Kinetic Studies of Ionospheric Transport in the Polar Cap and Auroral Zone.

摘要

We have studied and modeled several of the important coupling processes that involve particle and energy flow into and within the ionosphere in the polar cap and auroral zone. Understanding these coupling processes helps us better understand the response of the polar ionosphere to external stimuli, and thus helps us understand its structure and day-to-day variability. Modern models of the inner magnetosphere require an accurate treatment of ionospheric precipitation and backscatter to properly describe the population of the plasma sheet. We have developed a detailed kinetic model of the electron population in the inner portion of the magnetosphere including the effects of convection, pitch angle scattering, precipitation, and backscatter. Using numerical solutions of an electron transport equation with appropriate boundary conditions and sunlit polar cap observations, we find that two energetic electron populations (photoelectron and polar rain) are present and are needed to explain polar cap observations. Recently, the first self-consistent theory for the combined electron-proton-hydrogen atom aurora has been developed. We present the first test of this fully coupled three species transport model. Two dimensional plasma simulations and Monte Carlo simulations have been used to calculate the heating of the ions and electrons as well as the temporal evolution of plasma waves in the suprauroral region. E and F region fluid models have been developed and tested against various observations. We find that our models reproduce much of the observed climatology.