Ionospheric power consumption in global MHD Simulation predicted from solar wind measurements

Ionospheric power consumption in a global magnetohydrodynamic (MHD) simulation is investigated. The sum of Joule heating and precipitation power integrated over both hemispheres is calculated in four simulation runs. The simulation results of the total ionospheric dissipation are correlated with solar wind density, velocity, and magnetic field using a linear multi-variable fit and a power law. The fitting procedure yields similar power law exponents in three of the simulated events. The fourth event was a theoretical experiment in which the solar wind density and velocity were kept constant, and thus the power law exponents dependent on the density and velocity could not be determined; however, the exponent dependent on the interplanetary magnetic field (IMF) was close to the corresponding power law exponent in the three other events. It is shown that the ionospheric dissipation in the simulation can be predicted with over 80% correlation from the solar wind parameters using the power law. Furthermore, it is also speculated that the observational empirical proxies of ionospheric power consumption could, in principle, be reproduced from the power law, since earlier results suggest that the ionospheric Joule heating and precipitation powers given by the empirical proxies, are reasonably well-correlated with the simulation results of the two variables.