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1.
大气中定常行星波的Eliassen-Palm通量与波折射指数的关系 总被引：1，自引：1，他引：1
本文研究了β平面近似下波作用量守恒,得到波作用通量——Eliaaen-Palm通量的一般形式.本文还利用WKBJ方法求得球面大气中定常行星波的Eliassen-Palm通量与波折射指数的关系. 本文还用一个准地转34层球坐标模式计算了冬季北半球地形与定常热源强迫所产生的定常行星波的Eliassen-Palm通量,证明了冬季受迫定常行星波在垂直及侧向传播中存在着两支波导,从而证明了理论上所得到的关系. 相似文献
2.
经圈环流对定常波传播的影响 总被引：1，自引：0，他引：1
在一般斜压大气中，基本气流中包含经圈环流时，定常波传播不仅能穿过东风带，而且明显增强。在基流含有经圈环流的情况下，北半球中纬度地形强迫可引起低纬大气的显著响应，这表明经圈环流在中低纬定常响应的相互联系中起着重要作用；北半球中纬度热力强迫可产生类似北半球夏季季风环流的波列分布，这说明经圈环流在夏季季风环流的形成中起着一定的作用；在赤道东太平洋加热强迫情况下，在冬半球可引起ＰＮＡ型的定常波传播波列，而在夏半球却没有明显的ＰＮＡ特征。这表明经圈环流对冬、夏半球的定常波传播路径有着显著的影响。 相似文献
3.
大气经圈环流对波动和能量传输的影响 总被引：2，自引：0，他引：2
本文用斜压准地转模式讨论了经圈环流作为基流的一部分对不同风系中波动和能量传输的影响。特别指出在东风带中因经圈环流的存在,就可能形成定常和非定常的经向行星波,使夏季低纬度东风气流中的波动及其能量向中、高纬度传播。 文中还分析和计算了定常经向波和瞬变波的群速度和一些动力学性质。 相似文献
4.
Bjerknes提出了大气对外界强迫响应的概念。大量研究已证明这一遥响应机制的存在,且大气对强迫源的遥响应及其低频活动的共同特征都表现为类似大圆路径的波列,Hoskins的理论研究揭示了这现象的实质,他把叶笃正所提出的Rossby波的频散理论推广到球面上。黄荣辉曾利用波折射指数平方与EP通量系统地研究了北半球冬夏准定常行星波的传播规律。邹晓蕾、叶笃正、吴国雄提出了中高纬的相关链、定常地形波链,并指出北美与东亚相关型的差异与两区域地形准定常波在不同纬向流中传播的差异有关。观测分析亦表明,青藏高原是大气低频振荡的强迫源,且在此区域可产生向北、向南或向东、向西传播的波列。 相似文献
5.
电磁波在大气中传播，随着大气中的温度、压力、湿度高度的增加可以有不同的变化，因此产生了折射指数随高度的不同分布，致使雷达波在传播时有弯曲现象，一般分为标准大气折射、临界折射、超折射、负折射和零折射(见图1)，其中超折射在雷达探测中经常遇到，因此须加以识别。 相似文献
6.
1.引言在六十年代以前,在大气环流的诊断研究中,特别是在扰动与基本气流相互作用中都是应用动量通量及热量通量。在六十年代初,著名气象学家 Ch-arney 提出用波的折射指数来描述行星波在垂直切变基本气流的传播。与此同时,Eliassen 和Palm 也提出一个与动量通量及热量通量相关联的能量通量矢量来表征行星波在切变基本气流的传播。在七十年代,许多研究定常行星波的学者都用Eliassen 和 Palm 原来所定义的能量通量矢量来表征波的垂直及侧向传播。例如,Matsuno,Kasa-hara 等,Hayashi 和 Golder 都是应用能量通量矢量来表征定常行星波的传播。然而,当波在具有切变的基本气流中传播,波的能量是不守恒的。Anderew 和 McIntyre 从位涡 相似文献
7.
