12th Conference on Middle Atmosphere

Tuesday, 5 November 2002
Gravity wave effects on the mean flow and eddy mixing: possible comparison of the parameterization schemes.
Valery A. Yudin, NCAR, Boulder, CO
In this paper I analyze the relationships between the gravity wave (GW) induced momentum deposition, heating rates, and eddy mixing (or wave dissipation) in various GW parameterizations beginning from Lindzen's (1981) momochromatic scheme and its recent modifications as well as in recently proposed spectral schemes [Warner and McIntyre(1999, 2001), and Hines (1997) and its modifications]. In all of these parameterizations, the assumption of the steady state balance of the total gravity wave energy is employed to link the GW momentum deposition with wave dissipation (mono-type) or with the induced wave energy deposition (spectral type). Assumption of the steady state wave flow at given height can be replaced on the quasi-equailibrium condition which can be expressed as follows: all transient irreversible changes in the GW energy should be appeared in the mean flow energy equation.

Based on these two 'conservation' assumptions I discuss expressions for gravity wave 'heating rates' and eddy mixing for a number of GW schemes. In conclusion, I will discuss the numerical aspects of Hines's-97 scheme in the 'dissipative' atmosphere illustrating the importance of the accurate selection of the launch spectra parameters. The role of the molecular viscosity in the spectral schemes will be discussed using the wave action framework.

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