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简单海气耦合模式大气运动方程的非线性对ENSO循环模拟的影响 总被引：1，自引：1，他引：0
研究简单海气耦合模式大气运动方程非线性对ENSO循环的影响,即讨论大气运动方程的纬向非线性、经向非线性、纬向和经向非线性对ENSO循环的影响。同时,讨论了ENSO循环对大气运动方程非线性的敏感性问题。数值实验证明,大气运动方程的非线性对ENSO循环的影响明显,并且ENSO循环对大气运动方程的非线性非常敏感。因此,研究简单海气耦合模式中大气运动方程的非线性对ENSO循环的影响,对进一步理解ENSO循环的物理机制,具有一定的理论意义和实用价值。 相似文献
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不同类型ENSO对东亚季风的影响和机理研究进展 总被引：6，自引：1，他引：5
近十几年来有关热带太平洋存在不同类型的增暖型的研究成为热点课题,其中主要依据海温的空间形态将厄尔尼诺与南方涛动（ENSO）分为两类:一类为传统的东太平洋型ENSO,另一类为中太平洋型ENSO。该两类ENSO的形成机制、演变过程均有不同,产生的气候影响也有差异。本文简要回顾了国内外有关不同类型ENSO及其气候影响的研究进展,特别综述了近年来关于两类ENSO事件对东亚夏季风、东亚冬季风以及东亚冬夏季风关联的影响和机理方面的主要研究进展。文中侧重讨论了年际和年代际时间尺度上ENSO事件对东亚季风的影响,并提出了今后在该领域一些需要进一步研究的科学问题。 相似文献
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ENSO（El Niño-Southern Oscillation）的发生发展既受到来自热带西太平洋纬向海气过程的影响,也受到来自副热带太平洋经向海气过程的影响。本文概述了副热带太平洋海气异常影响ENSO研究方面的科学背景及研究进展,综述了前人提出的副热带太平洋大气海洋异常通过经向风应力以及北太平洋/南太平洋经向模态,影响ENSO发展演变的途径及相关物理机制,总结了近些年观测资料分析及数值模拟研究工作所提出的新观点,并讨论了相关研究中的学术分歧及有待进一步研究的问题。 相似文献
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ENSO对IOD与中国夏季降水关系的影响 总被引：17，自引：4，他引：13
利用1950～1999年Hadley中心海温资料、NCEP/NCAR再分析资料和中国160站降水资料,通过讨论印度洋偶极子(IOD)独立发生时及IOD与ENSO联合发生时中国夏季降水的差异,研究了ENSO对IOD与中国夏季降水关系的影响.IOD独立发生时,其正位相年以湖南为中心的华南地区夏季降水偏多;IOD与ENSO联合发生时,正位相年河套、华北地区夏季降水偏少,东南沿海地区降水偏多.ENSO对IOD与中国夏季降水关系的影响主要表现为:在华南西部、江淮流域、河套及华北地区起抵消作用,而在东南沿海地区起协同作用.还从环流场角度分析了ENSO对IOD与中国夏季降水关系影响的初步成因. 相似文献
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美国第25届气候诊断与预测年会 总被引：2，自引：0，他引：2
文章介绍了2000年美国第25届气候诊断与预测年会。着重讨论了如下8个问题：最近的ENSO特征，气候异常的诊断，季风降水，ENSO预测，ENSO影响的模拟，陆面过程，模式预测与可预报性，气候预测业务。 相似文献
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国际上针对海洋-大气系统的观测、理论和模拟方面已经开展了广泛而深入的研究,为短期气候预测水平的不断提升奠定了坚实基础,这其中中国学者做出了许多重要贡献。文中简要回顾了中国学者70年来在热带海-气相互作用与ENSO动力学及预测方面的研究进展。其中,热带海-气相互作用部分主要涉及4个方面的内容:热带太平洋气候特征与ENSO现象、热带印度洋海温主要模态及其与太平洋相互作用、热带大西洋海温主要模态及与海盆的相互作用、中高纬度海-气系统对ENSO的影响;ENSO动力学包括7个方面的内容:基本理论的相关研究、ENSO相关的诊断与模拟研究、两类ENSO相关研究、ENSO触发机制相关研究、ENSO与其他现象的相互作用、外部强迫与大气遥相关、气候变化与ENSO响应;ENSO预测主要包括2个方面的内容:动力-统计ENSO预测方法、ENSO预测系统与应用。最后,还讨论了上述相关方面亟待解决的问题。 相似文献
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系统回顾了近年来有关ENSO与印度洋海盆海温多时间尺度相互作用及其气候效应研究的相关成果。主要包括年际和年代际时间尺度上,ENSO与印度洋海盆海温之间相互联系的基本事实和机制,以及与之相关的气候影响,特别是上述联系对亚洲季风系统及气候异常的影响。在年际尺度上,ENSO通过“大气桥”过程主导着印度洋海温变化,而后者的异常也可通过纬向环流的“齿轮式耦合”对ENSO产生影响。在年代际尺度上,一方面印度洋海盆海温显著的夏季增暖可能来自ENSO暖事件持续时间的年代际延长,另一方面印度洋秋季海温空间分布模态的年代际变化,则对ENSO暖事件强度的年代际增强具有贡献。二者的多时间尺度相互作用进而通过影响大气和海洋环流、辐射反馈、蒸发降水等多种海气耦合过程产生显著的气候效应。研究成果表明印度洋海温变化对亚洲乃至全球气候异常的重要作用。在回顾上述研究成果的基础上,讨论了进一步研究ENSO与印度洋海盆海温多时间尺度变率影响全球气候的前景和重要意义。 相似文献
