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1.
利用7、8月全国756站站点降水资料、NCEP/NCAR再分析资料的月平均资料,研究了盛夏四川盆地西部地区降水年际变化的基本特征及其对应的环流异常,并分析了该地区与江南地区降水年际变化的关系及其对应的700 hPa环流异常。结果表明:四川盆地西部地区盛夏降水偏多年,四川盆地上空为显著的南风异常,说明西南涡较常年活跃,同时西太平洋副热带高压偏北;而降水偏少时,上述环流异常符号相反,但更加明显,说明西南涡明显弱于常年,西太平洋副热带高压偏南。此外,四川盆地西部盛夏降水年际变化和我国西北、华北地区降水呈明显的正相关关系,而与江南地区降水有明显的负相关关系。这些关系与对流层低层环流异常有关。  相似文献   

2.
利用近46年西太平洋副热带高压特征指数资料、四川地区123个测站的逐日降水资料集及NCEP\NCAR再分析资料,研究了四川地区夏季旱涝事件的空间分布特征及其与西太副高的关系。结果表明,四川盆地东西部经常出现"西旱东涝"或者"西涝东旱"的异常特征。西太平洋副热带高压的脊线、北界位置与四川盆地东(西)部区的旱涝之间存在很高正(负)相关关系。西太平洋副热带高压南北位置的异常变化对应着东亚地区大气环流的异常变化,从而影响四川盆地东部区及四川盆地西部区的旱涝变化。  相似文献   

3.
2006年川渝地区夏季干旱的成因分析   总被引:2,自引:1,他引:1  
利用NCEP/NCAR再分析月平均资料、全国160站降水资料、向外长波辐射OLR(outgoinglongwave radiation)资料和所计算的热源资料,分析了2006年夏季东亚大气环流的异常特征,并研究了热力异常与川渝地区夏季降水的关系。结果表明,2006年夏季由南向北的水汽输送较常年偏弱;西太洋副热带高压较常年异常偏强,脊线位置明显偏北,川渝地区受高压系统影响盛行下沉气流,中高纬环流场则表现为乌拉尔山地区和东北亚区域无明显阻塞高压形势,冷空气活动比常年弱;南亚高压比常年偏北偏强,持续控制川渝地区;2006年夏季青藏高原热源偏弱,热带西太平洋暖池区热源偏强,是引起西太平洋副热带高压偏北偏强的重要原因之一。川渝地区夏季降水与西太平洋副热带高压的异常变化有密切关系,川渝地区夏季干旱年,西太平洋副热带高压偏北,并且引起西太平洋副热带高压偏北的原因与2006年类似。  相似文献   

4.
利用1960~2011年广西西北部16个气象观测站逐月降水资料、NCEP/NCAR再分析月平均资料、NOAA向外长波辐射资料和国家气候中心提供的环流特征量资料,分析了广西西北部地区以往盛夏干旱年的中高纬环流、西太平洋副热带高压和水汽输送特征,重点探讨了2011年盛夏(7~8月)广西西北部特大干旱大气环流的异常特征。结果表明,2011年是1960年以来广西西北部盛夏降水最少的年份。广西西北部2011年盛夏大气环流与以往盛夏干旱年明显不同的是,西太平洋副热带高压较常年异常偏弱偏东,脊线位置明显偏北,中高纬环流平直,乌拉尔山地区和东北亚区域没有明显阻塞高压形势,冷空气活动比常年弱;印缅槽活动较常年偏弱,由南向北的水汽输送明显偏弱,广西西北部上空存在有弱的水汽通量辐散,垂直运动和对流活动均较常年偏弱,这些环流特征均不利于产生降水,造成2011年盛夏广西西北部地区出现特大干旱。  相似文献   

5.
利用我国160个站点58年(1951~2008年)的降水资料、NCEP/NCAR再分析环流资料和Hadley海表温度资料,对我国秋季降水年际变化的特征和可能成因进行了分析。结果显示,秋季降水前两模态分别反映长江流域及以南地区和长江以北的江淮、黄淮、华北、四川盆地北部至河套等地降水的变化,两降水模态的变化都以年际尺度为主,年代际变化特征不明显。就环流形势而言,第一模态的年际变化主要与西太平洋副热带高压的强度及相应的对流层低层菲律宾群岛附近的异常气旋/反气旋联系紧密,第二模态的年际变化则可能受到副热带高压的南北位置和相应的日本岛附近的异常气旋/反气旋的影响。同时,两模态及相应的异常环流还分别与热带东印度洋和热带西太平洋附近的异常垂直运动关系密切,热带地区的异常垂直运动可能通过经圈方向的异常环流影响到东亚地区。此外,两降水模态不仅与热带地区的异常环流关系密切,而且与热带海温异常也存在紧密的联系。与两模态相关联的热带太平洋海温异常显示出不同的分布特征,当热带东太平洋偏暖/冷,西太平洋偏冷/暖时,长江以南地区降水偏多/少。而当热带东太平洋和中太平洋一致偏暖/冷时,长江以北地区降水易偏少/多。两降水模态与热带海温及热带地区异常环流之间的密切关系显示热带太平洋海温异常的不同分布可能通过激发不同的热带地区异常垂直环流形势而对降水产生影响。  相似文献   

