Magnetosphere inflation during four magnetic storms in 1965

Abstract

Study of four magnetic storms in 1965, using Explorer 26 and ground observatory magnetic data, shows that both small and large magnetic storms develop through initial asymmetric inflation of the evening magnetosphere. Development times vary from 6 to 36 hours, and the development is sometimes interrupted. The inflating particles are injected as deep as L = 3 during the development phase in large storms but only to L = 4 in smaller storms. In the slow recovery phase there is a clear relation between the magnitude of the inflation and the location of the inflation belt. The April storm belt with 100-γ inflation at the beginning of slow recovery was at L = 3.7, whereas the February storm with 30-γ inflation was at L = 4.8. An unusual distortion of field direction on June 16 is interpreted as evidence for current flow along field lines at the onset of a substorm.