This article provides the first evidence of equatorial and low-latitude ionospheric electric field disturbances driven by quasi-periodic variations in the interplanetary magnetic field (IMF) By component, under a constant northward IMF Bz (∼+15 nT), solar wind dynamic pressure (∼8 nPa), solar wind velocity (∼450 km/s), and positive Sym-H (+10 nT). The virtual height of the F layer (h’F), measured by ionosondes at opposite longitudes in the American (Jicamarca, 11.9°S, -76.0°E; Fortaleza, 3.9°S, -38.52°E) and Indian (Trivandrum, 8.5°N, 77.0°E; Tirunelveli, 8.73°N, 77.7°E) sectors, shows electric field disturbances with opposite polarities during the day and night, driven by changes in the IMF. During northward IMF Bz conditions, vertical E×B plasma drifts measured by the Jicamarca Incoherent Scatter Radar (ISR), along with equatorial electrojet (EEJ) observations, reveal ...

The 2015 St. Patrick's Day geomagnetic storm with SYM‐H value of −233 nT is an extreme space weather event in the current 24th solar cycle. In this work, we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the Asian‐Australian sector and the American sector during this super storm event. The results reveal that the disturbed electric fields, which comprise penetration electric fields (PEFs) and disturbance dynamo electric fields (DDEFs), play a decisive role in the ionospheric storm effects in low latitude and equatorial regions. PEFs occur on 17 March in both the American sector and the Asian‐Australian sector. The effects of DDEFs are also remarkable in the two longitudinal sectors. Both the DDEFs and PEFs show the notable local time dependence, which causes the sector differences in the characteristics of the di...