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1.
热带平流层臭氧准两年周期振荡的特征及数值模拟 总被引：19，自引：1，他引：19
利用HALOE的观测资料、对热带地区平流层臭氧垂直分布的年际变化及其准两年周期振荡（QBO）进行研究，并同赤道上空平均的纬向风场的准两年周期振荡进行了模拟研究。资料分析结果表明，平流层臭氧浓度高值区的位置在南北方向上和垂直方向上的有明显的准两年周期，臭氧浓度高值中心的南北移动和上下移动又引起局地臭氧总量的周期性变化和准两年周期振荡南北半球不对称。而臭氧浓度中心位置的准两年周期变化与赤道上空平均纬向风的准两年周期振荡密切相关。资料分析还表明，赤道上空平流层中臭氧浓度QBO的位相随高度变化多次。模拟试验表明，纬向风QBO引起垂直经圈环流的变化，在平流层有三对余差环流圈。它们对O3在不同纬度和高度的输送是引起O3准两年周期振荡的重要动力原因。其中，余差环流在平流层中层（25－35km)的环流圈起着重要的作用。 相似文献
2.
Bohua Huang Zeng-Zhen Hu James L. Kinter III Zhaohua Wu Arun Kumar 《Climate Dynamics》2012,38(1-2):1-23
The stratospheric quasi-biennial oscillation (QBO) and its association with the interannual variability in the stratosphere and troposphere, as well as in tropical sea surface temperature anomalies (SSTA), are examined in the context of a QBO life cycle. The analysis is based on the ERA40 and NCEP/NCAR reanalyses, radiosonde observations at Singapore, and other observation-based datasets. Both reanalyses reproduce the QBO life cycle and its associated variability in the stratosphere reasonably well, except that some long-term changes are detected only in the NCEP/NCAR reanalysis. In order to separate QBO from variability on other time scales and to eliminate the long-term changes, a scale separation technique [Ensemble Empirical Mode Decomposition (EEMD)] is applied to the raw data. The QBO component of zonal wind anomalies at 30?hPa, extracted using the EEMD method, is defined as a QBO index. Using this index, the QBO life cycle composites of stratosphere and troposphere variables, as well as SSTA, are constructed and examined. The composite features in the stratosphere are generally consistent with previous investigations. The correlations between the QBO and tropical Pacific SSTA depend on the phase in a QBO life cycle. On average, cold (warm) SSTA peaks about half a year after the maximum westerlies (easterlies) at 30?hPa. The connection of the QBO with the troposphere seems to be associated with the differences of temperature anomalies between the stratosphere and troposphere. While the anomalies in the stratosphere propagate downward systematically, some anomalies in the troposphere develop and expand vertically. Therefore, it is possible that the temperature difference between the troposphere and stratosphere may alter the atmospheric stability and tropical deep convection, which modulates the Walker circulation and SSTA in the equatorial Pacific Ocean. 相似文献
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本文构造了一个３４层球坐标原始方程波－流相互耦合谱模式，利用此模式从拉格朗日平均环流的观点研究了在常定流下行星波对臭氧的输运作用。研究结果表明，行星波对臭氧的输运有明显的季节变化，在北半球冬季，由于行星波上传到平流层而大大增强了中高纬地区向极地向下的Ｏ３输运；并且还表明，热带纬向风的ＱＢＯ不仅通过影响东、西风切变而引起热带Ｏ３分布的年际变化，而且通过影响行星波的传播引起了行星波对Ｏ３输运的年际变化，这表现为当热带纬向风处于东风位相时，中高纬地区行星波对Ｏ３的输运比西风位相时强。 相似文献
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北半球冬季行星波的传播及其输运作用 总被引：20，自引：0，他引：20
利用变换欧拉平均方程讨论了行星波动力学。观测和模拟结果都表明,在北半球冬季准定常行星波的经向传播存在两支波导。一支为高纬度波导,另一支则为低纬度波导。这些结果与理论分析相当一致。通过对EP通量进一步的研究表明,平流层爆发性增温是沿高纬度波导传播的异常行星波与平均气流相互作用的结果。而热带风场的准两年周期振荡（QBO）是低纬度平流层下层大气纬向平均流的一个重要年际变化,它可以影响行星波沿低纬度波导的传播;此外,由一个行星波一平均流耦合模式模拟的结果表明,这个热带风场的变化还可以通过波流相互作用调制行星波沿高纬度波导的传播。 行星波对臭氧的输运作用在文中也进行了分析。行星波强迫出的剩余平均环流表明,耗散的行星波有强的输运作用;向北的涡动热量输送可以强迫出一个正的输运环流,其在低纬度上升并在高纬度下沉。同时研究还表明,热带风场的QBO对行星波传播的调制对输运环流也有重要影响,模式结果表明,在QBO的东风位相期间行星波引起的输运作用明显增强,其结果可用于解释平流层高纬度臭氧的年际变化。 相似文献
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The harmonic analyses of monthly mean total ozone in the atmosphere over the Northern Hemisphere for 26 years (1960-1985) are made by using the Fourier expansion. The analysed results show that there is obviously a quasi-biennial oscillation (QBO) in the interannual variations of the amplitudes of total ozone. Generally, the amplitudes of wavenumber 1 and 2 during the westerly of the equatorial QBO are larger than those during the easter-ly. In the early winter, the amplitude of wavenumber 1 during the easterly phase is larger, and in the late winter, it is larger during the westerly phase. These are in good agreement with the observational distributions. 相似文献