6.
运用NCEP/NCAR再分析资料和中国气候中心整编的160站月平均降水资料应用经验正交函数、线性相关分析等,分析了江淮地区夏季降水异常特征及其与西印度洋区域大气环流年际异常关系的变化及其可能的机理。结果表明:当500 hPa中纬度低槽活动偏多(少),西太平洋副热带高压偏强(弱),东亚夏季风偏强(弱)时,江淮地区降水偏多(少)。进一步分析还发现西印度洋上空的垂直环流与江淮夏季降水存在较好的关系,但这种年际异常之间的联系受到背景场的影响明显:1979—1993年西印度洋垂直上升运动与江淮夏季降水的变化趋势基本相反,两者线性相关系数为-0.43;1994—2010年两者的变化趋势基本一致,相关系数达0.71。即当西印度洋地区存在环流异常下沉(上升)时,西太平洋副热带高压通常异常减弱东退(增强西伸),副热带季风减弱(增强),有利于雨带偏南(北)。因此,在西太平洋副热带高压和副热带季风年代际偏强(弱)阶段,西印度洋环流与江淮夏季降水呈负(正)相关。  相似文献   

7.
贵州夏季降水异常的环流特征分析   总被引:2,自引:1,他引:2  
伍红雨  王谦谦 《高原气象》2006,25(6):1120-1126
利用美国NCEP/NCAR月平均高度及风场再分析资料和中国月平均降水资料,分析了贵州多、少雨年夏季环流的平均距平场特征.结果表明:贵州多、少雨年夏季环流具有明显的不同特征.多雨年南亚高压偏弱,西太平洋副热带高压较常年偏强,脊线明显偏南偏西,且影响贵州的印度西南季风、西太平洋副热带季风较常年也偏强,影响贵州的中、东路冷空气强.少雨年西太平洋副热带高压明显偏强,脊线较常年明显偏北,其它环流特征与多雨年相反.  相似文献   

8.
南亚高压和西太副高位置与中国盛夏降水异常   总被引:10,自引:4,他引:6  
张玲  智协飞 《气象科学》2010,30(4):438-444
用全国160站降水资料及ECMWF逐月再分析资料,采用合成分析方法,讨论了年际变化尺度上南亚高压与西太副高纬向位置异常与盛夏降水的关系。结果表明,当南亚高压与西太副高纬向异常重叠(分离)时,长江中下游流域存在异常上升(下沉)运动,江南的广大地区存在异常下沉(上升)运动。且当两个高压纬向异常重叠时,来自北印度洋及西太平洋的水汽,在长江中下游流域异常辐合,降水偏多。此时,江南地区水汽通量异常辐散,降水偏少。当两个高压纬向异常分离时,水汽主要来自北印度洋的西南风输送,长江流域降水偏少,江南地区降水偏多。  相似文献   

9.
孟加拉湾热源对亚洲夏季风环流系统的影响   总被引:8,自引:5,他引:8  
利用 1951—2000年NCEP/NCAR再分析逐日及月平均资料和我国 160个测站 1951—2000年月降水量资料,计算了夏季大气热源气候分布,分析了夏季孟加拉湾地区热源年际异常及亚洲季风环流系统的响应,以及夏季孟加拉湾地区热源与中国夏季降水的年际关系。结果表明:夏季亚洲季风区最强的热源中心位于孟加拉湾东北部一带。当孟加拉湾热源异常强 (弱 )时,南亚高压偏西 (东 ),西太平洋副热带高压位置偏东(西);印度夏季风偏强 (弱),东亚热带季风偏弱 (强 )。孟加拉湾热源异常对南亚高压、南亚季风、副热带高压的影响显著,对东亚热带季风的影响不显著。夏季孟加拉湾热源与同期长江以南、华南东部部分地区降水呈明显负相关,而与西南到华南西部地区降水呈明显正相关。  相似文献   

