Propagation of AGWs in inhomogeneous wind flows of the polar atmosphere
Рубрика:
| 1Fedorenko, AK, Kryuchkov, EI, 1Cheremnykh, OK, Melnychuk, SV 1Space Research Institute under NAS and National Space Agency of Ukraine, Kyiv, Ukraine |
| Kinemat. fiz. nebesnyh tel (Online) 2024, 40(1):24-37 |
| https://doi.org/10.15407/kfnt2024.01.024 |
| Язык: Ukrainian |
Аннотация: Satellite observations of acoustic-gravity waves in the polar regions of the atmosphere indicate a close connection of these waves with wind flows. The paper investigates the peculiarities of the propagation of AGWs in spatially inhomogeneous wind flows, where the flow speed slowly changes in the horizontal direction. A system of hydrodynamic equations was used for the analysis, which takes into account the wind flow with spatial heterogeneity. Unlike the system of equations written for a stationary medium (or a medium moving at a uniform speed), the resulting system contains components that describe the interaction of the waves with the medium. It is shown that the influence of heterogeneous background parameters of the medium can be separated from the effects of inertial forces by means of the special substitution of variables. The analytical expression was obtained that describes the changes in the wave amplitude in a medium moving with a non-uniform speed. This expression contains two functional dependencies: 1) the linear part caused by changes in the background parameters of the medium, which does not depend on the direction of wave propagation relative to the flow; 2) the exponential part associated with the inertia forces, which determines the dependence of the amplitudes of AGWs on the direction of their propagation. The exponential part shows an increase in the amplitudes of the waves in the headwind and a decrease in their amplitudes in the downwind. The obtained theoretical dependence of the amplitudes of AGWs on the wind speed is in good agreement with the data of satellite observations of these waves in the polar thermosphere. |
| Ключевые слова: acoustic-gravity wave, polar thermosphere, spatially inhomogeneous wind flow |
References:
1. Fedorenko A. K., Kryuchkov E. I., Cheremnykh O. K., Zhuk I. T. (2022). Wave disturbances of the atmosphere in a spatially inhomogeneous flow. Space Sci. and Technol. 28(6). 25-33. https://doi.org/10.15407/knit2022.06.025 2. Fedorenko A. K., Kryuchkov E. I., Cheremnykh O. K., Zhuk I. T. (2023). Acoustic-gravity wave spectrum filtering in the horizontally inhomogeneous atmospheric flow. Kinemat. Phys. Celest. Bodies. 39. 217-224. https://doi.org/10.3103/S0884591323040049 3. Bretherton F. P., Garrett C. J. R. (1969). Wavetrains in inhomogeneous moving media. Proc. Roy. Soc. A. 302. 529-554. https://doi.org/10.1098/rspa.1968.0034 4. Carignan G. R., Block B. P., Maurer J. C., Hedin A. E., Reber C. A., Spencer N. W. (1981). The neutral mass Spectrometer on Dynamics Explorer. Space Sci. Instrum. 5(4). 429-441. 5. Fedorenko A. K., Bespalova A. V., Cheremnykh O. K., Kryuchkov E. I. (2015). A dominant acoustic-gravity mode in the polar thermosphere. Ann. Geophys. 33. 101-108. doi:10.5194/angeo-33-101-2015. https://doi.org/10.5194/angeo-33-101-2015 6. Fedorenko A. K., Kryuchkov E. I., Cheremnykh O. K., Klymenko Yu. O., Yampolski Yu. M. (2018). Peculiarities of acoustic-gravity waves in inhomogeneous flows of the polar thermosphere. J. Atmos. and Solar-Terr. Phys. 178. 17-23. https://doi.org/10.1016/j.jastp.2018.05.009 7. Hines C. O. (1960). Internal gravity waves at ionospheric heights. Can. J. Phys. 38. 1441-1481. https://doi.org/10.1139/p60-150 8. Innis J. L., Conde M. (2002). Characterization of acoustic-gravity waves in the upper thermosphere using Dynamics Explorer 2 Wind and Temperature Spectrometer (WATS) and Neutral Atmosphere Composition Spectrometer (NACS) data. J. Geophys. Res. 107(A12). https://doi.org/10.1029/2002JA009370 9. Killeen T. L., Won Y. I., Nicieyewski R. J., Burns A. G. (1995). Upper thermosphere winds and temperatures in the geomagnetic polar cap: Solar cycle, geomagnetic activity, and interplanetary magnetic fields dependencies. J. Geophys. Res. 100. 21327-21342. https://doi.org/10.1029/95JA01208 10. Lighthill J. Waves in Fluids. Cambridge University Press. 1978. 504 р. 11. Lhr H., Rentz S., Ritter P., Liu H., Husler K. (2007). Average thermospheric wind pattern over the polar regions, as observed by CHAMP. Ann. Geophys. 25. 1093- 1101. (www.ann-geophys.net/25/1093/2007). https://doi.org/10.5194/angeo-25-1093-2007 12. Nappo C. J. An introduction to atmospheric gravity waves. Elsevier Science. 2002. 260. 13. Spencer N. W., Wharton L. E., Niemann H. B., Hedin A. E., Carignan G. R., Maurer J. C. (1981). The Dynamics Explorer wind and temperature spectrometer. Space Sci. Instrum. 5(4). 417-428. 14. Tolstoy I. (1963). The theory of waves in stratified fluids including the effects on gravity and rotation. Rev. Modern Phys. 35(1). 207-230. https://doi.org/10.1103/RevModPhys.35.207 15. Vadas S. L., Fritts M. J. (2005). Thermospheric responses to gravity waves: Influences of increasing viscosity and thermal diffusivity. J. Geophys. Res. 110, D15103, https://doi.org/10.1029/2004JD005574