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Using the SST data series in tropical ocean(20°N-20°S,50°E-80°W)during 1951-1997 to calculate its monthly mean square deviation,the work obtains results showing that interannual SST variability of the Pacific is more significant than that of the Indian Ocean.Especially near the central and eastern equatorial Pacific(165°W-90°W,6°N-6°S）。where it ranges from 2℃ to 4℃.The interannual SST variability is obvious in November and December but small in March and April.The interannual variabiltiy of “warm pool“SST is not so obvious as that of the eastern equatorial Pacific,Howerver,interannual SST variability of the Indian Ocean ranges from 1℃to 2℃ or so,being smaller than that of the Pacific,In the Indian ocean.Interannual SST variability of the Southern Hemisphere is more obvious than that of the Northern Hemisphere,According to above characterstics of interannual SST variability,the key sectors are determined. 相似文献
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This study applied the modified spatial simi- larity coefficient method to define the seasonal transition （ST） from winter to summer in the extratropical strato- sphere of the Northern Hemisphere. The features of the ST were examined using European Centre for Medium- Range Weather Forecasts （ECMWF） Interim reanalysis data; and the results showed that the time and duration of the ST, which is affected by the activity of planetary waves （PW） in the stratosphere, largely depended on the geophysical locations. This study also investigated the interannual variability of the ST and its relationship with stratospheric sudden warming （SSW） and the qua- si-biennial oscillation （QBO）. It was shown that the late-onset SSW events （after 22 January） are close to the start of the ST. An easterly （westerly） QBO hastens （de- lays） the onset of the ST in high and low latitudes, whereas it delays （hastens） the ST in midlatitudes. The duration of the ST is significantly affected by the QBO. The influence of SSW and the QBO have different sig- nificance in different latitudes, so they are both important and irreplaceable factors. 相似文献
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INTERANNUAL LOW-FREQUENCY OSCILLATIONS OF MERIDIONAL WINDS OVER THE EQUATORIAL INDIAN-PACIFIC OCEANS 
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下载免费PDF全文 Based on analysis of the meridional winds over oceanic areas and SST for 1950-1979 extracted from the data sets of COADS, the long-term variability of the meridional winds over the equatorial Indian-Pacific oceans and its relationship to the onset and development of El Nino events have been studied. The major results are as follows:(1) There is a great similarity between ITCZ over the Pacific and SST in the seasonal trend, with ITCZ and high SST found in the Southern Hemisphere in winter and in the Northern Hemisphere in summer.During El Nino years, unusual meridional winds were often observed, with significant convergence of meridional winds occurring over near-equatorial regions.(2) For the near-equatorial meridional winds, there are three types of interannual LFO:QBO, SO, FYO. QBO plays an important role in the unusual behavior of meridional winds for El Nino years, while SO is very important for both El Nino and cold water years. These two oscillations may fit well to the observed variation in the meridional wind. FYO may enhance the variation of meridional winds.(3) Interannual LFO of meridional winds originates in the Indian Ocean-Maritime Continent and coastal area of East Pacific. Unusual activities of winter monsoon in both hemispheres and trade winds off the coastal area of East Pacific are believed to be their major cause.(4) Monsoon-trade interaction shows up in the significant amplification of the disturbances of meridional winds while they propagate eastward from monsoon area to trade wind area. 相似文献
