Stationary waves are vitally important in the general circulation of the atmosphere. These planetary scale waves are generally attributed to large scale orography and diabatic heating. The purpose of the present study is to investigate stationary waves as a linear response to the large scale orography and steady-state diabatic heating by developing a linear steady-state spectral model with the primitive equations in the global domain, in which Rayleigh friction and Newtonian cooling as well as biharmonic horizontal diffusion are included. We use perturbation theory to linearize the nonlinear system of primitive equations with respect to the zonally symmetric component of the dependent variables. The structure of the dependent variables is described by truncated series of spherical harmonics in the horizontal and orthogonal functions in the vertical. The model solution is obtained by way of linear superimposition of zonal waves calculated in the spectral domain for each zonal wave. The three dimensional wave activity flux, which was derived by Plumb (1985) for linear quasi-geostrophic stationary waves on a zonal mean flow, as well as the EP flux are used as a diagnostic method for studying the three dimensional structure of wave propagation. The Plumb flux is a conservable measure of the wave activity flux which reduces to EP flux in the zonal mean, and is non-divergent for steady, conservative, linear waves. The results of this thesis may present new insights into forcing mechanisms of the stationary waves. The numerical experiments for the response to idealised orography in northern middle latitudes and actual global orography show that the northern middle latitude orographic forcing, in particular the Tibetan Plateau, plays the most important role in the maintenance of the orographically forced stationary waves in the middle and upper troposphere as well as lower stratosphere, while forcing by the orographic effect of the Antarctic plateau is also very important, but restricted only to the lower troposphere of the southern high latitudes.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660511 |
| Date | January 1992 |
| Creators | Peng, Tao-Yong |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11247 |
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