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1.
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。 相似文献
2.
利用1961—2016年我国400个气象台站夏季降水资料、NCEP/NCAR再分析资料和NOAA的海面温度资料,分析了黄淮地区夏季降水与同期大气环流及前期海面温度关系的年代际变化特征。结果显示,20世纪80年代之前（后）,前期冬季太平洋海面温度发生厄尔尼诺时,黄淮地区夏季降水偏少（多）,20世纪80年代中期之前,前期冬季印度洋海面温度全区一致型模态与黄淮地区夏季降水关系较弱,但是从20世纪80年代中期开始,正相关关系明显增强。进一步研究发现,前期印度洋海面温度一致偏高时,夏季500 hPa高度场上,副热带高压明显增强,这种相关关系20世纪80年代中期之后明显强于20世纪80年代之前,海平面气压场上,高相关区在20世纪80年代之后呈现明显的南方涛动模态,印度洋海面温度通过影响决定黄淮地区夏季降水异常的大气环流关键区域,使得其与黄淮地区夏季降水的关系随着年代际变化增强。 相似文献
3.
近百年中国东部夏季降水年代际变化特征及其原因 总被引：15，自引：4，他引：11
本文利用测站降水观测资料分析过去一百多年中国东部华北、长江流域以及华南夏季降水的年代际变化特征发现,尽管这三个地区的夏季降水具有不同的年代际转折时期,但是均同时在1910年代初期、1920年代初期、1940年代中期、1960年代中期、1970年代末期以及1990年代初期发生了跃变。近一百年间不同年代际时期东部夏季降水的分布型主要以南正北负或者南负北正的偶极型为主,并且无论是偶极型分布还是三极型分布,两个相邻年代际时期中国东部降水分布型发生完全反向变化的概率较高（60%）。此外,夏季的PDO、冬季的AO以及春季的北极海冰也同时在1920年代末期、1940年代中期、1970年代末期以及1990年代中期左右发生了跃变,这几次跃变时期与中国东部三个不同地区夏季降水发生跃变的时期一致,表现出近百年来太平洋年代振荡（PDO）、北极涛动（AO）以及北极海冰这三个因子对中国东部夏季降水年代际变化的协同作用。在年代际时间尺度上,夏季的PDO与华北夏季降水显著负相关。PDO的年代际变化能够在500 hPa位势高度场中激发出太平洋—日本（PJ）型年代际遥相关波列;同时在850 hPa风场中激发出类似于影响华北夏季降水年代际变化的大气环流型,从而影响华北降水的年代际变化。冬半年的AO与长江流域夏季降水存在显著正相关关系。冬季到春季正位相的AO导致亚洲大陆南部处于湿冷状态,土壤湿度的记忆性可将这种状态延续到夏季。因此,夏季海陆热力对比减弱,东亚夏季风发生年代际减弱,相应地长江流域的降水年代际增多。春季北极海冰与华南夏季降水显著负相关,北极海冰的年代际异常能在500 hPa位势高度场中激发出与静止Rossby波异常传播相联系的欧亚—华南年代际遥相关波列,从而影响华南降水的年代际变化。 相似文献
4.
中国春季降水异常及其与热带太平洋海面温度和欧亚大陆积雪的联系 总被引：11，自引：4，他引：7
利用降水观测资料, 研究了1979～2004年中国春季 (3～5月) 标准化累积降水异常的时空特征及其与前冬、 春热带太平洋海面温度和春季欧亚大陆积雪的关系。中国春季标准化累积降水量EOF第一模态最大变率位于中国东部中纬度地区, 主要反映了中国东部中纬度地区春季降水的变化特征。同时, 中国东部春季降水异常具有南、 北反相变化的特征。当长江以南大部分地区的降水偏少时, 长江以北地区的降水偏多。春季降水异常具有显著的年际变化, 但在1980年代末出现年代际转型, 即年际变化的振幅明显增大变强、 周期变长。从华北到长江流域中纬度地区的春季降水异常特征与前冬热带太平洋海面温度有密切的关系。当前冬、 春热带东太平洋海温偏暖, 西太平洋海温偏冷时, 中国东部从华北到长江流域中纬度地区的春季降水偏多, 反之亦然。虽然当春季欧亚大陆楚科奇半岛和青藏高原积雪偏多, 贝加尔湖到中国东北地区的积雪偏少时, 对应着中国东部从华北到长江流域中纬度地区的降水偏多, 但当去掉ENSO信号后, 这种关系并不显著。说明EOF第一模态所反映的中国东部从华北到长江流域中纬度地区春季降水与欧亚大陆积雪的相关关系可能是前冬热带太平洋海面温度异常的一个体现。 相似文献
5.
