s.     

Delayed Impacts of the E1 Nino Episodes in the Central Pacific on the Summertime Climate Anomalies of Eastern China in 2003 and 2007

In the summers of 2003 and 2007, eastern China suffered similar climate disasters with severe flooding in the Huaihe River valley and heat waves in the southern Yangtze River delta and South China. Using SST data and outgoing longwave radiation (OLR) data from NOAA along with reanalysis data from NCEP/NCAR, the 2002/03 and 2006/07 El Ni(n)o episodes in the central Pacific and their delayed impacts on the following early summertime climate anomalies of eastern China were analyzed. The possible physical progresses behaved as follows: Both of the moderate E1 Ni(n)o episodes matured in the central equatorial Pacific during the early winter. The zonal wind anomalies near the sea surface of the west-central equatorial Pacific excited equatorial Kelvin waves propagating eastward and affected the evolution of the E1 Ni(n)o episodes. From spring to early summer, the concurring anomalous easterly winds in the central equatorial Pacific and the end of upwelling Kelvin waves propagating eastward in the western equatorial Pacific, favored the equatorial warm water both of the SST and the subsurface temperature in the western Pacific. These conditions favored the warm state of the western equatorial Pacific in the early summer for both cases of 2003 and 2007. Due to the active convection in the western equatorial Pacific in the early summer and the weak warm SST anomalies in the tropical western Pacific from spring to early summer, the convective activities in the western Pacific warm pool showed the pattern in which the anomalous strong convection only appeared over the southern regions of the tropical western Pacific warm pool, which effects the meridional shift of the western Pacific subtropical high in the summer. The physical progress of the delayed impacts of the E1 Nifio episodes in the central equatorial Pacific and their decaying evolution on the climate anomalies in eastern China were interpreted through the key role of special pattern for the heat convection in the tropical western Pacific warm pool and the response of the western North Pacific anomalous anticyclone.     

基于MTM-SVD方法的黄河流域夏季降水年际变化及其主要影响因子分析

应用中国气象台站积雪日数资料和NCEP/NCAR再分析资料以及多锥度—奇异值分解方法 (MTM-SVD),分析了近50年来黄河流域夏季降水的时空变化及其影响因子.发现黄河流域夏季降水存在显著的2～3年周期.在准3年周期上黄河流域夏季降水对前冬青藏高原东部积雪日数有很好的响应,当前冬高原积雪日数以正 (负) 异常为主时,接下来的夏季黄河流域降水偏少 (多).这种响应存在年代际变化,在1983年之前最为明显,1983~1993年是个调整时期,1993年以后又开始明显.在准2年周期上黄河流域夏季降水对前冬西太平洋暖池SST有很好的响应,当前冬西太平洋暖池SST偏高 (低) 时,接下来的夏季黄河流域降水表现为东多 (少)西少 (多) 型.这一响应同样存在年代际变化.前冬高原积雪和西太平洋暖池SST是影响黄河流域夏季降水的重要因子.     

Delayed impacts of the El Niño episodes in the central Pacific on the summertime climate anomalies of eastern China in 2003 and 2007

In the summers of 2003 and 2007, eastern China suffered similar climate disasters with severe flooding in the Huaihe River valley and heat waves in the southern Yangtze River delta and South China. Using SST data and outgoing longwave radiation (OLR) data from NOAA along with reanalysis data from NCEP/NCAR, the 2002/03 and 2006/07 El Nino episodes in the central Pacific and their delayed impacts on the following early summertime climate anomalies of eastern China were analyzed. The possible physical progresses behaved as follows: Both of the moderate El Nino episodes matured in the central equatorial Pacific during the early winter. The zonal wind anomalies near the sea surface of the west-central equatorial Pacific excited equatorial Kelvin waves propagating eastward and affected the evolution of the El Ni\~no episodes. From spring to early summer, the concurring anomalous easterly winds in the central equatorial Pacific and the end of upwelling Kelvin waves propagating eastward in the western equatorial Pacific, favored the equatorial warm water both of the SST and the subsurface temperature in the western Pacific. These conditions favored the warm state of the western equatorial Pacific in the early summer for both cases of 2003 and 2007. Due to the active convection in the western equatorial Pacific in the early summer and the weak warm SST anomalies in the tropical western Pacific from spring to early summer, the convective activities in the western Pacific warm pool showed the pattern in which the anomalous strong convection only appeared over the southern regions of the tropical western Pacific warm pool, which effects the meridional shift of the western Pacific subtropical high in the summer. The physical progress of the delayed impacts of the El Ni\~no episodes in the central equatorial Pacific and their decaying evolution on the climate anomalies in eastern China were interpreted through the key role of special pattern for the heat convection in the tropical western Pacific warm pool and the response of the western North Pacific anomalous anticyclone.     

