On divergences of thermospheric meridional winds at midlatitudes

The existence of large scale (300 m/s) divergences, or convergences, of the meridional wind field is shown to be a common feature of the thermosphere at night during geomagnetic quiet times. This finding weakens the arguments used to invoke energetic neutral‐atom precipitation at low and midlatitudes to explain the divergence in the meridional wind during the geomagnetic storm of April 1, 1976. For this storm it is also shown that the maximum time rate of change of D st is accompanied by a maximum value of the AE index, thus indicating that energy is flowing into the high latitude thermosphere as well as into the magnetospheric ring current.