Anomalies of hydrometeorological fields in the Black Sea area associated with sea surface temperature gradients in the North Atlantic     

A. A. Sizov  A. E. Chekhlan 《Russian Meteorology and Hydrology》2010,35(7):476-482

To describe the spatial structure of hydrometeorological fields in the North Atlantic and in the Black Sea, the temperature indices (sea surface temperature gradients) representing the difference in sea surface temperature anomalies averaged throughout the water area and normalized by standard deviations are introduced. Temperature gradients between the Sargasso Sea and the tropics (STI), the Sargasso Sea and the subpolar cyclonic gyre (SNI), the Sargasso Sea and the Black Sea (SBI) are considered. The spatial structure of the sea surface temperature field anomalies in the North Atlantic and in the Black Sea at extreme values of STI and SBI is discussed. A sign-variable structure of air temperature and precipitation anomalies in the Black Sea area at extreme values of SBI is shown. Time scales of sign-variable variability of anomalies of hydrometeorological fields in the Black Sea area are estimated.  相似文献   

The North Atlantic Oscillation and oceanic precipitation variability     

Annarita Mariotti  Phillip Arkin 《Climate Dynamics》2007,28(1):35-51

Global North Atlantic Oscillation (NAO) oceanic precipitation features in the latter half of the twentieth century are documented based on the intercomparison of multiple state-of-the-art precipitation datasets and the analysis of the NAO atmospheric circulation and SST anomalies. Most prominent precipitation anomalies occur over the ocean in the North Atlantic, where in winter a “quadrupole-like” pattern is found with centers in the western tropical Atlantic, sub-tropical Atlantic, high-latitude eastern Atlantic and over the Labrador Sea. The extent of the sub-tropical and high-latitude center and the amount of explained variance (over 50%) are quite remarkable. However, the tropical Atlantic center is probably the most intriguing feature of this pattern apparently linking the NAO with ITCZ variability. In summer, the pattern is “tripole-like” with centers in the eastern Mediterranean Sea, the North Sea/Baltic Sea and in the sub-polar Atlantic. In the eastern Indian Ocean, the correlation is positive in winter and negative in summer, with some link to ENSO variability. The sensitivity of these patterns to the choice of the NAO index is minor in winter while quite important in summer. Interannual NAO precipitation anomalies have driven similar fresh water variations in these “key” regions. In the sub-tropical and high-latitude Atlantic in winter precipitation anomalies have been roughly 15 and 10% of climatology per unit change of the NAO, respectively. Decadal changes of the NAO during the last 50 years have also influenced precipitation and fresh water flux at these time-scales, with values lower (higher) than usual in the high-latitude eastern North Atlantic (Labrador Sea) in the 1960s and the late 1970s, and an opposite situation since the early 1980s; in summer the North Sea/Baltic region has been drier than usual during the period 1965–1975 when the NAO was generally positive.  相似文献   

An Observed Connection Between Wintertime Temperature Anomalies over Northwest China and Weather Regime Transitions in North Atlantic          下载免费PDF全文

LI Chao  ZHANG Qingyun 《Acta Meteorologica Sinica》2015,29(2):201-213

In this study, the association between wintertime temperature anomalies over Northwest China and the weather regime transitions in North Atlantic on synoptic scale is analyzed by using observational surface air temperature(SAT) data and atmospheric reanalysis data. Daily SAT anomaly and duration time are used in order to define SAT anomaly cases. Differences with regard to the circulation anomalies over the Ural Mountains and the upstream North Atlantic area are evident. It is found that the colder than normal SAT is caused by the enhanced Ural high and associated southward flow over Northwest China. Time-lagged composites reveal possible connections between the SAT anomalies and the different development phases of the North Atlantic Oscillation(NAO). The Ural highs tend to be strengthened during the negative phase of NAO(NAO–) to Atlantic ridge transition, which are closely related to the downstream-propagating Rossby wave activity. The opposite circulation patterns are observed in the warm SAT cases. A cyclonic circulation anomaly is distinctly enhanced over the Urals during the positive phase of NAO(NAO+) to Scandinavian blocking transition, which would cause warmer SAT over Northwest China. Further analyses suggest that the intensified zonal wind over North Atlantic would favor the NAO– to Atlantic ridge transition, while the weakened zonal wind may be responsible for the transition between NAO+ and Scandinavian blocking.  相似文献   

