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1.
ECMWF reanalysis (ERA–interim) data of winds for two solar cycles (1991–2012) are harmonically analyzed to delineate the characteristics and variability of diurnal tide over a tropical site (13.5° N, 79.5° E). The diurnal cycle horizontal winds measured by Gadanki (13.5° N, 79.2° E) mesosphere–stratosphere–troposphere (MST) radar between May 2005 and April 2006 have been used to compute 24 h tidal amplitudes and phases and compared with the corresponding results obtained from ERA winds. The climatological diurnal tidal amplitudes and phases have been estimated from surface to ～33 km using ERA interim data. The amplitudes and phases obtained in the present study are found to compare reasonably well with Global Scale Wave Model (GSWM–09). Diurnal tides show larger amplitudes in the lower troposphere below 5 km during summer and in the mid-stratosphere mainly during equinoctial months and early winter. Water vapor and convection in the lower troposphere are observed to play major roles in exciting 24-h tide. Correlations between diurnal amplitude and integrated water vapor and between diurnal amplitude and outgoing longwave radiation (OLR) are 0.59 and ?0.34, respectively. Ozone mixing ratio correlates (ρ?=?0.66) well with diurnal amplitude and shows annual variation in the troposphere whereas semi-annual variation is observed at stratospheric heights with stronger peaks in equinoctial months. A clear annual variation of diurnal amplitude is displayed in the troposphere and interannual variability becomes prominent in the stratosphere which could be partly due to the influence of equatorial stratospheric QBO. The influence of solar activity on diurnal oscillations is found to be insignificant. 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
3.
4.
Observations have shown that the monsoon is a highly variable phenomenon of the tropical troposphere, which exhibits significant variance in the temporal range of two to three years. The reason for this specific interannual variability has not yet been identified unequivocally. Observational analyses have also shown that EI Niño indices or western Pacific SSTs exhibit some power in the two to three year period range and therefore it was suggested that an ocean-atmosphere interaction could excite and support such a cycle. Similar mechanisms include land-surface-atmosphere interaction as a possible driving mechanism. A rather different explanation could be provided by a forcing mechanism based on the quasi-biennial oscillation of the zonal wind in the lower equatorial stratosphere (QBO). The QBO is a phenomenon driven by equatorial waves with periods of some days which are excited in the troposphere. Provided that the monsoon circulation reacts to the modulation of tropopause conditions as forced by the QBO, this could explain monsoon variability in the quasi-biennial window. The possibility of a QBO-driven monsoon variability is investigated in this study in a number of general circulation model experiments where the QBO is assimilated to externally controlled phase states. These experiments show that the boreal summer monsoon is significantly influenced by the QBO. A QBO westerly phase implies less precipitation in the western Pacific, but more in India, in agreement with observations. The austral summer monsoon is exposed to similar but weaker mechanisms and the precipitation does not change significantly. 相似文献
5.
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
6.
赤道低平流层纬向风垂直切变与ENSO变率的关系 总被引：1，自引：0，他引：1
利用NCEP／NCAR 40a再分析资料研究了赤道低平流层纬向风垂直切变与ENSO变率间的关系。结果得出，赤道低平流层纬向风的垂直切变呈现明显的准两年振荡，SOI和Nino3区SSTA的准两年周期成分与赤道低平流层纬向风垂直切变分别呈现反位相和同位相关系。赤道低平流层西（东）风切变位相时，OLR、1000hPa高度，2000hPa高度和温度、850hPa温度等要素的距平分布与其在El Nino(La Nina)时段的分布相似。 相似文献
7.
平流程准两年振荡(QBO)是赤道平流层(～100-1 hPa)变率的主要模态,可对中高纬地区的环流产生重要影响,但目前利用通用大气环流模式(GCM)对其进行准确模拟仍然是一个挑战.本文利用IAP大气环流模式(IAP-AGCM)的中高层大气模式版本(IAP-AGCML69)对QBO进行模拟,并对其动量收支情况进行分析.研究发现,QBO主要是由对流活动引起的重力波强迫(参数化)引起的,但该动量强迫被平流层赤道上升流所引起的平流过程显著削弱.模式可分辨尺度的波动强迫对赤道上空的QBO的总纬向风倾向有正贡献,在上平流层,其量值大小与参数化的重力波强迫相当.以上结果提供了QBO形成机制以及模式模拟差异可能原因的认识. 相似文献
8.
