Ionospheric Disturbances Observed Over the Peruvian Sector During the Mother's Day Storm (G5-Level) on 10–12 May 2024

This article presents the recent extreme and rare G5-level geomagnetic storm (Mother's Day Storm) effects on the equatorial and low-latitude ionosphere observed at the Peruvian sector by the Jicamarca (11.9°S, 76.8°W, magnetic dip 1°N) incoherent scatter radar and associated instruments. This storm was produced by multiple Earth-directed coronal mass ejections, which generated significant modifications in the Earth's magnetic field, leading to the Sym-H of ∼−518 nT. On the dayside, due to the strong eastward penetration electric field, vertical plasma drift and equatorial electrojet (EEJ) enhanced for 2–3 hr and remained consistent at values of ∼95 m/s and 260 nT between 1700 and 1900 UT (1200 and 1400 LT). At the same time, vertical E $\times$ B plasma drift uplifted the equatorial ionosphere, producing the dusk-side super plasma fountain and transferring electron density to higher latitudes. A huge increase (∼1,325%) in electron density (from 11 to 142 TECu) is observed at low and mid-latitudes from ∼20°S to 50°S between 2000 and 0400 UT (1500–2300 LT). The strong westward penetration electric field suppressed pre-reversal enhancement, leading to downward plasma drift (∼−96 m/s) at around 2400 UT (1900 LT). Overnight, vertical plasma drift fluctuated between ±90 m/s, and the combined effect of penetration and disturbance dynamo electric fields caused a significant increase (∼530 km) in ionospheric virtual height. In the main and early recovery phase, consistent short- and long-duration electric field disturbances persisted for approximately 30 hr, with periods of ∼48 and 90 min.