Keywords:Airglow, Atomic Oxygen Ions, Photochemical models, TIEGCM, Irkutsk
Three photochemical inversion models are derived to retrieve atomic oxygen ion density ([O+]) from 630.0 nm intensity emitted by O(1D) excited state, to understand the relation between 630.0 nm airglow emission and [O+]. Three experiments are performed in this study. The first experiment validated our inversion models with Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) results, with the derived [O+] showing high correlation with the TIE-GCM model truth. Sensitivity testing results show that molecular oxygen density ([O2]) used in the inversion process is most effective in determining the trends of calculated [O+]. The second and third experiments are applied with ground-based spectrometer 630.0 nm data from Geophysical Observatory of the Russian Academy of Sciences Siberian Branch near Irkutsk, Russia (51.8°N, 103.1°E) in 2016, but with unobserved background inputs from TIE-GCM and empirical models, respectively. A new height profile based on emission layer thickness and hmF2 derived 630 nm airglow intensity peak altitude for Gaussian distribution (GD) is applied for converting Rayleighs into Volume Emission Rate (VER) (Adachi et al., 2009), and is consistent with the TIE-GCM calculated airglow peak altitude. Future work will replace GD with Chapman distribution which should be closer to reality. With the new inversion models and preliminary height profile, estimations of [O+] using empirical models and airglow observation are possible and may be extended to estimate [O2] if combined with electron density measurements.