# Effects of the October 2024 Storm over the Global Ionosphere
## 2 Data and Methods  
As a first step in our investigation of the 10-11 October 2024 geomagnetic storm, we examined solar activity using solar and solar wind data from the SOHO/LASC-C2 instrument. These observations, covering the period from 10 to 12 October 2024, were accessed via the SOHO data repository ([[https://soho.nascom.nasa.gov/data/data.html](https://soho.nascom.nasa.gov/data/data.html)]([https://soho.nascom.nasa.gov/data/data.html](https://soho.nascom.nasa.gov/data/data.html)) accessed on 23 April 2025) to identify key solar features such as CMEs and their potential geoeffectiveness. To characterize geomagnetic conditions during the storm, we utilized high-resolution (1 min) OMNI data provided by NASA's Goddard Space Flight Center ([[http://omniweb.gsfc.nasa.gov](http://omniweb.gsfc.nasa.gov)]([http://omniweb.gsfc.nasa.gov](http://omniweb.gsfc.nasa.gov)) accessed on 23 April 2025) and supplemented it with geomagnetic indices from the International Service of Geomagnetic Indices ([[https://isgi.unistra.fr/indices_asy.php](https://isgi.unistra.fr/indices_asy.php)]([https://isgi.unistra.fr/indices_asy.php](https://isgi.unistra.fr/indices_asy.php)) accessed on 23 April 2025). To analyze the ionospheric response globally, we focused on F2-layer peak characteristics--foF2 and hmF2--across low to midlatitudes from the COSMIC--2 RO mission, provided by the University Corporation for Atmospheric Research (UCAR). Specifically, we used Level 2 \"ionPrf\" data files from the COSMIC Data Analysis and Archive Center (CDAAC), which contain electron density (Ne) profiles with respect to altitude derived via Abel inversion from slant TEC observations. Due to the low inclination of COSMIC--2 satellites, coverage is optimized for latitudes within \(\pm\)35\({}^{\circ}\) magnetic (\(\sim\)\(\pm\)45\({}^{\circ}\) geographic), making it ideal for equatorial and low- to midlatitude ionospheric studies [6]. To examine ionospheric drift velocities during the storm, we extracted vertical (Vz) and horizontal (Vnorth and Veast) drift velocities from the University of Massachusetts Lowell Center for Atmospheric Research (UMLCAR) Digisonde drift database ([[https://lgdc.uml.edu/common/DFDBFastStationList](https://lgdc.uml.edu/common/DFDBFastStationList)]([https://lgdc.uml.edu/common/DFDBFastStationList](https://lgdc.uml.edu/common/DFDBFastStationList)) accessed on 23 April 2025). Due to limited data availability, we focused on three stations: Lualualualei (21.43\({}^{\circ}\)N-158.15\({}^{\circ}\)E), Eglin (30.5\({}^{\circ}\)N-86.5\({}^{\circ}\)E), and Ascension Island (\(-\)7.95\({}^{\circ}\)N-14.4\({}^{\circ}\)E). Drift velocities from 00:00 UT on 10 October to 02:00 UT on 12 October were extracted using the DriftExplorer (version 1.2.14) tool ([[https://ulcar.uml.edu/Drift-X.html](https://ulcar.uml.edu/Drift-X.html)]([https://ulcar.uml.edu/Drift-X.html](https://ulcar.uml.edu/Drift-X.html)) accessed on 23 April 2025), offering insight into the electric field-driven plasma transport across different latitudes. Thermospheric composition data, particularly the atomic oxygen to molecular nitrogen ratio [O/N\({}_{2}\)], were obtained from the Global Ultraviolet Imager (GUVI) instrument onboardthe TIMED spacecraft. These data, covering the period from 10 to 12 October, were accessed from the GUVI data portal ([[http://guvitimed.jhuapl.edu/data_products](http://guvitimed.jhuapl.edu/data_products)]([http://guvitimed.jhuapl.edu/data_products](http://guvitimed.jhuapl.edu/data_products)) accessed on 25 April 2025) with October 6 as a reference. This compositional ratio serves as a critical indicator of neutral atmospheric dynamics that influence electron density during geomagnetic storms. In addition to these datasets, we analyzed in situ Ne measurements from the Swarm A and B satellite Langmuir probes (LP), accessed through the ESA VirES platform ([[https://vires.services/](https://vires.services/)]([https://vires.services/](https://vires.services/)) accessed on 24 April 2024).