Magnetotail Quasi-steady-state Structure And Dynamics Of The Process

A reliable three-dimention MHD (Magnetohydrodynamics) numerical model of the magnetosphere is very important to the geospace research and space whether forecasting. Implying the up-wind scheme and adaptive grids, we have established a 3-D simulation model of the magnetosphere based on the ideal MHD equations, and successfully achieved quasi-steady states.One of the main features of this model is that it can "close" the magnetic reconnection on the magnetopause by a method of dealing with IMF and the dipole magnetic field separately. By introducing the anti-parallel theory, this method can show the possible reconnection sites on the magnetopause distinctly like the gas dynamic model. We suggest that this model may be helpful to the study of Solar-Territorial interaction from a different point of shutting down the magnetic reconnection, and may reveal some important physical processes of the magnetosphere.By this numerical model, we have simulated and investigated problems like dawn-dusk asymmetry of the magnetosheath, reconnection patterns on the tail-magnetopause, plasma penetrating into the plasma sheet from the magnetosheath under quiet conditions, large-scale topologies of the magnetotail, accelerated flows adjacent to the tail-magnetopause, and so on. The results show that:The dawn-dusk asymmetry of the magnetosheath is substantial because of the Parker spiral IMF, and the magnetic reconnection on the magnetopause has no significant effects. When the IMF is northward and has a relatively small clock angle, magnetic reconnections on the magnetopause occur about 10-12RE downstream. This causes plasma transfers into the plasma sheet from the flanks, and the plasma sheet shows a large-scale four-vortex structure in the near and mid-tail.As the effects of the magnetic reconnection on the near-tail magnetopause and the anisotropic pressure of the IMF, the magnetotail shows a twisted and flattened profile. The bended IMF flux tubes and the magnetic reconnections on the near-tail magnetopause can accelerate plasma adjacent the magnetopause, and the plasma velocity may exceed the solar wind speed. This phenomenon is significantly influenced by the magnitude and the clock angle of the IMF, and the acceleration processes is greatly reduced when the strength of the IMF decreases or the clock angle of the IMF increased.