10.
杨文艳  王谦谦 《高原气象》2006,25(5):969-974
在分析辽宁汛期降水的气候特征基础上,着重对影响辽宁汛期降水的环流特征进行了分析,结果表明:(1)近44年辽宁汛期降水呈下降趋势并出现显著的年际、年代际变化特征。(2)辽宁汛期水汽来源于西南夏季风和我国东部海域,汛期降水异常与低空的西南、东南夏季风、中空的极涡、西风槽、西太平洋副热带高压活动及高空的南亚高压关系密切。  相似文献   

11.
本文利用中国气象科学数据共享服务网提供的中国地面降水日值0.1°×0.1°格点数据集(V2.0)、FY-2E逐小时红外黑体辐射亮温(Temperature of Black Body,以下简称TBB)资料和欧洲中心ERA-Interim0.5°×0.5°,6小时一次温度、风场、位势高度、相对湿度等资料对2012年7月21~22日一次四川暴雨进行了初步分析。结果表明,西南低涡活动为此次四川盆地强降水过程提供了有利的发生条件。在此基础之上,副热带高压引导的暖湿空气与西伯利亚南下的冷空气相汇于四川盆地,风切变的生成,大量不稳定能量在四川盆地东部累积,和盆地上空形成的上升气流,为此次降水过程提供了有利的天气条件。随着西南低涡的东移减弱,四川盆地此次降水过程也随之结束。   相似文献   

12.
Rainfall amount in mid-summer(July and August)is much greater over eastern than western Sichuan,which are characterized by basin and plateau,respectively.It is shown that the interannual variations of extreme rainfall over these two regions are roughly independent,and they correspond to distinct anomalies of both large-scale circulation and sea surface temperature(SST).The enhanced extreme rainfall over western Sichuan is associated with a southward shift of the Asian westerly jet,while the enhanced extreme rainfall over eastern Sichuan is associated with an anticyclonic anomaly in the upper troposphere over China.At low levels,on the other hand,the enhanced extreme rainfall over western Sichuan is related to two components of wind anomalies,namely southwesterly over southwestern Sichuan and northeasterly over northeastern Sichuan,which favor more rainfall under the effects of the topography.Relatively speaking,the enhanced extreme rainfall over eastern Sichuan corresponds to the low-level southerly anomalies to the east of Sichuan,which curve into northeasterly anomalies over the basin when they encounter the mountains to the north of the basin.Therefore,it can be concluded that the topography in and around Sichuan plays a crucial role in inducing extreme rainfall both over western and eastern Sichuan.Finally,the enhanced extreme rainfall in western and eastern Sichuan is related to warmer SSTs in the Maritime Continent and cooler SSTs in the equatorial central Pacific,respectively.  相似文献   

13.
East Asian summer climate is strongly affected by extratropical circulation disturbances.In this study,impacts of four atmospheric teleconnections over Eurasia on East Asian summer rainfall are investigated using National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data and Climatic Research Unit (CRU) land precipitation data during 1979-2009.The four teleconnections include the Scandinavian (SCA),the Polar/Eurasian (PEU),the East Atlantic/Western Russian (EAWR),and the circumglobal teleconnection (CGT).Moreover,the related changes of lower-tropospheric circulation are explored,specifically,the low pressure over northern East Asia (NEAL) and the subtropical high over the western North Pacific (WNPSH).The results presented are in the positive phase.The PEU and SCA induce significant negative anomalies in North China rainfall (NCR),while the CGT induces significant positive anomalies.In the past three decades,the PEU and SCA explain more than 20% of the variance in NCR,twice that explained by the CGT,suggesting a more important role of the former two teleconnections in NCR variation than the latter one.Meanwhile,the PEU and SCA reduce rainfall in Northeast China and South Korea,respectively,and the CGT enhances rainfall in Japan.The rainfall responses are attributed to the SCA-induced northward shift of the NEAL,and PEU-induced northward shift and weakening of the NEAL,respectively.For the CGT,the dipole pattern of rainfall anomalies between North China and Japan is affected by both westward extension of the NEAL and northwestward expansion of the WNPSH.In addition,the EAWR leads to an increase of sporadic rainfall in South China as a result of the eastward retreat of the WNPSH.  相似文献   

