| This dissertation discusses investigations into the physics of the propagation of solar generated disturbances in the interplanetary medium. The motivation to initiate this study was two folds: (i) understanding the fundamental physics of the nonlinear interactions of solar generated MHD shocks and non-homogeneous interplanetary medium, and (ii) understanding the physics of solar generated disturbance effects on the Earth's environment (i.e. the solar connection to the geomagnetic storm). In order to achieve these goals, the authors employed two numerical models to encompass these studies.; In the first part, a one-dimensional MHD code with adaptive grids is used to study the evolution of interplanetary slow shocks (ISS), the interaction of a forward slow shock with a reverse slow shock, and the interaction of a fast shock with a slow shock. Results show that the slow shocks can be generated by a decreasing density, velocity or temperature perturbation or by a pressure pulse by following a forward fast shock and that slow shocks can propagate over 1 AU; results also show that the ISS never evolves into fast shocks. Interestingly, it is also found that an ISS could be "eaten up" by an interplanetary fast shock (IFS) catching up from behind. This could be a reason that the slow shock has been difficult to observe near 1 AU. In addition, a forward slow shock could be dissipated by following a strong forward fast shock (Mach number greater than 1.7).; In the second part, a fully three-dimensional (3D), time-dependent, MHD interplanetary global model (3D IGM) is used to study the relationship between different forms of solar activity and transient variations of the north-south component, {dollar}Bsb{lcub}z{rcub}{dollar}, of the interplanetary magnetic field, IMF, at 1 AU. One form of solar activity, the flare, is simulated by using a pressure pulse at different locations near the solar surface and observing the simulated IMF evolution of {dollar}Bsb{lcub}theta{rcub}{dollar} (= {dollar}-Bsb{lcub}z{rcub}{dollar}) at 1 AU. Results show that, for a given pressure pulse, the orientation of the corresponding transient variation of {dollar}Bsb{lcub}z{rcub}{dollar} has a strong relationship to the location of the pressure pulse and the initial conditions of the IMF. |
