V. Rathore, Banaras Hindu University, vishnurathore1989@gmail.com
  A. Singh, Banaras Hindu University, abhay_s@rediffmail.com

In this paper, the ionospheric total electron content (TEC) derived from the GPS data recorded at the equatorial ionization anomaly (EIA) region; Varanasi is analyzed to study the geomagnetic storm signatures on low latitude ionosphere during 2012-14. We considered all possible geomagnetic storms and their Dst indices, interplanetary magnetic field (IMF) and plasma conditions during the same period. Two GPS scintillation receivers GSV4004B and trimble 5700 at the Varanasi low latitude, operating at L1 and L2 frequencies, experienced both phase and amplitude scintillation on several satellite-to-ground links during this period. Close examination of the GPS signals revealed the scintillation to be co-located with strong gradients in Total Electron Content (TEC) at the edge of the plasma stream. The data for storms is obtained from the OMNI database. The gradient-drift instability is a likely mechanism for the generation of the irregularities causing some of the scintillation at L band frequencies during this storm.

Penetration electric field, disturbance dynamo, neutral wind, neutral composition, etc., caused by geomagnetic storms have been reported. The results show variation of GPS derived total electron content (TEC) due to geomagnetic storm effect, local low latitude electrodynamics response to penetration of high latitude convection electric field and effect of modified fountain effect on GPS–TEC in low latitude region.