International equatorial electrojet year : the African sector

International audienceThis paper presents the IEEY project in the African sector. The amount of our interpreted data is presently too short to allow proper scientific conclusions. Nevertheless, fist typical results illustrate our network possibilities. Some preliminary observations are briefly pre- , sented for their interest towards immediate research goals

Performance prediction methods of HF radio systems

A survey of the historical development of methods for predicting the performance of ionospheric HF radio systems is presented, with special emphasis on modelling. The models considered are ionospheric characteristics and electron-density profile models, a propagation model, transmission loss and gain factors models, characteristics of radio noise models and a reliability model

Performance prediction methods of HF radio systems

A survey of the historical development of methods for predicting the performance of ionospheric HF radio systems is presented, with special emphasis on modelling. The models considered are ionospheric characteristics and electron-density profile models, a propagation model, transmission loss and gain factors models, characteristics of radio noise models and a reliability model

Spectral energy contributions of quasi-periodic oscillations (2-35 days) to the variability of the f_oF2

The relative contributions of quasi-periodic oscillations from 2 to 35 days to the variability of foF2 at middle northern latitudes between 42°N and 60°N are investigated. The foF2 hourly data for the whole solar cycle 21 (1976–1986) for four European ionospheric stations Rome (41.9°N, 12.5°E), Poitiers (46.5°N, 0.3°E), Kaliningrad (54.7°N, 20.6°E) and Uppsala (59.8°N, 17.6°E) are used for analysis. The relative contributions of different periodic bands due to planetary wave activity and solar flux variations are evaluated by integrated percent contributions of spectral energy for these bands. The observations suggest that a clearly expressed seasonal variation of percent contributions exists with maximum at summer solstice and minimum at winter solstice for all periodic bands. The contributions for summer increase when the latitude increases. The contributions are modulated by the solar cycle and simultaneously influenced by the long-term geomagnetic activity variations. The greater percentage of spectral energy between 2 to 35 days is contributed by the periodic bands related to the middle atmosphere planetary wave activity.Key words. Ionosphere · Ionosphere-atmosphere interactions · Mid-latitude ionosphere · Plasma waves and instabilitie