Ram Singh

and 7 more

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 hours and remained consistent at values of ~95 m/s and 260 nT between 1700 and 1900 UT (1200 and 1500 LT). At the same time, vertical E B plasma drift uplifted the equatorial ionosphere, producing the dusk-side super plasma fountain and transferring electron density to higher latitudes. A huge increase (~1325 %) in electron density (from 11 to 142 TECu) is observed at low and mid-latitudes from ~20o S to 50oS between 2000-0400 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 (1900LT). Overnight, the vertical plasma drift fluctuated between ±90 m/s owing to under- and over-shielding electric fields. On May 11, a long-duration (~6-8 hours) westward penetration electric field induced downward plasma drift and a strong westward EEJ (-240 nT). In the main and early recovery phase, consistent short- and long-duration penetration electric fields persisted for approximately 30 hours, with periods of 48 and 90 minutes.