Global patterns of equatorial plasma bubbles from ICON data

Equatorial plasma bubbles (EPBs) are ionospheric depletions that can disrupt satellite communication and navigation systems. This study examines the longitudinal, seasonal, and geomagnetic variability of EPBs using the full ion density dataset from NASA’s Ionospheric Connection Explorer (ICON) mission. A dual-parameter detection method, combining the $\sigma$ index ($\sigma ⩾0.5$) and a relative ion density depletion condition ($\Delta N_i<0$), was applied to identify EPBs from 2020 to 2022. The analysis focused on pre-midnight (18:00–23:00 SLT) observations within $\pm {10}^{\circ }$ magnetic latitude, with post-midnight (00:00–05:00 SLT) data included to compare responses under disturbed conditions. Pre-midnight EPBs were especially frequent over South America and the Atlantic sector, where occurrence rates peaked. However, high EPB activity was also observed in other regions, particularly the Indian, Southeast Asian, and East Asian sectors, during equinoxes, consistent with established climatology and the role of solar terminator alignment with the geomagnetic field. EPB occurrence rates were highest in 2022 and lowest in 2020, reflecting increasing solar activity during the ascending phase of Solar Cycle 25. Seasonally, occurrence was highest during the equinoxes, although a December solstice maximum was observed over South America. Under geomagnetically disturbed conditions, pre-midnight EPB rates declined modestly, particularly over South America, though not significantly at the global scale. In contrast, post-midnight EPBs showed a statistically significant increase during disturbed periods. These findings illustrate clear regional and local time dependencies in EPB responses to geomagnetic variability during the early years of the ascending phase of Solar Cycle 25.