Slant detection and error analysis of atmospheric carbon dioxide profile with a continuous-wave differential absorption lidar

The vertical profile of atmospheric carbon dioxide (CO2) with high spatiotemporal resolution is one of the critical parameters for understanding the carbon sources, sinks, climate change, and their feedback mechanisms on the ground and troposphere. Unfortunately, up to now, the vertical profile of atmospheric CO2 with high spatiotemporal resolution is still very scarce. Here, we preliminarily conducted slant detection experimental research of atmospheric CO2 with a self-made continuous-wave differential absorption lidar, which is based on the Scheimpflug principle. Multiple atmospheric CO2 profiles were obtained within a slant range of 2984 m (corresponding a vertical altitude about 1021 m) with an elevation angle of 20 degrees, and the detection results were compared with a CO2 GMP343 sensor located approximately 10 m above the ground. The preliminary comparison results indicated the detection results are reliable. In addition, the errors caused by atmospheric environmental fluctuations and wavelength drift were analyzed. The minimum relative error due to atmospheric environment fluctuations was 0.13 % at a slant range of 384 m (corresponding a vertical altitude about 131 m), while the maximum relative error was 0.73 % at a slant range of 2984 m (corresponding a vertical altitude about 1021 m), and the relative error caused by wavelength drift was 0.57 %.