References

ANGEO

Annales Geophysicae

ANGEO

Ann. Geophys.

1432-0576

Copernicus Publications

Göttingen, Germany

10.5194/angeo-25-1359-2007

Electron flux enhancement in the inner radiation belt during moderate magnetic storms

Tadokoro

¹ Tsuchiya

¹ Miyoshi

² Misawa

¹ Morioka

¹ Evans

D. S.

Planetary Plasma and Atmospheric Research Center, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan

Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan

Space Environment Center, NOAA, Boulder, CO 80305, USA

29 06 2007

25 6 1359 1364

2007

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During moderate magnetic storms, an electron channel (300–1100 keV) of the NOAA satellite has shown sudden electron flux enhancements in the inner radiation belt. After examinating the possibility of contamination by different energetic particles, we conclude that these electron flux enhancements are reliable enough to be considered as natural phenomena, at least for the cases of small to moderate magnetic storms. Here, we define small and moderate storms to be those in which the minimum <I>D<sub>st</sub></I> ranges between −30 and −100 nT. The electron flux enhancements appear with over one order of magnitude at L~2 during these storms. The enhancement is not accompanied by any transport of electron flux from the outer belt. Statistical analysis shows that these phenomena have a duration of approximately 1 day during the period, starting with the main phase to the early recovery phase of the storms. The flux enhancement shows a dawn-dusk asymmetry; the amount of increased flux is larger in the dusk side. We suggest that this phenomenon could not be caused by the radial diffusion but would be due to pitch-angle scattering at the magnetic equator. The inner belt is not in a stationary state, as was previously believed, but is variable in response to the magnetic activity.

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