Observation of thermospheric and ionospheric vortices during geomagnetic storms

During the recovery phase of the major geomagnetic superstorm of 10-11 May 2024, for the first time, unusual vortex-like structures were observed in the thermospheric composition O/N2 ratio and thermospheric temperature by the Global-scale observations of the Limb and Disk (GOLD) instrument (Evans et al., 2024). The features occurred over the American and Atlantic regions, and were also partly seen in the vertical total electron (VTEC) content maps. After that first-time discovery, Correira et al. (2025) further reported the occurrence of similar vortices but of smaller magnitude and smaller spatial scale during the October 2024 superstorm and during the April 2023 storm. Correira et al. (2025) also mentioned no evidence of the occurrence of the vortices in VTEC during these storms. In this work, we use data of the GOLD mission together with maps of GNSS-derived VTEC to study the correlation between the themospheric composition and the VTEC (Astafyeva et al., 2025). For the first time, we show that the lifetime and the evolution of the vortices in these two parameters differ: while the composition alters very slowly and the vortices slowly shift westward with their structure unchanged, the VTEC vortices can change very rapidly and their zonal drift is less evident. The link between the two parameters has been known for decades, however, the exact coupling remains poorly understood. The World’s most advanced simulation tools managed to reproduce the occurrence of an O/N2 vortex in the Southern Hemisphere, but not in the Northern Hemisphere (Wang et al., 2024). That same model or no other model was capable of reproducing such vortices in the VTEC during the May 2024 superstorm.We also show that VTEC vortices can occur during other intense storms, which means that the ionospheric VTEC can serve, to some extent, as a proxy of storm-time changes in the thermospheric composition.References:Astafyeva, E., B. Maletckii, I.D. Ouar, M. Förster, D.R. Themens, J.D. Huba, M. Hairston, W.R. Coley, and M.-C. H. Fok. (2025) An extraordinary dayside negative ionospheric storm and total electron content (TEC) vortices observed on 11 May 2024. J. Geophys. Res. - Space Physics, V.130, N12, doi: 10.1029/2025JA034571.Correira, J., J. S. Evans, J.D. Lumpe, R.W. Eastes, et al (2025) Upper Atmospheric Vortices Following Strong Geomagnetic Storms, Geophys. Res. Lett., V.52, N11, e2024GL113726, doi: 10.1029/2024GL113726Evans, S., J. Correira, J.D. Lumpe et al. (2024) GOLD Observations of the Thermospheric Response to the 10–12 May 2024 Gannon Superstorm, Geophys. Res. Lett., V.51, 16, e2024GL110506, doi:10.1029/2024GL110506.Wang, W., K.H. Pham, H. Wu, J.S. Evans, R.W. Eastes, D. Lin, V.G. Merkin (2024) MAGE (Multiscale Atmosphere-Geospace Environment) model simulations of the dynamic processes driving the thermospheric responses to the May 10, 2024 geomagnetic superstorm, AGU Annual Meeting, December 2024, Washington DC, USA