Induced precipitation of inner zone electrons, 1. Observations

Narrow precipitation spikes of energetic electrons observed in the inner zone drift loss cone during the 1968–1970 period by instrumentation on the OV1‐14 and OV1‐19 satellites are shown to have characteristics which are consistent with pitch angle scattering produced through a resonant interaction with ground‐based VLF transmissions. Analysis of the pitch angle distributions indicates that for virtually all of the events the electrons last interacted with the atmosphere in the vicinity of 55°–62° east longitude. The L dependency of the spikes as a function of energy is consistent with scattering by a monochromatic wave. The presumption is that the Russian station UMS, located at 44°E and operating at a frequency of 16.2 kHz during this period, was responsible for these precipitation events.