The model presented extends Charney (1947) model by including Newtonian cooling, Ekman dissipation, linear vertical variation of the stratification parameter and nonlinearity. / The unstable Green modes are similar in many respects to the transient planetary waves: They tilt westward with height in the troposphere and feature a barotopic structure in the stratosphere. They may extend up to 5-6 scale heights before being trapped and exhibit a major peak in the stratosphere. The wavelength (growth rate) of the most unstable Green mode is about three times (1/3 to 2/5) of that of the most unstable Charney mode. Its available potential energy is converted in the lower troposphere, as well as in the stratosphere, and its kinetic energy is generated in both the middle troposphere and the middle stratosphere, with significant destruction near the tropopause. / The vertical increase of the static stability reduces the wavelength of the most unstable modes and affects considerably the growth rate and vertical structure of the Green modes. / The evolutions of the finite amplitude Green modes in the presence of realistic (beta)-effect and moderate internal or Ekman dissipation lead to steady (propagating or stationary) wave states which are always stable to small perturbations. No stable limit cycles or chaotic behaviors are found. The approach to steady wave states may exhibit either a monotonic or a damped oscillatory behavior depending upon the relative magnitudes of the inviscid growth rate and the dissipation. / The Ekman dissipation does not affect wave tilt, while the internal dissipation changes wave tilt by adding a westward component so that the constant phase line, while oscillating, may tilt westward throughout the entire vacillating cycle. As a result, the horizontal heat flux is directed poleward even when the wave decays. The Ekman dissipation may yield a large amplitude, steady wave solution which depends on initial conditions and does not depend on the dissipation and shear supercriticality. In sharp contrast, the internal dissipation may lead to a relatively small amplitude, steady wave solution which does not depend on the initial conditions but depends on the dissipation and the supercriticality. / In a continuous model, the Ekman dissipation never displays a destabilizing effect, while a small amount of Newtonian cooling destabilizes both the wave-free zonal flow near the inviscid critical points and the nonlinear system. / Source: Dissertation Abstracts International, Volume: 45-08, Section: B, page: 2583. / Thesis (Ph.D.)--The Florida State University, 1984.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75368 |
| Contributors | WANG, BIN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 166 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
Page generated in 0.0069 seconds