## 5 Discussion and Conclusions
The spectacular loss of F\({}_{2}\) layer ionization observed during both storms can be due to an increase in the recombination rates, associated with a higher temperature and density caused by the injection of particles, in combination with the outflow of ionization. The analysis of Swarm data during the May event [10] shows an equatorward displacement of the mid-latitude ionospheric trough, confirming the importance of high-altitude influence. Even though from a geomagnetic perspective, the storm level was similar for both events discussed here, and both events started at about the same universal time, the reactions of the ionosphere and plasmasphere show some marked differences. The main reason for this is the different condition of the ionosphere and plasmasphere at the time of the storm onset. These differences in turn are due both to the different climatological background, i.e., the season during which the event happened, and to the persisting effects from prior, less severe disturbances. This illustrates one of the main issues with forecasting the geosphere effects of a storm, and the importance of analyzing effects in detail for each storm: severe storms are uncommon and rarely occur in comparable background conditions. Therefore, collecting a database with observations covering all possible conditions to allow the validation of the models and forecasting systems is still an ongoing work in progress. Conceptualization, V.P. ; methodology, V.P. and T.G.W.V. ; software, all; validation, V.P. and T.G.W.V. ; formal analysis, all; investigation, all; resources, V.P. ; data curation, T.G.W.V., A.W., J.-M.C. and N.B. ; writing--original draft preparation, V.P. ; writing--review and editing, all; visualization, all; supervision, V.P. ; project administration, V.P. ; funding acquisition, V.P. All authors have read and agreed to the published version of the manuscript. **Funding:** The project 21 GRD02 BIOSPHERE has received funding from the European Partnership on Metrology, co-financed from the European Union's Horizon Europe Research and Innovation Programme and by the Participating States. The authors thank the Horizon 2020 research and innovation programme funding from the European Union for the PITHIA-NRF project (Plasmas-phere Ionosphere Thermosphere Integrated Research Environment and Access services) with Grant Agreement 101007599. **Institutional Review Board Statement:** Not applicable. **Data Availability Statement:** Omni data were retrieved from [[https://omniweb.gsfc.nasa.gov/html/ow_data.html](https://omniweb.gsfc.nasa.gov/html/ow_data.html)]([https://omniweb.gsfc.nasa.gov/html/ow_data.html](https://omniweb.gsfc.nasa.gov/html/ow_data.html)), Dst data from [[https://wdc.kugi.kyoto-u.ac.jp/](https://wdc.kugi.kyoto-u.ac.jp/)]([https://wdc.kugi.kyoto-u.ac.jp/](https://wdc.kugi.kyoto-u.ac.jp/)) (accessed on 3 January 2025). The BSPM is accessible on [[https://esc.pithia.eu/](https://esc.pithia.eu/)]([https://esc.pithia.eu/](https://esc.pithia.eu/)) (accessed on 3 January 2025). VTEC is available on STCE.be. Swarm plasmapause proxy is found at [[https://swe.ssa.esa.int/elte-plasma-federated](https://swe.ssa.esa.int/elte-plasma-federated)]([https://swe.ssa.esa.int/elte-plasma-federated](https://swe.ssa.esa.int/elte-plasma-federated)) (accessed on 3 January 2025). A detailed description of all these new SWARM products as well as the detailed description of the processing algorithm can be found at [[https://earth.esa.int/eogateway/activities/plasmapause-related-boundaries-in-the-topside-ionosphere-as-derived-from-swarm-measurements](https://earth.esa.int/eogateway/activities/plasmapause-related-boundaries-in-the-topside-ionosphere-as-derived-from-swarm-measurements)]([https://earth.esa.int/eogateway/activities/plasmapause-related-boundaries-in-the-topside-ionosphere-as-derived-from-swarm-measurements](https://earth.esa.int/eogateway/activities/plasmapause-related-boundaries-in-the-topside-ionosphere-as-derived-from-swarm-measurements)) (PRISM docs) (accessed on 3 January 2025).