春季热带南大西洋海表温度异常与夏季亚澳季风区降水异常的联系

利用1979—2019年Hadley中心的海表温度资料、GPCP的降水资料以及NCEP-DOE的再分析资料等,分析了北半球春季热带南大西洋海表温度异常与北半球夏季亚澳季风区降水异常的联系。研究表明,北半球春季热带南大西洋海表温度异常与随后夏季热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区的降水异常为显著负相关（正相关）关系。北半球春季热带南大西洋的海表温度正异常可以引起热带大西洋和热带太平洋间的异常垂直环流,其中异常上升支（下沉支）位于热带大西洋（热带中太平洋）。热带中太平洋的异常下沉气流和低层辐散气流引起热带中西太平洋低层的异常东风,后者有利于热带中东太平洋海表温度出现负异常。通过Bjerknes正反馈机制,热带中东太平洋海表温度异常从北半球春季到夏季得到发展。热带中东太平洋海表温度负异常激发的Rossby波使得北半球夏季热带西太平洋低层出现一对异常反气旋。此时,850 hPa上热带西太平洋到海洋性大陆地区为显著的异常东风,有利于热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区出现异常的水汽辐散（辐合）,导致该地区降水减少（增加）。     

Decadal Relationship Between Atmospheric Heat Source and Winter-Spring Snow Cover over the Tibetan Plateau and Rainfall in East China

By using a reverse computation method and the NCEP/NCAR daily reanalysis data from 1960 to 2004, the atmospheric heat source （AHS） was calculated and analyzed. The results show that AHS over the Tibetan Plateau （TP） and its neighboring areas takes on a persistent downtrend in spring and summer during the foregone 50 years, especially the latest 20 years. Snow depth at 50 stations over the TP in winter and spring presents an increase, especially the spring snow depth exhibits a sharp increase in the late 1970s. A close negative correlation exists between snow cover and AHS over the TP and its neighboring areas, as revealed by an SVD analysis, namely if there is more snow over the TP in winter and spring, then the weaker AHS would appear over the TP in spring and summer. The SVD analysis between AHS over the TP in spring and summer and rainfall at 160 stations indicates that the former has a negative correlation with summer precipitation in the middle and lower reaches of the Yangtze River, and a positive correlation with that in South China and North China. The SVD analysis of both snow cover over the TP in winter and spring and rainfall at the same 160 stations indicates that the former has a marked positive correlation with precipitation in the middle and lower reaches of the Yangtze River, and a reversed correlation in South China and North China. On the decadal scale, the AHS and winter and spring snow cover over the TP have a close correlation with the decadal precipitation pattern shift （southern flood and northern drought） in East China. The mechanism on how the AHS over the TP influences rainfall in East China is discussed. The weakening of AHS over the TP in spring and summer reduces the thermodynamic difference between ocean and continent, leading to a weaker East Asian summer monsoon, which brings more water vapor to the Yangtze River Valley and less water vapor to North China. Meanwhile, the weakening of AHS over the TP renders the position of the subtropical high further westward and the r     

有关南半球大气环流与东亚气候的关系研究的若干新进展

南半球大气环流是全球大气环流的重要组成部分,也是影响气候变化和亚洲季风系统的一个重要因素.中国气象学家很早就注意到南半球大气环流对东亚夏季风降水的影响.近年来,有关南半球气候变率的研究目前正受到世界气象学家越来越多的关注.南半球中高纬大气资料的丰富及南极涛动的确定,使得认识南半球高中纬环流的年际变动规律及其与东亚气候关系成为可能.本文主要介绍近年来有关南极涛动的年际变化与沙尘天气发生频次及东亚冬春季气候的关系,古气候资料揭示的南极涛动与华北降水的关系,以及南半球大气环流与长江中下游夏季降水的关系和南极涛动变率的可预测性等方面的研究进展.并对未来研究方向作了初步的展望.     

中国冬季积雪特征及欧亚大陆积雪对中国气候影响

该文首先回顾了有关中国冬季积雪的研究进展,包括中国冬季积雪的空间分布气候特征以及季节、年际和年代际变化,中国冬季降雪特征,气象因子对中国冬季积雪水量平衡的影响,外强迫和大气环流系统在积雪形成中的作用等。冬春季欧亚大陆积雪对同期和后期中国气候影响的相关研究说明与欧亚大陆积雪异常相关联的中国气候异常以及积雪通过改变土壤湿度、表面温度和辐射分布,引起大气环流异常,进而对中国气候产生影响的物理过程。应用美国环境预测中心 (NCEP) 第2版气候预测系统 (CFSv2) 的回报试验结果,对CFSv2在欧亚大陆积雪变化及其与中国气候关系的可预报性方面的分析表明,CFSv2能够较好地回报出春季欧亚积雪的年际和年代际变异及其与中国夏季降水之间的联系。文章最后提出了在积雪及其气候效应研究方面一些有待解决的问题。     