定常行星波的垂直传播及其动力学效应 总被引：2，自引：1，他引：2
本文用一个β平面准地转模式考察了定常行星波在大气中垂直传播的特性，讨论了波的水平尺度和基本气流的结构等对定常行星波垂直传播的影响，指出了高低层大气之间相互作用的特点及条件。 相似文献
8.
理想基流中大气波动多折射的数值试验 总被引：3，自引：2，他引：1
利用含非绝热加热的准地转正压涡度方程全球谱模式,采用４种热带海表温度异常作为热源和１６种理想基流,进行了理想基流中大气波动多折射的数值试验,积分时间为３０ｄ。得到：热源所激发的扰动通常能产生二支或三支波列,并由第一支波列分支出第二,三支波列,或第二支分支出第三支波列;对于有些基流,第一支波列维持两周或更长时间后消失,而留下其他波列;第二支波列往往最强,对于某些基流,两支流列有汇合聚集的趋势。 相似文献
9.
本文在半地转近似下讨论了纬向切变基流中的非线性正压Ｒｏｓｓｂｙ波，给出了存在波解的切变基流条件。 相似文献
10.
地形对涡量传播和台风切向风速变化的参数敏感性 总被引：2，自引：1，他引：2
设计了一个高分辨率的浅水模式，以研究地形参数和纬向基流在涡旋Rossby波传播和台风切向风速变化中的作用。结果表明，无纬向基流条件下，岛屿地形的水平尺度对涡旋Rossby波传播的影响表现在：随地形水平方向尺度的增大，扰动涡度场环绕地形顺时针方向旋转的趋势增强，局域风速增幅减小，增强了平均风速的减弱。纬向东风基流条件下，热带气旋的局域风速及其平均切向风速的演变受台风与地形间距的改变以及地形作用时间长短的影响：当台风逐渐靠近地形时，局域风速增幅增强，平均风速逐渐减小；当台风逐渐远离地形时，出现相反的变化。 相似文献
11.
北半球环状模波流相互作用动力学研究进展 总被引：1，自引：0，他引：1
总结了国内外学者对于北半球环状模（NAM：Northern Hemisphere Annular Mode）及其活动中心形成原因的研究成果。主要从NAM的天气、气候影响,波流相互作用原理对NAM形成的解释,NAM在北太平洋、北大西洋和北极3个区域活动中心的天气尺度波和行星尺度波活动等方面论述。NAM在对流层的变化与天气尺度波有关,北太平洋和北大西洋两个活动中心是天气尺度波活跃的区域,其峰值区表现为风暴轴,其中北大西洋天气尺度波破碎过程会使得NAM指数急剧变化。NAM在平流层的变化和准定常行星波关系密切,冬季准定常行星波会上传并与高纬平流层纬向流发生相互作用,从而引起北极极涡发生改变。准定常行星波将NAM 3个活动中心有机联系起来：对流层准定常行星波的纬向传播会影响北太平洋风暴轴的位置,而风暴轴的变化会影响下游北大西洋波破碎过程,同时准定常行星波的上传可以影响极涡活动。 相似文献
12.
大气季节内振荡的活动与El Nino 总被引：13，自引：1，他引：13
用广东省４７个测站１９５４－１９９０年各月的平均气温、降水、日照时数的标准化资料分别作按时间点分解的主分量分析,取其前６个主分量作为各测站的气候特征量,用相关系数－重心法作聚类分析,作出各月、全年综合要素的气候分区。结果表明：（１）将广东各月分为有较显著差异的５个区,则冬半年（１０－翌年４月）各月的分区形式较类似且规律性明显,夏半年（５－９月）各月的分区逐月变化明显,且分区形式差别较大。（２）若用６个自然季节的平均气温、降水、日照时数标准化资料分别作主分量分析,各取前３个主分量作为全年气候分区的特征量,则广东全年的气候区可分为东南沿海、西南沿海、西北内陆３个区。 相似文献
13.
