Regional Ionospheric Super Bubble Induced by Significant Upward Plasma Drift During the 1 December 2023 Geomagnetic Storm

An unseasonal equatorial plasma bubble (EPB) event occurred in the East/Southeast Asian sector during the geomagnetic storm on 1 December 2023, causing strong amplitude scintillations from equatorial to middle latitudes. Based on the observations from multiple instruments over a large latitudinal and longitudinal region, the spatial features of the super EPB were investigated. The EPB developed vertically at a fast rising speed similar to 470 m/s over the magnetic equator and extended to a very high middle latitude more than 40 degrees N, despite that the storm intensity was not very strong with the minimum SYM-H index -132 nT. In the zonal direction, the super EPB covered over a specific region similar to 95-140 degrees E, where the local sunset roughly coincided with southward turning of interplanetary magnetic field (IMF) Bz component. Before the onset of the super EPB, significant upward plasma drift up to similar to 110 m/s was observed over the magnetic equator, which could amplify the growth rate of Rayleigh-Taylor instability and lead to the generation of the super EPB. The significant drift was likely caused by eastward penetration electric field (PEF) due to sharp southward turning of IMF Bz. The local time of storm onset and duration of IMF Bz southward turning during the storm main phase may partly determine the onset region and zonal coverage of the EPB. Previous studies have reported unexpected generation and development of equatorial plasma bubbles (EPBs) during geomagnetic storms, with different EPB morphology varied from case to case. It is important to figure out potential factors controlling the occurrence or absence of EPBs over a specific region during geomagnetic storms, their latitudinal and longitudinal development. In this study, super EPB extending to middle latitudes more than 40 degrees N was observed over a limited zonal region similar to 95-140 degrees E during the main phase of the 1 December 2023 geomagnetic storm. Significant upward plasma drift was observed before the onset of the EPB, which coincided with sharp southward turning of interplanetary magnetic field (IMF) Bz that could induce remarkable penetration electric field. Based on the combination of multiple kinds of observations over a large region, the potential factors controlling the generation and development of the EPB over latitude and longitude were investigated. It was suggested that the onset time, duration and intensity of IMF Bz southward turning during the main phase of geomagnetic storm play an important role in controlling the EPB spatial features, including the onset region, zonal coverage and latitudinal extension. Ionospheric super bubble with fast rising speed occurred during storm time, extended to more than 40 degrees N and caused strong midlatitude scintillation The super bubble occurred over a confined longitudinal sector similar to 95-140 degrees E where the local sunset roughly coincided with interplanetary magnetic field (IMF) Bz southward turning Significant upward plasma drift due to penetration electric field (PEF) could be responsible for the generation of the super bubbles