Dynamical effects of internal gravity waves in the equinoctial thermosphere

Yiğit, Erdal; Medvedev, Alexander S.; Aylward, A. D.; Ridley, A. J.; Harris, Mary; Moldwin, M. B.; Hartogh, P.

doi:10.1016/j.jastp.2011.11.014

Cited by 56 publications

(62 citation statements)

References 38 publications

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“…This could explain why a gravity wave source at mid-latitudes might also influence auroral latitudes. Interestingly, the mean dynamical effect of gravity waves is the deceleration of the mean zonal flow, and the gravity wave drag might be comparable to the ion drag (Yigit et al, 2012). The thermospheric horizontal body force is usually directed against the background wind flow (Vadas and Liu, 2009).…”

Section: On a Possible Physical Relation Of The Gws To The Skr Periodmentioning

confidence: 99%

“…from Saturn's troposphere up to the thermosphere would be needed for such an advanced model that might emerge in the next years and is clearly beyond the scope of this paper. GCMs of the whole atmosphere exist for the Earth (e.g., Miyoshi and Fujiwara, 2008;Yigit et al, 2012), and they do emphasize the importance of gravity waves created in the troposphere for thermospheric temperatures and winds.…”

Section: On the Difficulty Of Proving The Skr-gws Relationmentioning

confidence: 99%

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A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

Fischer

Groene

et al. 2014

Ann. Geophys.

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Abstract. The periodicity of Saturn kilometric radiation (SKR) varies with time, and its two periods during the first 5 years of the Cassini mission have been attributed to SKR from the northern and southern hemisphere. After Saturn equinox in August 2009, there were long intervals of time (March 2010 to February 2011 and September 2011 to June 2012) with similar northern and southern SKR periods and locked SKR phases. However, from March to August 2011 the SKR periods were split up again, and the phases were unlocked. In this time interval, the southern SKR period slowed down by ~ 0.5% on average, and there was a large jump back to a faster period in August 2011. The northern SKR period speeded up and coalesced again with the southern period in September 2011. We argue that this unusual behavior could be related to the so-called Great White Spot (GWS), a giant thunderstorm that raged in Saturn's atmosphere around that time. For several months in 2011, the visible head of the GWS had the same period of ~ 10.69 h as the main southern SKR modulation signal. The GWS was most likely a source of intense gravity waves that may have caused a global change in Saturn's thermospheric winds via energy and momentum deposition. This would support the theory that Saturn's magnetospheric periodicities are driven by the upper atmosphere. Since the GWS with simultaneous SKR periodicity measurements have only been made once, it is difficult to prove a physical connection between these two phenomena, but we provide plausible mechanisms by which the GWS might modify the SKR periods.

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Section: On a Possible Physical Relation Of The Gws To The Skr Periodmentioning

confidence: 99%

Section: On the Difficulty Of Proving The Skr-gws Relationmentioning

confidence: 99%

A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

Fischer

Groene

et al. 2014

Ann. Geophys.

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“…Using an extended gravity wave scheme (Yigit et al, 2008) that accounts for realistic wave propagation and dissipation showed that lower atmospheric gravity waves propagate into the thermosphere and affect the general circulation of the high-latitude thermosphere under various conditions (Yigit et al, 2009(Yigit et al, , 2012(Yigit et al, , 2014. Also, numerical simulations suggest that gravity waves propagate from the surface to the thermosphere (Hickey et al, 2009(Hickey et al, , 2010.…”

Section: Wind Control Of Agwsmentioning

confidence: 99%

A dominant acoustic-gravity mode in the polar thermosphere

et al. 2015

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Abstract. The article presents a summary of the main findings of the systematic study of acoustic-gravity waves (AGWs) in the polar thermosphere. This study was based on the in situ measurements made by the Dynamics Explorer 2 (DE2) spacecraft late in its mission when it descended low enough (250-400 km). It was found out that AGWs in the polar thermosphere are observed within a narrow frequency band close to the Brunt-Väisälä frequency and with horizontal wavelengths about 500-600 km. The broadband spectrum of travelling ionospheric disturbance (TID) frequencies observed by radars is caused by the Doppler effect. The AGW amplitudes do not depend on the altitude, but grow almost linearly with the wind velocity. They propagate towards the wind.

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“…Yu and Hickey (2007), Liu et al (2008), Matsumura et al (2011), and Occhipinti et al (2011) performed numerical simulations of AGWs in the atmosphere. Besides direct numerical simulations, propagation and dissipation of mesoscale internal gravity waves generated in the lower atmosphere have recently been studied in a general circulation model (Yi˘git et al 2009(Yi˘git et al , 2012) involving a parameterization of gravity wave effects, their nonlinear saturation and dissipation in the thermosphere (Yi˘git et al 2008). Gavrilov and Kshevetskii (2013a) solved two-dimensional nonlinear AGW equations using a numerical method described by Kshevetskii and Gavrilov (2005) and taking into account fundamental conservation laws.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional numerical simulation of nonlinear acoustic-gravity wave propagation from the troposphere to the thermosphere

Гаврилов

Кшевецкий

2014

Earth Planet Sp

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Three-dimensional nonlinear breaking acoustic-gravity waves (AGWs) propagating from the Earth's surface to the upper atmosphere are simulated numerically. Horizontally moving periodical structures of vertical velocity on the Earth's surface are used as AGW sources in the model. The 3D algorithm for hydrodynamic equation solution uses finite-difference analogues of basic conservation laws. This approach allows us to select physically correct generalized wave solutions of hydrodynamic equations. The numerical simulation covers altitudes from the ground up to 500 km. Vertical profiles of the mean temperature, density, molecular viscosity, and thermal conductivity are specified from standard models of the atmosphere. Atmospheric waves in a few minutes can propagate to high altitudes above 100 km after activation of the surface wave forcing. Surfaces of constant phases are quasi-vertical first, and then become inclined to the horizon below about 100 km after some transition time interval. Vertical wavelengths decrease with time and tend to theoretically predicted values after times longer than several periods of the wave forcing. Decrease in vertical wavelengths and increase in AGW amplitudes can lead to wave instabilities, accelerations of the mean flow and wave-induced jet streams at altitudes above 100 km. AGWs may transport amplitude modulation of atmospheric wave sources in horizontal directions up to very high levels. Low wave amplitudes in the beginning of transition processes after activation of atmospheric wave sources could be additional reasons for slower amplitude grows with height compared to the nondissipative exponential growth predicted for stationary linear AGWs. Production of wave-induced mean jets and their superposition with nonlinear unstable dissipative AGWs can produce strong narrow peaks of horizontal speed in the upper atmosphere. This may increase the role of transient nonstationary waves in effective energy transport and variations of atmospheric parameters and gas admixtures in a broad altitude range. Findings

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Dynamical effects of internal gravity waves in the equinoctial thermosphere

Cited by 56 publications

References 38 publications

A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

A possible influence of the Great White Spot on Saturn kilometric radiation periodicity

A dominant acoustic-gravity mode in the polar thermosphere

Three-dimensional numerical simulation of nonlinear acoustic-gravity wave propagation from the troposphere to the thermosphere

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