Topographic and Rotation Effects on Gravity-Wave Dynamics in the Atmosphere

Theoretical models for the generation of gravity internal waves by flow over topography have been developed, in an effort to understand the role of orographically induced gravity waves in atmospheric turbulence production. For given background wind speed and distribution of buoyancy frequency, the l...

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Bibliographic Details
Main Author: Akylas, Triantaphyllos R
Format: Report
Language:English
Subjects:
ATMOSPHERIC MOTION
Atmospheric Physics
Geography
GRAVITY WAVES
HYDROSTATICS
INTERNAL WAVES
MATHEMATICAL MODELS
Mechanics
OROGRAPHY
PERIODIC VARIATIONS
ROTATION
STRATOSPHERE
THREE DIMENSIONAL
TOPOGRAPHY
TROPOPAUSE
TROPOSPHERE
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Summary:Theoretical models for the generation of gravity internal waves by flow over topography have been developed, in an effort to understand the role of orographically induced gravity waves in atmospheric turbulence production. For given background wind speed and distribution of buoyancy frequency, the location of the tropopause (the borderline between the troposphere and the stratosphere) is found to have a significant effect, consistent with observations of increased gravity-wave activity over New Mexico when the tropopause is 10-11 km above ground. Based on a finite-amplitude hydrostatic model that accounts for three dimensional effects, a theoretical explanation has been proposed for certain intense oblique gravity wave trains observed downstream of islands. Finally, the effects of periodic variations in the background buoyancy frequency have been studied, Under certain conditions, such fluctuations are found to cause trapping of mountain waves well below the tropopause while, in other instances, they result in unusually strong gravity-wave activity owing to a resonance phenomenon.