Abstract
Abstract. The mechanism of generation of internal gravity waves (IGW) by mesoscale turbulence in the troposphere is considered. The equations that describe the generation of waves by hydrodynamic sources of momentum, heat and mass are derived. Calculations of amplitudes, wave energy fluxes, turbulent viscosities, and accelerations of the mean flow caused by IGWs generated in the troposphere are made. A comparison of different mechanisms of turbulence production in the atmosphere by IGWs shows that the nonlinear destruction of a primary IGW into a spectrum of secondary waves may provide additional dissipation of nonsaturated stable waves. The mean wind increases both the effectiveness of generation and dissipation of IGWs propagating in the direction of the wind. Competition of both effects may lead to the dominance of IGWs propagating upstream at long distances from tropospheric wave sources, and to the formation of eastward wave accelerations in summer and westward accelerations in winter near the mesopause.
Highlights
Internal gravity waves (IGWs) play an important role in the formation of the general circulation, thermal regime, and composition of the middle and upper atmosphere.According to present knowledge, the main portion of internal gravity waves (IGW) energy reaches the middle and upper atmosphere from tropospheric sources
Several parametrizations have been developed for the turbulent viscosity, meanow drag and heating rates produced by dissipating IGWs (Lindzen, 1981; Matsuno, 1982; Holton, 1983; Gavrilov, 1990; Fritts and Lu, 1993; Medvedev and Klaassen, 1995; Hines, 1997)
In this study the parametrization of IGW dynamic and thermal eects developed by Gavrilov (1990)
Summary
Internal gravity waves (IGWs) play an important role in the formation of the general circulation, thermal regime, and composition of the middle and upper atmosphere. The generation of long-period inertia-gravity waves by synoptic scale motions is described by the theory of quasi-geostrophic adjustment that was developed in the dynamic meteorology beginning with Rossby, (1937), Obukhov, (1949), and Kibel, (1955). According to this theory, wave motions appear as the result of permanent competition between the violation of equilibrium of pressure and velocity and the tendency of the atmosphere to establish the quasi-geostrophic balance of these ®elds (Pedlosky, 1982; Gill, 1982; Gavrilov, 1987; Fritts and Luo, 1992; Medvedev and Gavrilov, 1995). In the present study only the generation and propagation of monochromatic plane IGW harmonics is studied, but the parametrization developed here may serve as a basis for statistical numerical models of IGW spectrum, similar to the model developed by Medvedev and Klaassen (1995)
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