A numerical study of propagation characteristics of gravity wave packets propagating in a dissipative atmosphere

Zhang, Shaodong; Yi, Fan

doi:10.1029/2001jd000864

Cited by 49 publications

(48 citation statements)

References 42 publications

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“…This result cannot be explained on the basis of linear GW theory in a time-invariant backgroundfield frame, which predicts that the ground-based frequency of GWs does not change. Zhang et al (2000) and Zhang and Yi (2002) have numerically shown that nonlinearity and height-dependent molecular viscosity decrease the GW frequency, but they have not found a similar frequency increase as in the present study. More interestingly, the timevariable frequency increases at some heights but decreases at other heights.…”

Section: Ground-based Frequency Of the Gwscontrasting

confidence: 51%

Frequency variations of gravity waves interacting with a time-varying tide

et al. 2013

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Abstract. Using a nonlinear, 2-D time-dependent numerical model, we simulate the propagation of gravity waves (GWs) in a time-varying tide. Our simulations show that when a GW packet propagates in a time-varying tidal-wind environment, not only its intrinsic frequency but also its ground-based frequency would change significantly. The tidal horizontalwind acceleration dominates the GW frequency variation. Positive (negative) accelerations induce frequency increases (decreases) with time. More interestingly, tidal-wind acceleration near the critical layers always causes the GW frequency to increase, which may partially explain the observations that high-frequency GW components are more dominant in the middle and upper atmosphere than in the lower atmosphere. The combination of the increased ground-based frequency of propagating GWs in a time-varying tidal-wind field and the transient nature of the critical layer induced by a time-varying tidal zonal wind creates favorable conditions for GWs to penetrate their originally expected critical layers. Consequently, GWs have an impact on the background atmosphere at much higher altitudes than expected, which indicates that the dynamical effects of tidal-GW interactions are more complicated than usually taken into account by GW parameterizations in global models.

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Section: Ground-based Frequency Of the Gwscontrasting

confidence: 51%

Frequency variations of gravity waves interacting with a time-varying tide

et al. 2013

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“…Fully nonlinear numerical simulations of GW packets with quasi-monochromatic spectra were performed by Zhang and Yi (2002) to study the propagation of temporally and spatially localized GW packets in a dissipative thermosphere. They showed that λ z decreases as the GW packet dissipates, because of the vertical inhomogeneity of molecular viscosity.…”

Section: Liu Et Al: the Momentum Deposition Of Small Amplitude Grmentioning

confidence: 99%

“…Only GWs with large λ z can propagate deep into the thermosphere ). Eventually, every GW dissipates in the thermosphere (Pitteway and Hines, 1963;Hines, 1973;Richmond, 1978;Hickey and Cole, 1988;Zhang and Yi, 2002;VF05;Walterscheid and Hickey, 2011;Vadas and Nicolls, 2012;Nicolls et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere

Liu

Yue

et al. 2013

Ann. Geophys.

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Abstract. We study the momentum deposition in the thermosphere from the dissipation of small amplitude gravity waves (GWs) within a wave packet using a fully nonlinear two-dimensional compressible numerical model. The model solves the nonlinear propagation and dissipation of a GW packet from the stratosphere into the thermosphere with realistic molecular viscosity and thermal diffusivity for various Prandtl numbers. The numerical simulations are performed for GW packets with initial vertical wavelengths (λ z ) ranging from 5 to 50 km. We show that λ z decreases in time as a GW packet dissipates in the thermosphere, in agreement with the ray trace results of Vadas and Fritts (2005) (VF05). We also find good agreement for the peak height of the momentum flux (z diss ) between our simulations and VF05 for GWs with initial λ z ≤ 2πH in an isothermal, windless background, where H is the density scale height. We also confirm that z diss increases with increasing Prandtl number. We include eddy diffusion in the model, and find that the momentum deposition occurs at lower altitudes and has two separate peaks for GW packets with small initial λ z . We also simulate GW packets in a non-isothermal atmosphere. The net λ z profile is a competition between its decrease from viscosity and its increase from the increasing background temperature. We find that the wave packet disperses more in the non-isothermal atmosphere, and causes changes to the momentum flux and λ z spectra at both early and late times for GW packets with initial λ z ≥ 10 km. These effects are caused by the increase in T in the thermosphere, and the decrease in T near the mesopause.

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“…According to the ray trace solutions presented by Vadas and Fritts (2005), when gravity waves propagate upward in the thermosphere, their vertical wavelengths may diminish because of the effect of diffusion gradient. Previous numerical studies with similar diffusivity profiles indicate that the dissipation below 100 km is not strong enough to cause a decrease of the vertical wavelengths of upward propagating gravity waves, and the vertical wavelength begins to reduce at a certain height above 110 km (Zhang and Yi, 2002). In case 2, the excited wave does not attain the height of 100 km at t = 10 h, as shown in Fig.…”

Section: Effect Of Atmospheric Dissipationmentioning

confidence: 68%

“…The molecular kinematic and thermal diffusivities exponentially increase with the decreasing atmospheric density, and strong eddy diffusion exists in the mesopause region (Balsley et al, 1983;Hocking, 1987;Lübken, 1997;Xu et al, 2009a). Intensely dissipative gradient can decrease the vertical wavelength of gravity waves propagating in the thermosphere (Zhang and Yi, 2002;Vadas and Fritts, 2005). However, we lack an adequate understanding at present of the influences of atmospheric inhomogeneous temperature and dissipation on nonlinear interaction of gravity waves.…”

Section: K M Huang Et Al : Nonlinear Interaction Of Gravity Waves 265mentioning

confidence: 98%

Nonlinear interaction of gravity waves in a nonisothermal and dissipative atmosphere

Huang

Zhang

et al. 2014

Ann. Geophys.

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Abstract.Starting from a set of fully nonlinear equations, this paper studies that two initial gravity wave packets interact to produce a third substantial packet in a nonisothermal and dissipative atmosphere. The effects of the inhomogeneous temperature and dissipation on interaction are revealed. Numerical experiments indicate that significant energy exchange occurs through the nonlinear interaction in a nonisothermal and dissipative atmosphere. Because of the variability of wavelengths and frequencies of interacting waves, the interaction in an inhomogeneous temperature field is characterised by the nonresonance. The nonresonant three waves mismatch mainly in the vertical wavelengths, but match in the horizontal wavelengths, and their frequencies also tend to match throughout the interaction. Below 80 km, the influence of atmospheric dissipation on the interaction is rather weak due to small diffusivities. With the further propagation of wave above 80 km, the exponentially increasing atmospheric dissipation leads to the remarkable decay and slowly upward propagation of wave energy. Even so, the dissipation below 110 km is not enough to decrease the vertical wavelength of wave. The dissipation seems neither to prevent the interaction occurrence nor to prolong the period of wave energy exchange, which is different from the theoretical prediction based on the linearised equations. The match relationship and wave energy evolution in numerical experiments are helpful in further investigating interaction of gravity waves in the middle atmosphere based on experimental observations.

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A numerical study of propagation characteristics of gravity wave packets propagating in a dissipative atmosphere

Cited by 49 publications

References 42 publications

Frequency variations of gravity waves interacting with a time-varying tide

Frequency variations of gravity waves interacting with a time-varying tide

Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere

Nonlinear interaction of gravity waves in a nonisothermal and dissipative atmosphere

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