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1.
The representation of the wintertime North Atlantic Oscillation (NAO) and its relationship with atmospheric blocking and the Atlantic jet stream is investigated in a set of CMIP5 models. It is shown that some state-of-the-art climate models are unable to correctly simulate the physical processes connected to the NAO. This is especially true for models with a strongly underestimated frequency of high-latitude blocking over Greenland. In these models the first empirical orthogonal function (EOF1) of the Euro-Atlantic sector can represent at least three different categories of dominant modes of variability associated with different prevalent regions of blocking occurrence and jet stream displacements. It is therefore possible to show that such “biased NAOs” are connected with different dynamical processes with respect to the canonical NAO seen in observations. Since the NAO is a widely used concept in scientific community, the consequent “dynamical misinterpretation” of the NAO that can result when climate models are analyzed may have important implications for the NAO-related studies. This may be especially relevant for the ones involving climate scenarios, since these modeled NAOs may react differently to greenhouse gas forcing. 相似文献
2.
In the Northern hemisphere, regions characterized by an enhanced frequency of atmospheric blocking overlap significantly with
those associated with the major extra-tropical patterns of large-scale climate variability—namely the North Atlantic Oscillation
(NAO) and the Pacific North American (PNA) pattern. There is likewise an overlap in the temporal band-width of blocks and
these climate patterns. Here the nature of the linkage between blocks and the climate patterns is explored by using the ERA-40
re-analysis data set to examine (1) their temporal and spatial correlation and (2) the interrelationship between blocks and
the NAO/PNA. It is shown that a strong anti-correlation exists between blocking occurrence and the phase of the NAO (PNA)
in the North Atlantic (western North Pacific), and that there are distinctive inter-basin differences with a clear geographical
(over North Atlantic) and quantitative (over North Pacific) separation of typical blocking genesis/lysis regions during the
opposing phases of the climate patterns. An Empirical Orthogonal Function (EOF) analysis points to a significant influence
of blocking upon the NAO pattern (identifiable as the leading EOF in the Euro-Atlantic), and a temporal analysis indicates
that long-lasting blocks are associated with the development of negative NAO/PNA index values throughout their life-time.
In addition an indication of a cause-and effect relationship is set-out for the North Atlantic linkage. 相似文献
3.
The atmospheric low frequency variability at a regional or global scale is represented by teleconnection. Using monthly dataset of the Climatic Research Unit (CRU) for the period 1971–2016, the impacts of four large-scale teleconnection patterns on the climate variability over Southwest Asia are investigated. The large-scale features include the El Niño-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the East Atlantic (EA) teleconnection patterns, as well as western tropical Indian Ocean (WTIO) sea surface temperature anomaly index. Results indicate that ENSO and EA are the first leading modes that explain variation of Southwest Asian precipitation, with positive (negative) anomalies during El Niño (La Niña) and the negative (positive) phase of EA. Variation of Southwest Asian near-surface temperature is most strongly related to WTIO index, with above-average (below-average) temperature during the positive (negative) phase of WTIO index, although the negative (positive) phase of NAO also favours the above-average (below-average) temperature. On the other hand, temperature (precipitation) over Southwest Asia shows the least response to ENSO (WTIO). ENSO and EA individually explain 13 percent annual variance of precipitation, while WTIO index explains 36 percent annual variance of near-surface temperature over Southwest Asia. Analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis Interim (ERA-Interim) data indicated establishments of negative (positive) geopotential height anomalies in the middle troposphere over Southwest Asia during El Niño (La Niña) or the negative (positive) phase of NAO, EA and WTIO. The response of precipitation variability over Southwest Asia to NAO is opposite to that expected from the geopotential height anomalies, but the correlation between precipitation and NAO is not statistically significant. Due to predictability of large-scale teleconnections, results of this study are encouraging for improvement of the state-of-the-art seasonal prediction of the climate over Southwest Asia. 相似文献
4.
