Occurrence of equatorial spread F during intense geomagnetic storms

Abstract

AbstractEquatorial spread F (ESF) has been observed in response to the prompt penetration of magnetospheric electric field to equatorial latitudes during intense (minimum Dst ≤ −100 nT; Bz ≤ −10 nT for at least 3 h) magnetic storms using global ion density plots of Defense Meteorological Satellite Program (DMSP) over nearly one solar cycle (1996–2005). Geostationary amplitude scintillation observations from Calcutta at VHF and L band for 1996–2005 and GPS amplitude scintillation measurements during 2004–2005 from the Indian Satellite Based Augmentation System Geostationary and GPS Navigation Outlay (GPS Aided GEO Augmented Navigation) network of stations all over India have been used to corroborate the DMSP observations. Subsequent to the time of southward interplanetary magnetic field Bz crossing −10 nT for an intense storm, it has been observed that within 4 h, ESF is generated at a longitude where the local time is dusk.