Extreme two-phase change of ionospheric electron temperature overshoot during geomagnetic storms

A.S. is supported by Deutsche Forschungsgemeinschaft (DFG), project number 520916080. E.K. is supported by the DFG Heisenberg grant under number 516641019. F.P. acknowledges the Research Council of Finland for supporting the project 'Exploring the Upper Limits of the Ionosphere' (EULI), under decision number 362096. A.S. is grateful to S.A. Gilder for useful discussions. This research was partly supported by the International Space Science Institute (Bern, Switzerland) through the ISSI International Team project #24-609 ("1-100 keV Electrons in the Earth's Magnetosphere: Unique and Unpredictable?").

All data used in this study are publicly available. The solar (wind) data and the SYM-H index were obtained from the OMNIWeb database (https://omniweb.gsfc.nasa.gov/). CHAMP observations were obtained from the Data Services archive of GFZ Potsdam (https://doi.org/10.5880/GFZ.2.3.2019.007). The Hp30 index is also provided by GFZ Potsdam (https://kp.gfz-potsdam.de/hp30-hp60). Jicamarca, Arecibo, and Millstone Hill ISRs data are available via the public access Madrigal portal at http://cedar.openmadrigal.org. The data and model files, as well as the source codes are provided through the open access Zenodo repository: https://doi.org/10.5281/zenodo.14770872.