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N. E. Graham C. M. Ammann D. Fleitmann K. M. Cobb J. Luterbacher 《Climate Dynamics》2011,37(5-6):1217-1245
Widely distributed proxy records indicate that the Medieval Climate Anomaly (MCA; ~900–1350 AD) was characterized by coherent shifts in large-scale Northern Hemisphere atmospheric circulation patterns. Although cooler sea surface temperatures in the central and eastern equatorial Pacific can explain some aspects of medieval circulation changes, they are not sufficient to account for other notable features, including widespread aridity through the Eurasian sub-tropics, stronger winter westerlies across the North Atlantic and Western Europe, and shifts in monsoon rainfall patterns across Africa and South Asia. We present results from a full-physics coupled climate model showing that a slight warming of the tropical Indian and western Pacific Oceans relative to the other tropical ocean basins can induce a broad range of the medieval circulation and climate changes indicated by proxy data, including many of those not explained by a cooler tropical Pacific alone. Important aspects of the results resemble those from previous simulations examining the climatic response to the rapid Indian Ocean warming during the late twentieth century, and to results from climate warming simulations—especially in indicating an expansion of the Northern Hemisphere Hadley circulation. Notably, the pattern of tropical Indo-Pacific sea surface temperature (SST) change responsible for producing the proxy-model similarity in our results agrees well with MCA-LIA SST differences obtained in a recent proxy-based climate field reconstruction. Though much remains unclear, our results indicate that the MCA was characterized by an enhanced zonal Indo-Pacific SST gradient with resulting changes in Northern Hemisphere tropical and extra-tropical circulation patterns and hydroclimate regimes, linkages that may explain the coherent regional climate shifts indicated by proxy records from across the planet. The findings provide new perspectives on the nature and possible causes of the MCA—a remarkable, yet incompletely understood episode of Late Holocene climatic change. 相似文献
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This study investigates the variations in the tropical ascending branches(TABs) of Hadley circulations(HCs) during past decades, using a variety of reanalysis datasets. The northern tropical ascending branch(NTAB) and the southern tropical ascending branch(STAB), which are defined as the ascending branches of the Northern Hemisphere HC and Southern Hemisphere HC, respectively, are identified and analyzed regarding their trends and variability. The reanalysis datasets consistently show a persistent increase in STAB during past decades, whereas they show less consistency in NTAB regarding its decadalto multidecadal variability, which generally features a decreasing trend. These asymmetric trends in STAB and NTAB are attributed to asymmetric trends in the tropical SSTs. The relationship between STAB/NTAB and tropical SSTs is further examined regarding their interannual and decadal-to multidecadal variability. On the interannual time scale, the STAB and NTAB are essentially modulated by the eastern-Pacific type of ENSO, with a strengthened(weakened) STAB(NTAB) under an El Ni ?no condition. On the decadal-to multidecadal time scale, the variability of STAB and NTAB is closely related to the southern tropical SSTs and the meridional asymmetry of global tropical SSTs, respectively. The tropical eastern Pacific SSTs(southern tropical SSTs) dominate the tropical SST–NTAB/STAB relationship on the interannual(decadal-to multidecadal)scale, whereas the NTAB is a passive factor in this relationship. Moreover, a cross-hemispheric relationship between the NTAB/STAB and the HC upper-level meridional winds is revealed. 相似文献
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中国降水准2年主振荡模态与全球500 hPa环流联系的年代际变化 总被引：8，自引：0，他引：8