Synoptic eddy feedback and air–sea interaction in the North Atlantic region     

Lin-Lin Pan 《Climate Dynamics》2007,29(6):647-659

This paper explores the role of synoptic eddy feedback in the air-sea interaction in the North Atlantic region, particularly the interaction between the North Atlantic Oscillation (NAO) and the North Atlantic sea surface temperature anomalies (SSTA) tripole. A linearized five-layer primitive equation atmospheric model with synoptic eddy and low-frequency flow (SELF) interaction is coupled with a linearized oceanic mixed-layer model to investigate this issue. In this model, the “climatological” storm track/activity (or synoptic eddy activity) is characterized in terms of spatial structures, variances, decay time scales and propagation speeds through the complex empirical orthogonal function (CEOF) analysis on the observed data, which provides a unique tool to investigate the role of synoptic eddy feedback in the North Atlantic air–sea coupling. Model experiments show that the NAO-like atmospheric circulation anomalies can produce tripole-like SSTA in the North Atlantic Ocean, and the tripole-like SSTA can excite a NAO-like dipole with an equivalent barotropic structure in the atmospheric circulation, which suggests a positive feedback between the NAO and the SSTA tripole. This positive feedback makes the NAO/SSTA tripole-like mode be the leading mode of the coupled dynamical system. The synoptic eddy feedback plays an essential role in the origin of the NAO/SSTA tripole-like leading mode and the equivalent barotropic structure in the atmosphere. Without synoptic eddy feedback, the atmosphere has a baroclinic structure in the response field to the tripole-like SSTA forcing, and the leading mode of the dynamic system does not resemble NAO/SSTA tripole pattern.  相似文献   

Observed Long- and Short-lived North Atlantic Oscillation Events: Role of the Stratosphere     

Jie SONG  Jingjing ZHAO 《大气科学进展》2020,37(12):1338-1358

Utilizing three different sets of reanalysis data, this study examines the long- and short-lived observed positive North Atlantic Oscillation (NAO) events (referred to as NAO+_LE and NAO+_SE) and long- and short-lived observed negative NAO events (referred to as NAO?_LE and NAO?_SE). Composite results indicate that the NAO-like circulation anomalies associated with the long-lived NAO events can reach the stratosphere, while they are primarily confined to the troposphere in the short-lived NAO events. Thus, the coupling/connection of stratospheric and tropospheric circulation anomalies is much better (worse) in the long-lived (short-lived) NAO events. A series of modified stratospheric initial-value experiments conducted with a simplified model indicate that a better (worse) connection between stratospheric and tropospheric circulation anomalies in the initial-value fields tend to gradually induce the NAO-like tropospheric circulation anomalies in the troposphere on the subsequent days, and thus naturally elongate (reduce) the lifetimes of the original NAO events by altering the tropospheric synoptic eddy vorticity flux over the North Atlantic region.  相似文献   

Changes of Air–sea Coupling in the North Atlantic over the 20th Century   总被引：1，自引：0，他引：1  

YANG Yun  WU Lixin 《大气科学进展》2015,32(4):445-456

Changes of air–sea coupling in the North Atlantic Ocean over the 20 th century are investigated using reanalysis data,climate model simulations, and observational data. It is found that the ocean-to-atmosphere feedback over the North Atlantic is significantly intensified in the second half of the 20 th century. This coupled feedback is characterized by the association between the summer North Atlantic Horseshoe(NAH) SST anomalies and the following winter North Atlantic Oscillation(NAO). The intensification is likely associated with the enhancement of the North Atlantic storm tracks as well as the NAH SST anomalies. Our study also reveals that most IPCC AR4 climate models fail to capture the observed NAO/NAH coupled feedback.  相似文献   

