The day-glow data application of FY-3D IPM in monitoring O/N-2

摘要

The Ionosphere Photometer (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite FY-3D, which was launched on November 25th, 2017. The F-2 layer peak electron density (NmF2) and O/N-2 the column density ratio can be deduced by far ultraviolet measurements of night-time OI 135.6 nm emissions, which are produced by the recombination of O+ ions and electrons, and the day-time OI 135.6 nm and N2LBH wavelength emissions produced by the photoelectron impact excitation of atomic oxygen O and molecular nitrogen N-2. Analysis of the IPM data indicated the stray light at 135.6 nm wavelength is under deducted. Based on comparison with the emissive intensity calculation of AURIC model, the day-time data was conducted to make a revision of stray light. The reliable factor (1.13) of stray light subtraction was obtained by fitting the median values of the observed data points per each latitude bin to the model data. According to the O/N-2 error estimation from the estimated factor of the stray light, when the factor does not change by more than 0.03, the error of O/N-2 ratio from the factor will not exceed 20%. The O/N-2 changes retrieved from revised IPM data during storms in April and August 2018 are well correlated with Dst indices. The research results show that the IPM data could provide a good monitoring of O/N-2 changes during magnetic storms.