Efficiency of solar wind energy coupling to the ionosphere

The ionospheric energy coupling efficiencies are defined as the ratios of the ionospheric energy deposition (namely auroral precipitation, Joule heating, and their total) to the solar wind energy input.

We find that the ionospheric energy coupling efficiencies decrease exponentially with the solar wind energy input. Moreover, it is the same case under geomagnetic storm conditions. Our results also show that the energy coupling efficiencies are dependent on the IMF clock angle and almost independent of the solar wind dynamic pressure.