Dusk-side precipitation as an possible loss process of radiation belt electrons

Since the discovery of Earth's radiation belt by Van Allen in 1958, the electron acceleration/loss process has been one of main issues in the field of space plasma physics. In our presentation, we show > 1MeV electron flux on GEO orbit has good correlation with electron precipitation into polar region. To estimate total number of electrons precipitated into Earth's atmosphere, we analyzed six NOAA-POES satellite data. In our analysis, we note most electron precipitation occurred on the dusk-side polar region. This implies the dominant electron loss process might be caused by EMIC wave interaction because the wave activity is enhanced in the same region. In addition, POES satellite data clearly shows the dusk-side precipitation is not associated with only loss process but acceleration process. Surprisingly, our analysis indicates energetic electrons are accelerated and also drain into atmosphere at the same time. Simultaneous measurement of precipitating and trapped electrons with wave activity on equatorial might give a clue to understand how electrons are accelerated and lost from radiation belt. RBSP mission will provide such data.