Gravity Wave Modeling and Airglow Applications
Abstract
This grant supported numerical, theoretical, and observational studies of gravity wave and shear instability processes in the atmosphere and their impact on airglow layers near the mesopause. Among our results, two stand out in their importance. The first was numerical confirmation of the instability processes initiating the transition to turbulence in Kelvin-Helmholtz instability in an unstable shear flow. The second, and even more significant, was the identification of the vortex dynamics accounting for the transition to, and the cascade within, fully developed turbulence. We expect that these dynamics will play a critical role in virtually all turbulent flows and will thus be key to understanding turbulence transitions and effects in many geophysical and fluid applications. Also examined were the instability processes accompanying lower-frequency gravity waves, where similar transitions were found to occur and were found, in particular, to provide an explanation for apparent instability signatures in airglow data. Finally, we considered the dynamics and instabilities accompanying vortex pairs in two and three dimensions analytically and numerically. Environmental shear and stratification were found to have large influences on the occurrence and character of instabilities, suggesting that turbulence transitions and effects cannot be anticipated without knowledge of these fields.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 28, 1998
- Accession Number
- ADA356249
Entities
People
- David C Fritts
Organizations
- University of Colorado Boulder