Fig. 1. Schematic diagram of the atmospheric oxygen airglow generation mechanism

Fig. 2. Number density profile of oxygen molecules and oxygen airglow transmittance at different tangent heights. (a) Number density profile of oxygen molecules; (b) oxygen airglow transmittance

Fig. 3. Flowchart for calculating atmospheric O₂A airglow emission spectrum

Fig. 4. Schematic diagram of geometric transmission of airglow radiation

Fig. 5. Calculation results of airglow spectral lines at different tangent heights

Fig. 6. Limb-viewing geometry of TOPS

Fig. 7. Structural diagram and optical path diagram of TOPS. (a) Structural diagram; (b) light path diagram

Fig. 8. Spectral calibration results. (a) Wavelength diagram; (b) Gaussian fitting results

Fig. 9. TOPS on-ground radiometric response coefficient

Fig. 10. TOPS in-orbit data processing chart

Fig. 11. TOPS in-orbit limb observation spectra

Fig. 12. TOPS in-orbit O₂A airglow detection spectra. (a) O₂A airglow at different tangent heights; (b) O₂A airglow at different solar zenith angles

Fig. 13. Selection of wavelength for TOPS temperature profile inversion. (a) Atmospheric transmittance at 70 km; (b) radiation intensity of strong line 761 nm, middle line 765 nm, and weak line 766 nm at different tangent heights; (c) transmittance of strong line 761 nm, middle line 765 nm, and weak line 766 nm at different tangent heights

Fig. 14. Weighting function and averaging kernel function of temperature profile inversion. (a) Weighting function; (b) averaging kernel function

Fig. 15. TOPS temperature profile inversion error

Fig. 16. Temperature profile inversion results. (a) Inversion results of 50°S; (b) inversion results of 63°S