Geomagnetic Effects

A major geomagnetic storm (maximum Kp = 6) and associated aurorae were produced by the extended interval of negative Bz in the front part of the magnetic cloud (Zwickl, private communication). As the magnetic cloud moved past the earth, the magnetic field rotated northward giving an extended interval with positive Bz in which the geomagnetic activity subsided. Near the rear of the magnetic cloud the northward fields were further enhanced by the shock and the interaction with the corotating stream, resulting in a return of the magnetosphere to a quiet state.