Variations of total electron content as influenced by geomagnetic activity

A recent statistical study based on one year's worth of data has shown that the geomagnetic activity as inferred by the geomagnetic storm index, Dst, is one of the driving forces on the occurrence of seasonal peaks of ionospheric total electron content (TEC) in the northern hemispheric equatorial anomaly region [Wu et al., 2003]. In this study we use three years' worth of published TEC data (October 1985 - September 1988) by Huang et al [1989] to further study the geomagnetic effect. It is found that the monthly peaks of seasonal equatorial anomaly (four maxima and six minima) of the TEC during this period are well correlated with the monthly peaks of the Dst index, with three exceptions. These exceptions are also investigated. Detail data will be presented. Possible mechanisms associated with geomagnetic activity that affect the TEC anomaly will be discussed. Wu, C.-C. et al., variation in the Equatorial Anomaly Region during the solar minimum: September 1996 - August 1997, J. Atmos. Terr. Physics, in revision, 2003. Huand, Y.-N. et al., JGR, 94, 13515, 1989.