Investigation of the relative bottomside/topside contribution to the total electron content estimates

High-resolution vertical electron density true height profiles from Athens Digisonde are used to calculate the electron content up to the peak of the F 2 layer (bottomside electron content) and also the topside electron content up to 1000 km, using the Huang-Reinisch method, to investigate the relative behavior of these two parameters during storm events. It was shown that the topside electron content represents roughly the 2/3 of the total electron content of the ionosphere and it is strongly affected by the geomagnetic activity, much more than the bottomside electron content. During daylight hours the values of the topside electron content exhibit intense fluctuations, while they become smoother in nature during events of night-time F 2 layer uplifting caused by the auroral activity. All these facts demonstrate that the Huang-Reinisch method provides a realistic tool for monitoring the variations of the ionospheric ionisation at a given location and it could be used in the frames of a world wide effort for the development of realistic models to accurately predict the electron content and to support effectively earth-space communications including navigation systems.