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Accession Number
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ADA562556
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Title
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Nonlinear Aspects of Internal Waves in the Atmosphere.
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Publication Date
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Aug 2009
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Media Count
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78p
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Personal Author
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J. P. McHugh
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Abstract
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Internal waves in the atmosphere are responsible for a significant percentage of atmospheric turbulence, particularly at the tropopause. This turbulence can interfere with Air Force operations, and is in need of improved prediction methods. The research has considered a sequence of idealized phenomena aimed at this ultimate goal. The results show that nonlinear effects enhance wave amplitude at the altitude where the buoyancy frequency changes suddenly. Vertically propagating wave packets result in a horizontal mean flow which is due to the wave reflection at by the tropopause. This wave-induced mean flow causes a reduction in the Richardson number both above and below the tropopause, and ultimately forces upwardly propagating waves to overturn and break. Non-Boussinesq effects are important, but must be treated differently than the Boussinesq case to achieve a uniformly valid solution. Simulations of a vortex pair show that the tropopause may act as a boundary for turbulence.
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Keywords
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Air force operations
Atmospheric motion
Buoyancy
Internal waves
Methodology
Nonlinear systems
Richardson number
Tropopause
Turbulence
Vortices
Wave propagation
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Source Agency
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Non Paid ADAS
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NTIS Subject Category
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47C - Physical & Chemical Oceanography
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Corporate Author
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New Hampshire Univ., Durham.
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Document Type
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Technical report
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Title Note
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Final performance rept. 1 Jun 2005-31 May 2009.
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NTIS Issue Number
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1225
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Contract Number
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FA9550-05-1-0439
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