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El Nio期间印度洋海温异常对
亚洲气候的影响 总被引：18，自引：4，他引：14
El Nio事件发生时,赤道东太平洋海温出现高达2～3 ℃的正异常,同时,印度洋海温也会出现异常。但每次El Nio事件期间,印度洋异常海温的结构是不相同的,翘翘板型的海表温度结构,是印度洋海温异常的一种典型分布。利用IAP-GCM 9L模式,我们对El Nio期间,印度洋东冷西暖异常海温分布对气候的影响,特别是对亚洲气候的影响,作了数值模拟研究。模拟研究的结果表明,印度洋海温主要影响孟加拉湾、中南半岛、印尼、印度次大陆及中国大陆南部地区的气候变化。在El Nio发生期间,东冷西暖的印度洋海温结构,加大了东太平洋海温异常给东亚季风区带来的影响,它使中南半岛到印尼更加干旱,中国华北到山东半岛的降水减少,而使中国西南到华南的降水明显增加。在其影响下,东亚地区的雨带呈纬向分布,形成旱涝相间的纬向带状异常分布型,使模式模拟结果与中国旱涝的实际分布更加接近。同时,在对高度场、流场的分析中可以看到,印度洋东冷西暖海温分布使夏季副高位置偏南,印度洋到南海的西南风减弱,在中国西南到华南为气旋性环流控制,这些特征与降水分布是一致的。模拟试验表明,印度洋海温异常对我国El Nio期间降水异常的分布型有重要影响。 相似文献
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A region of low sea surface temperature (SST) extends southward in the central part of southern South China Sea during boreal winter, which is called the South China Sea cold tongue (SCS CT). The present study investigates the factors of interannual variation of SST in the SCS CT region and explores the individual and combined impacts of El Niño-Southern Oscillation (ENSO) and East Asian winter monsoon (EAWM) on the SCS CT intensity. During years with ENSO alone or with co-existing ENSO and anomalous EAWM, shortwave radiation and ocean horizontal advection play major roles in the interannual variation of the SCS CT intensity. Ocean advection contributes largely to the SST change in the region southeast of Vietnam. In strong CT years with anomalous EAWM alone, surface wind-related latent heat flux has a major role and shortwave radiation is secondary to the EAWM-induced change of the SCS CT intensity, whereas the role of ocean horizontal advection is relatively small. The above differences in the roles of ocean advection and latent heat flux are associated with the distribution of low level wind anomalies. In anomalous CT years with ENSO, low level anomalous cyclone/anticyclone-related wind speed change leads to latent heat flux anomalies with effects opposite to shortwave radiation. In strong CT years with anomalous EAWM alone, surface wind-related latent heat flux anomalies are large as anomalous winds are aligned with climatological winds.
相似文献13.
