Abstract

Energy input into the upper atmosphere during geomagnetic storms takes the form of enhanced electric fields, currents and energetic particle precipitation. This storm-time energy input affects the ionosphere-thermosphere coupling which leads to the balance between the storm-induced circulation and the regular circulation determines the spatial distribution of negative and positive storm effects. This study revealed episodes of positive and negative ionospheric storm effects during these storm events with positive effects dominating the main phases at the Toro, Nigeria IGS network station while the recovery period is characterized by either positive or negative effects or a combination of both. The geomagnetic storm time was determined using geomagnetic Dst index, southward interplanetary magnetic field and AE-index. The development of the positive ionospheric storm effect at the low latitudes is caused by upward movement of ionization to regions of reduced recombination rate.

Key words: Total electron content, geomagnetic storm, ionospheric, scintillation