Total electron content of the ionosphere during the geomagnetic storm on 10 January 1997

Measurements at GPS ground stations of the International GPS Service (IGS) have been used to derive the total electron content (TEC) of the ionosphere over Europe and over three North American stations for the 6-11 January 19 97 storm event. The derived TEC data indicate large deviations from the ave rage behaviour especially at high latitudes on the night-side:early morning longitude sector. The high-latitude perturbation causes a well-pronounced positive phase on t he day-side sector over Europe. Both meridional winds as well as transient electric fields are assumed to c ontribute to the signature of the ionospheric perturbation propagating from high to low latitudes. The observations indicate a subsequent enhanced pla sma loss which is probably due to the equatorward expansion of storm induce d composition changes. (C) 1999 Elsevier Science Ltd. All rights reserved.