Study of ionospheric variability during geomagnetic storms

Abstract

The dual frequency Global Positioning System (GPS) receivers provide an opportunity to determine Total Electron Content (TEC) over the crest of equatorial ionization anomaly region Bhopal by taking advantage of the dispersive nature of the ionospheric medium. The TEC values observed for eight geomagnetic storms of the period 2004-2005 is used in this paper to discuss the behaviour of ionospheric total electron content (TEC) during geomagnetically disturbed periods. Variation of TEC is studied in correlation with the geomagnetic index Dst and southward component of interplanetary magnetic field Bz. The main purpose of this study is to know how TEC varies from its average values with geomagnetic storms. The TEC variability is found to vary between 49%-104% with the maximum negative excursion of Dst index during the geomagnetic storms days. Positive phases are observed for all the storms studied. Maximum TEC variability is observed during the recovery phase of the storms. The study of storm time TEC behaviour is very important due to recent increase in satellite-based navigation applications.