Morphology of outer radiation zone electron (E> 35 keV) acceleration mechanisms

A study of outer radiation zone electron intensities at times of magnetic storms is reported. The purpose of the study is to determine how well the intensity at one local time tracks the intensity at the same invariant latitude but at a different local time. Any difference in the intensity time profiles might be expected to yield information about the mechanisms responsible for acceleration of outer-zone electrons, particularly the locations of these mechanisms. The measurements refer to selected periods of several days each and have been obtained at altitudes below 3500 km, invariant latitudes in the range 50° to 72°, and at several pairs of local times. At times of magnetic storms the tracking at the two local times is often quite poor at latitudes as low as 55°. For short periods around local midnight and on the morning side of the earth the intensities observed are appreciably higher than those on the afternoon side. It is concluded from these observations that most of the storm-time acceleration of electrons to energies about 35 kev takes place on the night and morning sides of the earth. The measurements are used to place an upper limit on stably trapped fluxes in the outer radiation zone that agrees reasonably well with the whistler mode limiting flux calculated by Kennel and Petschek [1966].