Articles | Volume 35, issue 1
Ann. Geophys., 35, 53–70, 2017
Ann. Geophys., 35, 53–70, 2017

Regular paper 05 Jan 2017

Regular paper | 05 Jan 2017

Ground-based acoustic parametric generator impact on the atmosphere and ionosphere in an active experiment

Yuriy G. Rapoport1,2, Oleg K. Cheremnykh1, Volodymyr V. Koshovy3, Mykola O. Melnik4, Oleh L. Ivantyshyn3, Roman T. Nogach4, Yuriy A. Selivanov1, Vladimir V. Grimalsky5, Valentyn P. Mezentsev4, Larysa M. Karataeva4, Vasyl. M. Ivchenko2, Gennadi P. Milinevsky2, Viktor N. Fedun6, and Eugen N. Tkachenko2 Yuriy G. Rapoport et al.
  • 1Space Research Institute NASU-SSAU, Kyiv, 03187, Ukraine
  • 2Taras Shevchenko National University of Kyiv, Kyiv, 01601, Ukraine
  • 3G. V. Karpenko Physical-Mechanical Institute NASU, Lviv, 79053, Ukraine
  • 4Lviv Centre of the Institute of Space Research NASU-NSAU, Lviv, 79053, Ukraine
  • 5Autonomous University of State Morelos (UAEM), Cuernavaca, Morelos, 62209, Mexico
  • 6Department of Automatic Control and Systems Engineering, The University of Sheffield, Sheffield, S1 3JD, UK

Abstract. We develop theoretical basics of active experiments with two beams of acoustic waves, radiated by a ground-based sound generator. These beams are transformed into atmospheric acoustic gravity waves (AGWs), which have parameters that enable them to penetrate to the altitudes of the ionospheric E and F regions where they influence the electron concentration of the ionosphere. Acoustic waves are generated by the ground-based parametric sound generator (PSG) at the two close frequencies. The main idea of the experiment is to design the output parameters of the PSG to build a cascade scheme of nonlinear wave frequency downshift transformations to provide the necessary conditions for their vertical propagation and to enable penetration to ionospheric altitudes. The PSG generates sound waves (SWs) with frequencies f1 = 600 and f2 = 625 Hz and large amplitudes (100–420 m s−1). Each of these waves is modulated with the frequency of 0.016 Hz. The novelty of the proposed analytical–numerical model is due to simultaneous accounting for nonlinearity, diffraction, losses, and dispersion and inclusion of the two-stage transformation (1) of the initial acoustic waves to the acoustic wave with the difference frequency Δf = f2 − f1 in the altitude ranges 0–0.1 km, in the strongly nonlinear regime, and (2) of the acoustic wave with the difference frequency to atmospheric acoustic gravity waves with the modulational frequency in the altitude ranges 0.1–20 km, which then reach the altitudes of the ionospheric E and F regions, in a practically linear regime. AGWs, nonlinearly transformed from the sound waves, launched by the two-frequency ground-based sound generator can increase the transparency of the ionosphere for the electromagnetic waves in HF (MHz) and VLF (kHz) ranges. The developed theoretical model can be used for interpreting an active experiment that includes the PSG impact on the atmosphere–ionosphere system, measurements of electromagnetic and acoustic fields, study of the variations in ionospheric transparency for the radio emissions from galactic radio sources, optical measurements, and the impact on atmospheric aerosols. The proposed approach can be useful for better understanding the mechanism of the acoustic channel of seismo-ionospheric coupling.

Short summary
Before many catastrophic phenomena such as earthquakes, sound is generated at a very low frequency. It is already established that it can disturb the upper layer of the atmosphere – the ionosphere. Control of disasters' precursors is important. Using the unique, powerful sound generator, whose loudness is comparable to an ascending jet, we have constructed the theory and conducted a series of experiments trying to model acoustic action of disasters on the ionosphere.