Lu Peisheng 《大气科学进展》1992,9(2):157-166
Monthly or seasonally mean anomalies of large-scale atmospheric circulation are better represented by wave packets or their combination. Both qualitative and quantitative analyses of equations of wave packet dynamics, which are obtained by the use of WKB approximation, are very helpful for the understanding of structure, formation and propagation of stationary and quasi-stationary planetary wave packet patterns in the atmosphere. Indeed, these equations of wave packet dynamics can be directly solved by the method of characteristic lines, and the results can be simply and clearly interpreted by physical laws. In this paper, a quasi-geostrophic barotropic model is taken for simplicity, and the wave packets superimposed on several ideal profiles of the basic current and excited by some ideal forcings are investigated in order to make comparison of the accuracy of calculation with the analytical solution. It is revealed that (a) the rays of stationary planetary wave packet do not coincide with but go away from the great circle with significant difference if the shear of the basic zonal flow is not too small; (b) being superimposed on a westerly jet flow with positive shear (Uλ/y>0), the stationary wave packets excited by low-latitudinal forcing are first intensified during their northeastward propagation in the Northern Hemisphere, then reach their maximum of amplitude at some critical latitude, and after that weaken again; (c) the connected line of extremes (the positive and negative centres) of wave packet does not coincide with but crosses the ray by an angle, the larger the scale of external forcing, the larger the angle; and (d) the whole pattern of a trapped stationary wave packet is complicated by the interference between the incident and reflected waves. 相似文献
14.
ANALYSES OF THE DYNAMIC EFFECTS ON WINTER CIRCULATION OF THE TWO MAIN MOUNTAINS IN THE NORTHERN HEMISPHERE--Ⅱ.VERTICAL PROPAGATION OF PLANETARY WAVES 
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下载免费PDF全文 A linear,hemispheric and stationary spectral model with multilayers in the vertical was employed to simulate the vertical propagation of waves triggered by mountains.Results show that,in cooperation with the East Asia zonal mean flow,Tibetan Plateau can excite a strong wavenumber 1 perturbation in the stratosphere with its ridge and trough located over the Pacific and Atlantic Oceans respectively.On the other hand,the stratospheric wavenumber 1 perturbation caused by the mechanical forcing of the Rocky Mountains in cooperation with the North America zonal mean flow is very weak.Calculations from observational data of the vertical profile of critical wavenumber for vertically propagating waves imply that the tropospheric wavenumber 1 perturbation can hardly penetrate the North America tropopause upwards,whereas it can freely propagate through the East Asia tropopause into the stratosphere.Two-dimensional E-Pcross-sections obtained from both observational data and simulated results also demonstrate that waves excited by the Rocky Mountains are refracted towards low latitudes in the troposphere during their upward propagation:whereas,in addition to the above mentioned equatorward leaning branch,the wavenumber 1 and 2 planetary waves excited by the Tibetan Plateau possess another branch which is refracted to high latitudes during upward propagation and penetrates the tropopause into the stratosphere.It is therefore concluded that the difference in the horizontal and vertical wave propagations in the two hemispheres is a result of the different dynamical forcing induced by the two main mountains in the Northern Hemisphere. 相似文献
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16.
