Fig. 1. Absorption line strength and spectral distributions of CO₂ and O₂ molecules in the visible and near infrared bands. (a) CO₂; (b) O₂

Fig. 2. Atmospheric absorption of O₂ molecules in different bands. (a) Atmospheric absorption in 0.76 μm band; (b) atmospheric absorption in 1.27 μm band

Fig. 3. Volume emission rate of airglow in different O₂ band

Fig. 4. Airglow radiance (dashed line) and backscattered solar radiance (solid line)

Fig. 5. Spectral fitting results and residuals for a reference signal-to-noise ratio R_SNref of 1000. (a) Fitting results and residuals of ignoring airglow at spectral sampling interval of 0.01 nm; (b) fitting results and residuals of considering airglow at spectral sampling interval of 0.01 nm; (c) fitting results and residuals of ignoring airglow at spectral sampling interval of 0.05 nm; (d) fitting results and residuals of considering airglow at spectral sampling interval of 0.05 nm

Fig. 6. Variations of spectral fitting error and relative standard deviation with spectral sampling. (a) Fitting error and relative standard deviation without the consideration of airglow; (b) fitting error and relative standard deviation with the consideration of airglow

Fig. 7. Variations of relative standard deviation of the spectral fitting with the reference signal-to-noise ratio and spectral sampling. (a) In the range of 0.01‒0.10 nm for spectral sampling; (b) in the range of 0.10‒1.00 nm for spectral sampling