Holocene climate modes are identified by the statistical analysis of reconstructed sea surface temperatures (SSTs) from the tropical and North Atlantic regions. The leading mode of Holocene SST variability in the tropical region indicates a rapid warming from the early to mid Holocene followed by a relatively weak warming during the late Holocene. The dominant mode of the North Atlantic region SST captures the transition from relatively warm (cold) conditions in the eastern North Atlantic and the western Mediterranean Sea (the northern Red Sea) to relatively cold (warm) conditions in these regions from the early to late Holocene. This pattern of Holocene SST variability resembles the signature of the Arctic Oscillation/North Atlantic Oscillation (AO/NAO). The second mode of both tropical and North Atlantic regions captures a warming towards the mid Holocene and a subsequent cooling. The dominant modes of Holocene SST variability emphasize enhanced variability around 2300 and 1000 years. The leading mode of the coupled tropical-North Atlantic Holocene SST variability shows that an increase of tropical SST is accompanied by a decrease of SST in the eastern North Atlantic. An analogy with the instrumental period as well as the analysis of a long-term integration of a coupled ocean-atmosphere general circulation model suggest that the AO/NAO is one dominant mode of climate variability at millennial time scales. 相似文献
5.
The variable link between PNA and NAO in observations and in multi-century CGCM simulations 总被引：1，自引：1，他引：0
The link between the Pacific/North American pattern (PNA) and the North Atlantic Oscillation (NAO) is investigated in reanalysis data (NCEP, ERA40) and multi-century CGCM runs for present day climate using three versions of the ECHAM model. PNA and NAO patterns and indices are determined via rotated principal component analysis on monthly mean 500?hPa geopotential height fields using the varimax criteria. On average, the multi-century CGCM simulations show a significant anti-correlation between PNA and NAO. Further, multi-decadal periods with significantly enhanced (high anti-correlation, active phase) or weakened (low correlations, inactive phase) coupling are found in all CGCMs. In the simulated active phases, the storm track activity near Newfoundland has a stronger link with the PNA variability than during the inactive phases. On average, the reanalysis datasets show no significant anti-correlation between PNA and NAO indices, but during the sub-period 1973?C1994 a significant anti-correlation is detected, suggesting that the present climate could correspond to an inactive period as detected in the CGCMs. An analysis of possible physical mechanisms suggests that the link between the patterns is established by the baroclinic waves forming the North Atlantic storm track. The geopotential height anomalies associated with negative PNA phases induce an increased advection of warm and moist air from the Gulf of Mexico and cold air from Canada. Both types of advection contribute to increase baroclinicity over eastern North America and also to increase the low level latent heat content of the warm air masses. Thus, growth conditions for eddies at the entrance of the North Atlantic storm track are enhanced. Considering the average temporal development during winter for the CGCM, results show an enhanced Newfoundland storm track maximum in the early winter for negative PNA, followed by a downstream enhancement of the Atlantic storm track in the subsequent months. In active (passive) phases, this seasonal development is enhanced (suppressed). As the storm track over the central and eastern Atlantic is closely related to the NAO variability, this development can be explained by the shift of the NAO index to more positive values. 相似文献
6.
Decadal trends of main Eurasian oscillations and the Eastern Mediterranean precipitation 总被引：1，自引：0，他引：1
Summary ?The role of the two main European low-frequency oscillations – the East Atlantic/West Russian (EA/WR) and the North Atlantic
Oscillation (NAO), in controlling the precipitation in the Eastern Mediterranean region is investigated based on the NCEP/NCAR
reanalysis and the Israeli precipitation data for 1958–1998. The data on the EA/WR and NAO indices, received from the NCEP
Climate Prediction Center, are also adapted. Composite mean sea level and precipitation anomaly patterns are constructed and
analyzed. In addition to the widely investigated positive NAO trend, another, also positive EA/WR trend characterized atmospheric
developments during the period. During NAO positive months, the EA/WR-associated positive SLP anomaly areas were shifted from
the east Atlantic to southwest Europe. The areas were shifted to the north during the NAO-negative months and were located
over central and northern Europe. This demonstrates that the use of fixed pressure NAO patterns may be not the optimum way
to understand climate variability. Analysis of the NAO, EA/WR patterns, as well as that of their decadal trends, demonstrated
a relationship between the main European oscillations and the EM precipitation. The results allow explanation of the observed
reduction of the north Israeli precipitation by the EA/WR positive trend during the period.
Received April 5, 2001; Revised February 14, 2002 相似文献
7.
