Numerical Simulation of Dipolarization Fronts in the Plasma Sheet of Magnetotail

This paper focuses on the numerical simulation of the physical and evolution features of the Dipolarization Fronts (DFs) by using the eight-wave MHD equations based on the conservation TVD scheme. Firstly, a numerical model of DFs which is produced by BBF flux is built up. It is made up of three parts, i.e., magnetotail balance model, substorm growth phase model and substorm triggering BFF model. The result of numerical simulation presents the features of the DFs caused by BBF flux. With the appearance of high speed flow, magnetic field B_z component shows the changing asymmetric bipolar structure, which means that pre-front decreases to negative while expands rapidly on the DFs. When B_z increases to its maximum, it falls and becomes stable. With the DFs moving earthward while the high speed flow heading to the same direction, B_z on the DFs changes less and less. The generations of high speed flux and the DFs make a wider differentiation in the tail. Therefore, B_z component starts sinking, which can be explained as the plasma of the earthward compression of the DFs generated by the speed differentiation.