The effect of geomagnetic storm on GPS derived Total Electron Content (TEC) at Varanasi, India

In this paper we studied the effect of geomagnetic storm on Global Positioning System (GPS) derived total electron content (TEC) at low latitude Varanasi (Geomagnetic lat 14 degrees, 55'N, geomagnetic long 154 degrees E) during the period of May 2007 to April 2008. During this period 2 storms were found, which were occurred on 20 November 2007 and 9 March 2008. In this study vertical total electron content (VTEC) of single Pseudorandom Noise (PRN) and average of VTEC of same PRN before 10 days of storm, which is called background TEC, were used to see the effect of these storms on the variation of TEC. From this study this is found that during the storm of March 2008 the TEC increases in main phase of storm while in the case of November 2007 storm, TEC decreases during the main phase of storm but increases in the recovery phase (next day) of storm.