Detection of CO₂ Concentration Profile Using Differential Absorption LiDAR

  Objectives  Carbon dioxide(CO₂) is the main component of greenhouse gases. Facing the urgent need of carbon peak and carbon neutralization, differential absorption light detection and ranging(LiDAR) is an ideal remote sensing method for measuring CO₂. In view of the characteristics that the obvious distribution change of atmospheric CO₂ in the troposphere, the low-altitude CO₂ concentration profile is obtained by differential absorption LiDAR.

  Methods  Using the self-developed CO₂ detection differential absorption LiDAR based on dye differential frequency laser technology, long-term observations were carried out in Huainan City, Anhui Province. Subject to low signal-to-noise ratio in the daytime, only nighttime observations were conducted. And through the development of advanced signal processing methods, high-space, high-time resolution CO₂ concentration profile and low-level average concentration were obtained.

  Results  The measurement results can representatively reflect the variation of the vertical distribution of CO₂ concentration in the plains of the middle and lower reaches of the Yangtze River. The typical CO₂ vertical distribution in winter and summer nights in low tropospheric is concluded: The CO₂ concentration continues to increase during nighttime. And the increase of CO₂ concentration in summer night is greater than that in winter. The lowest CO₂ concentration occurred in summer and the highest one occurred in winter.

  Conclusions  Ground based differential absorption LiDAR can obtain the spatial distribution of CO₂, which can provide key data in the quantitative study of carbon source and carbon sink. At present, the equipment has been transported to the Yangbajing area of ​​Tibet (4 300 m above sea level) for continuous observation, and the key CO₂ profile information has been successfully obtained. It can be used for comparative analysis of the vertical distribution characteristics of CO₂ in plains and plateaus, and provides important observational data for studying the transmission effect of the Qinghai-Tibet Plateau on greenhouse gases.