Properties of acoustic-gravity waves at the boundary of two isothermal media

Heading: 
Dynamics and Physics of Solar System Bodies
1Fedorenko, AK, Kryuchkov, EI, 1Cheremnykh, OK, Melnychuk, SV, 1Zhuk, IT
1Space Research Institute under NAS and National Space Agency of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2022, 38(6):79-95
https://doi.org/10.15407/kfnt2022.06.079
Language: Ukrainian
Abstract: 

The properties of evanescent acoustic-gravity waves that can propagate at the boundary of two isothermal half-spaces with different temperatures are studied. For the known surface f-mode in such a model, the condition of simultaneous decrease in the density of wave energy up and down from the interface between the media is not satisfied. The paper shows that at the boundary of two isothermal media it is possible to implement evanescent waves in the form of combinations of f-modes and pseudo-modes (-modes) for both half-spaces. The nature of the matching of solutions at the boundary depends on the spectral parameters and the magnitude of the temperature jump. As the wavelength increases, the properties of the waves at the boundary change and their dispersion and polarization acquire features characteristic of acoustic-type waves. These differences are manifested not only in the dispersion dependence of the waves, but also in the change in their amplitudes with height, polarization, and velocity divergence at the media boundary. It was also found that for large temperature differences in the lower and upper half-space, there is a spectral region where solutions satisfying the boundary condition cannot decrease in energy simultaneously down and up. In this region of the spectrum, -modes decreasing in energy in the upper half-space and f-modes increasing in energy in the lower half-space are joined at the boundary. The considered waves at the boundary of two media can be observed in the stratified atmosphere at heights with a sharp temperature change, for example, in the lower part of the Earth’s thermosphere or in the chromosphere-corona transition region on the Sun.
Keywords: acoustic-gravity wave, boundary conditions, evanescent wave mode

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References: 

1. Kryuchkov E. I., Fedorenko A. K. (2012) Peculiarities of energy transport in the atmosphere by acoustic gravity waves, Geomagn. Aeron. (Engl. Transl.) 52(2), 235- 241.
https://doi.org/10.1134/S0016793212010057

2. Bernstein I. B., Book D. L. (1983) Effect of compressibility on Rayleigh-Taylor instability. Physics of Fluids. 26(2). 453458,
https://doi.org/10.1063/1.864158

3. Cheremnykh O. K., Fedorenko A. K., Kryuchkov E. I., Selivanov Y. A. (2019) Evanescent acoustic-gravity modes in the isothermal atmosphere: systematization, applications to the Earth's and Solar atmospheres. Ann. Geophys. 37(3). 405-415.
https://doi.org/10.5194/angeo-37-405-2019

4. Cheremnykh O. K., Fedorenko A. K., Selivanov Y. A., Cheremnykh S. O. (2021) Continuous spectrum of evanescent acoustic-gravity waves in an isothermal atmosphere. Mon. Notic. Roy. Astron. Soc. 503(4). 5545-5553.

5. Hines C. O. (1960) Internal gravity waves at ionospheric heights. Can. J. Phys. 38. 1441-1481.
https://doi.org/10.1139/p60-150

6. Jones W. L. (1969) Non-divergent oscillations in the Solar Atmosphere. Solar Phys. 7. 204-209.
https://doi.org/10.1007/BF00224898

7. Miles Alan J., Roberts B. (1992) Magnetoacoustic-gravity surface waves. I. Constant Alfven Speed. Solar Phys. 141. 205-234.
https://doi.org/10.1007/BF00155176

8. Rosental C. S., Gough D. O. (1994) The Solar f-mode as interfacial mode at the chromosphere-corona transition. Astrophys. J. 423. 488-495.
https://doi.org/10.1086/173826

9. Roy A., Roy S., Misra A. P. (2019) Dynamical properties of acoustic-gravity waves in the atmosphere. J. Atmos. and Solar-Terr. Phys. 186. 78-81.
https://doi.org/10.1016/j.jastp.2019.02.009

10. Stenflo L., Shukla P. K. (2009) Nonlinear acoustic gravity wave. J. Plasma Phys. 75. 841-847.
https://doi.org/10.1017/S0022377809007892

11. Tolstoy I. (1963) The theory of waves in stratified fluids including the effects of gravity and rotation. Rev. Modern Phys. 35(1).
https://doi.org/10.1103/RevModPhys.35.207

12. Vadas S. L., Fritts M. J. (2005) Thermospheric responses to gravity waves: Influences of increasing viscosity and thermal diffusivity. J. Geophys. Res. 110(D15103). doi:10.1029/2004JD005574.
https://doi.org/10.1029/2004JD005574

13. Waltercheid R. L., Hecht J. H. (2003) A reexamination of evanescent acoustic-gravity waves: Special properties and aeronomical significance. J. Geophys. Res. 108(D11). 4340. doi:10.1029/2002JD002421.
https://doi.org/10.1029/2002JD002421

14. Zhang S. D., Yi F. (2002) A numerical study of propagation characteristics of gravity wave packets propagating in a dissipative atmosphere. J. Geophys. Res. 107(D14). 1-9.
https://doi.org/10.1029/2001JD000864