This research work is devoted to the study of the coupling and propagation of hydromagnetic waves in the magnetosphere. A dipole magnetic field model of the magnetosphere is considered for having a realistic simulation of the earth's magnetosphere. The analysis allows for a spatial variation of Alfven speed, arbitrary azimuthal asymmetry, and arbitrary plasma density profile. The hydromagnetic waves of poloidal mode and toroidal mode are then shown to be coupled through the plasma inhomogeneity and governed by two mixed-type coupled partial differential equations having variable coefficients. A numerical scheme for solving these two equations has been developed. The stability condition of this numerical scheme is examined by the Fourier method and matrix method. A boundary value problem has then been solved to demonstrate the relevance and applicability of the work to the study of magnetospheric Pc 4-5 micropulsations. The main contribution of the developed numerical code is enable to reconstruct the global structures of geomagnetic micropulsations based on limited localized data obtained by satellites. This is done by matching the solutions of hydromagnetic wave equations with the features deduced from the satellite observations. The results of the solutions then display the global structures of the micropulsations. Specifically, the data of storm time Pc 5 waves of the events on November 14-15 1979, obtained simultaneously from the four satellites SCATHA(P78-2), GOES2, GOES3, and GEOS2 is used to demonstrate the point. Four distinct features deduced by Takahashi et al. (1987) from the observational data are used as the imposed conditions of the solutions. Numerical solutions which can satisfy all the features have been obtained. Moreover, using the numerical code, the dependence of the characteristic of hydromagnetic waves on the azimuthal (East-West) mode number (degree of asymmetry) has also been studied.
- Pub Date:
- January 1990
- Physics: Fluid and Plasma, Physics: Astronomy and Astrophysics