Impacts of the stratospheric quasi-biennial oscillation on the tropospheric circulation and climate in the Northeast Asia–North Pacific region in early summer 
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下载免费PDF全文 《大气和海洋科学快报》2023,16(3):100319
Previous studies have indicated that the stratospheric quasi-biennial oscillation (QBO) has a global impact on winter weather, but relatively less attention has been paid to its effect in summer. Using ERA5 data, this study reports that the QBO has a significant impact on the tropospheric circulation and surface air temperature (SAT) in the extratropics in Northeast Asia and the North Pacific in early summer. Specifically, a QBO-induced mean meridional circulation prevails from Northeast Asia to the North Pacific in the westerly QBO years, exhibiting westerly anomalies in 20°–35°N and easterly anomalies in 35°–65°N from the lower stratosphere to troposphere. This meridional pattern of zonal wind anomalies can excite positive vorticity and thus lead to anomalous low pressure and cyclonic circulation from Northeast Asia to the North Pacific, which in turn cause northerly wind anomalies and decreased SAT in Northeast Asia in June. Conversely, in the easterly QBO years, the QBO-related circulation and SAT anomalies are generally in an opposite polarity to those in the westerly QBO years. These findings provide new evidence of the impact of the QBO on the extratropical climate, and may benefit the prediction of SAT in Northeast Asia in early summer.摘要本文研究了平流层准两年振荡 (QBO) 对东北亚-北太平洋地区初夏对流层环流和地表气温的影响. 在QBO西风位相年, 东北亚至北太平洋地区存在一支由QBO引发的平均经向环流异常, 该经向环流异常可在东北亚至北太平洋地区激发正涡度, 并形成异常气旋式环流. 气旋左侧出现的异常偏北风导致6月东北亚地表气温下降. QBO东风位相年的结果与西风位相年大致相反. 这些结果为QBO对热带外地区天气,气候的影响提供了新的证据, 并为东北亚初夏地表气温的预测提供了新的线索. 相似文献
9.
对流层大气环流的甚低频振荡 总被引：3，自引：0，他引：3
对１９５１—１９９２共４２ａ５００ｈＰａ北半球高度场的月平均资料进行了纬圈谐波分析，计算了３５°Ｎ与５５°Ｎ超长波振幅及位相，以及３５—５５°Ｎ北半球月平均纬向风距平百分比。对超长波振幅及纬向风距平百分比做了小波转换。结果表明，对流层大气环流变化中存在３种准周期性的甚低频振荡：１．年代际的振荡；２．准２ａ周期振荡（ＱＢＯ）；３．半年韵律。同时发现对流层ＱＢＯ和平流层赤道纬向风ＱＢＯ之间可能没有联系。 相似文献
10.
S. A. Sitnov 《Climate Dynamics》2009,32(1):1-17
Using the longest and most reliable ozonesonde data sets grouped for four regions (Japan, Europe, as well as temperate and
polar latitudes of Canada) the comparative analysis of regional responses of ozone, temperature, horizontal wind, tropopause
and surface pressure on the equatorial quasi-biennial oscillation (QBO effects), manifesting in opposite phases of the 11-year
solar cycle (11-yr SC) was carried out. The impact of solar cycle is found to be the strongest at the Canadian Arctic, near
one of two climatological centres of polar vortex, where in solar maximum conditions the QBO signals in ozone and temperature
have much larger amplitudes, embrace greater range of heights, and are maximized much higher than those in solar minimum conditions.
The strengthening of the temperature QBO effect during solar maxima can explain why correlation between the 11-yr SC and polar
winter stratospheric temperature is reversed in the opposite QBO phases. At the border of polar vortex the 11-yr SC also modulates
the QBO effect in zonal wind, strengthening the quasi-biennial modulation of polar vortex during solar maxima that is associated
with strong negative correlation between stratospheric QBO signals in zonal wind and temperature. Above Japan the QBO effects
of ozone, temperature, and zonal wind, manifesting in solar maxima reveal the downward phase dynamics, reminding similar feature
of the zonal wind in the equatorial stratosphere. Above Europe, the QBO effects in solar maxima reveal more similarity with
those above Japan, while in solar minima with the effects obtained at the Canadian middle-latitude stations. It is revealed
that the 11-yr SC influences regional QBO effects in tropopause height, tropopause temperature and surface pressure. The influence
most distinctly manifest itself in tropopause characteristics above Japan. The results of the accompanying analysis of the
QBO reference time series testify that in the period of 1965–2006 above 50-hPa level the duration of the QBO cycle in solar
maxima is 1–3 months longer than in solar minima. The differences are more distinct at higher levels, but they are diminished
with lengthening of the period. 相似文献
11.
Summary An attempt has been made in this paper to examine different modes of oscillation in the wind field during different seasons
over Thiruvananthapuram (lat. 8.29° N, long. 76.59° E, located at the extreme southwest coast of India) based on daily upper
air observations for the period from January 1997 to December 1999. A power spectral analysis is carried out with the upper
air data of the station. The study shows that one and half cycle of Quasi–Biennial Oscillation (QBO) and the power spectra
of the meridional wind component exhibit peaks between the period of four days and seven days (corresponding frequency range
between 0.25 day−1 and 0.15 day−1) during all seasons. The seasonal variation of these large-scale oscillations over the station depends upon the background
mean zonal flow, which in turn closely related to the QBO structure.
