Global equatorial F- and E-region ionospheric irregularities from COSMIC-RO and SCINDA-GNSS observations

Abstract This study utilizes data from the FORMOSAT-3/Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation (COSMIC-RO) observations and ground-based Scintillation Network Decision Aid (SCINDA) GNSS recordings at four longitudinal stations situated in the vicinity of the magnetic equator for probing the characteristics of the ionospheric F and E region irregularities in the equatorial region. We utilize the amplitude scintillation index (S4) derived from these datasets to understand the morphology of nighttime and daytime plasma irregularities in the equatorial ionosphere. By combining ground-based data with a limb-viewing geometry from space, valuable complementary information has been obtained on the nighttime/daytime scintillation occurrences and their morphological associations with the equatorial irregularities in the F (equatorial plasma bubbles, EPB) and E (sporadic E layer; Es) region ionosphere. The occurrence of amplitude scintillation retrieved from COSMIC RO data was calculated to analyze its diurnal and seasonal variations. By conducting a statistical analysis on a dataset in 2013, we observed that the occurrence of ionospheric scintillation, as measured by both techniques, displayed similar variations. In this study, it is observed that scintillation in daytime is associated with Es and is predominantly seen over the Asian sector whilst nighttime scintillation associated with plasma bubbles is most frequently observed in the African sector. These results emphasize the need for RO profiles from active missions to serve as effective tools for monitoring scintillation events both regionally and globally.