Comparing Northern Hemisphere Mid-Latitude Thermosphere-Ionosphere Response to Two Recent Geomagnetic Storms

Understanding the variability of the thermosphere–ionosphere (T–I) system across different conditions is especially important, as its state critically affects the operation and safety of numerous low Earth orbit (LEO) satellites. In the absence of routine thermospheric monitoring, ionosonde measurements and satellite data can be used to retrieve key aeronomic parameters at mid-latitudes during noontime via the THERION (THERmospheric parameters from IONosonde observations) method.

This study applies the THERION technique to analyze the T–I response in the European and American longitudinal sector to two recent severe geomagnetic storms (October 2024 and January 2025). Validated ionosonde data from Rome, Juliusruh, Millstone Hill and Eglin were used to assess ionospheric variability and derive thermospheric parameters such as neutral composition, temperature, and wind. Results are compared with outputs from the MSISE00 empirical model, highlighting THERION's improved capability in capturing thermospheric dynamics under storm conditions.

Additional datasets—including co-located GNSS-derived TEC, geomagnetic field data from the INTERMAGNET network, and interplanetary/magnetospheric conditions—were integrated to provide a comprehensive view of the events and the unique T-I coupling processes associated with each storm.

This study is carried out within the Space It Up project funded by the Italian Space Agency, ASI, and the Ministry of University and Research, MUR, under contract n. 2024-5-E.0 - CUP n. I53D24000060005.