EFFECTS OF A LIGHTNING DISCHARGE DETECTED BY THE DE-2 SATELLITE OVER HURRICANE DEBBIE

We report the satellite observation of a large, approximately 40 mV m-1, transient electric field disturbance over Hurricane Debbie in September 1982. The event lasted less than a second and correlated closely with a burst of highly field-aligned, upward moving electrons with nearly 1 keV of energy. The electric field event is viewed as a spheric disturbance from a lightning discharge in the active weather system located beneath the satellite. A spheric interpretation of the observed electric field transient is consistent with a subsequent observation of energetic electrons precipitating from the radiation belts. Measured quasi-dc electric fields and cold plasma density variations are only roughly consistent with model predictions for ULF wave propagation from a storm system to the ionosphere. To understand this first observation of upward moving electrons in the ionosphere associated with a lightning event, we compare the several mechanisms for electron acceleration by electric fields with components (E parallel-to) along the magnetic field. In our scenario. "runaway" electrons were accelerated in approximately 1 ms by a downward directed E parallel-to pulse of approximately 1 V m-1 magnitude. Such fields can result from rapidly exposed, negative space charges near the tops of clouds during positive cloud-to-ground discharges. High-frequency Fourier components of the E parallel-to pulse must propagate through the low-conducting nighttime atmosphere to the ionosphere with little dissipation.