MHD simulation of sawtooth events in meridional plane driven by various solar wind velocities

Abstract

The meridional global MHD modeling of magnetosphere sawtooth events is performed for three values of the solar wind velocity: 200 km/s, 400 km/s and 800 km/s. The tooth cycle period of the open magnetic field specific flux decreases from 6.4 to 2.0 ks, respectively, while the oscillations amplitude changes inessentially. The tail magnetic field topology evolve through all the standard phases and events. In the distant tail the flapping current sheet is disturbed by the Alfven waves. In the dipole magnetic field domain the night-side attached vortices splitting and their subsequent shedding occur forming the Karman like vortex street. The vortex shedding period falls from 200 s to 110 s with the increase of the solar wind velocity. In the day-side shocked layer the vertically elongated thin magnetic island with the two neutral points is located. The magnetic island accounts for the deflection of the solar plasma inflow around the magnetosphere.