IPCC AR4中海气耦合模式对中国东部夏季降水及PDO、NAO年代际变化的模拟能力分析 总被引：5，自引：1，他引：4
利用1880—1999年中国东部35站的观测降水资料、英国Hadley中心的海温和海平面气压资料以及IPCC第4次评估报告（AR4）中20世纪气候模拟试验（20C3M）的模式输出结果,对IPCCAR4中22个耦合模式所模拟的我国东部夏季降水的年代际变化情况以及太平洋年代际涛动（PDO）和北大西洋涛动（NAO）的年代际变化情况进行了分析。结果显示,这些模式对20世纪我国东部夏季降水年代际变化的模拟结果并不理想,但对降水在20世纪70年代中期前后的突变具有一定的模拟能力。其中IAP_FGOALSL_0_G可以大致模拟出20世纪70年代中期前后降水型的突变特征,而BCCR_BCM2_0和UKMO_HadGEM1则可以模拟出华北地区降水在20世纪70年代中期之后减少的现象。对于引起我国东部夏季降水年代际变化的重要因子PDO和NAO,模式对它们年代际变化的模拟效果略好于降水。多数模式都可以模拟出PDO和NAO的空间模态,其中CNRM_CM3和UKMO_HadGEM1对PDO年代际变化（8 a以上）的模拟与实际情况比较相似,并可以模拟出20世纪70年代中期之后PDO由负位相转变为正位相的情况,而模式UKMO_HadGEM1也对NAO的年代际变化以及1980年以来不断加强的趋势模拟较好。 相似文献
8.
9.
A Review of Decadal／Interdecadal Climate Variation Studies in China 总被引：22，自引：4，他引：18
Decadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation have also been completed by Chinese scientists in recent years. In this paper, an introduction in outline for interdecadal climate variation research in China is presented. The content includes the features of interdecadal climate variability in China, global warming and interdecadal temperature variability,the NAO (the North Atlantic Oscillation)/NPO (the North Pacific Oscillation) and interdecadal climate variation in China, the interdecadal variation of the East Asian monsoon, the interdecadal mode of SSTA(Sea Surface Temperature Anomaly) in the North Pacific and its climate impact, and abrupt change feature of the climate. 相似文献
10.
M. J. Salinger 《Climatic change》2013,119(1):23-35
Climatic variability has profound effects on the distribution, abundance and catch of oceanic fish species around the world. The major modes of this climate variability include the El Niño-Southern Oscillation (ENSO) events, the Pacific Decadal Oscillation (PDO) also referred to as the Interdecadal Pacific Oscillation (IPO), the Indian Ocean Dipole (IOD), the Southern Annular Mode (SAM) and the North Atlantic Oscillation (NAO). Other modes of climate variability include the North Pacific Gyre Oscillation (NPGO), the Atlantic Multidecadal Oscillation (AMO) and the Arctic Oscillation (AO). ENSO events are the principle source of interannual global climate variability, centred in the ocean–atmosphere circulations of the tropical Pacific Ocean and operating on seasonal to interannual time scales. ENSO and the strength of its climate teleconnections are modulated on decadal timescales by the IPO. The time scale of the IOD is seasonal to interannual. The SAM in the mid to high latitudes of the Southern Hemisphere operates in the range of 50–60 days. A prominent teleconnection pattern throughout the year in the Northern Hemisphere is the North Atlantic Oscillation (NAO) which modulates the strength of the westerlies across the North Atlantic in winter, has an impact on the catches of marine fisheries. ENSO events affect the distribution of tuna species in the equatorial Pacific, especially skipjack tuna as well as the abundance and distribution of fish along the western coasts of the Americas. The IOD modulates the distribution of tuna populations and catches in the Indian Ocean, whilst the NAO affects cod stocks heavily exploited in the Atlantic Ocean. The SAM, and its effects on sea surface temperatures influence krill biomass and fisheries catches in the Southern Ocean. The response of oceanic fish stocks to these sources of climatic variability can be used as a guide to the likely effects of climate change on these valuable resources. 相似文献
11.
