Equatorial electrojet dependence on solar activity in the Southeast Asia sector

Abstract

A:The equatorial electrojet (EEJ) is a current system caused by the enhanced ionospheric conductivity near the dayside magnetic dip equator. We examined the dependence of the EEJ on solar activity, represented by the 10.7 cm solar radio flux (F10.7). For this analysis, we used a new equatorial electrojet index, EUEL, provided by the MAGDAS/CPMN network in the Southeast Asia sector for the year 2011. Using a two-station method, the EEJ strength was calculated as the difference between the EUEL index of the dip equator station and the EUEL index of the off-dip equator station located outside the narrow channel (±3°in latitudinal range) of the EEJ band. The relationship between the EEJ component and the F10.7 index was then examined using power spectrum and correlation analyses. We found approximate 24-day and 28-day periodicities in the EEJ component, which are in phase with F10.7 variations. On the other hand, the daily values of EEJ showed low correlation with the daily F10.7 variations during the study period.