Diffusion in the equatorialFlayer

The theoretical form of the ionospheric F layer near the magnetic equator is discussed for conditions of equilibrium. A digital computer is used to solve an equation which includes photoionization, loss, and the diffusion of ionization along geomagnetic field lines, thus enabling electron densities to be computed as a function of latitude and height. A small equatorial ‘trough’ is found in the peak electron density, but this is much smaller than the well-known Appleton anomaly of the actual F layer. Below the peak, the ionization is approximately in ‘photochemical equilibrium’; the shape of the layer above the peak corresponds approximately to ‘diffusive equilibrium.’