Thermospheric Disturbance Observed by Triple Ionosphere PhotoMeter Onboard the Chinese Meteorological Satellite FY3E During 10–11 May 2024 Storm

The Triple Ionospheric PhotoMeter (TriIPM) carried on the newly launched early morning FY3E meteorological satellite measures the spectral radiances of the Earth's far ultraviolet airglow in atomic oxygen 135.6 nm (OI 135.6 nm) and N₂ Lyman-Birge-Hopfield (N₂ LBH) bands. In this paper, the TriIPM instrument data are used for the first time to record the thermospheric O/N₂ ratio variations during geomagnetic storms through the case study of the superstorm on 10–11 May 2024. The variations of the TriIPM O/N₂ ratio and the ionospheric peak density at F2 layer (NmF2) derived from the modified IRI2016 model are also compared to explore the relationship between the storm-time thermospheric and ionospheric responses. Our results show that the TriIPM O/N₂ ratio depletion extends down to the equator in the Northern Hemisphere during the main phase of the storm period. The TriIPM O/N₂ ratio depletion shows a good quantitative agreement with the NmF2 depletion within the disturbed region at a local time period between 1100 and 1900 LT. The good agreement between the TriIPM O/N₂ ratio and NmF2 indicates that the new satellite TriIPM instrument may provide a good opportunity for understanding how the thermosphere-ionosphere system responds to geomagnetic storms.