东印度洋海温对中国南方冬季降水的影响 总被引：8，自引：2，他引：6
利用NCEP再分析的大气环流资料、海表温度资料和全国160 站降水资料,研究了冬季东印度洋海温对我国江南-华南地区同期降水的影响。结果指出,冬季东印度洋海温(Sea Surface Temperature in the Eastern Indian Ocean,EIOSST)和同期的江南-华南降水呈显著的正相关关系。当EIOSST偏高时,江南-华南的冬季降水偏多。而当EIOSST偏低时,江南-华南的冬季降水偏少。这种影响的可能机制是:冬季东印度洋海温异常通过影响南支槽上的扰动活动和水汽输送来影响同期的江南-华南降水。当东印度洋海温偏高时,局地对流加强,引起南支槽地区的上升运动加强,南支槽活跃。活跃的南支扰动向下游传播,南支槽前的西南气流将水汽从孟加拉湾向华南和江南输送,引起华南和江南的降水偏多。进一步的分析显示,东印度洋海温对南支槽和江南-华南的降水的影响独立于ENSO的影响。二者对南支槽和江南-华南地区冬季降水的影响过程一致,只是东印度洋海温的影响较弱。当东印度洋海温和ENSO的作用相叠加时,江南-华南可能会出现较异常的冬季降水。
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The spatio-temporal variations of eastern China spring rainfall are identified via empirical orthogonal function (EOF) analysis of rain-gauge (gridded) precipitation datasets for the period 1958–2013 (1920–2013). The interannual variations of the first two leading EOF modes are linked with the El Niño–Southern Oscillation (ENSO), with this linkage being modulated by the Pacific Decadal Oscillation (PDO). The EOF1 mode, characterized by predominant rainfall anomalies from the Yangtze River to North China (YNC), is more likely associated with out-of-phase PDO–ENSO events [i.e., El Niño during cold PDO (EN_CPDO) and La Niña during warm PDO (LN_WPDO)]. The sea surface temperature anomaly (SSTA) distributions of EN_CPDO (LN_WPDO) events induce a significant anomalous anticyclone (cyclone) over the western North Pacific stretching northward to the Korean Peninsula and southern Japan, resulting in anomalous southwesterlies (northeasterlies) prevailing over eastern China and above-normal (below-normal) rainfall over YNC. In contrast, EOF2 exhibits a dipole pattern with predominantly positive rainfall anomalies over southern China along with negative anomalies over YNC, which is more likely connected to in-phase PDO–ENSO events [i.e., El Niño during warm PDO (EN_WPDO) and La Niña during cold PDO (LN_CPDO)]. EN_WPDO (LN_CPDO) events force a southwest–northeast oriented dipole-like circulation pattern leading to significant anomalous southwesterlies (northeasterlies) and above-normal (below-normal) rainfall over southern China. Numerical experiments with the CAM5 model forced by the SSTA patterns of EN_WPDO and EN_CPDO events reproduce reasonably well the corresponding anomalous atmospheric circulation patterns and spring rainfall modes over eastern China, validating the related mechanisms. 相似文献
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ZONG Haifeng 《大气科学进展》2014,31(6):1395-1406
The physical processes involved in the formation of the ENSO cycle,as well as the possible roles of the Hadley circulation （HC）,Walker circulation （WC）,and the propagating waves of the Southern Oscillation/Northern Oscillation （SO/NO） in its formation,were studied using composite and regression methods.The analysis showed that the convection and heat release triggered by ENSO in the central-eastern equatorial Pacific are the primary drivers for the 3-5 year cycle of the HC,WC and the meridional/zonal circulation.The HC plays a key role in the influence of ENSO on the circulation outside the tropics through angular momentum transportation.Meanwhile,the feedback effects of the anomalous circulation in the mid-high latitudes on ENSO are accomplished by the propagating waves of SO/NO associated with the evolutions of HC and WC.These propagating waves are the main agents of the connections among the meridional/zonal circulation outside the tropics,the Asian/Australian monsoon,the anomalous easterly/westerly winds over the tropical Pacific,and ENSO events.It was found that the 3-5 year cycle of the meridional/zonal circulation forced by ENSO is quite different from the several-week variation of the circulation index triggered by the inner dynamic processes of the atmosphere.The former occurs at the global scale with a definite flow pattern,while the latter occurs only in a wide area without a definite flow pattern.Finally,a physical model for the formation of the ENSO cycle composed of two fundamental processes at the basin and global scale,respectively,is proposed. 相似文献
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Yongxin Zhang Yun Qian Valérie Dulière Eric P. Salathé Jr L. Ruby Leung 《Climatic change》2012,110(1-2):315-346
Surface temperature, precipitation, specific humidity and wind anomalies associated with the warm and cold phases of ENSO simulated by WRF and HadRM are examined for the present and future decades. WRF is driven by ECHAM5 and CCSM3, respectively, and HadRM is driven by HadCM3. For the current decades, all simulations show some capability in resolving the observed warm-dry and cool-wet teleconnection patterns over the PNW and the Southwest U.S. for warm and cold ENSO. Differences in the regional simulations originate primarily from the respective driving fields. For the future decades, the warm-dry and cool-wet teleconnection patterns in association with ENSO are still represented in ECHAM5-WRF and HadRM. However, there are indications of changes in the ENSO teleconnection patterns for CCSM3-WRF in the future, with wet anomalies dominating in the PNW and the Southwest U.S. for both warm and cold ENSO, in contrast to the canonical patterns of precipitation anomalies. Interaction of anomalous wind flow with local terrain plays a critical role in the generation of anomalous precipitation over the western U.S. Anomalous dry conditions are always associated with anomalous airflow that runs parallel to local mountains and wet conditions with airflow that runs perpendicular to local mountains. Future changes in temperature and precipitation associated with the ENSO events in the regional simulations indicate varying responses depending on the variables examined as well as depending on the phase of ENSO. 相似文献
