Tomographic investigations of temporal variations of the ionospheric electron density and the implied fluxes



[1] A new technique is introduced for determining plasma fluxes using tomographic images of ionospheric electron density. Pairs of images are used to estimate the time derivative of the F-region electron density in the region of the northern equatorial anomaly at 120°E longitude. Characteristics of temporal variations are described, and two different methods are used to infer electron fluxes from the measured time derivaties. The height-dependent latitudinally-averaged vertical flux and a 2D “potential” flux are derived based on reasonable assumed boundary conditions. Examples illustrate that average vertical plasma fluxes in the local morning and evening hours are upward and downward, respectively, with peak magnitudes on the order of 109 cm−2s−1. The 2D plasma fluxes in a meridional cross-section through the equatorial anomaly are calculated, and clearly illustrate the characteristic flow associated with the equatorial fountain effect.