Three-dimensional detection of CO₂ and wind using a 1.57 µm coherent differential absorption lidar

A 1.57-µm coherent differential absorption lidar is demonstrated for measuring three-dimensional CO₂ and wind fields simultaneously. The maximum detection range of CO₂ is up to 6 km with a range resolution of 120 m and a time resolution of 1 min. A preliminary assessment of instrument performance is made with a 1-week continuous observation. The CO₂ concentration over a column from 1920 to 2040 m is compared with the one measured by an optical cavity ring-down spectrometer placed on a 2 km-away meteorological tower. The concentration is strongly correlated with the in-situ spectrometer with a correlation coefficient and RMSE of 0.91 and 5.24 ppm. The measurement accuracy of CO₂ is specified with a mean and standard deviation of 2.05 ppm and 7.18 ppm, respectively. The regional CO₂ concentration and the three-dimensional wind fields are obtained through different scanning modes. Further analysis is conducted on vertical mixing and horizontal transport of CO₂ by combining with the measured wind fields.