Quiet time solar illumination effects on the fluxes and characteristic energies of ionospheric outflow

We report on the characteristic energy, intensity, and flow rate of escaping ionospheric ions as a function of solar illumination. The data presented here were acquired with the Toroidal Ion Mass‐Angle Spectrograph (TIMAS) instrument on the Polar satellite at altitudes of 6000 to 9000 km, during solar minimum. To obtain uniform coverage under various solar illumination conditions, data were restricted to geomagnetically quiet intervals when the Dst index was above −50 nT. We explicitly report data for four magnetic local time ranges. Our investigation confirms many of the characteristics of ion outflows deduced from earlier episodic studies and identifies an anticorrelation in the dependence of beam and conic fluxes on solar illumination, which we attribute to variations in the altitude at which auroral acceleration processes occur. We find that the cusp is an important but not dominant source of ionospheric plasma for the magnetosphere. We conclude that significantly different plasma energization and/or transport mechanisms are dominant in the cusp and the midnight sectors. In addition, we conclude that variations in the solar EUV and geomagnetic energy inputs into the ionosphere, rather than the longer timescale seasonal and annual variations in solar illumination, determine the global rates of H+ and O+ outflow. The data presented here provide comprehensive and realistic boundary conditions for large‐scale magnetospheric models during nonstorm times.