This project will develop a model of the spatial and temporal variation of electron precipitation in the diffuse aurora. The project will utilize an existing, physics-based model of Earth's ring current and add electron losses due to pitch-angle scattering. The existing model will be improved to include a realistic magnetic field model as opposed to a simple dipole model and to have a self-consistent description of the electric field. The modeled electron precipitation will be used to calculate the ionospheric conductivity tensor for different magnetic conditions.
The model will be made available to the space science community and will be useful in developing a Geospace General Circulation Model (GGCM) which is one of the main goals of the Geospace Environment Modeling (GEM) program. The ability to calculate ionospheric conductances will be useful in understanding the coupling of the magnetosphere to the ionosphere. The project will improve our predictive space weather capabilities, which will have societal and economic benefits.
The broad objective of this research project was to understand dynamic global features in the electron diffuse aurora during magnetic storms. The diffuse aurora is a glow in the sky that may not be visible to the naked eye. Both electrons and ions that precipitate into the ionosphere as they drift from the Earth’s plasma sheet produce diffuse aurora. However, electron diffuse auroral precipitation accounts for the majority of the energy flux into the ionosphere. The distribution of precipitating electrons that produce diffuse aurora depend on variations of the source distributions in the plasma sheet, electron drift in changing magnetic and electric fields, and electron scattering due to interaction with waves in the magnetosphere. In this study we have investigated the transport and loss of plasmasheet electrons into the magnetosphere and how conductivity changes in the ionosphere due to diffuse-auroral electron precipitation affects hot-plasma transport. Our approach was to perform magnetically and electrostatically self-consistent numerical simulations of plasmasheet electron and ion transport and compare our results with observations. Through detailed model and observational data comparisons, we found that our self-consistent simulation model can simultaneously reproduce reasonably well observed magnetic fields and ion fluxes in the inner magnetosphere during the main phase of a magnetic storm. The simulations could account for observed electron fluxes during the early part of a magnetic storm on the night side, but not as well on the dayside. While we used fairly simple electron loss models in our simulations, a sophisticated dynamic model of electron loss due to wave-particle interactions that depends on magnetic activity is needed in order to explain the observed electron fluxes. We found that the inner magnetospheric electrons play a bigger role in affecting the electric field rather than the magnetic field. While electrons are not the largest contributors to the "hot" particle energy, electrons precipitating into the ionosphere affect ionospheric conductances and ionospheric electric potentials. One of the impacts of this study is that it contributes toward better modeling of space weather during magnetic storms.
