The ionospheric electric field perturbations during CME and CIR driven geomagnetic storms

The extreme inospheric electric field impacts is investigated associated with two interplanetary coronal mass ejections (ICMEs) that occurred during 06-08 September 2017. The magnitude of prompt penetration (PP) is found to be 150 m/s which is one of the highest ever measured in evening time over Jicamarca sector. The disturbance dynamo (DD) generated eastward electric field perturbation over Jicamarca during post-midnight on 08 September 2017 caused an upward vertical drift of ∼55 m/s which is also one of the highest observed during nightime. Based on global TEC observations, it is shown that these unusually large eastward PP and westward DD electric field enhanced and suppressed the low latitude F region plasma fountain significantly during daytime. In addition to this result, the daytime ionospheric effects are investigated during the CIR-driven geomagnetic storm by using the equatorial electrojet strength over Jicamarca. It is found that the PP electric field affects the equatorial ionosphere when the average solar wind azimuthal angle is below 6⁰ at the first Lagrangian point (L1) of the Sun-Earth system. Therefore, this result, for the first time, provides a method to forecast the geoeffectiveness of CIR events based on the observations from the L1 point.