Start Date: 2007-05-01 End Date: 2009-10-31
The goal of the project was to establish certain properties of the behaviour of waves in the Earth's ionosphere that might be useful as earthquake precursors. From our theoretical and numerical investigations, based on fluid dynamics and the system of MHD equations, we obtained the following results:
1) We investigated the propagation of acoustic-gravity waves in the weakly ionized D, E, and F layers of the Earth's ionosphere. We found that when the acoustic-gravity waves are excited by external events their amplitudes grow to the point that these waves are able to self-organize into nonlinear vortex solitary structures.We analyzed a novel mechanism for the generation of low-frequency large-scale zonal flows by higher-frequency, small-scale, finite-amplitude internal gravity (IG) waves. The nonlinear generation mechanism is based on the parametric excitation of convective cells by finite-amplitude internal gravity waves. We determined the growth rates of the zonal flow instabilities and the conditions for exciting them.
2)We found that low-frequency internal gravity waves that are generated by seismic activity and non-linearly propagated through the stably stratified atmosphere can cause the green-line emission of atomic oxygen to be intensified. The corresponding nonlinear vortices provide a mechanism for increasing the concentration of atomic oxygen in the E-layer , which leads to an associated increase in the intensity of the green light radiation at 557.7 nm.
3)On basis of the results that we obtained , we have proposed a new method for the determination of both ionospheric particle-number densities and local wind velocities.
4)We pointed out that there is some evidence that the presence of solitary wave structures with certain properties may prove to be a way of forecasting probable conditions for earthquakes.