Comparing and contrasting CME-driven ionospheric changes on 4-5 November 2023: A multi-instrument study

In this study, we analyze the ionospheric and thermospheric changes from three coronal mass ejections (CMEs) that triggered a composite geomagnetic storm on 4-5 November 2023 with two activity periods. The first CME arrival on 4 November resulted in moderate activity (SYM-H=-60 nT), while two CMEs that arrived on 5 November caused intense geomagnetic disturbances (SYMH=-188 nT). Using global observations of vertical total electron content (VTEC) and the normalized VTEC storm-time index, we examine ionospheric anomalies during these events. Additionally, we use satellite observations of thermospheric composition, temperature and density, along with ionosonde-derived estimations of the large-scale traveling ionospheric disturbances velocities. Our results show that initial ionospheric changes in both activity periods were driven by prompt penetration electric fields, leading to positive VTEC anomalies. However, the delayed effects were vastly different. Due to weak high-latitude heating, the negative phase in 4 November event was largely inhibited. In contrast, on 5 November, high-latitude thermospheric heating was significant and led to strong decreases in the O/N2 ratios and setup global disturbance winds, causing severe negative VTEC anomalies. Despite weaker overall effects in VTEC, the moderate 4 November event caused a much more pronounced degradation of the GNSS availability due to stronger auroral scintillations. Our results underscore the highly dynamic nature of the ionosphere-thermosphere system and showcase that even similarly driven and temporally close events can nevertheless produce markedly different ionospheric responses. Notably, events with weaker geomagnetic activity can pose greater hazard and need to be carefully monitored to mitigate their potential impacts. Information & Authors Information Version history Copyright This work is licensed under a Non Exclusive No Reuse License.

Authors Metrics & Citations Metrics Article Usage 250views 136downloads Citations Download citation Artem Smirnov, Eric Nana Asamoah, Victor Navas-Portella, et al. Comparing and contrasting CME-driven ionospheric changes on 4-5 November 2023: A multi-instrument study. Authorea. 28 February 2025. DOI: https://doi.org/10.22541/au.174077607.71470720/v1 DOI: https://doi.org/10.22541/au.174077607.71470720/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu. Cited by - Features of disturbances during November 4–5, 2023, multi-step geospace storm: comparative study of the “ionosphere-thermosphere” system response, Advances in Space Research, 77, 9, (9704-9732), (2026).https://doi.org/10.1016/j.asr.2026.03.012 Loading...