The role of solar wind dynamic pressure in driving geoeffectiveness: Global MHD simulation results

The ionospheric energy deposition analysis carried out using a global MHD simulation has yielded a high-correlation power law between the solar wind parameters (density, velocity and IMF) and the total ionospheric power consumption. In particular, the energy budget analysis has demonstrated that the solar wind dynamic pressure has a role in the ionospheric Joule heating. The working hypothesis has been that since the Region 1 field-aligned currents close to the Chapman-Ferraro currents driven by the dynamic pressure variations, the Joule heating produced by the closure of Region 1 currents would be controlled by the solar wind dynamic pressure. Furthermore, the global MHD simulation results show that the energy content inside various volumes within the simulation magnetosphere appears to be driven by the solar wind dynamic pressure. Therefore we argue that the solar wind dynamic pressure has a strong contribution to the global energetics of the magnetosphere and ionosphere as determined from a global MHD simulation (GUMICS-4). We demonstrate quantitatively both the role of solar wind dynamic pressure on the Region 1 currents as well as its effect on the ionospheric Joule heating by using GUMCS-4. We discuss the role of weak Region 2 currents in GUMICS-4 in the interrelation of the solar wind dynamic pressure and the ionospheric Joule heating.