Fig. 1. Diagram of open-path FTIR system

Fig. 2. Experimental apparatus. (a) Open range FTIR active telemetry system; (b) reflector telescope; (c) small room for installation of reflector telescope

Fig. 3. Correlation analysis of mass concentrations of CO₂, CH₄ and CO measured by Picarro greenhouse gas analyzer and OP-FTIR system. (a) CO₂; (b) CH₄; (c) CO

Fig. 4. Measured spectra, fitted spectra, residual spectra and transmittance spectra of H₂O, CO₂, CH₄ and CO in the corresponding wavelength bands. (a) CO₂; (b) CH₄; (c) CO

Fig. 5. Weather conditions during trial. (a) Temporal variation of relative humidity, temperature and wind speed; (b) relationship between wind speed and wind direction variation

Fig. 6. Gas mass concentration in relation to temperature and relative humidity. (a) CO₂; (b) CH₄; (c) CO

Fig. 7. Gas mass concentration in relation to wind direction and wind speed. (a) CO₂; (b) CH₄; (c) CO

Fig. 8. Time series variation of CO₂, CH₄ and CO mass concentration. (a) CO₂; (b) CH₄; (c) CO

Fig. 9. Correlation between CO or CH₄ and CO₂. (a) CH₄ and CO₂; (b) CO and CO₂