用近51年(1951～2001年)观测资料,研究太平洋年代际振荡(PDO)冷暖位相中国降水量准2年主振荡型传播特征的差异,并讨论对应的全球500 hPa环流低频波列传播途径的变化及可能原因.同时提出年际振荡强度不稳定指数,讨论了中国降水和全球500 hPa高度准2年周期振荡(QBO)强度时间不稳定的空间分布.通过主振荡型分析(POP)发现,在PDO冷位相(1951～1976年),准2年时间尺度的中国降水POP1的主要活动区域在长江中游地区,对应的500 hPa低频场是大西洋欧亚波列(AEU)和西大西洋遥相关型(WA)以及南太平洋副热带波列(SSP);在PDO暖位相(1977～2001年),POP1的活动区域迅速北移并扩大到整个长江和淮河流域,对应的500 hPa低频场变为欧亚太平洋-南印度洋-南北大西洋波列(EUP-SI-SNA).因此,PDO冷暖位相中影响中国降水准2年主振荡模态的低频波列的传播途径和强度存在显著差异,PDO对中国降水量准2年主振荡型主要模态(POP1)及其伴随的全球500 hPa环流低频波列活动区域的时间变化有重要调制作用,与两个半球中纬度西风气流强度的年代际变化密切相关.由振荡强度时间变化指数分析表明,中国降水QBO强度不稳定区域位于长江中游、长江下游、浙江东部、广东东部、华北地区和青藏高原东北侧附近地区,这些地区降水QBO的强度随PDO位相转变而发生显著的年代际突变.对于全球500 hPa高度,其QBO强度不稳定区域在南太平洋中高纬度、副热带南北大西洋地区和亚洲、北太平洋、北美大陆中高纬度地区、北半球副热带西太平洋地区以及南北半球热带和副热带东太平洋地区,表现为对于赤道的非对称空间分布,特别是南北太平洋热带和副热带地区500hPa环流QBO强度在年代际时间尺度上呈现正负反向变化的空间结构,而且南北极附近地区的QBO强度在PDO暖位相显著增强,反映了全球大气环流QBO强度与PDO相互作用的空间特征. 相似文献
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1. IntroductionOzone is one of the trace gases in the atmosphere distributed in 10--50 km altitude withthe maximum in 20--28 km. Ozone is significant in the following three aspects impacting theclimate and environment: 1) Ozone absorbs harmful solar ultra--violet radiation for protecting the ecological system on the Earth; 2) ozone heats the stratosphere and forces the circulation systems in this layer; 3) ozone variation in the stratosphere can change the incomingradiation at the surface leve… 相似文献
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根据形成机制的不同将平流层准零风层（Quasi-Zero Wind Layer,QZWL）划分为由平流层准两年周期振荡（Quasi-Biennial Oscillation,QBO）各高度处于不同位相形成的第一类QZWL和由于平流层低层经向温度梯度逆转而形成的第二类QZWL;利用ERA-40再分析资料分析了两类QZWL在不同季节中空间结构的变化规律,讨论了平流层QBO对两类QZWL年际变化产生的影响。研究结果表明：第一类QZWL集中出现在冬季赤道附近地区,第二类QZWL在夏季热带外地区和冬季20°N～40°N太平洋地区上空;QZWL夏季高度比冬季低约3 km,夏季QZWL出现高度比冬季稳定,约在50～70 hPa之间;由于受到QBO的直接影响,第一类QZWL出现的高度和纬度范围存在明显的年际变化,第二类QZWL受到QBO的影响主要体现在QBO西风位相年和东风位相年相比,冬季20°N～40°N范围内存在第二类QZWL的概率较高。 相似文献
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RESEARCH ON INTERANNUAL CHANGE ABOUT TELECONNECTION OF GENERAL CIRCULATION IN SUMMER DURING 1980s OVER THE NORTHERN HEMISPHERE 下载免费PDF全文
下载免费PDF全文 In the paper the 5°×10°latitude-longitude grid point data of daily 500 hPa geopotential height over the NorthernHemisphere(NH)in summer(June—August)during 1980s are used.The base point(20°N,120°E)is selected to calcu-late point correlation between the base point and other grid points.We find that the summer heat source anomaly of thetropical western Pacific causes anomaly of summer general circulation over NH and teleconnection of general circula-tion similar to PNA pattern forms from East Asia to North America.The teleconnections show great interannualchanges. 相似文献
15.
Physical processes responsible for the interannual variability of sea ice concentration in Arctic in boreal autumn since 1979 下载免费PDF全文
下载免费PDF全文 Arctic sea ice concentration (ASIC) in boreal autumn exhibits prominent interannual variability since 1979. The physical mechanism responsible for the year-to-year variation of ASIC is investigated through observational data analyses and idealized numerical modeling. It is found that the ASIC interannual variability is closely associated with the anomalous meridional circulations over the Northern Hemisphere, which is further linked with the tropical sea surface temperature (SST) forcing. A tropics-wide SST cooling anomaly leads to an enhanced meridional SST gradient to the north of the equator in boreal summer, generating strengthened and northward shifting Hadley circulation over the Northern Hemisphere. Consequently, the meridional circulations are enhanced and pushed poleward, leading to an enhanced descending motion at the North Pole, surrounded by an ascending motion anomaly; the surface outflow turns into easterly anomalies, opposing the mean-state winds. As a result, positive cloudiness and weakened surface wind speed emerge, which reduce ASIC through changes in the surface latent heat flux and the downward longwave radiation. 相似文献
16.
