The effect of diffusion on the equilibrium electron density distribution in the<i>F</i>region near the magnetic equator

Abstract

On the basis of the assumptions that electrons are constrained to move along the lines of force of the earths magnetic field, and that the primary forces acting are due to gravity and pressure gradients, a two-dimensional partial differential equation is derived for the equilibrium electron density distribution around the magnetic equator in an isothermal F region. A solution is developed in the form of a power series in magnetic latitude. By using a Chapman profile at the equator as a boundary condition, we show that the solution exhibits the major features of the well-known geomagnetic anomaly as observed at the equinoxes. The solution also predicts the electron density distribution above the F2 electron peak, where there are presently no observations as a function of magnetic latitude. It is also suggested that there are additional perturbations, not included in this theory, which give rise to the asymmetries observed at other seasons, but these are not responsible for the main effects.