The relationship that exists between the occurrence of sporadic E and the incidence of visual aurora is utilized as the basis for the determination of the lifetimes of discrete auroral events in the range of > or = 15 minutes from measurements of durations of sporadic E ionization. Intercomparisons of optical and ionosonde data from aircraft and ground-based installations are presented.

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Communications, Navigation and Surveillance Systems operating in/through the aerospace EM propagation environment are affected by the state/variability of the propagation media. The range of phenomena need for their elucidation, observations and analysis on a global scale since only an understanding of the complex global interaction can improve the means of predictability and assessment of localized phenomena suggesting methods for mitigating adverse propagation conditions. With this goal, ionospheric dynamics, ionosphere/magnetosphere and ionosphere/atmosphere interactions were analysed and discussed at this symposium.