Excitation of the ionospheric resonance cavity by neutral winds at middle latitudes
- 1Moscow State Engineering Physics Institute, 115409, Moscow, 31 Kashirskaya road, Russia
- 2Institute of Physics of the Earth, 123995 Moscow, 10 Bolshaya Gruzinskaya str., Russia
- 3Laboratoire de Physique et Chimie de l’Environnement, Centre National de la Recherche Scientifique, Orléans, France
- 4The University of Electro-Communications, Chofu, Tokyo, Japan
Abstract. A new mechanism for the ionospheric Alfvén resonator (IAR) excitation at middle latitudes is considered. It is shown that the ionosphere wind system in this region is capable of sustaining the generation of geomagnetic perturbations that can be detected by ground magnetometers. The general IAR dispersion relation describing the linear coupling of the shear Alfvén and fast magnetosonic/compressional modes is obtained. The dependence of the IAR eigenfrequencies and damping rates on the perpendicular wave number and on the ground conductivity during the day- and nighttime conditions is analyzed both analytically and numerically. In order to demonstrate the IAR excitation by neutral winds the power spectra of the geomagnetic perturbation on the ground surface are calculated. Furthermore, it is found that Kolmogorov spectra of the ionospheric turbulent neutral winds and the IAR eigenfrequencies lie in the same frequency range that make it possible to enhance the IAR excitation. The relevance of the developed theoretical model to the ground-based observations is stressed.