Mauro Dall’Amico Lesley J. Gray Karen H. Rosenlof Adam A. Scaife Keith P. Shine Peter A. Stott 《Climate Dynamics》2010,34(2-3):381-398
In most climate simulations used by the Intergovernmental Panel on Climate Change 2007 fourth assessment report, stratospheric processes are only poorly represented. For example, climatological or simple specifications of time-varying ozone concentrations are imposed and the quasi-biennial oscillation (QBO) of equatorial stratospheric zonal wind is absent. Here we investigate the impact of an improved stratospheric representation using two sets of perturbed simulations with the Hadley Centre coupled ocean atmosphere model HadGEM1 with natural and anthropogenic forcings for the 1979–2003 period. In the first set of simulations, the usual zonal mean ozone climatology with superimposed trends is replaced with a time series of observed zonal mean ozone distributions that includes interannual variability associated with the solar cycle, QBO and volcanic eruptions. In addition to this, the second set of perturbed simulations includes a scheme in which the stratospheric zonal wind in the tropics is relaxed to appropriate zonal mean values obtained from the ERA-40 re-analysis, thus forcing a QBO. Both of these changes are applied strictly to the stratosphere only. The improved ozone field results in an improved simulation of the stepwise temperature transitions observed in the lower stratosphere in the aftermath of the two major recent volcanic eruptions. The contribution of the solar cycle signal in the ozone field to this improved representation of the stepwise cooling is discussed. The improved ozone field and also the QBO result in an improved simulation of observed trends, both globally and at tropical latitudes. The Eulerian upwelling in the lower stratosphere in the equatorial region is enhanced by the improved ozone field and is affected by the QBO relaxation, yet neither induces a significant change in the upwelling trend. 相似文献
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东亚季风系统的动力过程和准定常行星波活动的研究进展 总被引：14，自引：5，他引：9
本文系统地回顾了近几年来关于东亚季风系统的动力过程与机理方面的研究,特别是关于东亚季风系统年际和年代际变异与准定常行星波活动关系的研究。最近的许多研究表明东亚夏季风系统变异的动力过程主要与东亚／太平洋型(即EAP型)遥相关有关,利用EAP型遥相关理论不仅可以说明东亚夏季风系统各成员之间内在联系的机理,而且可以揭示热带西太平洋热力和菲律宾周围对流活动影响东亚夏季风系统季节内、年际变化及其异常的经向三极子结构的动力过程;除了EAP型遥相关外,研究还表明北半球夏季从北非到东亚的对流层上层经向风异常存在一个沿急流传播的遥相关型,它对东亚夏季风系统异常的经向三极子型分布也有重要影响。并且,最近关于东亚冬季风变异与行星波活动的关系已做出许多研究,并获得很大进展。这些研究表明:北半球冬季准定常行星波传播波导在年际和年代际变化上存在着反相振荡特征,即若“极地波导”加强,则“低纬波导”将减弱,反之亦然;准定常行星波两支波导的反相振荡与北半球环状模(NAM)的年际和年代际振荡有紧密联系,而NAM的变化通过行星波活动的异常可以导致东亚冬季风的年际和年代际变化;此外,准定常行星波活动的年际变化与东亚冬季风异常之间的关系明显地受热带平流层纬向风准两年周期振荡(QBO)的调制,进一步的研究还提出了可能的机理。最后本文还指出:2005～2007年冬季东亚冬季风的异常不仅与西伯利亚高压和阿留申低压的变异有关,而且与极涡的演变和准定常行星波活动密切相关。 相似文献
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本文利用从1950－1998年共计49年的马里兰（Maryland）大学全球海洋同化分析资料和NCEP全球大气再分析资料，分析了全球海气系统年际和年代际变化的主要时空特征，结果表明：1）全球上层海洋年际变化的主要模态是位于热带太平洋的ENSO模态，海洋年代际变化的最显著区域为南半球高纬度及中纬度海洋特别是赤道以外区域的热带东太平洋和大西洋；2）全球大气年际和年代际变化都主要位于中高纬度地区尤其是两极地区，在年际时间尺度上，气温异常和气压异常没有明显的对应关系，但在年代际时间尺度上，气温增暖（变冷）常常伴随着气压的降低（升高）；3）在年际时间尺度上，发生在中高纬度陆地地区的大气年际变化和主要发生热带海洋上层海洋年际变化没有一致性的内在联系，前者主要表现为大气的内部（浑沌）变化，而后者主要为热带海气相互作用产生的ENSO变化；4）在年代际时间尺度上，全球海洋大气系统大约在70年代前后，均一致性地经历了一次跃变，其结果是导致80年代以来，全球大范围地区（尤其是两极和西伯利亚地区）气温明显偏暖，赤道两侧的热带东太平洋、北美和南美西海岸、及非洲西海岸等海域海表面温度偏高，伴随着这种全球大范围背景增暖现象，青藏高原北部和格陵兰岛区域气温具有变冷的趋势，而南半球高纬度海域海表温度也表现为降低。 相似文献