Energies of precipitating electrons during pulsating aurora events derived from ionosonde observations

The time-history of particle energies and fluxes associated with pulsating auroras in the morning sector is derived from ionosonde measurements. All the pulsating auroras studied showed a similar history with the pulsations occurring during a time interval of the order of an hour during which the average auroral Maxwellian characteristic energy stays relatively constant but the energy flux decreases progressively during the event. A possible explanation for this behaviour in terms of an injection of particles into a magnetospheric "bottle" near the midnight meridian and the progressive precipitation out of the bottle during the pulsating event is suggested.