Earth's atmosphere in dynamic coupling envisaged through atmospheric tides and atmospheric gravity waves: A view on the past-present-future research

Abstract. Recent investigations of atmospheric gravity waves (AGW) and travelling ionospheric disturbances (TID) in the Earth\\'s thermosphere and ionosphere are reviewed. In the past decade, the generation of gravity waves at high latitudes and their subsequent propagation to low latitudes have been studied by several global model simulations and coordinated observation campaigns such as the Worldwide Atmospheric Gravity-wave Study (WAGS), the results are presented in the first part of the review. The second part describes the progress towards understanding the AGW/TID characteristics. It points to the AGW/TID relationship which has been recently revealed with the aid of model-data comparisons and by the application of new inversion techniques. We describe the morphology and climatology of gravity waves and their ionospheric manifestations, TIDs, from numerous new observations.

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Influence of atmospheric winds and tides on the propagation direction of mesospheric gravity waves observed in OH airglow in the Alpine region

10.5194/egusphere-egu2020-3609 ◽

2020 ◽

Author(s):

Patrick Hannawald ◽

Sabine Wüst ◽

Michael Bittner ◽

Friederike Lilienthal ◽

Christoph Jacobi

Keyword(s):

Gravity Waves ◽

Lower Thermosphere ◽

Phase Speed ◽

Alpine Region ◽

Propagation Direction ◽

Atmospheric Tides ◽

Prevailing Wind ◽

Atmospheric Gravity Waves ◽

Energy And Momentum ◽

Atmospheric Gravity

Atmospheric gravity waves transport energy and momentum trough the different atmospheric layers from the troposphere up to the mesosphere and above. On the one hand this transport has influence on atmospheric circulation patterns and drives for example the meridional circulation in the mesosphere. On the other hand the prevailing wind field selectively influences the vertical propagation conditions of gravity waves of different phase speed and horizontal propagation direction.The OH-airglow layer at ca. 86 km altitude (upper mesosphere / lower thermosphere, UMLT) is well-suited for the investigation of atmospheric dynamics, allowing continuous observations of the night-sky throughout the year. Especially, atmospheric gravity waves are prominent features in the data of airglow imaging systems. Furthermore, this altitude region is known to be a region where wave breaking occurs quite often making it particular interesting for quantifying the amount of energy and momentum released due to gravity waves.Five years of airglow observations with three FAIM (Fast Airglow Imager) systems in and around the Alpine region are analysed regarding high-frequency gravity waves. Prevailing wind fields and tides from meteor radar wind data and ERA5 data are compared with the propagation direction of these waves and show patterns with high correlation. On seasonal timescales, the gravity waves clearly propagate predominantly to the East in summer and to the West in winter regarding the zonal direction. The meridional direction varies between the different years. On diurnal timescales, we find that atmospheric tides significantly impact the main propagation directions of the gravity waves.We further present a case study of a stereoscopic reconstruction using two synchronized airglow-imagers with overlapping field-of-views. This allows deriving the wave amplitude and a 3D visualization of gravity wave patterns within the airglow layer.This work received funding from the Bavarian State Ministry of the Environment and Consumer Protection.

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An Introduction to Atmospheric Gravity Waves

10.1016/s0074-6142(02)x8001-2 ◽

2002 ◽

Keyword(s):

Gravity Waves ◽

Atmospheric Gravity Waves ◽

Atmospheric Gravity

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Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra

Natural Hazards and Earth System Science ◽

10.5194/nhess-7-625-2007 ◽

2007 ◽

Vol 7 (5) ◽

pp. 625-628 ◽

Cited By ~ 36

Author(s):

A. Rozhnoi ◽

M. Solovieva ◽

O. Molchanov ◽

P.-F. Biagi ◽

M. Hayakawa

Keyword(s):

Gravity Waves ◽

Fresnel Zone ◽

Signal Amplitude ◽

Magnetic Storms ◽

Frequency Range ◽

Atmospheric Gravity Waves ◽

Period Range ◽

Before And After ◽

Atmospheric Gravity ◽

Large Earthquakes

Abstract. We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.

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Rolls of the internal gravity waves in the Earth's atmosphere

Annales Geophysicae ◽

10.5194/angeo-32-181-2014 ◽

2014 ◽

Vol 32 (2) ◽

pp. 181-186 ◽

Cited By ~ 7

Author(s):

O. Onishchenko ◽

O. Pokhotelov ◽

W. Horton ◽

A. Smolyakov ◽

T. Kaladze ◽

...

Keyword(s):

Nonlinear Dynamics ◽

Gravity Waves ◽

Closed System ◽

Wind Shear ◽

Internal Gravity Waves ◽

Temperature Gradients ◽

System Of Equations ◽

Vertical Temperature ◽

Earth’S Atmosphere ◽

Earth's Atmosphere

Abstract. The effect of the wind shear on the roll structures of nonlinear internal gravity waves (IGWs) in the Earth's atmosphere with the finite vertical temperature gradients is investigated. A closed system of equations is derived for the nonlinear dynamics of the IGWs in the presence of temperature gradients and sheared wind. The solution in the form of rolls has been obtained. The new condition for the existence of such structures was found by taking into account the roll spatial scale, the horizontal speed and wind shear parameters. We have shown that the roll structures can exist in a dynamically unstable atmosphere.

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A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes

Annales Geophysicae ◽

10.1007/s00585-997-1048-4 ◽

1997 ◽

Vol 15 (8) ◽

pp. 1048-1056 ◽

Cited By ~ 41

Author(s):

R. L. Balthazor ◽

R. J. Moffett

Keyword(s):

Gravity Waves ◽

Large Scale ◽

Ionospheric Disturbance ◽

Magnetic Equator ◽

Ionospheric Disturbances ◽

Atmospheric Gravity Waves ◽

Opposite Hemisphere ◽

Travelling Ionospheric Disturbances ◽

F Region ◽

Atmospheric Gravity

Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.

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