|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | ZONAL MEAN STRUCTURES OF THE EXTRATROPICAL TROPOSPHERE显示文摘The study of mean circulation fields requires evaluation of eddy foreings in the atmosphere.Due to the difficulty incalculating the eddy forcings on theory,the mean state equations including the eddy forcings were used mostly fordiagnostic studies only.Using the geostrophic perturbation solutions obtained by McHall (1991a),we may deal withtheoretically the eddy fluxes and their convergence.This allows us to employ the mean state equations for the study ofmean circulation fields.It will be found that the time averaged zonal mean structure and circulation of the troposphereat middle and high latitudes can be reproduced basically in terms of the mass and momentum balances in geostrophicwave circulations. | Y.L.McHall Department of Earth,Atmospheric and Planetary Sciences,MIT,MA 02139,USA | 1993 | Acta meteorologica Sinica1993，7，2： | 5 |
| 2 | Nonlinear Planetary Wave Instability and Blocking显示文摘The instability of geostrophic wave circulations related to the nonlinear processes involved in the zonal mean heat balance equations is studied. It is found that the planetary waves may be destabilized by thermal forcing in specific baroclinic layers, called the breaking layers. The critical conditions of the instability will be given. In the troposphere, these conditions may be provided in blocking regions and the development of planetary perturbations is characterized distinctly by the unset, maintenance and decay of observed blocks. The whole blocking episode cannot be described as either the barotropic or baroclinic process only. The limitations on the study of wave-wave interaction using spectral models or spectrum analyses will be discussed also. | Yong.L.McHall | 1992 | Advances in Atmospheric Sciences1992，9，2： | 4 |
| 3 | Wintertime Stratospheric Anomalies-Part II: Sudden Warmings显示文摘The process of stratospheric sudden warmings from development of planetary waves to.the sudden cooling after reversal of mean zonal circulation will be studied with the primitive equations of heat and momentum balances. It will be explained that the sudden warmings may occur only in the polar regions of winter stratosphere where zonal mean temperature decreases poleward. The heating rate in the order of major warmings is produced by developed planetary waves in the stratospheric breaking layers. The particular perturbation structure characterized by large amplitude of wave 1 together with minimum of wave 2 discovered by Labitzke (1977) is crucial for initiation of major warmings. The cooling by the same mechanism can be produced in the regions with reversed mean temperature gradient. | Y.L.McHall | 1992 | Advances in Atmospheric Sciences1992，9，3： | 3 |
| 4 | Large Scale Perturbations in Extratropical Atmosphere-Part Ⅰ: On Rossby Waves显示文摘This study reexamines the propagation mechanism and geostrophic property of the classical two-dimensional Rossby waves in a non-divergent barotropic atmosphere. It will be found that propagation of large scale atmospheric waves depends crucially on horizontal divergence. A small Rossby number in Rossby waves is not sufficient for the waves to have a small ageostrophic component, because the two-dimensional classical Rossby waves do not manifest the geostrophic balance as good as observed in the atmosphere. | Y. L. McHall | 1993 | Advances in Atmospheric Sciences1993，10，2： | 3 |
| 5 | Large Scale Perturbations in Extratropical Atmosphere-Part Ⅱ: On Geostrophic Waves显示文摘We have examined, in Part Ⅰ, the propagation mechanism and geostrophic property of classical Rossby waves in a non-divergent barotropic atmosphere. As we found that the non-divergent Rossby waves do not propagate in a hydrostatically equilibrium atmosphere, and do not manifest a good geostrophic property, an alternative large scale circulation pattern of geostrophic waves has been proposed (McHall, 1991a). The propagation mechanism and geostrophic property of these waves are examined in the present study. | Y.L. McHall | 1993 | Advances in Atmospheric Sciences1993，10，2： | 2 |
| 6 | Wintertime Stratospheric Anomalies-Part I: Warm Pools显示文摘The stratospheric worm pools, called the 4-day wave also, are mainly the temperature anomalies in the polar regions of winter hemisphere. It will be shown that their occurrence, propagation speed and specific structure can be explained by the lower frequency coherent heating resulting from the wave interaction in the breaking layers of the stratosphere. Although their vertical phase slope is negligibly small, the warm pools cannot be considered as a barotropic anomaly. | Y.L.McHall | 1992 | Advances in Atmospheric Sciences1992，9，3： | 2 |
| 7 | Group Velocity of Anisotropic Waves-Part Ⅰ: Mathematical Expression显示文摘The group velocity used in meteorology in the last 30 years was derived in terms of conservation of wave energy or crests in wave propagation. The conservation principle is a necessary but not a sufficient condition for deriving the mathematical form of group velocity, because it cannot specify a unique direction in which wave energy or crests propagate. The derived mathematical expression is available only for isotropic waves. But for anisotropic waves, the traditional group velocity may have no a definite direction, because it varies with rotation of coordinates. For these reasons, it cannot be considered as a general expression of group velocity. A ray defined by using this group velocity may not be the trajectory of a reference point in an anisotropic wave train. The more general and precise expression of group velocity which is applicable for both isotropic and anisotropic waves and is independent of coordinates will be derived following the displacement of not only a wave envelope phase but also | Yong L.McHall | 1993 | Advances in Atmospheric Sciences1993，10，4： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员