春夏东亚大气环流年代际转折的影响及其可能机理 总被引：2，自引：0，他引：2
本文通过多变量联合经验正交分解(MV-EOF)方法揭示了近30年(1979~2010年) 春季和夏季东亚大气环流所发生的年代际转折及其与中国南方降水年代际季节反相变化的内在联系,探讨了局地性大气热源年代际变化影响东亚大气环流年代际转折的可能机理.结果表明:(1)东亚大气环流春季第一模态和夏季第二模态在90年代中期都发生了明显的年代际转折;(2)与春季大气环流第一模态和夏季大气环流第二模态年代际转折相对应的是中国南方降水明显的年代际季节反相变化,即春季降水年代际减少,夏季降水年代际增多;(3)春季青藏高原和夏季贝加尔湖地区大气热源年代际变化对东亚大气环流年代际转折有一定贡献,是造成中国南方降水年代际季节反相变化的直接原因;(4)春季青藏高原大气热源的年代际减弱,使得高原东南侧的西南风减弱,导致中国南方上空水汽输送不足,春季降水减少.夏季贝加尔湖大气热源偶极型分布由“南负北正”转变为“南正北负”,由此在贝湖上空激发高压异常,使得夏季雨带北进受阻而停滞南方,造成中国南方夏季降水增多. 相似文献
6.
基于气候变暖背景下中国南方旱涝时空格局发生变化的基本事实,回顾了中国南方降水的主要模态和旱涝年际年代际尺度变化特征及其成因的主要研究进展。研究指出,El Ni?o发展年,中国南方大部地区降水偏少,尤其在长江及其以南地区,而El Ni?o衰减年则相反。强调热带印度洋海盆一致偏暖使西太平洋副热带高压增强,位置偏南,导致西北太平洋反气旋异常的形成和维持,有利于中国南方降水加强。青藏高原冬春季积雪多,春夏季高原感热和上升运动较弱,导致夏季风偏弱,有利于长江流域降水偏多易涝,反之亦然。关于多因子协同作用对南方旱涝影响,指出南方旱涝是多因子协同影响的结果, 如菲律宾反气旋受冬季青藏高原积雪、El Ni?o与前期春季印度洋海温等多因子协同影响。南方旱涝与影响因子发生了年际关系的年代际变化,在气候变暖背景下,随着后者的年代际转型,其对前者的影响关系也发生了年代际变化。因此,提出了应该关注南方旱涝的预测策略与方法,提高旱涝预测技巧。 相似文献
7.
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 总被引：9，自引：2，他引：7
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. 相似文献
8.
利用1880—2010年中国东部66站夏季降水数据,开展夏季长序列降水的年代际变化特征研究。结果表明,中国东部夏季降水年代际变化特征显著,华北、江淮和华南地区存在明显的差异。经验正交分解结果表明,偶极型("-+"和"+-")和三极型("+-+"和"-+-")分布是中国东部夏季的两种主要降水模态。夏季500 h Pa高度场年代际分量与同期太平洋SST典型相关分析(BP-CCA)得出,太平洋年代际振荡(PDO,Pacific Decadal Oscillation)正位相可以激发出负的PJ型遥相关波列,导致长江中下游地区降水偏多,华北降水偏少;反之亦然。同时,通过滑动相关分析发现,中国东部不同区域的夏季降水对PDO不同位相的响应特征存在差异。 相似文献
9.
我国华北地区春季降水的年代际变化特征及其可能成因的探讨 总被引：10，自引：1，他引：9
利用我国160个台站1951~2000年逐月和华北地区80个台站逐日降水观测资料,分析了我国,特别是华北地区春季降水的年代际变化特征。分析结果表明:华北地区春季降水具有明显的年代际变化,1951~1965年华北地区春季降水略偏少,1966~1976年华北地区春季降水更加偏少,春旱较严重,1977~2000年为华北春季降水明显偏多,这时期5~6月降水比1966~1976年有明显增多;并且,分析结果也表明了华北地区和黄河流域春季降水存在着与夏季降水相反的年代际变化特征。另外,作者还利用欧洲中心ERA40资料集的1958~2000年月平均700 hPa风场再分析资料,分析了东亚上空春季700 hPa风场的年代际异常情况,从而来探讨华北地区春季降水年代际变化的成因。其分析结果表明:1965年以前,蒙古高原上空存在着明显的反气旋距平环流,我国华北地区有偏北风距平,这使得我国华北地区在1965年以前春季降水偏少;1966~1976年,我国华北地区仍为偏北风距平,且我国东部沿海到南海上空的偏北风距平增强,这使得华北地区春季降水进一步减少;1977~2000年,东亚上空700 hPa环流场发生了一个明显的变化,华北地区出现偏南风距平,且我国东部沿海到南海上空的偏南风距平增强,这使得我国南方暖湿气流易输送到华北地区,从而造成我国华北地区春季降水增加。 相似文献
10.
