In May 2024, during a period of intense solar and geomagnetic activity, including the G5-class Gannon storm and X-class flares, we had a unique opportunity to study how these space weather events affected the ionospheric disturbance in low-to-mid latitude regions (40˚S to 40˚N) across America. This research examines the impacts of solar flares (SFs) and the Gannon storm on ionospheric electron density (Ne) and total electron content (TEC), utilizing data from the FORMOSAT-7/COSMIC-2 mission, ground-based ionosondes, and independent global TEC maps. Significant Ne enhancements were observed above 300 km, with Ne increasing by 137.7 % in the northern (0–40°N) and 129.2 % around 200 km in the southern (0–40°S) low-to-mid latitude regions during the storm peak, relative to quiet-time values on May 8 (DOY 129). Disk flares had a stronger impact on low-latitude regions, raising Ne by 28.66 % compared to mid-latitudes, while geomagnetic disturbances affected mid-latitudes more, with increases of 44.6 % during the storm’s peak, defined by the minimum Dst value (–412 nT) on May 12. Moreover, the IROTI index, calculated as the product of the time-integrated Detrended TEC (IDTEC) and ROTI, was more effective than Detrended TEC (DTEC) and ROTI in differentiating the impacts of SFs and geomagnetic storms but less so during recovery. Our findings underscore the complex interactions between space weather events and the ionosphere, highlighting the need for improved models and the use of multiple indices (e.g., IROTI, DTEC, ROTI) to enhance the reliability and integrity of GNSS positioning by improving ionospheric corrections. |
