Modeling particle precipitation and effects on the ionospheric conductivity

Particle precipitation originated from the magnetosphere provides important energy source to the upper atmosphere, leading to ionization and enhancement of conductivity, which in turn changes the electric potential in the MI system to influence the plasma convection in the magnetosphere. In this study, we simulate ring current particle precipitation caused by several important loss mechanisms, including electron precipitation due to whistler wave scattering, ion precipitation due to EMIC wave diffusion and field line curvature scattering. These physical mechanisms are implemented in the kinetic ring current model via diffusion equation with associated pitch angle diffusion coefficients. The precipitation is subsequently input to a two-stream transport model at the top of ionosphere in order to examine its impact on the ionsopheric conductivity. It is found that during intense storm time, electron precipitation of tens of keV dominates in the dawn sector and leads to significant enhancement of conductivity at low altitudes. On the other hand, proton precipitation on the nightside mostly occurs for energy below 10 keV, and contributes to ionization above 100 km, resulting in enhancement of conductivity there. Consequently, the height profile of both Pedersen and Hall conductivity exhibits two layers, potentially complicating the current closure in the ionosphere system.