A mathematical model of the middle and high latitude ionosphere

Abstract

A time-dependent three-dimensional model of the middle and high latitude ionosphere is described. The density distributions of six ion species (NO+, N 2 + , N 2 + , O+, N+, He+) and the electron and ion temperatures are obtained from a numerical solution of the appropriate continuity, momentum and energy equations. The equations are solved as a function of height for an inclined magnetic field atE andF region altitudes. The three-dimensional nature of the model is obtained by following flux tubes of plasma as they convect or corotate through a moving neutral atmosphere. The model takes account of field-aligned diffusion, cross-field electrodynamic drifts, thermospheric winds, polar wind escape, energy-dependent chemical reactions, neutral composition changes, ion production due to solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow and local heating and cooling processes. The model also takes account of the offset between the geomagnetic and geographic poles. A complete description of the ionospheric model is given, including a derivation of the relevant transport equations, formulas for all of the chemical and physical processes contained in the model, a discussion of the numerical technique, and a description of the required model inputs. The effects that various chemical and physical processes have on the ionosphere are also illustrated.