Arctic Oscillation and Antarctic Oscillation in Internal Atmospheric Variability with an Ensemble AGCM Simulation 总被引：1，自引：0，他引：1
In this study, we investigated the features of Arctic Oscillation （AO） and Antarctic Oscillation （AAO）, that is, the annular modes in the extratropics, in the internal atmospheric variability attained through an ensemble of integrations by an atmospheric general circulation model （AGCM） forced with the global observed SSTs. We focused on the interannual variability of AO/AAO, which is dominated by internal atmospheric variability. In comparison with previous observed results, the AO/AAO in internal atmospheric variability bear some similar characteristics, but exhibit a much clearer spatial structure： significant correlation between the North Pacific and North Atlantic centers of action, much stronger and more significant associated precipitation anomalies, and the meridional displacement of upper-tropospheric westerly jet streams in the Northern/Southern Hemisphere. In addition, we examined the relationship between the North Atlantic Oscillation （NAO）/AO and East Asian winter monsoon （EAWM）. It has been shown that in the internal atmospheric variability, the EAWM variation is significantly related to the NAO through upper-tropospheric atmospheric teleconnection patterns. 相似文献
12.
In this paper, the interannual variability simulated by the coupled ocean-atmosphere general circulation model of the Institute of Atmospheric Physics (IAP CGCM) in 40 year integrations is analyzed, and compared with that by the corresponding IAP AGCM which uses the climatic sea surface temperature as the boundary condition in 25 year integrations.The mean climatic states of January and July simulated by IAP CGCM are in good agreement with that by IAP AGCM, i.e., no serious ‘climate drift’ occurs in the CGCM simulation. A comparison of the results from AGCM and CGCM indicates that the standard deviation of the monthly averaged sea level pressure simulated by IAP CGCM is much greater than that by IAP AGCM in tropical region. In addition, both Southern Oscillation (SO) and North Atlantic Oscillation (NAO) can be found in the CGCM simulation for January, but these two oscillations do not exist in the AGCM simulation.The interannual variability of climate may be classified into two types: one is the variation of the annual mean, another is the variation of the annual amplitude. The ocean-atmosphere interaction mainly increases the first type of variability. By means of the rotated EOF, the most important patterns corresponding to the two types of interannual variability are found to have different spatial and temporal characteristics. 相似文献
13.
Simulating the winter North Atlantic Oscillation: the roles of internal variability and greenhouse gas forcing 总被引：5，自引：2，他引：5
T. J. Osborn 《Climate Dynamics》2004,22(6-7):605-623
Analysis of simulations with seven coupled climate models demonstrates that the observed variations in the winter North Atlantic Oscillation (NAO), particularly the increase from the 1960s to the 1990s, are not compatible with either the internally generated variability nor the response to increasing greenhouse gas forcing simulated by these models. The observed NAO record can be explained by a combination of internal variability and greenhouse gas forcing, though only by the models that simulate the strongest variability and the strongest response. These models simulate inter-annual variability of the NAO index that is significantly greater than that observed, and can no longer explain the observed record if the simulated NAO indices are scaled so that they have the same high-frequency variance as that observed. It is likely, therefore, that other external forcings also contributed to the observed NAO index increase, unless the climate models are deficient in their simulation of inter-decadal NAO variability or their simulation of the response to greenhouse gas forcing. These conclusions are based on a comprehensive analysis of the control runs and transient greenhouse-gas-forced simulations of the seven climate models. The simulations of mean winter circulation and its pattern of inter-annual variability are very similar to the observations in the Atlantic half of the Northern Hemisphere. The winter atmospheric circulation response to increasing greenhouse gas forcing shows little inter-model similarity at the regional scale, and the NAO response is model-dependent and sensitive to the index used to measure it. At the largest scales, however, sea level pressure decreases over the Arctic Ocean in all models and increases over the Mediterranean Sea in six of the seven models, so that there is an increase of the NAO in all models when measured using a pattern-based index. 相似文献
14.
