Global and Regional Ionospheric Response to a Moderate Storm in South America and Antarctica Using a Multi-Instrumental Approach

In this study, we investigate the ionospheric disturbances caused by a moderate geomagnetic storm (maximum Kp = 6) occurring between 26th February and 1 March 2023. Ionospheric response for the coupling between the solar wind, magnetosphere, and ionosphere systems can be observed across various regions of the globe and it may vary according to the local/regional background ionospheric conditions. We analyzed space and ground-based instruments (e.g., ionosondes, total electron content, GUVI imager, incoherent scatter radar) covering from Antarctica to equatorial latitudes in South America. From a global perspective, we observed two ionospheric storms. The first, with a negative phase observed as a significant decrease (>30%) in the F2-layer critical frequency (foF2), occurred on February 27th at 01:00 UT. This negative phase storm was observed in all the considered regions, with the intensity progressively decreasing from higher to lower latitudes. It is worth mentioning that, for the Antarctic station, we consider the local regime of the Weddell Sea Anomaly. The second ionospheric storm occurred during the recovery phase of the geomagnetic storm on 28th February. In this last case, an enhancement above 30% in foF2 was observed only in the low-latitude station. Subsequently, the geomagnetic storm produced a super fountain effect at the Equatorial Ionization Anomaly resulting in the enhancement of foF2.