The time sequence of power spectra shows that the disturbances with periods between four days and seven days dominantly prevail
in the upper troposphere and lower stratosphere throughout the year. The regimes of high power spectral intensity in this
period range are maintained in the levels where the mean zonal flow (westerly or easterly) weakens and changes with height.
The study establishes the fact that disturbances (mixed Rossby-gravity waves) acquire maximum power in the winter season whereas
the south-west monsoon exhibits minimum spectral intensity when spreading of energy over a frequency range takes place. 相似文献
12.
Zeng-Zhen Hu Bohua Huang James L. Kinter III Zhaohua Wu Arun Kumar 《Climate Dynamics》2012,38(1-2):25-43
The interdecadal variation of the association of the stratospheric quasi-biennial oscillation (QBO) with tropical sea surface temperature (SST) anomalies (SSTA) and with the general circulation in the troposphere and lower stratosphere is examined using the ERA40 and NCEP/NCAR reanalyses, as well as other observation-based analyses. It is found that the relationship between the QBO and tropical SSTA changed once around 1978–1980, and again in 1993–1995. During 1966–1974, negative correlation between the QBO and NINO3.4 indices reached its maximum when the NINO3.4 index lagged the QBO by less than 6?months. Correspondingly, the positive correlations were observed when the NINO3.4 index led the QBO by about 11–13?months or lagged by about 12–18?months. However, maximum negative correlations were shifted from the NINO3.4 index lagging the QBO by about 0–6?months during 1966–1974 to about 3–12?months during 1985–1992. During 1975–1979, both the negative and positive correlations were relatively small and the QBO and ENSO were practically unrelated to each other. The phase-based QBO life cycle composites also confirm that, on average, there are two phase (6–7?months) delay in the evolution of the QBO-associated anomalous Walker circulation, tropical SST, atmospheric stability, and troposphere and lower stratosphere temperature anomalies during 1980–1994 in comparison with those in 1957–1978. The interdecadal variation of the association between the QBO and the troposphere variability may be largely due to the characteristic change of El Ni?o-Southern Oscillation. The irregularity of the QBO may play a secondary role in the interdecadal variation of the association. 相似文献
13.
14.
低平流层准两年变率研究 总被引：6，自引：2，他引：4
分析ＮＣＡＲ／ＮＣＥＰ４０年分析资料得出,赤道低平流层纬向风年际变率的平均周期约２８．２个月,最大振幅的２０ｈＰａ,西（东）风距平平垂直下传平均速度１．２１（１．０４）ｋｍ／月。用１０ｈＰａ和７０ｈＰａ月平均纬向风标准化距平之差反映整层准两年变率的相位。低平流层两半球中纬气温有与之配合的振荡,西（东）风切变时,中纬气温偏低（高）。赤道纬向风准两年变率引起的经圈环流异常是联系低续续向风与中纬气温准年 相似文献
15.
The coupling between the stratosphere and the troposphere has been investigated by analysing low-frequency variations in: (1) the meridional mass flux into the polar cap (north of 60°N), computed separately for the stratosphere and the troposphere; (2) the polar cap mean surface pressure, and (3) the surface level meridional pressure gradient and zonal wind around 60°N. The analysis has been done for the 1979–93 Northern Hemisphere (NH) winters, using ECMWF reanalysis data. The results show that for all winters the meridional mass flux variations in the stratosphere precede those in the troposphere, by about one day. This result can also be obtained qualitatively with a very simple model, based on the zonally averaged zonal and meridional momentum equations. The lag is not very sensitive to the latitude of the southern boundary of the polar cap. The analysed variations in the polar cap mean surface pressure associated with variations in the meridional mass flux, determine most of the variability in the analysed meridional surface pressure gradient and the associated surface zonal wind around 60°N. The results also show that in the stratosphere the Coriolis force associated with the zonal-mean meridional wind is in near-balance with the convergence of the eddy momentum flux, and in the lower troposphere with the zonal frictional force. In summary, the results indicate that in the extratropical northern winter hemisphere, low-frequency variations in the meridional wind in the stratosphere induce low-frequency variations in the zonal wind near the surface. 相似文献
16.
I. V. Kozlov 《Russian Meteorology and Hydrology》2008,33(6):369-376
A problem of simulation of a stationary random process (SRP) is studied. A computer program is developed for modeling SRP, should the parameters required be estimated beforehand. The programming methods used are well known, but the numerical scheme of modeling the SRP needs some explanations; therefore, it is considered in detail in the article, being its basic subject for consideration, although basic characteristic features of the program are also considered. Examples show how the program is used to simulate the solar cycle and the quasi-biennial oscillation of the solar wind in the equatorial stratosphere (QBO). A distinguishing feature of this work, compared with the previous one, is also simulation of the solar cycle taking into account the variability of the sunspot dispersion. The SRP parameters are estimated for the QBO. It is found that the annual mean wind speed variation behavior is similar to the SRP. 相似文献
17.
