The nonlinear interactions of whistlers in the ionospheric plasma during strong thunderstorms

Abstract

<p>  It is not new knowledge that whistler are always present in the ionosphere during the thunderstorms. The terrestrial ionosphere is mainly a plasma region which is very sensitive for different disturbances. A wide range of plasma instabilities can develop  in this region, which are often nonlinear processes and leading to the development of plasma turbulence.  Turbulence is one of the most universal events phenomena in nature. It plays a crucial role in the dynamics of the space plasma processes. The turbulence appears when some physical parameter exceeds a certain level. It can have place during strong thunderstorms. The ionosphere is sometimes treated as plasma physics laboratory with unique possibility to study fundamental plasma processes. The use of ionospheric satellite  gives the chance to perform insitu measurement of plasma parameters during dynamic processes. For our analysis we used set of selected data  of the electric and magnetic fields variations in ELF and VLF ranges originating from the all French microsatellite DEMETER which was operating on the circular orbit with inclination of about 80<sup>0</sup> at altitude of 660 km from July 2004 until December 2010.</p> <p>The  Fourier, wavelet and bispectral analysis of these signals has been performed. The 3 waves processes has been identified during few very strong strokes. In some cases the nonlinear interactions of whistlers with VLF signals of ground based transmitters. The character of spectra suggests the presence of Richardson’s cascade. Our conclusion is that these results are related to whistler turbulence.</p>