Theoretical and Observational Studies of Gravity Wave Excitation, Propagation and Dissipation.
Final rept. Apr 82-May 86,
ALASKA UNIV FAIRBANKS GEOPHYSICAL INST
Pagination or Media Count:
Research under this grant focussed on several aspects of gravity wave excitation, propagation, and dissipation that are expected to be important in the atmosphere. Initial studies addressed the excitation of propagating waves by unstable shear layers and found that the nonlinear interaction of evanescent unstable modes is an efficient source of such motion. Other mumerical studies examined the consequences of gravity wave propagation and saturation in the middle atmosphere. Important findings include an amplitude limit imposed by wave field instabilities, the self-accelerations of large-amplitude motions which may greatly expand the phase speed distribution of mesospheric wave motions, and the field instability. Observational studies revealed wave field dynamics to be largely consistent with linear instability theory, with turbulence produces at that site in the wave field where the motion is most unstable. Wave amplitudes were seen to be near saturation value and easily descrived by a simple saturation model of the evolving gravity wave spectrum throughout the atmosphere. Additional theoretical studies addressed the turbulent transport of hear and constituents and the induced mean vertical motions to vertically propagating gravity waves, contributing to our understanding of apparent differences between observations and modeling results.
- Atmospheric Physics
- Fluid Mechanics