Interplanetary drivers of ionospheric prompt penetration electric fields

In this paper we discussed the penetration effects of common interplanetary magnetic cloud (MC) structures like sheath region, both sheath and magnetic cloud boundary layer (MCBL), MC body, and shock-running into a preceding MC on the equatorial ionosphere during intense (SYM-H ≤-100. nT) geomagnetic storms. Using solar wind data obtained from the ACE and WIND spacecraft, we have identified these four types of MC structures responsible for the electric field penetration events detected by Jicamarca incoherent scatter radar. After elimination of the propagation delay, the observations show that the equatorial electric field (EEF) was changed immediately following the arrival of solar wind disturbance. Moreover, the duration of EEF corresponded well with that of the corresponding MC structure interval. We suggest that identifying the solar wind structures associated with penetration electric field may shed light on the understanding of the penetration processes and further help exploring their effects on the ionospheric plasma.