Precipitation (P) and freshwater (E-P) fluxes at the air-sea interface are investigated in the Atlantic Ocean sector using the reanalyses of the European Centre
for Medium Range Weather Forecasts (ERA) and of the National Centers for Environmental Prediction (NCEP). A canonical correlation
analysis method between these fields and sea level pressure (SLP) is used to identify patterns. We also test whether precipitation
and freshwater fluxes can be reconstructed from SLP data. In the winter months, patterns associated with both the North Atlantic
Oscillation (NAO) and the East Atlantic (EA) mode are identified. The signals are strong enough to be reconstructed from the
reanalysis fields, and they correspond to a significant part of the variability. The NAO signal is more robust than the EA
one. The NAO-related variability mode is also present when the monthly precipitation rate is averaged for the winter season
and even for annual averages. However, in the later case, other variability of natural origin (for instance, ENSO variability)
or noise from the model and assimilation system prevents the reconstruction of E-P associated with NAO from SLP variability. Difficulties are identified in the tropical Atlantic with a different behaviour
of NCEP and ERA precipitation variability, especially near the Inter Tropical Convergence Zone (ITCZ). The ERA patterns suggest
a NAO signature in the tropical Atlantic which has clear monthly patterns and indicates a link between the phase of NAO and
changes in the position and intensity of ITCZ. However, the analysis of winter rainfall based on satellite and in situ data
does not support the monthly tropical pattern of ERA precipitation although it suggests a relation between convection near
15°S and NAO during northern winter.
Received: 10 February 2000 / Accepted: 7 May 2001 相似文献
15.
Ivana Tošić Ivana Hrnjak Milivoj B. Gavrilov Miroslava Unkašević Slobodan B. Marković Tin Lukić 《Theoretical and Applied Climatology》2014,117(1-2):331-341
Annual and seasonal variability of precipitation observed at 92 stations in Vojvodina (Serbia) were analyzed during the period 1946–2006. The rainfall series were examined by means of the empirical orthogonal functions (EOF). The first set of singular vectors explains from 68.8 % (in summer) to 81.8 % (in winter) of the total variance. The temporal variability of the time series associated with the main EOF configurations (the principal components, PCs) was examined using the Mann–Kendall test and the spectral analysis. The time series of PC1 revealed decreasing trend in the winter and spring precipitation and increasing trend in the autumn, summer, and annual precipitation. The relationships between the first PC and circulation patterns, such as the North Atlantic Oscillation (NAO), the East Atlantic (EA) pattern, and East Atlantic/West Russia pattern, were also investigated. The PC1, displaying temporal behavior of the first mode, demonstrated evident correspondence with the NAO index in analysis of the annual, winter, and autumn precipitation. Power spectra of the PC1 show statistically significant oscillations of about 3.3 years for the spring precipitation and about 8 and 15 years for the winter precipitation. Comparisons with spectral analysis of authors for some regions in Europe, most of them in the Mediterranean domain, show that similar periodicities are detected. 相似文献
16.
Prediction of primary climate variability modes at the Beijing Climate Center 总被引：3，自引：2，他引：1 
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下载免费PDF全文 Hong-Li Ren Fei-Fei Jin Lianchun Song Bo Lu Ben Tian Jinqing Zuo Ying Liu Jie Wu Chongbo Zhao Yu Nie Peiqun Zhang Jin Ba Yujie Wu Jianghua Wan Yuping Yan Fang Zhou 《Acta Meteorologica Sinica》2017,31(1):204-223
Climate variability modes, usually known as primary climate phenomena, are well recognized as the most important predictability sources in subseasonal–interannual climate prediction. This paper begins by reviewing the research and development carried out, and the recent progress made, at the Beijing Climate Center (BCC) in predicting some primary climate variability modes. These include the El Niño–Southern Oscillation (ENSO), Madden–Julian Oscillation (MJO), and Arctic Oscillation (AO), on global scales, as well as the sea surface temperature (SST) modes in the Indian Ocean and North Atlantic, western Pacific subtropical high (WPSH), and the East Asian winter and summer monsoons (EAWM and EASM, respectively), on regional scales. Based on its latest climate and statistical models, the BCC has established a climate phenomenon prediction system (CPPS) and completed a hindcast experiment for the period 1991–2014. The performance of the CPPS in predicting such climate variability modes is systematically evaluated. The results show that skillful predictions have been made for ENSO, MJO, the Indian Ocean basin mode, the WPSH, and partly for the EASM, whereas less skillful predictions were made for the Indian Ocean Dipole (IOD) and North Atlantic SST Tripole, and no clear skill at all for the AO, subtropical IOD, and EAWM. Improvements in the prediction of these climate variability modes with low skill need to be achieved by improving the BCC’s climate models, developing physically based statistical models as well as correction methods for model predictions. Some of the monitoring/prediction products of the BCC-CPPS are also introduced in this paper. 相似文献
17.
