February 5, 2010, 12:00 pm - 1:00 pm

February 5, 2010, 12:00 pm - 1:00 pm

The Role of the Y-component of the Interplanetary Magnetic Field in Transpolar Potential Saturation and Ring Current Response as found in Data and Simulation

Elizabeth (Betsey) J. Mitchell (University of Texas at Arlington)

The interplanetary magnetic field (IMF) couples with the magnetosphere-ionosphere system through dayside merging, night side reconnection, and viscous interactions. These processes cause enhanced plasma convection in the magnetosphere and ionosphere, which in turn form the ring current and the transpolar potential, respectively. The role of the Y-component of the IMF (By) in the coupling between the solar wind and magnetosphere is poorly understood. We use the LFM global simulation, the CRCM, and data to quantify the transpolar potential and ring current responses to By. As with Bz, we find the transpolar potential saturates for large values of By. Furthermore, the transpolar potential saturates at approximately the same magnitude of the magnetic field, but with a much smaller transpolar potential value. This suggests the saturation of the transpolar potential depends on the balance of the forces in the magnetosheath rather than the region 1 current. Unlike with Bz, we find the ring current does not respond to changes in By. This indicates a decoupling of the plasma convection in the ionosphere from convection in the magnetosphere. We will present these findings and discuss how they change some of the current paradigms and theories in solar wind- magnetosphere coupling.