STRONG LOCALIZED VARIATIONS OF THE LOW-ALTITUDE ENERGETIC ELECTRON-FLUXES IN THE EVENING SECTOR NEAR THE PLASMAPAUSE

Specific type of energetic electron precipitation accompanied by a sha rp increase in trapped energetic electron flux are found in the data o btained from low-altitude NOAA satellites. These strongly localized va riations of the trapped and precipitated energetic electron flux have been observed in the evening sector near the plasmapause during recove ry phase of magnetic storms. Statistical characteristics of these stru ctures as well as the results of comparison with proton precipitation are described. We demonstrate the spatial coincidence of localized ele ctron precipitation with cold plasma gradient and whistler wave intens ification measured on board the DE-1 and Aureol-3 satellites. A simult aneous localized sharp increase in both trapped and precipitating elec tron flux could be a result of significant pitch-angle isotropization of drifting electrons due to their interaction via cyclotron instabili ty with the region of sharp increase in background plasma density.