Relativistic electron microbursts and flux variations of trapped MeV electrons: SAMPEX and Van Allen Probes observations

Abstract:

It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Loss by relativistic electron microbursts has been considered as an important loss mechanism of radiation belt electrons. Here we report relationship between relativistic electron microbursts and flux variation of trapped MeV electrons during the 9 October 2012 storm, based on the SAMPEX and Van Allen Probes observations. Observations by the satellites show that relativistic electron microbursts are associated well with rapid enhancement of trapped MeV electron fluxes, indicating that acceleration by chorus is much more efficient than the microburst loss. The observations also show a lack of both strong microburst activities and significant MeV electron flux variations in association with strong chorus wave activities. These results suggest that the microburst loss does not always contribute to relativistic electron flux dropout during the main phase of geomagnetic storms. We also suggest that relativistic electron microbursts can be a proxy of efficient acceleration of MeV electrons by chorus.