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An Atlantic influence on Amazon rainfall 总被引：2，自引：2，他引：0
Rainfall variability over the Amazon basin has often been linked to variations in Pacific sea surface temperature (SST), and in particular, to the El Niño/Southern Oscillation (ENSO). However, only a fraction of Amazon rainfall variability can be explained by ENSO. Building upon the recent work of Zeng (Environ Res Lett 3:014002, 2008), here we provide further evidence for an influence on Amazon rainfall from the tropical Atlantic Ocean. The strength of the North Atlantic influence is found to be comparable to the better-known Pacific ENSO connection. The tropical South Atlantic Ocean also shows some influence during the wet-to-dry season transition period. The Atlantic influence is through changes in the north-south divergent circulation and the movement of the ITCZ following warm SST. Therefore, it is strongest in the southern part of the Amazon basin during the Amazon’s dry season (July–October). In contrast, the ENSO related teleconnection is through anomalous east-west Walker circulation with largely concentrated in the eastern (lower) Amazon. This ENSO connection is seasonally locked to boreal winter. A complication due to the influence of ENSO on Atlantic SST causes an apparent North Atlantic SST lag of Amazon rainfall. Removing ENSO from North Atlantic SST via linear regression resolves this causality problem in that the residual Atlantic variability correlates well and is in phase with the Amazon rainfall. A strong Atlantic influence during boreal summer and autumn is particularly significant in terms of the impact on the hydro-ecosystem which is most vulnerable during the dry season, as highlighted by the severe 2005 Amazon drought. Such findings have implications for both seasonal-interannual climate prediction and understanding the longer-term changes of the Amazon rainforest. 相似文献
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使用NCEP/NCAR再分析资料、中国气象局台站降水资料和GPCC降水资料,系统研究了在冬季平流层准两年振荡(Quasi-Biennial Oscillation, QBO)调制下,厄尔尼诺-南方涛动(El Ni?o-Southern Oscillation, ENSO)不同阶段与中国夏季降水的可能联系。根据两者的位相和强度,可将它们的配置分为QBO西风/El Ni?o、QBO西风/La Ni?a、QBO东风/El Ni?o、QBO东风/La Ni?a。研究结果表明,在年际时间尺度上,ENSO和QBO无显著相关关系。冬季QBO西风位相时,El Ni?o发展年夏季,我国整体偏旱,而华南偏涝;衰减年夏季,华南、华东北部偏旱,东北、长江流域偏涝。La Ni?a发展年夏季,我国东部降水异常呈负-正-负的三极分布;衰减年夏季,东南沿海偏涝。冬季QBO东风位相时,El Ni?o发展年夏季,长江以北偏旱;衰减年夏季,我国东部降水异常呈负-正-负的三极分布。La Ni?a发展年夏季,江淮和华南南部偏旱;衰减年夏季,我国东部沿海偏涝。ENSO是影响我国夏季降水异常的重要因子,而QBO的调制作用在ENSO衰减年夏季更为显著。相比冬季QBO东(西)风位相,QBO西(东)风位相时El Ni?o (La Ni?a)期间赤道西太平洋负(正)海温异常更强,衰减年夏季位于西太平洋的异常下沉(上升)运动和印度洋的异常上升(下沉)运动更强更深厚,西太平洋副热带高压范围更大(小),南亚高压更偏东(西)。 相似文献
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In this study, we assess the prediction for May rainfall over southern China (SC) by using the NCEP CFSv2 outputs. Results show that the CFSv2 is able to depict the climatology of May rainfall and associated circulations. However, the model has a poor skill in predicting interannual variation due to its poor performance in capturing related anomalous circulations. In observation, the above-normal SC rainfall is associated with two anomalous anticyclones over the western tropical Pacific and northeastern China, respectively, with a low-pressure convergence in between. In the CFSv2, however, the anomalous circulations exhibit the patterns in response to the El Ni?o-Southern Oscillation (ENSO), demonstrating that the model overestimates the relationship between May SC rainfall and the ENSO. Because of the onset of the South China Sea monsoon, the atmospheric circulation in May over SC is more complex, so the prediction for May SC rainfall is more challenging. In this study, we establish a dynamic-statistical forecast model for May SC rainfall based on the relationship between the interannual variation of rainfall and large-scale ocean-atmosphere variables in the CFSv2. The sea surface temperature anomalies (SSTAs) in the northeastern Pacific and the central-eastern equatorial Pacific, and the 500-hPa geopotential height anomalies over western Siberia in previous April, which exert great influence on the SC rainfall in May, are chosen as predictors. Furthermore, multiple linear regression is employed between the predictors obtained from the CFSv2 and observed May SC rainfall. Both cross validation and independent test show that the hybrid model significantly improve the model''s skill in predicting the interannual variation of May SC rainfall by two months in advance. 相似文献