Rapid increases in the proton and electron fluxes in the magnetosphere

Three rapid increases in the low-energy, electron (20–100 kev) and proton (>100 kev) flux were observed on October 27, October 28, and December 1, 1961. The increases were marked by a drastic change in the intensity and/or spectrum of the measured radiation during a 2- to 3-minute interval. The time histories of the intensities and spectra are presented. The close association between the events and the occurrence of polar substorms is shown. The similarity of the events and those of December 20, 1962, and April 15, 1965, is discussed. It is also shown that the October 28, 1961, event is consistent with adiabatic acceleration of particles during a storm sudden commencement.