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361.
The baroclinic primitive equation model used for short and medium range forecasting admits high frequency as well as desirable
Rossby modes. These high frequency oscillations are excited by initial imbalances between the observed mass and wind fields.
In this paper we determine and describe the normal modes of the linearized version of the general circulation model of Laboratoire
de Meteorologie Dynamique, Paris. These normal modes are then used to initialize the model through Machenhauer’s nonlinear
correction scheme. The adiabatic nonlinear normal mode initialization technique is shown to be superior to dynamic initialization
in terms of elimination of high-frequency oscillations in the forecast. Normal modes of a particular model depend on the finite
difference scheme chosen to approximate the governing system of model equations. The results presented correspond to enstrophy-conserving
finite difference scheme. 相似文献
362.
R. L. Walterscheid 《Pure and Applied Geophysics》1980,118(1):239-265
This paper reviews the theory and observations of some traveling planetary waves in the stratosphere. Two categories of waves which appear prominently in the literature are discussed: westward propagating waves of periods in the range 3–7 days (the 5-day wave) and in the range 10–20 days (the 16-day wave). Although the observations seem to indicate that these waves are waves of the Rossby type (planetary waves), the evidence is less clear regarding (1) the question of whether these waves are forced internal waves or free (resonant) external waves, and (2) the identification of the observed waves with specific theoretical waves of the Rossby type. When recent observations are compared with theory, the evidence seems to favor the notion that the 5-day and 16-day waves of longitudinal wave number 1 may be identified, respectively, with the gravest and next gravest symmetric free Rossby modes. However, the observational evidence seems to be less clear regarding the nature of the 16-day wave than the 5-day wave. 相似文献
363.
We have studied the response of normal modes to perturbations in inner-core shear velocity and attenuation, using fully coupled mode synthetics. Our results indicate that (i) mode pairs n S l – n ±1 S l are strongly coupled by anelasticity, (ii) this coupling causes shear velocity perturbations to strongly affect the Q values of modes through exchange of inner-core characteristics, (iii) there is no evidence for a weakly attenuating inner core in shear, and (iv) the discrepancy between attenuation models returned from normal modes and body waves is small. These results suggest that inversions for inner-core attenuation and shear velocity should be performed simultaneously and should take account of the strong cross-coupling due to attenuation. 相似文献
364.
我国是一个多山的国家。随着高速公路的迅猛发展,在山丘区修筑高速公路,由于线路及地形的限制,必然伴随着大量公路隧道的出现。小净距隧道是目前公路隧道中最常见的一种型式。在我国目前还处于研究和发展阶段。论文在现有单洞隧道围岩破坏模式分析的基础上,开展了小净距双洞公路隧道围岩破坏模式的研究。通过文献综述、现场量测以及数值分析成果,归纳总结了小净距隧道的5种典型破坏模式:挤压破坏、拉伸破坏、中夹岩柱剪切破坏、爆破震动破坏及复合型破坏。针对不同的破坏模式。论文详细阐述其破坏规律和特点,以便在设计中人们能够事先知道其薄弱环节,在施工时能够及时采取有效的处理措施,从而确保整个隧道施工和运营的安全。 相似文献
365.
Zdeněk Martinec 《Pure and Applied Geophysics》2007,164(4):663-681
We derive the matrix propagator for the response of a multi-layered, Maxwell viscoelastic sphere to a surface toroidal force
in analytical form. Several numerical methods for 2-D and 3-D glacial-isostatic adjustment (GIA) modelling have been applied
recently. The present analytical approach may be used as an aid for testing more general algorithms of GIA. The propagator-matrix
solution has been tested by comparing it with the analytical solution of two-layer and three-layer spheres, with full agreement
obtained. 相似文献
366.
lNTR0DUCTI0NThemechanismofsedimenttransp0rtinshall0wchanneIfiowscanbequitec0mplicateddependingupona)themechanismofsoildetachment,b)thesizeandshaperanges0ftheavailablesediment,c)thesedimentc0ncentrati0n,d)theenergeticc0nditi0n0ftheflow,e)thechannelsurfacec0nditi0n,Dtherateofwaterinfiltrati0nandg)thechemicalc0nstituentspresentinthes0ilandthesurfacewater.Th0ughthedetachment0fs0ilparticlesbyrainfallistheprimarys0urce0favailablesediment,theeffect0fdynarnicwaterwavesandwind-gustsals0playasignifi… 相似文献
367.
368.
国外区域发展规划的全新审视及对中国的借鉴* 总被引:21,自引:3,他引:18
从100年来国外区域发展规划总体演变历程入手,提出了国家“高度指令+强制干预”体制下、“统一领导+总体协调”体制下和“不统不控+政策当先”体制下区域发展规划的三大生成模式,认为国家政治经济体制的变革主宰着规划的命运,作为特定时期政府一项重要职能的规划的局限性在所难免。中国在区域发展规划中必须重视计划与市场的适度结合,公众参与与政治参与的有机协调,建立健全规划中的立法管理体系,并注重对生态环境和可持续发展问题的研究。 相似文献
369.
Normal-mode splitting due to inner-core anisotropy 总被引:1,自引:0,他引:1
Jeroen Tromp 《Geophysical Journal International》1995,121(3):963-968
370.
In this paper, a system reliability analysis of rock slope stability with considering all input parameters as stochastic parameter is presented. To perform reliability analysis a cut-set system has been used. For this purpose, Sequential Compounding Method (SCM) as a powerful method for reducing the computational time and accurate evaluation is employed to determine the reliability indices with considering correlations between failure modes which are calculated by defining equivalent linear safety margin for each failure mode. Furthermore, the 3-D system probability of failure surface is presented and the probabilistic model is developed to evaluate the rock slope probability of failure. 相似文献