Detection of magneto-gravity waves in the ionosphere by analysis of the maximum observable frequencies on oblique-sounding paths

Abstract

The existence of magneto-gravity waves stipulated by the substorm activity can lead to the occurrence of traveling ionospheric disturbances, whose velocity exceeds the sound speed. For detection of magneto-gravity waves, we used experimental data on propagation of decameter radio waves on the midlatitude and subauroral oblique sounding paths Inskip-Rostov-on-Don, Cyprus-Rostovon-Don, Irkutsk-Rostov-on-Don, and Norilsk-Rostov-on-Don in December 2006 and March 2007 under conditions of weak geomagnetic disturbance. Time delays between the AE indices of polar electrojets and the maximum observable frequencies for the considered paths were established by calculation of linear correlations. These delays correspond to the times required for transport of gravity disturbances from the auroral region to the reflection points of radio waves on respective paths. Among the obtained time shifts, we mention the 5-10-min ones which correspond to increased velocity of the disturbances compared with the usual velocities of acoustic-gravity waves for the paths under study. Such cases can be related to the transport of magneto-gravity waves. Study of the spectral composition of the AE-index disturbances and recorded maximum observable frequencies shows consistency of their spectral features in the cases of increased correlation for small time delays. It is also found that the spectral features of the AE-index disturbances coincide with the spectral features of the disturbances of the horizontal component of the geomagnetic field on ground-based magnetic stations. According to calculated dispersion curves, the frequencies of magneto-gravity waves were estimated, and they turned out to be equal to ω ≈ (1-2) · 10 −4 Hz.

Reflection of the dynamics of interplanetary space parameters in the maximum observable frequencies on different ionospheric oblique-sounding paths

“…A detailed method of MOF purification from the diurnal variation is presented in [11]. As a result, we obtained new values of the frequencies which contain only MOF variations.…”

Synchronization of geomagnetic and ionospheric disturbances over Kazan station

“…However, the excitation of MHD waves in the magnetosphere and conducting ionospheric layers may not necessarily be due to the development of global geomagnetic disturbances. For example, Barkhatova et al [2009Barkhatova et al [ , 2015 have identified MS waves generated by the eastward electrojet and largemagnitude earthquakes. In addition, along with geomagnetic disturbances in the ULF range there were synchronous disturbances in the conducting F2 layer.…”

Spectral characteristics of magnetogravity waves generated by high-energy mass source in the equatorial region of the atmosphere, Part I

“…Some part of this is due to disturbances caused by of acoustic gravity waves, which changes in the electron concentration of ionospheric layers (Hocke et al, 1996;Kirchengast, 1997;Balthazor and Moffett, 1997;Cai et al, 2011;Song et al, 2012) and well known as traveling iono spheric disturbances (TIDs). It is noted (Sorokin and Fedorovich, 1982;Barkhatova et al, 2009;Barkhatov et al, 2012) that passage of magnetogravity type waves disturb ionospheric layers density as well as geomag netic field components. As sources of ionospheric dis turbances including TIDs auroral electrojets are often considered (Hunsucker, 1982;Afraimovich et al, 2000;Zhivet'ev et al, 2005), natural geophysical events (earthquakes and tsunamis) (Pulinets et al, 1998;Liu J.Y., et al, 2000;Liperovsky et al, 1992;Dabas et al, 2007;Hickey et al, 2009;Perrone et al, 2010;Xu et al, 2010;Liu et al, 2011) as well as high energy events of artificial origin-ground and altitude explosions and artificial heating of the ionosphere (Alperovitch et al, 1985a,b,c) ;Nagorskiy, 1985;Chernogor and Frolov, 2013a,b).…”