Electrodynamic coupling processes between the magnetosphere and the equatorial ionosphere during a 5-day HILDCAA event

We present a statistical analysis of equatorial F-peak height vertical drifts during a 5-day HILDCAA event (3–7 July 2003). Prompt penetration-PP drifts have been identified in this study by means of a correlation analysis carried out between the magnitude of disturbed height variations over the equatorial station São Luís-SL (44.6W, 2.33S, dip angle 1.5S) and the magnitudes of the interplanetary electric field at the magnetopause. A comparison between the correlation coefficients for the HILDCAA and the post-HILDCAA days clearly shows that coupling on the post-HILDCAA period is suppressed. The daytime (nighttime) ionospheric responses to magnetopause electric field changes were found to occur within ∼55 min (∼45 min). ►A positive (negative) correlation is shown between the equatorial disturbed hight variations and the interplanetary electric fields (IEF) during daytime (nighttime). ►The IEF demonstrates closer coupling with the AE index during the HILDCAA event. ►The prompt penetration perturbation drifts occur with different time delays for daytime and nighttime. ►Reversal of the disturbance dynamo zonal electric field occur around 22 LT at a Brazilian equatorial station during the HILDCAA period.