Impact of the North Atlantic sea surface temperature tripole on the East Asian summer monsoon   总被引：10，自引：0，他引：10  

左金清  李维京  孙丞虎  任宏利 《大气科学进展》2013,30(4):1173-1186

A strong (weak) East Asian summer monsoon (EASM) is usually concurrent with the tripole pattern of North Atlantic SST anomalies on the interannual timescale during summer, which has positive (negative) SST anomalies in the northwestern North Atlantic and negative (positive) SST anomalies in the subpolar and tropical ocean. The mechanisms responsible for this linkage are diagnosed in the present study. It is shown that a barotropic wave-train pattern occurring over the Atlantic-Eurasia region likely acts as a link between the EASM and the SST tripole during summer. This wave-train pattern is concurrent with geopotential height anomalies over the Ural Mountains, which has a substantial effect on the EASM. Diagnosis based on observations and linear dynamical model results reveals that the mechanism for maintaining the wave-train pattern involves both the anomalous diabatic heating and synoptic eddy-vorticity forcing. Since the North Atlantic SST tripole is closely coupled with the North Atlantic Oscillation (NAO), the relationships between these two factors and the EASM are also examined. It is found that the connection of the EASM with the summer SST tripole is sensitive to the meridional location of the tripole, which is characterized by large seasonal variations due to the north-south movement of the activity centers of the NAO. The SST tripole that has a strong relationship with the EASM appears to be closely coupled with the NAO in the previous spring rather than in the simultaneous summer.  相似文献   

冬季与北大西洋涛动相关Rossby波列传播特征及对下游气候的影响     

李纵横  宋洁  殷明  尹锡帆 《气候与环境研究》2019,24(3):289-301

利用再分析数据,以在北半球冬季与北大西洋涛动(North Atlantic Oscillation,NAO)相关的向下游传播的准定常波列在欧洲地区是否发生反射为标准,将1957/1958年至2001/2002年这45个冬季分为高纬型和低纬型两类冬季,分别简称为在H型和L型冬季。在H(L)型冬季,和NAO相联系的向下游传播的Rossby波列主要沿高纬度(低纬度)路径传播。对比了在两种类型冬季NAO与同期大气环流、近地面温度(Surface Air Temperature,SAT)、海表面温度(Sea Surface Tempertaure,SST)和降水的关系。结果表明:大气环流方面,在H型冬季,300 hPa位势高度异常在西-西伯利亚和中-西伯利亚西部与NAO呈现正相关,而在L型冬季300 hPa位势高度异常在亚洲东海岸(约40°N)和北太平洋呈现正相关,在H型冬季与NAO相关的经向风异常在中纬度形成波列,而在L型冬季与NAO相关的经向风异常在副热带形成波列;SAT方面,在H型冬季SAT异常在欧亚大陆腹地高纬度地区与NAO呈现正相关,而在L型冬季与NAO相关的SAT异常在欧亚大陆腹地的高纬度地区相对较弱,但NAO造成的SAT异常可以扩展到亚洲东北部;降水方面,H型冬季与L型冬季主要区别在中国南方,在H型冬季降水异常与NAO的关系相对较弱,而在L型冬季降水异常与NAO呈现正相关关系;SST方面,同期SST异常在北大西洋中纬度海域与NAO呈现正相关,而在L型冬季与NAO相关的SST异常在北大西洋中纬度地区相对较弱,在北大西洋北部和南部较强。总体而言,在H型和L型冬季,NAO具有不同下游影响。  相似文献   

Cyclone activity and circulation oscillations in the North Atlantic     

N. A. Vyazilova 《Russian Meteorology and Hydrology》2012,37(7):431-437

Carried out is the comparative analysis of the cyclone activity for different combinations of positive and negative values of the North Atlantic Oscillation (NAO) and East Atlantic Oscillation (EA) indices. The integral characteristics of the cyclone activity (density and intensity of cyclones) are computed on the basis of the method of automatic indication of cyclone centers from the sea-level pressure data. It is demonstrated that the NAO index is really the major indicator of cyclone activity anomaly formation in the North Atlantic, however, the variations of cyclone activity in the European region, of the number of cyclones and their integral intensity are better characterized by the EA index.  相似文献   

