INTENSE CONTINUING CURRENTS FOLLOWING POSITIVE CLOUD-TO-GROUND LIGHTNING ASSOCIATED WITH RED SPRITES

In July-August, 1996, Stanford University carried out broadband ELF/VL F measurements of the magnetic field radiated by positive cloud-to-gro und (CG) discharges associated with Red Sprites. We report these measu rements for 17 Sprite associated discharges that occurred during a 15 minute period on August 1, 1996. The current and charge moments for ea ch of the events are deduced, and it is found that, in every case, int ense continuing currents of similar to 1 ms duration are responsible f or most of the positive charge transfer to ground that precedes the ap pearance of the Sprite. The time delay between the causative positive discharge and the video field in which the Sprite first appeared varie d from 0 to 15 ms for the larger events to as much as 100 ms for the s maller events. We suggest that in the smaller events the removal of si gnificant positive charge during this delay interval is accomplished t hrough a horizontal intracloud discharge.