Abstract

not-yet-known not-yet-known not-yet-known unknown Using a cluster of ground-based and in-situ Swarm satellite observations, an unusual super plasma bubble (SPB) was observed in the ionosphere over the European longitudes during a weak geomagnetic storm (Dst$<$-50 nT) on 4 November 2023. The plasma depletions extended an extensive geographical latitudinal range of 46°N. We observed enhanced ROTI values and strong range spread in the mid-latitudes. Simultaneous Swarm-A and C electron density shows plasma depletion between 20°S-38°N and 9°E, which agrees with the ROTI data. To explore the cause of this SPB, the prompt penetration equatorial electric field model and magnetometer data have been analyzed. We found an enhancement in the equatorial electrojet during the post-sunset hours that supported the anomalous pre-reversal enhancement as a consequence an SPB was generated. Furthermore, the enhanced eastward prompt penetration electric field could support evolution and its long duration. The daytime EEJ observed on 04 and 05 November 2023 are approximately five times stronger than the average quiet-time values. This study provides observational evidence of SPB in weak geomagnetic conditions and sheds light on the causative mechanism.