利用大气环流模式模拟北大西洋海温异常强迫响应   总被引：3，自引：1，他引：3  

李建  周天军  宇如聪 《大气科学》2007,31(4):561-570

北大西洋地区的海温异常能够在多大程度上对大气产生影响，一直是一个有争议的问题。作者利用伴随北大西洋涛动出现的海温异常对大气环流模式CAM2.0.1进行强迫，考察了模式在冬季（12月、1月和2月）对三核型海温异常的响应。通过与欧洲中期天气预报中心提供的再分析资料的对比，发现该模式可以通过海温强迫在一定程度上再现具有北大西洋涛动特征的温度场和环流场。在北大西洋及其沿岸地区，模式模拟出了三核型的准正压响应，与经典的北大西洋涛动型大气异常是一致的。模式结果与北大西洋地区大气内部主导模态的差别主要体现在两个方面:一是异常中心位置多偏向于大洋上空，在陆地上的异常响应强度很弱；二是高纬地区对海温异常的响应不显著，没有强迫出与实际的大气模态相对应的异常中心，表明该地区海洋的反馈作用较弱。  相似文献   

Prediction skill of monthly SST in the North Atlantic Ocean in NCEP Climate Forecast System version 2   总被引：1，自引：0，他引：1  

Zeng-Zhen Hu  Arun Kumar  Bohua Huang  Wanqiu Wang  Jieshun Zhu  Caihong Wen 《Climate Dynamics》2013,40(11-12):2745-2759

This work evaluates the skill of retrospective predictions of the second version of the NCEP Climate Forecast System (CFSv2) for the North Atlantic sea surface temperature (SST) and investigates the influence of El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) on the prediction skill over this region. It is shown that the CFSv2 prediction skill with 0–8 month lead displays a “tripole”-like pattern with areas of higher skills in the high latitude and tropical North Atlantic, surrounding the area of lower skills in the mid-latitude western North Atlantic. This “tripole”-like prediction skill pattern is mainly due to the persistency of SST anomalies (SSTAs), which is related to the influence of ENSO and NAO over the North Atlantic. The influences of ENSO and NAO, and their seasonality, result in the prediction skill in the tropical North Atlantic the highest in spring and the lowest in summer. In CFSv2, the ENSO influence over the North Atlantic is overestimated but the impact of NAO over the North Atlantic is not well simulated. However, compared with CFSv1, the overall skills of CFSv2 are slightly higher over the whole North Atlantic, particularly in the high latitudes and the northwest North Atlantic. The model prediction skill beyond the persistency initially presents in the mid-latitudes of the North Atlantic and extends to the low latitudes with time. That might suggest that the model captures the associated air-sea interaction in the North Atlantic. The CFSv2 prediction is less skillful than that of SSTA persistency in the high latitudes, implying that over this region the persistency is even better than CFSv2 predictions. Also, both persistent and CFSv2 predictions have relatively low skills along the Gulf Stream.  相似文献   

Interannual-to-decadal variability of the North Atlantic from an ocean data assimilation system     

S.?MasinaEmail author  P.?Di Pietro  A.?Navarra 《Climate Dynamics》2004,23(5):531-546

