Wave Transience in a Compressible Atmosphere.
Abstract
Vertically propagating internal waves give rise to mean flow accelerations in an atmosphere due to wave transience resulting from the effect of compressibility. Such accelerations appear to culminate in the spontaneous formation and descent of regions of strong mean zonal wind shear. Both analytical and numerical solutions are obtained within the context of an approximate, quasi linear model which describes this effect. Numerical simulations of transient equatorial waves in the quasi-biennial oscillation are discussed. The prototype standing internal wave model (Plumb, 1977) is modified by making use of the explicit equatorial wave dispersion formulae. It is suggested that wave transience be regarded as the primary cause of the oscillation in a chronological sense, with wave absorption as a necessary, but chronological secondary, cause. This result constitutes a significant revision of the original Holton-Lindzen theory. It is apparent that a fundamental difference exists between the atmospheric oscillation and its laboratory analog. In the latter, damping, and not transience, is the principal driving mechanism.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1980
- Bibcode:
- 1980PhDT........22D
- Keywords:
-
- Physics: Atmospheric Science;
- Atmospheric Physics;
- Compressible Flow;
- Flow Stability;
- Internal Waves;
- Vertical Air Currents;
- Wave Propagation;
- Damping;
- Equatorial Atmosphere;
- Oscillating Flow;
- Wave Interaction;
- Geophysics