In this study, we analyze the atypical ionospheric irregularity patterns observed during the geomagnetic storm of October 10-13, 2024. This analysis is based on high-resolution Rate of Total Electron Content Index (ROTI) maps derived from data collected by approximately 1,600 Global Navigation Satellite System (GNSS) stations distributed across the American continent and Antarctica, complemented by local ionospheric observations. The morphological characteristics of equatorial and polar ionospheric irregularities during this extreme event are investigated. Our findings reveal a reversed-C-shaped depletion band extending from the magnetic equator to auroral latitudes, driven by the intensification of both vertical drift velocities at the equator and zonal drift velocities near the auroral region. Thus, the polar irregularity region expanded to midlatitudes, converging with stretched Equatorial Plasma Bubble (EPB) structures near ~45{degree sign} MLAT, highlighting a dynamic coupling mechanism between these regions. Additionally, distinct longitudinal asymmetries in EPB behavior were observed, as they extended into midlatitudes and tied up with the polar irregularities along the western coast of South America (~0{degree sign} MLON) but remained confined to the equatorial region along the eastern coast (~20{degree sign} MLON). These asymmetries are attributed to variations in electric field penetration efficiency due to seasonally enhanced ionospheric conductivity. Finally, disturbance dynamo electric fields sustained F-region height, leading to an atypical occurrence of post-sunrise EPBs.

In this study, we present the results of an analysis of the morphological features of Equatorial Plasma Bubbles (EPBs) over South America. In this context, we analyzed data from the Disturbance Ionosphere indeX (DIX) maps calculated using around 450 Global Navigation Satellite System (GNSS) stations. To mitigate the influence of magnetic disturbances on bubble development, only data from geomagnetically quiet days were utilized. This study covered the period from the post-peak of solar cycle 24 (2015) to the pre-peak of solar cycle 25 (2023), totaling 1321 nights with EPB occurrences, representing the largest dataset of EPBs ever compiled for South America. Our analysis unveiled several key findings regarding EPBs and their behavior over the South American region. Firstly, we observed that the amplitude of plasma depletions and the EPB latitudinal development follow an approximately 11-year cycle driven by solar radiation levels. Furthermore, our analysis highlights the significant influence of factors such as vertical plasma drift velocity during the pre-reversal enhancement (PRE), longitudinal variations associated with magnetic declination, as well as the saturation behavior of EPB development with extreme solar flux. Finally, we outline an empirical model to calculate the maximum latitudinal extent of EPBs based on solar flux and magnetic declination as an attempt to provide insights for anticipating EPB behavior across different solar cycle stages and in different longitude sectors.