Diffusion in the equatorialFlayer

Abstract

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.’

Physical mechanisms responsible for forming the 4-peak longitudinal structure of the 135.6nm ionospheric emission: First results from the Canadian IAM

“…In this case the distinct WN4 structure is absent which confirms the importance of the ionospheric dynamo in forming the longitudinal structure. However, in this case the equatorial ionosphere bears no resemblance to reality: even the equatorial trough is absent (note, similar results were obtained by Rishbeth et al (1963) in earlier attempts to model the EIA without the dynamo electric field). In order to diagnose the F region wind impact in a more realistic way, an additional set of model experiments was run.…”

Plasma diffusion in the ionosphere

“…The results obtained in the preceding section are not in agreement with the findings of KENDALL (1962), LYON (1963), RISHBETH et al (1963) and GOLDBERG and SCHNERLING ( 1 963) even though all these authors have studied the case of plasma diffusion along the field lines. The disagreement arises due to the fact that they have not taken into account the additional constraint on V,, given by equation (28) which automatically results from the assumption of field aligned plasma diffusion.…”

Variation of ionospheric total electron content in Indian low latitude region of the equatorial anomaly during May 2007–April 2008

“…Many theories, like the diffusion theory (Mitra, 1946) and the electrodynamic drift theory (Martyn, 1955;Duncan, 1960), have been put forward to explain the anomaly. The diffusion theory has been shown to be important but not sufficient to explain the observations (Rishbeth et al, 1963). The electrodynamic drift theory, on the other hand, has been successful in explaining the observations (Bramley and Peart, 1965;Moffett and Hanson, 1965).…”