14.
中国西南地区春季降水的时空变化及其异常的环流特征   总被引:3,自引:0,他引:3  
夏阳  万雪丽  严小冬  吴磊  龙园 《气象学报》2016,74(4):510-524
利用中国气象局国家气象信息中心整编的中国西南地区97站逐日观测资料及美国国家环境预报中心/大气研究中心(NCEP/NCAR)再分析资料,对中国西南地区1961—2013年春季降水的时空分布特征进行了分析,并研究了造成西南地区春季降水异常的环流成因。结果表明,中国西南地区春季降水的主模态呈现为全区一致型,该模态具有明显的2.5—3.5a及准5a的活动周期。对流层中低层副热带地区的异常气旋式环流波列形成的异常气流将洋面上空的水汽向中国西南内陆地区输送,暖湿气流与异常活跃的北方冷空气活动相配合,加上西南地区大气低层辐合、高层辐散而产生抽吸作用,使得当地对流层中低层出现较强的沿地形抬升的上升气流,从而有利于西南地区降水的形成,反之亦然。造成环流异常的原因除了与西南地区、热带地区的异常辐合/辐散运动造成的位涡扰动能量有关,亦与中高纬度波扰动能量下欧亚大陆下游地区的频散及辐合有关。此外,冬季1月的青藏高原地面加热场特征可作为预测后期西南地区春季降水异常变化的一个前期信号。  相似文献   

15.
studying the relationship between SST in the tropical Indian Ocean (TIO), tropical western Pacific (TWP), and tropical eastern Pacific (TEP) and East Asian summer rainfall (EASR), using data provided by NOAA/OAR/ESRL PSD and the National Climate Center of China for the period 1979-2008, an index, SSTDI, was defined to describe the SST difference between the TIO and TWP. In comparison with the winter ENSO, the spring SST contrast between the TIO and TWP was found to be more significantly associated with summer rainfall in East Asia, especially along the EASR band and in Northeast China. This spring SST contrast can persist into summer, resulting in a more significant meridional teleconnection pattern of lower-tropospheric circulation anomalies over the western North Pacific and East Asia. These circulation anomalies are dynamically consistent with the summer rainfall anomaly along the EASR band. When the SSTDI is higher (lower) than normal, the EASR over the Yangtze River valley, Korea, and central and southern Japan is heavier (less) than normal. The present results suggest that this spring SST contrast can be used as a new and better predictor of EASR anomalies.  相似文献   

16.
Impacts of the MJO on Winter Rainfall and Circulation in China   总被引:10,自引:0,他引:10  
Impacts of the MJO on winter rainfall and circulation in China are investigated using a real-time multivariate MJO index.Composite results using the daily rainfall anomalies and "rainy day" anomalies according to eight different MJO phases show that the MJO has considerable influence on winter rainfall in China. Rainfall anomalies show systematic and substantial changes(enhanced/suppressed) in the Yangtze River Basin and South China with the eastward propagation of the MJO convective center from the Indian Ocean to the western Pacific.When the MJO is in phase 2 and 3(MJO convective center is located over the Indian Ocean),rainfall probability is significantly enhanced.While in phase 6 and 7(MJO convective center is over the western Pacific),rainfall probability is significantly reduced. MJO in winter influences the rainfall in China mainly through modulating the circulation in the subtropics and mid-high latitudes.For the subtropics,MJO influences the northward moisture transport coming from the Bay of Bengal and the South China Sea by modulating the southern trough of the Bay of Bengal and the western Pacific subtropical high.For the mid-high latitudes,the propagation of the low frequency perturbations associated with the eastward-propagating MJO convection modulate the circulation in the mid-high latitudes,e.g.the East Asian winter monsoon and the low trough over central Asia.  相似文献   

17.
Xinyu LI  Riyu LU 《大气科学进展》2018,35(10):1231-1242
There is a well-known seesaw pattern of precipitation between the tropical western North Pacific(WNP) and the Yangtze River basin(YRB) during summer. This study identified that this out-of-phase relationship experiences a subseasonal change;that is, the relationship is strong during early summer but much weaker during mid-summer. We investigated the large-scale circulation anomalies responsible for the YRB rainfall anomalies on the subseasonal timescale. It was found that the YRB rainfall is mainly affected by the tropical circulation anomalies during early summer, i.e., the anticyclonic or cyclonic anomaly over the subtropical WNP associated with the precipitation anomalies over the tropical WNP. During mid-summer, the YRB rainfall is mainly affected by the extratropical circulation anomalies in both the lower and upper troposphere. In the lower troposphere, the northeasterly anomaly north of the YRB favors heavier rainfall over the YRB by intensifying the meridional gradient of the equivalent potential temperature over the YRB. In the upper troposphere, the meridional displacement of the Asian westerly jet and the zonally oriented teleconnection pattern along the jet also affect the YRB rainfall. The subseasonal change in the WNP–YRB precipitation relationship illustrated by this study has important implications for the subseasonalto-seasonal forecasting of the YRB rainfall.  相似文献   

