Single particle simulation on the storm-time ring current formation and DST variation Original Research Article

A single particle simulation has been carried out to understand the connection between interplanetary disturbances and the ring current formation. The calculated Dst is found to be in rough agreement with the observed one during three successive storms of April 1997 if we vary the plasma sheet density. We assumed that the plasma sheet density depends linearly on the solar wind density. We found that the plasma sheet density (as well as the temperature) plays a crucial role not only in the development but also recovery of Dst. If we only decrease the plasma sheet density, Dst exhibits a rapid recovery with a characteristic time of several hours. If we only decrease the plasma sheet temperature, Dst recovers rapidly and subsequently develops again. Such variations in the plasma sheet population are essential in the dynamics of the ring current.