Abstract: The diffusive and photochemical processes of NOand NO₂ exhaust plumes in Elayer during the daytime have been investigated and a spherical approximation is assumed for the plume diffusive process. NOexhaust plume in Elayer causes a temporal 7.5-fold increase of electron density ne, while NO₂ exhaust plume gives rise to a 24-fold increase of ne as a result of photo-ionization and dissociative recombination reactions. The chemical reactions between molecules and ions become more and more important in Flayer and may lead to a temporal distinct decrease of ne after release of NO₂ exhaust plume.