The interaction of thermally excited gravity waves with mean flows

Fels, Stephen B.; Lindzen, Richard S.

doi:10.1080/03091927409365793

Cited by 123 publications

(73 citation statements)

References 17 publications

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“…Below 70km the effect of eddy diffusion is not important, and Fu has the sense to induce an easterly in an anti-phase region, while it has the sense to induce a westerly in an in-phase region. This result is consistent with the general theories by Fels and Lindzen (1974) and by Andrews and McIntyre (1976). In the region above 70 km, the wave is dissipated by the eddy diffusion, and above 100 km it is dissipated by the molecular viscosity and conductivity and the ion drag.…”

supporting

confidence: 82%

Solar Diurnal Tides and the Induced Zonal Mean Flows By Saburo Miyahara

Miyahara

1980

Journal of the Meteorological Society of Japan

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supporting

confidence: 82%

Solar Diurnal Tides and the Induced Zonal Mean Flows By Saburo Miyahara

Miyahara

1980

Journal of the Meteorological Society of Japan

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“…The eastward torque provided by the tides in low latitude (< 30 N) middle atmosphere is indicated also in another model simulation (Moudden and Forbes 2008). The EP fluxes for the migrating diurnal and semidiurnal tides are plotted with arrows in Figs , and indicates an enhanced thermal excitation of tides (Fels and Lindzen 1974). The other area of strong EP flux divergence is located over 30 N at @ 0.02 mb, where the vertical shear u z < 0 is large (Fig.…”

Section: Resultsmentioning

confidence: 99%

On Forcing the Winter Polar Warmings in the Martian Middle Atmosphere during Dust Storms

Kuroda

Medvedev

Hartogh

et al. 2009

Journal of the Meteorological Society of Japan

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Using a Martian general circulation model, we investigated the changes in the meridional circulation during planet-encircling dust storms on Mars that produce strong temperature vertical inversions in the middle atmosphere over winter polar regions. It is shown that vigorous poleward and downward transport, and, consequently, the adiabatic heating are caused by dissipating thermal tides, planetary and resolved small-scale gravity waves and eddies in almost equal degree. The increase of tidal forcing is mainly due to a stronger excitation in the summer hemisphere. Contribution of the stationary planetary wave (SPW) with the zonal wavenumber s ¼ 1 increases during dust storms due to intensified generation in the lower atmosphere as well as due to more favorable vertical propagation. SPW ðs ¼ 2Þ varies less with the dust load, dissipates lower, and contributes to the warming only below @ 0.1 mb. Transient planetary wave (s ¼ 1, period @ 5 sols) with a barotropic/baroclinic vertical structure provides up to 1/3 of the forcing by SPW ðs ¼ 1Þ. For the first time, we demonstrated a significance of small-scale gravity waves and eddies in maintaining the meridional circulation in Martian middle atmosphere, at least in high winter latitudes during dust storms.

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“…They have asserted that migrating dayside-nightside heating Whitehead 1969, Thompson 1970), vertically propagating thermal tide (Fels and Lindzen 1974), and meridional circulation (Gierasch 1975) are important for super-rotation formation and maintenance mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Multiple Equilibrium States Appearing in a Venus-Like Atmospheric General Circulation Model

Kido

Wakata

2008

Journal of the Meteorological Society of Japan

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969 IntroductionVenus has a thick CO 2 atmosphere with surface pressure of 9.2 × 10 4 hPa. The surface temperature is about 730 K because of the greenhouse effect imparted by thick CO 2 gas. Sulfuric acid clouds blanket the entire planet at about 47−70 km. An important characteristic of Venus is its very slow rotation: its rotation period is 243 earth days. One Venus Solar day is 117 days considering both daily rotation and revolution. It might therefore be speculated that convection between dayside and nightside dominates the atmospheric circulation, and that the convection pattern moves slowly together with slowly migrating subsolar and antisolar points. However, such a convection has not been observed, and observations have confirmed that fast zonal winds, called super-rotation or four-day circulation, are predominant. The Venusian cloud pattern rotates in the same direction as the rotation of the solid Venus with about four days around Venus along the equator. The zonal wind speed increases with height; its velocity is about 100 m s −1 at the cloud top level (about 70 km). The wind is 60 times faster than the solid planet. The reason why dayside-nightside circulation does not appear but super-rotation (four-day circulation) is dominant remains still unclear. Furthermore, the mechanism producing and maintaining such a fast zonal wind Japan, Vol. 86, No. 6, pp. 969−979, 2008 Journal of the Meteorological Society of AbstractWe investigated the existence of multiple equilibrium states in the Venusian atmospheric general circulation suggested by Matsuda (1980Matsuda ( , 1982 using a Venus-like atmospheric general circulation model. We ran the model from two initial conditions: a state with large zonal wind increasing with height and a motionless state. For the large zonal wind initial state, a strong zonal wind with weak meridional circulation, i.e., super-rotation, appears. However for the motionless initial condition, slow zonal wind with strong meridional circulation relative to the farmer state appears. Each circulation reached a quasi-steady state. These results have the same features suggested by Matsuda. The presence of multiple equilibrium states was sensitive to the horizontal eddy viscosity parameter. For the strong zonal wind state, the acceleration of the zonal mean zonal wind results from the horizontal EP flux divergence from the wavenumber one component on the equator, which is mainly maintained by the Gierasch mechanism (1975). The presence of multiple equilibrium states suggests that an alternative slow zonal wind state could appear in the Venusian atmosphere if an appropriate initial condition or drastic fluctuation is assigned.

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The interaction of thermally excited gravity waves with mean flows

Cited by 123 publications

References 17 publications

Solar Diurnal Tides and the Induced Zonal Mean Flows By Saburo Miyahara

Solar Diurnal Tides and the Induced Zonal Mean Flows By Saburo Miyahara

On Forcing the Winter Polar Warmings in the Martian Middle Atmosphere during Dust Storms

Multiple Equilibrium States Appearing in a Venus-Like Atmospheric General Circulation Model

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