Seasonal Transition Study of Thermospheric Composition Ratios at Twilight Detected by the Fengyun-3E Satellite_dataSet

Multiple Fengyun-3 satellites in China are equipped with ionospheric photometers, which can detect the integrated radiation flux of airglow in the OI 135.6nm and N2 LBH spectral bands, and obtain the ratio of the two (referred to as the 135.6/LBH ratio). Among them, Fengyun-3E satellite is the second generation of near polar sun synchronous orbit satellite, which can perform airglow observations in the morning and evening orbits. The 135.6/LBH ratio is usually proportional to the O/N2 ratio of the atmospheric composition in the thermosphere, reflecting changes in the O/N2 ratio and is an important parameter that causes changes in ionospheric electron density. In previous studies, it has been found that the O/N2 ratio and corresponding changes in ionospheric electron density exhibit complex characteristics during the seasonal transition from winter to summer, and further research is needed. This article collected data from the OI 135.6nm and N2 LBH spectral bands of the E-star ionospheric photometer in the past two years, and obtained a 135.6/LBH ratio. The seasonal transformation patterns of each parameter in the mid to low latitudes were analyzed, and the seasonal transformation patterns and latitude variation characteristics of each parameter were obtained, as well as the differences between the northern and southern hemispheres. The formation mechanism and possible effects on the thermosphere and ionosphere were explored. The research results show that the seasonal transition characteristics of radiation intensity in the OI 135.6nm and N2 LBH bands are similar, with both mainly winter and summer modes, and rapid seasonal transitions occurring during the spring and autumn seasons; The seasonal variation characteristics of both vary with latitude. Similarly, the seasonal variation characteristics of the 135.6/LBH ratio also vary with latitude, and there is a rapid transition in the spring and autumn seasons. However, its seasonal pattern, that is, the period when its peak and valley values appear, is significantly different from the radiation of the OI 135.6nm and N2 LBH bands. The 135.6/LBH ratio exhibits two main seasonal patterns at mid latitude: high values in winter and low values in summer, with significant annual variations. However, near the equator, it exhibits high values in spring and autumn and low values in winter and summer, with semi annual variations. Further analysis reveals that the seasonal transformation of the 135.6/LBH ratio exhibits asymmetry and varies with latitude and hemisphere variations. The results of this study indicate that the atmospheric radiation ratio detected by the Fengyun satellite ionospheric photometer reflects the seasonal, latitude, and hemispherical variations of the atmospheric composition ratio in the thermosphere well, providing a reliable foundation for research and modeling related to the ionospheric thermosphere and the application of space weather forecasting.