Magnetic field aligned modeling for the upper F region and for the plasmasphere

Abstract

Existing empirical models, e.g., the IRI and the PRIME model, have shortcomings for the uppermost F region and usually have no realistic formulation for the plasmasphere. These shortcomings can be overcome by replacing purely height oriented modeling by magnetic field aligned approaches. A magnetic field approximation is presented which uses dipole field lines with apexes above the dip equator. Modeling along these field lines can be based on diffusive equilibrium. For a single ion plasma (e.g., an H+ plasma) the integrations which are necessary to model along the field lines in a realistic way can be carried out by means of series expansions. For a multiple ion plasma and in case of arbitrary dependence of electron and ion temperatures on the coordinates one has to apply numerical integration. The principles of joining a field aligned model to a height oriented one are discussed including a method to cross the dip equator in a consistent way. A practical example is presented with a plasmasphere model added to the global model NeUoG which was developed at the University of Graz. The future development aims at replacing all of the topside F region of the model by a magnetic field aligned approach.