年代际气候变化与1998年长江大水

由于海温、高原积雪和大气环流异常等特定条件,引发了１９９８年夏季长江的特大洪涝,而９０年代的气候特征也对１９９８年长江大水起到一定的作用。从中国夏季降水、大气环流、冬季高原积雪和海温等方面分析年代际气候变化对１９９８年长江大水提供有利的气候环境。     

Interannual and decadal variations of snow cover over Qinghai-Xizang Plateau and their relationships to summer monsoon rainfall in China

Interannual and decadal variations of winter snow cover over the Qinghai-Xizang Plateau (QXP) are analyzed by using monthly mean snow depth data set of 60 stations over QXP for the period of 1958 through 1992. It is found that the winter snow cover over QXP bears a pronounced quasi-biennial oscillation, and it underwent an obvious decadal transition from a poor snow cover period to a rich snow cover period in the late 1970’s during the last 40 years.It is shown that the summer rainfall in the eastern China is closely associated with the winter snow cover over QXP not only in the interannual variation but also in the decadal variation. A clear relationship exists in the quasi-biennial oscillation between the summer rainfall in the northern part of North China and the southern China and the winter snow cover over QXP. Furthermore, the summer rainfall in the four climate divisions of Qinling-Daba Mountains, the Yangtze-Huaihe River Plain, the upper and lower reaches of the Yangtze River showed a remarkable transition from drought period to rainy period in the end of 1970’s, in good correspondence with the decadal transition of the winter snow cover over QXP.     

On the relationship between the winter Eurasian teleconnection pattern and the following summer precipitation over China

The Eurasian teleconnection pattern(EU) is an important low-frequency pattern with well-known impacts on climate anomalies in Eurasia. The difference of low-level v-winds in several regions in the Eurasian mid–high latitudes is defined as the EU index(EUIV). In this study, the relationship between the winter EUIVand precipitation in the following summer over China is investigated. Results show that there is a significant positive(negative) correlation between the winter EUIVand the following summer precipitation over North China(the Yangtze River–Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980 s.Thus, the proposed EUIVmay have implications for the prediction of summer precipitation anomalies over China. In positive winter EUIVyears, three cyclonic circulation anomalies are observed—over the Ural Mountains, the Okhotsk Sea, and the subtropical western North Pacific. That is, the Ural blocking and Okhotsk blocking are inactive, zonal circulation prevails in the mid–high latitudes, and the western Pacific subtropical high tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China, and significant positive(negative) precipitation anomalies over North China(the Yangtze River–Huaihe River basins), and vice versa. Further examination shows that the SST anomalies over the Northwest Pacific and subtropical central North Pacific may both contribute to the formation of EUIV-related circulation anomalies over the western North Pacific.     

Cross-season relation of the South China Sea precipitation variability between winter and summer

The present study reveals cross-season connections of rainfall variability in the South China Sea (SCS) region between winter and summer. Rainfall anomalies over northern South China Sea in boreal summer tend to be preceded by the same sign rainfall anomalies over southern South China Sea in boreal winter (denoted as in-phase relation) and succeeded by opposite sign rainfall anomalies over southern South China Sea in the following winter (denoted as out-of-phase relation). Analysis shows that the in-phase relation from winter to summer occurs more often in El Niño/La Niña decaying years and the out-of-phase relation from summer to winter appears more frequently in El Niño/La Niña developing years. In the summer during the El Niño/La Niña decaying years, cold/warm and warm/cold sea surface temperature (SST) anomalies develop in tropical central North Pacific and the North Indian Ocean, respectively, forming an east–west contrast pattern. The in-phase relation is associated with the influence of anomalous heating/cooling over the equatorial central Pacific during the mature phase of El Niño/La Niña events that suppresses/enhances precipitation over southern South China Sea and the impact of the above east–west SST anomaly pattern that reduces/increases precipitation over northern South China Sea during the following summer. The impact of the east–west contrast SST anomaly pattern is confirmed by numerical experiments with specified SST anomalies. In the El Niño/La Niña developing years, regional air-sea interactions induce cold/warm SST anomalies in the equatorial western North Pacific. The out-of-phase relation is associated with a Rossby wave type response to anomalous heating/cooling over the equatorial central Pacific during summer and the combined effect of warm/cold SST anomalies in the equatorial central Pacific and cold/warm SST anomalies in the western North Pacific during the mature phase of El Niño/La Niña events.