A magnetic field aligned approach to model the topside F2 layer

Abstract

Any model for the topside F2 layer has to match the latitudinal/longitudinal structure of the F2 layer peak. In the IRI this structure is dominated by the location of the dip equator. Therefore a field aligned approach has to use magnetic field lines with apexes above the dip equator. It is proposed to use dipole field lines instead of the IRI (CCIR) field model, constructed in the following way: the poles of the centric dipole define the magnetic meridians but for each magnetic meridian artificial poles are chosen distant by +90 and −90 deg. from the crossing point with the IRI dip equator. The field aligned modelling approach with this “equivalent dipole field” configuration can start at the F2 layer peak or in a suitably chosen height above the peak. One (but certainly not the only possible) application is field aligned diffusive O + H + equilibrium. One example is shown.