Fig. 1. The schematic diagram of principle of laser heterodyne detection

Fig. 2. High resolution laser heterodyne detection system for solar radiation

Fig. 3. Interference spectrum of F-P etalon and linear function of system instrument. (a) Interference spectrum of etalon;(b) instrument linear function

Fig. 4. The flow chart of retrieving atmospheric CO₂ profiles

Fig. 5. The prior profiles of atmospheric pressure and temperature at various altitude

Fig. 6. The fitting results of atmospheric CO₂ heterodyne spectra (a) and corresponding fitting residuals (b)

Fig. 7. The prior vertical profiles and retrieved vertical profiles of CO₂

Fig. 8. Sum of average kernel functions for CO₂ (a) and total error of profile retrieval (b)