Dependence of relativistic electron precipitation in the ionosphere on EMIC wave minimum resonant energy at the conjugate equator

We show that the occurrence rate of >0.7 MeV electron precipitation recorded by POES during those times strongly increases, reaching statistically significant levels when the minimum electron energy for cyclotron resonance with hydrogen or helium band EMIC waves at the equator decreases below similar or equal to 1.0-2.5 MeV, as expected from the quasi-linear theory.

Both hydrogen and helium band EMIC waves can be effective in precipitating MeV electrons. However, >0.7 MeV electron precipitation is more often observed (at statistically significant levels) when the minimum electron energy for cyclotron resonance with hydrogen band waves is low (E-min = 0.6-1.0 MeV), whereas it is more often observed when the minimum electron energy for cyclotron resonance with helium band waves is slightly larger (E-min = 1.0-2.5 MeV).