Magnetospheric substorm associated with SC

The present work describes on the basis of magnetograms at Kiruna and Honolulu and OGO-5 magnetograms a magnetospheric substorm which occurred simultaneously with the sudden commencement of 2345 UT, September 30, 1968. The storm occurred following a gradual development of the plasma sheet thinning under a continuation of the southward interplanetary Bz field. Gradual increases of B and Bx fields and gradual decrease of the Bz field were observed at the OGO-5 during plasma sheet thinning. A large increase of the By field began simultaneously with a southward turning of the northward Bz field at the OGO-5 during sudden commencement rise time. This increase, which amounted to 30 gammas, may be explained by the field-aligned current of 0.024 A/m flowing into the dawn-side auroral zone.