On Detection of Super Equatorial Plasma Bubbles in the American Sector During the 10–11 October 2024 Geomagnetic Storm

Abstract

Multi-instrument analysis of ground-based and satellite observations (GNSS, ionosondes, magnetometers, Swarm, GOLD) revealed the formation of giant equatorial plasma bubbles (super-EPBs) in the American sector during the 10–11 October 2024 geomagnetic storm. Development of spectacular depletions, stretching between 30°N and 50°S (∼40°MLAT) across American continents with estimated apex altitudes of ∼3,500–4,000 km, was linked to storm-induced prompt penetration electric fields. Sudden southward turning of interplanetary magnetic field Bz component occurred at ∼22:40 UT, 10 October 2024, when the dusk sector reached western South America. Following a strong uplift of the ionosphere over Jicamarca/Peru by more than 400 km, the super-EPBs developed in this region, rapidly reaching midlatitudes. In the equatorial region, super-EPBs were confined to 65°–75°W longitudes. This fortunate localization gives a rare chance to trace super-EPB evolution near-entirely, from equatorial to middle latitudes in both hemispheres, due to extensive ground-based GNSS coverage. This allows us to unveil the complexity of super-EPB evolution with storm's progress: (a) Initial formation of post-sunset super-EPBs as field-oriented, inverted C-shape structures near 65°–75°W, (b) westward drift of outmost parts of these structures across midlatitudes from their original location, (c) formation of fresh post-midnight EPBs over the same locations as post-sunset EPBs, persisting until early morning. Ionosondes in North America midlatitudes (∼42°MLAT) registered rare observations of Spread-F associated with storm-induced EPBs. Strong amplitude scintillations were observed from sunset to sunrise. Super-EPBs bringing ionospheric irregularities and scintillations to unexpectedly high latitudes represent a perplexing phenomenon connecting physical processes across equatorial, middle and high latitudes during geomagnetic disturbances.