ANALYSES OF THE DYNAMIC EFFECTS ON WINTER CIRCULATION OF THE TWO MAIN MOUNTAINS IN THE NORTHERN HEMISPHERE——Ⅱ.VERTICAL PROPAGATION OF PLANETARY WAVES 下载免费PDF全文
下载免费PDF全文 A linear,hemispheric and stationary spectral model with multilayers in the vertical was employed to simulate thevertical propagation of waves triggered by mountains.Results show that,in cooperation with the East Asia zonal meanflow,Tibetan Plateau can excite a strong wavenumber 1 perturbation in the stratosphere with its ridge and trough lo-cated over the Pacific and Atlantic Oceans respectively.On the other hand,the stratospheric wavenumber 1 perturbationcaused by the mechanical forcing of the Rocky Mountains in cooperation with the North America zonal mean flow isvery weak.Calculations from observational data of the vertical profile of critical wavenumber for vertically propagatingwaves imply that the tropospheric wavenumber 1 perturbation can hardly penetrate the North America tropopause up-wards,whereas it can freely propagate through the East Asia tropopause into the stratosphere.Two-dimensional E-Pcross-sections obtained from both observational data and simulated results also demonstrate that waves excited by theRocky Mountains are refracted towards low latitudes in the troposphere during their upward propagation:whereas,inaddition to the above mentioned equatorward leaning branch,the wavenumber 1 and 2 planetary waves excited by theTibetan Plateau possess another branch which is refracted to high latitudes during upward propagation and penetratesthe tropopause into the stratosphere.It is therefore concluded that the difference in the horizontal and vertical wavepropagations in the two hemispheres is a result of the different dynamical forcing induced by the two main mountains inthe Northern Hemisphere. 相似文献
17.
线性、定常、多层半球谱模式模拟结果表明,在东亚纬向气流下,青藏高原能在平流层激发出强大的1波扰动,脊槽分别位于太平洋和大西洋上空。在北美纬向气流下,落基山在平流层激发的1波很弱。观测资料计算指出,对流层行星1波很难通过北美对流层顶上传,但却能自由穿过东亚高纬度地区的对流层顶向平流层传播。北美地形所激发的波动在上传过程中均折向低纬传播。青藏高原所激发的行星1波和2波在上传过程中有分支:折向低纬的一支主要局限在对流层中;折向高纬的一支进入平流层。模拟和分析证明,这些差异是北半球两大地形不同的动力作用的结果。 相似文献
18.
本文根据Whitham和Lighthill等人的射线理论,研究了具有非均匀层结和流场切变的大气中惯性重力内波的传播和折射问题。定义了一个由背景场参数N2(静力稳定度)、ξa(惯性稳定度)和Ux(与斜压稳定性有关)的梯度组合而成的所谓“环境稳定度”矢量 ,它对重力波的折射有决定性的作用。结果表明:局地波导方向垂直于矢量 ;稳定度中心之间的过渡地带沿稳定度等值线方向为波能传播的有利通道。 相似文献
19.
Lu Peisheng 《大气科学进展》1993,10(3):287-295
The propagation of disturbances excited by low-frequency oscillations in the tropics is investigated by applying the theory of wave packet dynamics. For simplicity, a linearized barotropic model is adopted and the zonal circulation is taken as basic current. Suppose that the disturbances or waves are superimposed on jet-like westerly basic cur-rent and excited by the forcing in the tropics. We have (1) only the eastward propagating (m>0, n>0 and σ>0) low-frequency disturbances and the stationary (σ = 0) waves can propagate into the middle and high latitudes in the Northern Hemisphere; the others, such as the westward propagating low-frequency wave (m>0, n<0, σ<0) and the high-frequency waves, are restricted only in the vicinity of source region; (2) a stationary wave (σ = 0) reaches a given latitude even more quickly than some low-frequency ones (σ>0) due to the fact that the group velocity of stationary wave is larger; (3) there is a whole wave train excited by the forcing in the tropics and extended into the middle and high latitudes, if the amplitude of the source is independent on time, especially, the low-frequency wave (σ > 0) is of travelling type propagating along the ray; (4) if the source lasts only for an interval of time, namely, its amplitude also has the character of low-frequency oscillation, the excited wave train is not always a whole one, but is restricted in the vicinity of source region in the beginning, extended from the source region to the middle and high latitudes in its saturated stage, after that it gradually becomes weaker and weaker and is detectable only in some area at high latitude, and eventually disappears. Undoubtedly, case (4) is closer to the reality, even though case (3) gives a more impressive wavy pattern. 相似文献