Altitude profile of the polar wind velocity and its relationship to ionospheric conditions

We present Akebono observations of the polar wind velocity and the ambient electron temperature in the polar ionosphere. The velocity of the H+ polar wind increases from about 1 km/s at 2000 km altitude to about 6 km/s at 4000 km altitude, and correlates with the local electron temperature at a given altitude. It is only weakly dependent on magnetic activity, but is generally more variable at active times. Our observation demonstrates the direct relationship between the local magnitude of ion acceleration and that of the ambipolar electric field responsible for the acceleration.