18.
An extreme rainfall event occurred over the middle and lower reaches of the Yangtze Basin(MLY) during the end of June 2016, which was attributable to a Tibetan Plateau(TP) Vortex(TPV) in conjunction with a Southwest China Vortex(SWCV). The physical mechanism for this event was investigated from Potential Vorticity(PV) and omega perspectives based on MERRA-2 reanalysis data. The cyclogenesis of the TPV over the northwestern TP along with the lowertropospheric SWCV was found to involve a midtropospheric large-scale flow reconfiguration across western and eastern China with the formation of a high-amplitude Rossby wave. Subsequently, the eastward-moving TPV coalesced vertically with the SWCV over the eastern Sichuan Basin due to the positive vertical gradient of the TPV-related PV advection,leading the lower-tropospheric jet associated with moisture transport to intensify greatly and converge over the downstream MLY. The merged TPV-SWCV specially facilitated the upper-tropospheric isentropic-gliding ascending motion over the MLY. With the TPV-embedded mid-tropospheric trough migrating continuously eastward, the almost stagnant SWCV was re-separated from the overlying TPV, forming a more eastward-tilted high-PV configuration to trigger stronger ascending motion including isentropic-gliding, isentropic-displacement, and diabatic heating-related ascending components over the MLY. This led to more intense rainfall. Quantitative PV diagnoses demonstrate that both the coalescence and subsequent re-separation processes of the TPV with the SWCV were largely dominated by horizontal PV advection and PV generation due to vertically nonuniform diabatic heating, as well as the feedback of condensation latent heating on the isentropicdisplacement vertical velocity.  相似文献   

19.
This study investigates the circulation and precipitation anomalies associated with different configurations of the western North Pacific subtropical high(WNPSH) and the East Asian westerly jet(EAJ) in summer on interannual timescales. The in-phase configuration of the WNPSH and EAJ is characterized by the westward(eastward) extension of the WNPSH and the southward(northward) shift of the EAJ, which is consistent with the general correspondence between their variations. The out-of-phase configuration includes the residual cases. We find that the in-phase configuration manifests itself as a typical meridional teleconnection. For instance, there is an anticyclonic(cyclonic) anomaly over the tropical western North Pacific and a cyclonic(anticyclonic) anomaly over the mid-latitudes of East Asia in the lower troposphere. These circulation anomalies are more conducive to rainfall anomalies over the Yangtze River basin and south Japan than are the individual WNPSH or EAJ. By contrast, for the out-of-phase configuration, the mid-latitude cyclonic(anticyclonic) anomaly is absent, and the lower-tropospheric circulation anomalies feature an anticyclonic(cyclonic)anomaly with a large meridional extension. Correspondingly, significant rainfall anomalies move northward to North China and the northern Korean Peninsula. Further results indicate that the out-of-phase configuration is associated with the developing phase of ENSO, with strong and significant sea surface temperature(SST) anomalies in the tropical central and eastern Pacific which occur simultaneously during summer and persist into the following winter. This is sharply different from the in-phase configuration, for which the tropical SSTs are not a necessity.  相似文献   

20.
华南6月降水异常及其与东亚—太平洋遥相关的关系   总被引:3,自引:0,他引:3  
利用1959~2010年共52年的大气环流和降水资料,我们分析了华南前汛期季风降水 (6月降水) 的变化特征,发现6月华南降水与同期EAP (East Asia-Pacific,东亚—太平洋) 遥相关型有显著的相关关系,两者之间的相关系数为0.35.EAP指数为正时,长江中下游以南的地区降水偏多,而长江以北和黄河之间的地区降水偏少.将华南6月降水分为与EAP相关的降水序列和与EAP独立的降水序列,比较了二者所对应环流异常的异同点.结果表明,与EAP相关的降水异常对应着EAP相关型的环流异常分布特征,降水为正异常时,850hPa风场从低纬度到高纬度呈现“反气旋、气旋、反气旋”的异常分布,湿的偏南风和干的偏北风在华南上空交汇,降水增多;而整个淮河流域上空为偏北风异常,导致南风带来的水汽输送减少,降水偏少,因此降水异常呈现偶极子分布.相比之下,与EAP独立的降水正异常对应的环流异常表现为热带西北太平洋上空的反气旋性环流异常,华南地区上空为显著的西南风异常,输送到华南地区的水汽增多,导致降水偏多.  相似文献   

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