A climatology of
            F
            region gravity wave propagation over the middle and upper atmosphere radar

Abstract. The high-frequency and small horizontal scale gravity waves may be reflected and ducted in non-hydrostatic simulations, but usually propagate vertically in hydrostatic models. To examine gravity wave propagation, a preliminary study has been conducted with a global ionosphere–thermosphere model (GITM), which is a non-hydrostatic general circulation model for the upper atmosphere. GITM has been run regionally with a horizontal resolution of 0.2° long × 0.2° lat to resolve the gravity wave with wavelength of 250 km. A cosine wave oscillation with amplitude of 30 m s−1 has been applied to the zonal wind at the low boundary, and both high-frequency and low-frequency waves have been tested. In the high-frequency case, the gravity wave stays below 200 km, which indicates that the wave is reflected or ducted in propagation. The results are consistent with the theoretical analysis from the dispersion relationship when the wavelength is larger than the cutoff wavelength for the non-hydrostatic situation. However, the low-frequency wave propagates to the high altitudes during the whole simulation period, and the amplitude increases with height. This study shows that the non-hydrostatic model successfully reproduces the high-frequency gravity wave dissipation.

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The influence of active meteorological systems on the ionospheric F-region

Annals of Geophysics ◽

10.4401/ag-3708 ◽

1999 ◽

Vol 42 (1) ◽

Author(s):

C. R. Martinis ◽

J. R. Manzano

Keyword(s):

Wave Propagation ◽

Gravity Wave ◽

Opposite Effect ◽

The Other ◽

Physical Mechanisms ◽

F Region ◽

Before And After ◽

Mesoscale Convective ◽

Meteorological Systems ◽

Electronic Concentration

Effects on the F region of two active meteorological systems will be analyzed. These systems are known as Mesoscale Convective Complexes (MCCs). Ionospheric data from a vertical sounder located in Tucumán will be used. By comparing the behaviour of the F region parameters on the days before and after the MCC storm day, we see outstanding differences. These differences occur during night and dawn hours in both cases. The two phenomena show influences on the F region. One case shows an increase in electronic concentration followed by a decrease and the other shows the opposite effect. Gravity wave propagation from the top of clouds could be connected to these MCCs effects. Other possible physical mechanisms are also discussed.

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The impact of gravity waves rising from convection in the lower atmosphere on the generation and nonlinear evolution of equatorial bubble

Annales Geophysicae ◽

10.5194/angeo-27-1657-2009 ◽

2009 ◽

Vol 27 (4) ◽

pp. 1657-1668 ◽

Cited By ~ 30

Author(s):

E. Alam Kherani ◽

M. A. Abdu ◽

E. R. de Paula ◽

D. C. Fritts ◽

J. H. A. Sobral ◽

...

Keyword(s):

Wave Propagation ◽

Gravity Wave ◽

Gravity Waves ◽

Nonlinear Evolution ◽

Lower Atmosphere ◽

Plasma Bubble ◽

Plasma Bubbles ◽

F Region ◽

Interchange Instability ◽

Do So

Abstract. The nonlinear evolution of equatorial F-region plasma bubbles under varying ambient ionospheric conditions and gravity wave seeding perturbations in the bottomside F-layer is studied. To do so, the gravity wave propagation from the convective source region in the lower atmosphere to the thermosphere is simulated using a model of gravity wave propagation in a compressible atmosphere. The wind perturbation associated with this gravity wave is taken as a seeding perturbation in the bottomside F-region to excite collisional-interchange instability. A nonlinear model of collisional-interchange instability (CII) is implemented to study the influences of gravity wave seeding on plasma bubble formation and development. Based on observations during the SpreadFEx campaign, two events are selected for detailed studies. Results of these simulations suggest that gravity waves can play a key role in plasma bubble seeding, but that they are also neither necessary nor certain to do so. Large gravity wave perturbations can result in deep plasma bubbles when ionospheric conditions are not conducive by themselves; conversely weaker gravity wave perturbations can trigger significant bubble events when ionospheric conditions are more favorable. But weak gravity wave perturbations in less favorable environments cannot, by themselves, lead to strong plasma bubble responses.

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Airglow Measurements of Gravity Wave Propagation and Damping over Kolhapur (16.5°N, 74.2°E)

International Journal of Geophysics ◽

10.1155/2014/514937 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 6

Author(s):

R. N. Ghodpage ◽

A. Taori ◽

P. T. Patil ◽

S. Gurubaran ◽

A. K. Sharma ◽

...

Keyword(s):

Wave Propagation ◽

Gravity Wave ◽

Meridional Wind ◽

Vertical Wavelength ◽

Emission Layer ◽

Positive Correlation ◽

Intensity Measurements ◽

Wind Shears ◽

The Waves ◽

Airglow Intensity

Simultaneous mesospheric OH and O (1S) night airglow intensity measurements from Kolhapur (16.8°N, 74.2°E) reveal unambiguous gravity wave signatures with periods varying from 01 hr to 9 hr with upward propagation. The amplitudes growth of these waves is found to vary from 0.4 to 2.2 while propagating from the OH layer (~87 km) to the O (1S) layer (~97 km). We find that vertical wavelength of the observed waves increases with the wave period. The damping factors calculated for the observed waves show large variations and that most of these waves were damped while traveling from the OH emission layer to the O (1S) emission layer. The damping factors for the waves show a positive correlation at vertical wavelengths shorter than 40 km, while a negative correlation at higher vertical wavelengths. We note that the damping factors have stronger positive correlation with meridional wind shears compared to the zonal wind shears.

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