Abstract: This study utilizes radio occultation observations from the Macau Science Satellite-1 mission (MSS-1) to investigate ionospheric response to the May 2024 G5 geomagnetic storm within the South Atlantic Anomaly (SAA) region. The distinctive data from MSS-1, complemented by observations from the ground-based Global Navigation Satellite System (GNSS) and the Constellation Observing System for Meteorology, Ionosphere, and Climate follow-on satellite mission (COSMIC-2), reveal a super plasma fountain effect during the main phase of the storm. This effect was marked by peaks in the equatorial ionization anomaly that extended beyond their typical latitude range. The MSS-1 observations, particularly in the northern hemisphere of the SAA region, confirm the role of prompt penetration electric fields in driving ionospheric disturbances and amplifying scintillation at higher altitudes. The study also identifies a decrease in total electron content and a reduction in scintillation occurrence during the recovery phase of the storm. The results demonstrate the pivotal role that MSS-1 observations can play, when combined with ground-based and COSMIC-2 observations, in providing a more comprehensive understanding of ionospheric response to severe geomagnetic storms.