Solar and particle contributions to auroral height-integrated conductivities from EISCAT data - A statistical study

Ionospheric electron density data from more than 3 years of EISCAT CP-3 experiments have been used to study the solar and particle precipitation contributions to the height-integrated conductivities. An empirical model of solar-produced conductances is provided, which relates these height-integrated conductivities to the solar zenith angle. The particle contribution is then derived by subtracting the modeled solar contribution from the observed conductance. These particle-produced height-integrated conductivities are then compared to a statistical model obtained from precipitating electron characteristics measured on board the polar DMSP satellites. It is shown that the EISCAT-derived particle-produced conductances agree well with the DMSP model in the morning sector, but are systematically larger than the model in the evening sector. It is suggested that this difference is due to E-region electron production by energetic ion precipitation which occurs preferentially in the evening sector.