Electric currents above Saint-Santin 3. A preliminary study of disturbances, June 6, 1978;March 22, 1979;Marvh 23, A979.
Résumé
This paper presents three case studies of ionospheric disturbances in electric field, currents and winds during periods of geomagnetic storms. These disturbances are detected by the Saint-Santin incoherent scatter radar. The disturbances are shown to originate from two distinct physical mechanisms: (1) penetration of the electric fields to lower latitude during times of rapid change in the magnetospheric convections; and (2) the action of the disturbed ionospheric dynamo driven by storm-induced wind disturbances. The storm of June 6, 1978, shows a simple illustration of penetrative convection fields. the storm of March 22, 1979, gives additional example of this effect both when the Bz component of the interplanetary fields turns southward and nothward. The observed events on March 23 are clearly identifiable as the delayed response of the disturbance ionospheric dynamo