中国东部夏季降水型的年代际变化及其与北太平洋海温的关系 总被引：28，自引：12，他引：16
采用中国160站降水资料、NOAA ERSST海温资料以及ERA－40大气再分析资料, 分析了中国东部夏季降水型的年代际变化特征及其与北太平洋海温的可能联系。结果表明: 中国东部夏季降水型在近50年中经历了两次年代际变化, 第1次发生在20世纪70年代中后期, 北太平洋中纬度地区冬季海温由正距平向负距平转变, 太平洋年代际振荡(PDO, Pacific decadal oscillation) 由负位相向正位相转变, 通过影响东亚夏季风环流, 使东亚夏季风减弱, 中国东部夏季降水从北到南呈现出“＋－＋” 转变为“－＋－”的三极分布形态, 这次年代际变化体现了同一模态正负位相的转变; 第2次发生在20世纪80年代末90年代初, 北太平洋海温转变为日本以南西北太平洋的正距平分布, 同时菲律宾群岛附近海温偏暖, 西太平洋副热带高压偏南偏西, 使得中国东部夏季降水由北至南转变成“－＋”的偶极分布形态, 这次年代际变化体现了一种模态向另一种模态的转变。 相似文献
11.
The Decadal Shift of the Summer Climate in the Late 1980s over Eastern China and Its Possible Causes 总被引：2，自引：0，他引：2 
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下载免费PDF全文 In this paper, it is pointed out that a notable decadal shift of, the summer climate in eastern China occurred in the late 1980s. In association with this decadal climate shift, after the late 1980s more precipitation appeared in the southern region of eastern China （namely South China）, the western Pacific subtropical high stretched farther westward with a larger south-north extent, and a strengthened anticyclone at 850 hPa appeared in the northwestern Pacific. The decadal climate shift of the summer precipitation in South China was accompanied with decadal changes of the Eurasian snow cover in boreal spring and sea surface temperature （SST） in western North Pacific in boreal summer in the late 1980s. After the late 1980s, the spring Eurasian snow cover apparently became less and the summer SST in western North Pacific increased obviously, which were well correlated with the increase of the South China precipitation. The physical processes are also investigated on how the summer precipitation in China was affected by the spring Eurasian snow cover and summer SST in western North Pacific. The change of the spring Eurasian snow cover could excite a wave-train in higher latitudes, which lasted from spring to summer. Because of the wave-train, an abnormal high appeared over North China and a weak depression over South China, leading to more precipitation in South China. The increase of the summer SST in the western North Pacific reduced the land-sea thermal contrast and thus weakened the East Asian summer monsoon, also leading to more precipitation in South China. 相似文献
12.
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 总被引：1，自引：0，他引：1
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。 相似文献
13.
Boreal summer continental monsoon rainfall and hydroclimate anomalies associated with the Asian-Pacific Oscillation 总被引：1，自引：0，他引：1
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. 相似文献
14.
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. 相似文献
15.
Decadal variations of summer rainfall during 1951 through 1990 are analyzed by using summer rainfall data of 160 stations in China. Four major patterns of decadal variations are identified. The decadal variations of summer rainfall showed northward shift in the eastern China from South China through the Yangtze-Huaihe River to North China. Summer rainfall in the Yangtze-Huaihe River valley underwent two obvious decadal transitions during the 40 years: one from rainy period to drought period in the end of the 1950’s, the other from drought period to rainy period in the late 1970’s. Correspondingly, the atmospheric circulation over East Asia through the western North Pacific showed two similar obvious transitions. The East Asian/ Pacific (EAP) pattern switched from high index to low index in the end of the 1950’s and from low index to high index in the late 1970’s, respectively. Hence, summer rainfall in the Yangtze-Huaihe River valley is closely associated with the EAP pattern not only in the interannual variation but also in the decadal variation. 相似文献
16.
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 总被引：7，自引：1，他引：6
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. 相似文献
17.
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. 相似文献
18.
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）。 相似文献
19.
Decadal Relationship Between Atmospheric Heat Source and Winter-Spring Snow Cover over the Tibetan Plateau and Rainfall in East China 下载免费PDF全文
下载免费PDF全文 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 相似文献