Global MHD simulations of the relative effects of solar wind features on cold dense plasma sheet formation during the August 31 2005 storm

The solar wind data for the August 31 2005 storm incorporates a prolonged period of northward Bz followed by a sudden transition to an extended period of southward Bz. This northward to southward transition is one condition that leads to the formation of the cold dense plasma sheet. In addition to this evolution in Bz, the data also exhibits substantial variation in the solar wind By and dynamic pressure. In this study we present results from the Multi-Fluid-Lyon-Fedder-Mobarry (MFLFM) global simulation model of the August 31 storm. A baseline run incorporating the measured solar wind data is contrasted with more controlled simulations where the solar wind By is set to zero and the dynamic pressure is held constant for extended periods of time. The relative influence of these two parameters on the formation and evolution of the cold dense plasma sheet are studied along with the their influence on magnetosphere-ionosphere coupling. Initial results suggest that solar wind By has a stronger influence on the global characteristics of the system within the context of this storm. Additionally, results from a complementary analysis incorporating the effects of ionospheric oxygen outflow are reported.