ИСТИНА

We considered the fluxes of relativistic electrons during two sequent (separated for only 12 hours) magnetic storms of 7-8 September 2017 on the basis of low-orbiting POES/MetOp and magnetospheric satellite data. The first storm was characterized by a dropout of the trapped electron flux in the heart of the radiation belt, while during the second storm the trapped flux decreased at higher L-shells, and it increased in the radiation belt heart. Since during both storms the magnetopause shifts Earthward of geosynchronous orbit, we suggest the magnetopause shadowing as the main reason of the flux dropouts, especially for the first storm. The POES/MetOp satellites cannot detect microbursts of precipitation, but can observe so called precipitation bands. There were no precipitation bands of the relativistic electrons (REP events) during the first storm. During the interval under study the majority of the REP events was observed at the main and early recovery phases of the second storm. Dividing all REP events in three groups according to the classification by Yahnin et al. (2016; 2017) we showed that most of observed REP events belongs to the group, which is related to waves that are able to scatter energetic electrons only. Apparently, EMIC waves, which are able to scatter both relativistic electron and energetic protons, did not play a role in the relativistic electron precipitation during this storm. These features as well as the mutual location of the REP events of different groups relative to the plasmapause generally agree with findings described by Yahnin et al. (2016, 2017). In addition, another type of relativistic electron precipitation was detected, which appearance is clearly correlated with intensity of the trapped flux. The latitudinal size of this precipitation is comparable with the size of the trapped population. The intensity of this precipitation follows the intensity of the trapped population, but is less for one-two orders. We conclude that this is the result of weak diffusion into the loss cone, which can, however, be a significant component of relativistic electron losses.