Storm‐enhanced plasma density (SED) features, auroral and polar plasma enhancements, and rising topside bubbles of the 31 March 2001 superstorm

This study focuses on the 31 March 2001 superstorm's evening and nighttime sectors. We specified forward fountain circulation and equatorial ionization anomaly (EIA), storm‐enhanced density (SED) plume plasma flows, auroral zones, polar cap regions, and traveling ionospheric disturbances (TIDs). These permitted analyzing low‐latitude plasma structures, and middle‐ and high‐latitude plasma buildups. Results reveal significant low‐latitude plasma structuring around Ancon due to topside rising bubbles during the initial phase under disturbance conditions. The deep equatorial plasma depletion, appearing over the Pacific during the main phase, is an EIA‐trough‐bubble structure. Topside bubbles and TID‐related drift perturbations structured SED plume plasma. Plasma distribution maximized when TIDs were in phase with fountain circulation and SED plume plasma flows, and equatorward wind surges maintained high plasma densities. Plasma density and plasma flow measurements demonstrate the SED plume plasma's poleward migration through the auroral zone into the polar region and the maintenance and increase of auroral and polar enhancements forming a polar tongue of ionization (TOI). Our results contradict previous studies on this superstorm reporting the suppression of bubble formation over Ancon and the absence of TOI and explaining the development of equatorial depletion with no E × B drift action. Our results oppose the current hypothesis that plasma enhancements are transported over many hours into the polar region. Indeed, SED plume plasma (produced by plasmaspheric detachment processes) creates multiple downward plasma flows (stretching from the midlatitude trough's equatorward edge to the polar cap region) that in turn create plasma buildups at various latitudes where flow stagnates.