An ocean analysis, assimilating both surface and subsurface hydrographic temperature data into a global ocean model, has been produced for the period 1958–2000, and used to study the time and space variations of North Atlantic upper ocean heat content (HC). Observational evidence is presented for interannual-to-decadal variability of upper ocean thermal fluctuations in the North Atlantic related to the North Atlantic Oscillation (NAO) variability over the last 40 years. The assimilation scheme used in the ocean analysis is a univariate, variational optimum interpolation of temperature. The first guess is produced by an eddy permitting global ocean general circulation forced by atmospheric reanalysis from the National Center for Environmental Prediction (NCEP). The validation of the ocean analysis has been done through the comparison with objectively analyzed observations and independent data sets. The method is able to compensate for the model systematic error to reproduce a realistic vertical thermal structure of the region and to improve consistently the model estimation of the time variability of the upper ocean temperature. Empirical orthogonal function (EOF) analysis shows that an important mode of variability of the wintertime upper ocean climate over the North Atlantic during the period of study is characterized by a tripole pattern both for SST and upper ocean HC. A similar mode is found for summer HC anomalies but not for summer SST. Over the whole period, HC variations in the subtropics show a general warming trend while the tropical and north eastern part of the basin have an opposite cooling tendency. Superimposed on this linear trend, the HC variability explained by the first EOF both in winter and summer conditions reveals quasi-decadal oscillations correlated with changes in the NAO index. On the other hand, there is no evidence of correlation in time between the NAO index and the upper ocean HC averaged over the whole North Atlantic which exhibits a substantial and monotonic warming trend during the last two decades of the analysis period. The maximum correlation is found between the leading principal component of winter HC anomalies and NAO index at 1 year lag with NAO leading. For SST anomalies significant correlation is found only for winter conditions. In contrast, for HC anomalies high correlations are found also in the summer suggesting that the summer HC keeps a memory of winter conditions.  相似文献   

冬季北大西洋涛动与中国北方极端低温相关性的年代际变化     

韩方红  陈海山  马鹤翟 《大气科学》2018,42(2):239-250

本文基于中国地面气温日值网格数据集（V2.0）,采用滑动相关和相关分析等方法,揭示了冬季北大西洋涛动（NAO）对中国北方极端低温影响的事实,进一步证实了东北后冬（1、2月）冷日（夜）与同期NAO相关性的年代际变化。研究发现:在20世纪80年代中期前,东北后冬冷日（夜）频发,与NAO的相关性较好,而在80年代中期后东北后冬冷日（夜）少发,与NAO的相关性减弱。其中,1月在1969~1988阶段,东北冷日（夜）与NAO的相关性最好,相关区域显著,相关系数可达-0.68（-0.66）,而在1989~2009阶段二者相关性最弱,相关区域不显著。进一步分析发现,在不同年代际背景下,NAO引起的大气环流异常是导致东北1月冷日（夜）与1月NAO相关性年代际变化的重要原因。相关性较好的年代,NAO引起的环流异常有利于冷涡等天气系统维持在贝加尔湖到东北一带,使东北地区气温偏低,冷日（夜）频发;相关性较弱的年代,不利于冷空气南下,使东北地区气温偏高,冷日（夜）少发。  相似文献   

Relationship between the Late Spring NAO and Summer Extreme Precipitation Frequency in the Middle and Lower Reaches of the Yangtze River   总被引：4，自引：0，他引：4       下载免费PDF全文

TIAN Bao-Qiang  FAN Ke 《大气和海洋科学快报》2012,5(6):455-460

The relationship between the late spring North Atlantic Oscillation (NAO) and the summer extreme precipitation frequency (EPF) in the middle and lower reaches of the Yangtze River Valley (MLYRV) is examined using an NECP/NCAR reanalysis dataset and daily precipitation data from 74 stations in the MLYRV. The results show a significant negative correlation between the May NAO index and the EPF over the MLYRV in the subsequent summer. In positive EPF index years, the East Asian westerly jet shifts farther southward, and two blocking high positive anomalies appear over the Sea of Okhotsk and the Ural Mountains. These anomalies are favorable to the cold air from the mid-high latitudes invading the Yangtze River Valley (YRV). The moisture convergence and the ascending motion dominate the MLYRV. The above patterns are reversed in negative EPF index years. A wave train pattern that originates from the North Atlantic extends eastward to the Mediterranean and then moves to the Tibetan Plateau and from there to the YRV, which is an important link in the May NAO and the summer extreme precipitation in the MLYRV. The wave train may be aroused by the tripole pattern of the SST, which can explain why the May NAO affects the summer EPF in the MLYRV.  相似文献   

