Seasonal dependence of solar flare induced Total Electron Content over low latitude ionosphere

Abstract

Solar flares represent a significant element in the broader context of space weather phenomena, exerting a direct influence on the Earth’s ionosphere. The ionosphere is a region of the Earth’s atmosphere that is ionized by solar radiation, which also undergoes seasonal changes. The present study is concerned with elucidating the seasonal fluctuations in differential vertical total electron content (DVTEC) of the ionosphere during solar flare events of solar cycle 24. The present study examines M and C solar flares during the ascending (2013), peak (2014), and descending phases (2015) of solar cycle 24. A total of 207 solar flare events were observed over a three-year period. The IISC is the low-latitude GNSS site in Bangalore, India (geographic latitude 13.02°N, geographic longitude 77.57°E) was utilized for this study. The results indicate the presence of an anomalous winter phenomenon in 2014, as well as a peak in DVTEC during the winter season. The recombination process, which involves the O/N<inf>2</inf> ratio, is responsible for the higher ΔDVTEC observed during the winter season. Additionally, modifications to dissociation-recombination during the summer season and vertical advection in the F layer contributed to the 2014 winter anomaly. Among the solar indices examined, a correlation of 0.45, between d(EUV flux)/dt and ΔDVTEC, indicating EUV flux as the primary source of ionization in the ionosphere. © 2025 Elsevier B.V., All rights reserved.