A Statistical Study of Magnetosphere-Ionosphere Conjugate Observations of the Energetic Electron Precipitation by the Whistler Mode Waves

The whistler mode wave can scatter the energetic electrons and those scattered electrons can precipitate into the ionosphere and lead the formation of the auroras. Previous statistical studies show the strong electron precipitation region is coincident with the strong whistler mode wave region. The case studies of the Magnetosphere-Ionosphere (M-I) conjugate observation have confirmed the causal relationship from whistler mode waves to the auroras. However, no statistical study for the M-I conjugate events is done to show how good/often this causal relationship is statistically in the global scale. To answer this question, we present a statistical study of the M-I conjugate observation between whistler mode intensity, magnetospheric electron flux and precipitating electron flux. We use THEMIS A, D and E to provide the whistler mode wave intensity (B_w) and electron flux in the magnetosphere (T_eflux) and use DMSP F16, F17 and F18 to provide the precipitating electron flux (D_eflux) in the ionosphere from 2010 to 2014. We find good correlations between B_w and D_eflux at the dawnside from L=4-10 and L=12-16 and at the duskside from L=4-14. A bad correlation between B_w and D_eflux is found at the nightside. A good correlation is found between T_eflux and D_eflux at the nightside and dawnside. The whistler mode wave power is much larger at the dawnside than that at the daskside with L=4-16. The results above indicate that (1) even though the correlations between B_w and D_eflux at the duskside are comparable to the values at the dawnside, the whistler mode wave mainly precipitate energetic electrons at the dawnside because of the dawn-dusk asymmetry of the wave power and electron flux in the magnetosphere. (2) The energetic electrons in the magnetosphere are easier to precipitate at the nightside and dawnside and the whistler waves are not responsible to the energetic electron precipitation at the nightside with L>8.