资料分析表明，西太平洋副高活动有准两年振荡特征，副高的相对强度和副高脊线的纬度位置都清楚地表现出这种振荡。而且分析还表明，平流层低层纬向风的垂直切变同西太平洋副高活动有关，东（西）风切变对应着脊线位置偏北的较强（弱）副高形势。平流层低层东（西）垂直切变在赤道对流层上部所引起的异常上升（下沉）运动，导致Hadley环流的异常加强（减弱）可能是平流层QBO影响西太平洋副高准两年振荡的重要机制。用IAP-GCM所作的数值模拟试验得到了同观测资料分析相一致的结果。 相似文献
18.
Mauro Dall’Amico Peter A. Stott Adam A. Scaife Lesley J. Gray Karen H. Rosenlof Alexey Yu. Karpechko 《Climate Dynamics》2010,34(2-3):399-417
An improved stratospheric representation has been included in simulations with the Hadley Centre HadGEM1 coupled ocean atmosphere model with natural and anthropogenic forcings for the period 1979–2003. An improved stratospheric ozone dataset is employed that includes natural variations in ozone as well as the usual anthropogenic trends. In addition, in a second set of simulations the quasi biennial oscillation (QBO) of stratospheric equatorial zonal wind is also imposed using a relaxation towards ERA-40 zonal wind values. The resulting impact on tropospheric variability and trends is described. We show that the modelled cooling rate at the tropopause is enhanced by the improved ozone dataset and this improvement is even more marked when the QBO is also included. The same applies to warming trends in the upper tropical troposphere which are slightly reduced. Our stratospheric improvements produce a significant increase of internal variability but no change in the positive trend of annual mean global mean near-surface temperature. Warming rates are increased significantly over a large portion of the Arctic Ocean. The improved stratospheric representation, especially the QBO relaxation, causes a substantial reduction in near-surface temperature and precipitation response to the El Chichón eruption, especially in the tropical region. The winter increase in the phase of the northern annular mode observed in the aftermath of the two major recent volcanic eruptions is partly captured, especially after the El Chichón eruption. The positive trend in the southern annular mode (SAM) is increased and becomes statistically significant which demonstrates that the observed increase in the SAM is largely subject to internal variability in the stratosphere. The possible inclusion in simulations for future assessments of full ozone chemistry and a gravity wave scheme to internally generate a QBO is discussed. 相似文献
19.
AbstractThe solar backscattered ultraviolet (SBUV/SBUV-2) merged ozone datasets, version 8.6, including column ozone and ozone profiles for the 1979–2012 period are examined for the 35°N–60°N zonal belt in the northern hemisphere mid-latitudes and four sub-regions: central Europe, continental Europe, North America, and East Asia. The residual long-term patterns for total ozone and ozone profiles are extracted by smoothing the time series of differences between the original and the modelled ozone time series. Modelled ozone is obtained using the standard trend model accounting for ozone variability due to changes in stratospheric halogens and various dynamical factors commonly used in previous ozone trend analyses. Since about 2005 spring and summer total ozone in the troposphere and lower stratosphere has decreased in some regions (central and continental Europe, North America, and the 35°N–60°N zonal belt) compared with modelled ozone. The negative departure from modelled ozone in 2010 is approximately 2–3% of the overall 1979–2012 monthly mean level. It seems that this decrease is a result of yet unknown dynamical processes rather than to chemical destruction because the differences have a longitudinal structure, and total ozone in the upper stratosphere still follows changes in stratospheric halogen loading. 相似文献
20.
平流层大气动力学及其与对流层大气相互作用的研究:进展与问题 总被引：2，自引：2，他引：0
本文综述了近年来关于平流层大气动力学及其与对流层大气相互作用动力过程的研究进展,特别是回顾了近年来关于平流层大气环流和行星波动力学、热带平流层大气波动及其与基本气流相互作用、平流层大气环流变异对对流层环流和气候变异的影响及其动力过程、平流层大气数值模拟以及在全球变暖背景下平流层大气的长期演变趋势预估等的研究进展。最近的研究揭示了大气准定常行星波传播波导的振荡现象、重力波在热带平流层准两年振荡和全球物质输送中的作用、平流层长期的变冷趋势变化、平流层在对流层天气和气候变化中的作用等现象,表明了平流层大气动力学研究的重要性。平流层大气动力学的深入研究,以及对数值模式中平流层模拟性能的提高,最终都会推动整个大气科学和气候变化研究的进一步发展。 相似文献