Fig. 1. Simulated O₂ absorption spectrum at 250 K/300 K and 1 atm pressure

Fig. 2. Simulated profiles of the atmospheric temperature and the pressure. (a) Temperature profile; (b) Pressure profile

Fig. 3. Simulated profiles of the atmospheric backscattering coefficients, extinction coefficients and backscatter ratio. (a) The backscattering coefficients; (b) The extinction coefficients; (c) The backscatter ratio

Fig. 4. Lidar signals with noise. (a) Lidar curve; (b) DIAL ratio curve; (c) The signal-to-noise ratio (SNR) of lidar curve; (d) The SNR of DIAL ratio curve

Fig. 5. The retrieved results of 300 m (pale blue), 500 m (pink) and 1000 m (pale green) segmented fitting distance under the influence of noise. (a) Retrieved temperature profiles; (b) Temperature deviations

Fig. 6. Emission spectra, scattering spectra, and O₂ absorption spectra. (a) Emission spectra and O₂ absorption spectra; (b) Scattering spectra and O₂ absorption spectra

Fig. 7. (a) Upward and downward transmittance curves at λ_on and λ_off wavelengths; (b) Lidar curves of λ_on and λ_off; (c) DIAL ratio curves with and without Doppler effect

Fig. 8. Retrieved temperature profiles and deviations. (a) Retrieved temperature profiles; (b) Temperature deviations

Fig. 9. Models of different aerosol distributions. (a) The backscattering coefficients of aerosols; (b) The backscatter ratio

Fig. 10. O₂ absorption spectra under different specific humidities

Fig. 11. (a) DIAL ratio curves, (b) retrieved temperature profiles and (c) temperature deviations under different specific humidities

Fig. 12. DIAL ratio curves and retrieved temperature profiles under different frequency-shifts. (a) DIAL ratio curves; (b) Retrieved temperature profiles; (c) Temperature deviations

Fig. 13. DIAL ratio curves under different frequency-fluctuations

Fig. 14. The retrieved temperature profiles under different frequency fluctuations. (a) Retrieved temperature profiles; (b) Temperature deviations

Fig. 15. The retrieved temperature deviations under different frequency shifts and fluctuations. Frequency shifts: (a) 0 MHz (0 pm); (b) 50 MHz (0.1 pm); (c) 100 MHz (0.2 pm); (d) 150 MHz (0.3 pm); (e) 200 MHz (0.4 pm); (f) 250 MHz (0.5 pm)