瞬变天气涡旋对北大西洋涛动的增强效应   总被引：3，自引：2，他引：1  

张冬斌  金飞飞  李建平 《大气科学》2011,35(5):927-937

使用NCEP/NCAR再分析资料计算了冬季北大西洋瞬变涡旋活动强度与北大西洋涛动(NAO)逐日指数的时间序列,结果发现:当涡旋活动强度出现峰值后会伴随NAO模态增强现象;而随着NAO的增强,涡旋能量同落.为了判断是否涡流相互作用将天气尺度的能量转换为低频尺度的能量,使用瞬变涡度通量来研究涡度与能量的传输.通过分析瞬变涡...  相似文献   

20世纪90年代以后华北初春低温增强和北大西洋海温关系     

徐玮平  张杰  刘晨  孟祥新 《大气科学》2020,44(6):1167-1187

本文利用ECMWF再分析资料及Hadley中心提供的海温数据分析了20世纪90年代以后华北地区初春低温增强的原因,并通过数值模拟结果予以验证。结果表明,北大西洋“马蹄型”海温模态与影响我国华北地区的欧亚波列存在显著的相关关系。同时该海温模态与1997年以后北大西洋关键区垂直波作用通量有着较密切的相关关系,1997年以后北大西洋地区的500 hPa环流模态,整体呈现出东移南撤的趋势。1997年以后格陵兰岛东侧表面温度受异常热力强迫导致正值区增多,同时此处西风急流加大,有利于Rossby波向下游传播,导致其下游欧洲大陆地区形成暖脊。通过局地多尺度能量涡度分析法（Localized Multiscale Energy and Vorticity Analysis,简称MS-EVA）证明格陵兰岛东侧关键区表面温度的异常热力强迫作用与气压梯度力在对流层整层做正功,导致高层动能的增加并向外辐散,使得脊加强向北伸展。通过欧亚波列致使下游华北地区上空气旋式异常加强,促使亚洲极涡加强和稳定维持,华北地区温度下降剧烈,极端低温事件增多。最后通过CAM5.1模式模拟研究了北大西洋“马蹄型”海温模态对大气环流异常及华北地区极端低温的影响。模拟结果很好地验证了观测结果,进一步表明该海温模态可以通过激发出欧亚波列,影响欧亚大陆大气环流异常,进而导致我国华北地区气旋性加强和经向环流加大,极端低温事件增多。  相似文献   

Impacts of SST anomalies on the North Atlantic atmospheric circulation: a case study for the northern winter 1995/1996     

T. Losada  B. Rodríguez-Fonseca  C. R. Mechoso  H-Y. Ma 《Climate Dynamics》2007,29(7-8):807-819

The present paper selects the northern winter of December 1995–February 1996 for a case study on the impact of sea surface temperature (SST) anomalies on the atmospheric circulation over the North Atlantic and Western Europe. In the Atlantic, the selected winter was characterized by positive SST anomalies over the northern subtropics and east of Newfoundland, and negative anomalies along the US coast. A weak La Niña event developed in the Pacific. The North Atlantic Oscillation (NAO) index was low, precipitation over the Iberian Peninsula and northern Africa was anomalously high, and precipitation over northern Europe was anomalously low. The method of study consists of assessing the sensitivity of ensemble simulations by the UCLA atmospheric general circulation model (UCLA AGCM) to SST anomalies from the observation, which are prescribed either in the World Oceans, the Atlantic Ocean only, or the subtropical North Atlantic only. The results obtained are compared with a control run that uses global, time-varying climatological SST. The ensemble simulations with global and Atlantic-only SST anomalies both produce results that resemble the observations over the North Atlantic and Western Europe. It is suggested that the anomalous behavior of the atmosphere in the selected winter over those regions, therefore, was primarily determined by conditions within the Atlantic basin. The simulated fields in the tropical North Atlantic show anomalous upward motion and lower (upper) level convergence (divergence) in the atmosphere overlying the positive SST anomalies. Consistently, the subtropical jet intensifies and its core moves equatorward, and precipitation increases over northern Africa and southern Europe. The results also suggest that the SST anomalies in the tropical North Atlantic only do not suffice to produce the atmospheric anomalies observed in the basin during the selected winter. The extratropical SST anomalies would provide a key contribution through increased transient eddy activity, which causes an extension of the subtropical jet eastward from the coast of North America.  相似文献   

