Comparison of ionospheric irregularities observed by the COSMIC satellites with ground-based scintillation observations over the low latitude African Region

Abstract

This study compared the ionospheric irregularities as observed using two different techniques, namely; the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites and the scintillation intensity index (S4) data measured by the Scintillation Network and Decision Aid (SCINDA) receiver which operated at Nairobi University (geog lon 36.8 E, geog lat 1.3 S, dip lat −24.1 , Kenya. The data compared were those of the years 2009 (low solar activity) and 2011 (ascending phase of solar cycle 24), for both quiet (Kp 3) and disturbed (Kp 5) geomagnetic conditions. For the cases of Global Positioning System (GPS) satellites with elevation angle 0 as observed by the COSMIC satellites, a geo-location of the COSMIC S4 data associated with the link between GPS and COSMIC satellites was proposed at the tangent point. The COSMIC S4 data whose geo-locations fall in the vicinity of Nairobi were compared with the S4 data measured by the SCINDA receiver. The coefficient of determination which represents the percentage of the variation in COSMIC S4 data associated with the variation in SCINDA S4 was 50 %. The two data sets depict that scintillation occurs mostly in the seasons of March and September equinoxes of high solar activity conditions. However, there was a moderate positive correlation (Pearson correlation coefficient, r = 0.52 on quiet days) between COSMIC and SCINDA S4 data. The results presented signify that the COSMIC S4 could be analyzed to study ionospheric irregularities (which cause scintillations) over locations such as deserts and oceans where it is usually difficult to deploy equipment. © 2026 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.