J. Garc��a-Serrano B. Rodr��guez-Fonseca I. Blad�� P. Zurita-Gotor A. de la C��mara 《Climate Dynamics》2011,37(9-10):1727-1743
The dominant variability modes of the North Atlantic-European rotational flow are examined by applying a principal component analysis (PCA/EOF) to the 200?hPa streamfunction mid-winter anomalies (Jan?CFeb monthly means). The results reveal that, when this norm is used, the leading mode (EOF1) does not correspond to the traditional North Atlantic Oscillation (NAO, which appears in our analysis as the second leading mode, EOF2) but is the local manifestation of the leading hemispheric streamfunction EOF. The regression of this regional mode onto the global SST field exhibits a clear El Ni?o signature, with no signal over the Atlantic, while the associated upper height anomalies resemble the Tropical/Northern Hemisphere (TNH) pattern. East of North America, this TNH-like wavetrain produces a meridional dipole-like pattern at lower levels. Although in some ways this pattern resembles the NAO (EOF2), the dynamics of these two modes are very different in that only EOF2 is associated with a latitudinal shift of the North Atlantic stormtrack. Thus, the choice of the streamfunction norm in the EOF analysis allows the separation of two different phenomena that can produce similar dipolar surface pressure anomalies over the North Atlantic but that have different impact on European climate. These two modes also differ on their contribution to variability at lower levels: while NAO-EOF2 is mostly confined to the North Atlantic, TNH-EOF1 has a more annular, global character. At upper levels NAO-EOF2 also produces a global pattern but with no annular structure, reminiscent of the ??circumglobal?? teleconnection. 相似文献
18.
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
19.
The impacts of four teleconnection patterns on atmospheric circulation components over Eurasia and the Pacific region, from low to high latitudes in the Northern Hemisphere (NH), were investigated comprehensively in this study. The patterns, as identified by the Climate Prediction Center (USA), were the East Atlantic (EA), East Atlantic/Western Russia (EAWR), Polar/Eurasia (POLEUR), and Scandinavian (SCAND) teleconnections. Results indicate that the EA pattern is closely related to the intensity of the subtropical high over different sectors of the NH in all seasons, especially boreal winter. The wave train associated with this pattern serves as an atmospheric bridge that transfers Atlantic influence into the low-latitude region of the Pacific. In addition, the amplitudes of the EAWR, SCAND, and POLEUR patterns were found to have considerable control on the “Vangengeim–Girs” circulation that forms over the Atlantic–Eurasian region in winter or spring. The EA and EAWR mainly affect the westerlies in winter and spring and the POLEUR and SCAND, respectively, in summer and winter. Strong westerlies confine the extension of the North Polar vortex, which generally results in a small weak vortex and a shallow East Asian trough located in a position further east than normal. Furthermore, the North Polar vortex presents significant connections with the patterns during winter and summer. Analyses in this work suggest that the teleconnection patterns in summer could be driven, at least partly, by the Atlantic Multidecadal Oscillation, which to some degree might transmit the influence of the Atlantic Ocean to Eurasia and the Pacific region. 相似文献
20.
The North Atlantic Oscillation （NAO） is one of the leading modes of climate variability in the Northern Hemisphere. It has been shown that it clearly relates to changes in meteorological variables, such as surface temperature, at hemispherical scales. However, recent studies have revealed that the NAO spatial pattern also depends upon solar forcing. Therefore, its effects on meteorological variables must vary depending upon this factor. Moreover, it could be that the Sun affects climate through variability patterns, a hypothesis that is the focus of this study. We find that the relationship between the NAO/AO and hemispheric temperature varies depending upon solar activity. The results show a positive significant correlation only when solar activity is high. Also, the results support the idea that solar activity influences tropospheric climate fluctuations in the Northern Hemisphere via the fluctuations of the stratospheric polar vortex . 相似文献