春季北大西洋三极型海温异常变化及其与NAO和ENSO的联系   总被引：1，自引：0，他引：1  

李忠贤  于怡秋  邓伟涛  曾刚  吴玲玲 《气象科学》2019,39(6):721-730

利用1951—2016年HadISST逐月海表温度(Sea Surface Temperature,SST)资料,NCEP/NCAR再分析资料以及1958—2016年美国伍兹霍尔海洋研究所(Woods Hole Oceanographic Institution,WHOI)提供的OAFlux数据集,运用经验正交函数分解(Empirical Orthogonal Function,EOF)和偏相关分析等统计方法,研究了春季北大西洋海温异常的主要特征及其与春季NAO和前期冬季ENSO联系。结果表明:春季北大西洋海温异常EOF的第一模态是自北而南出现的三极结构的海温距平型,其方差贡献率为35.7%。春季北大西洋三极型海温异常的形成主要受到春季NAO主导作用,还受到前期冬季热带中东太平洋海温异常的影响。消除前期冬季Niňo3.4的影响后,春季北大西洋三极型海温异常指数与同期北大西洋涛动(North Atlantic Oscillation,NAO)指数的偏相关系数分别为0.50,通过了99%置信度水平的显著性检验。消除春季NAO的影响后,春季北大西洋三极型海温异常指数与前期冬季Niňo3.4指数的偏相关系数为-0.26,通过了95%信度水平的显著性检验。春季NAO正(负)位相引起的海表风场和海表湍流热通量的异常,进而激发出正(负)位相的北大西洋三极型海温异常。前期冬季ENSO事件可以引起春季大气环流异常和热带外海温异常,进而调制春季NAO对北大西洋三极型海温异常的影响。  相似文献   

Ensemble Simulations of a Nonlinear Barotropic Model for the North Atlantic Oscillation          下载免费PDF全文

ZHANG Dong-Bin  JIN Fei-Fei  LI Jian-Ping  DING Rui-Qiang 《大气和海洋科学快报》2010,3(5):277-282

A numerical ensemble-mean approach was employed to solve a nonlinear barotropic model with stochastic basic flows to analyze the nonlinear effects in the formation of the North Atlantic Oscillation (NAO). The nonlinear response to external forcing was more similar to the NAO mode than the linear response was, indicating the importance of nonlinearity. With increasing external forcing and enhanced low-frequency anomalies, the effect of nonlinearity increased. Therefore, for strong NAO events, nonlinearity should be considered.  相似文献   

Temperature and surface pressure anomalies in Israel and the North Atlantic Oscillation     

T. Ben-Gai  A. Bitan  A. Manes  P. Alpert  Y. Kushnir 《Theoretical and Applied Climatology》2001,69(3-4):171-177

Summary Teleconnections associated with changing patterns of temperature and pressure anomalies over Israel during the second half of the 20th century are investigated. Relatively high, statistically significant, correlation coefficients of −0.8 and +0.9 were found between the North Atlantic Oscillation (NAO) Index anomalies and smoothed (5 year running mean) cool season temperature and surface pressure anomalies in Israel, respectively. A relatively high positive correlation, (r = 0.8) was also found between the NAO Index anomalies and smoothed geopotential height of the 1000 hPa pressure level, during the cool season at Bet Dagan radiosonde station located on the Israel Mediterranean coastal plain. Correlation coefficients between NAO Index anomalies and the higher standard pressure levels, 850 and 700 hPa, decrease gradually and become negative (not statistically significant) for the 500 hPa level. Received January 25, 2000/Revised March 6, 2001  相似文献