| Anthropogenic greenhouse gas emissions are an important driving force of global warming in the last century.The key to controlling global warming is to control the emission of greenhouse gases.Carbon dioxide is an important greenhouse gas.Research and development of scientific carbon dioxide gas emission monitoring technology and scientific identification of regional carbon dioxide emission and absorption are of great significance to serving my country’s carbon emission policies at different stages.At present,neither passive remote sensing technology nor active path integration radar can provide high-resolution carbon dioxide point source emissions in the region.Based on differential absorption laser radar gas monitoring technology and coherent laser radar wind measurement technology,the paper innovatively developed a calculation model for CO2 gas emission flux monitoring,and developed a carbon dioxide flux detection lidar system.The computational model was validated experimentally.This thesis mainly includes the following four aspects:1.A lidar-based CO2 flux calculation model was innovatively constructed,and a horizontal net flux calculation model was proposed for the first time.The distribution and transport of CO2 concentration in the scanning area can be obtained by analyzing the horizontal net flux.By a single scan of a single lidar,the emission source can quickly be locked and carbon sinks can be identified.Thus,the horizontal transport and dynamic distribution of carbon sources and sinks in the target area are presented.2.A new LiDAR system for carbon dioxide flux detection was developed.By integrating the receivers of direct detection differential absorption lidar and coherent Doppler wind lidar,the system combines the respective advantages of coherent detection and direct detection,and achieves maximum simplification in structure.By combining differential absorption carbon dioxide concentration measurement technology and coherent lidar wind measurement technology,the system can measure the two-dimensional concentration distribution of carbon dioxide and the synchronous wind field distribution with high resolution,and calculate the CO2 flux information.3.The receiver of the developed lidar system is optimized to improve the stability of the system.The optimization consists of two parts:First,a stable mode distribution is achieved in the multimode fiber by mode scrambling on the multimode fiber,thereby suppressing the fluctuation of the multi-channel detection efficiency of the detetcor caused by the inhomogeneity of the multimode fiber mode.Secondly,temperature control is carried out on the multimode optical fiber to solve the influence of ambient temperature on the detection efficiency.Through optimization,the stability of the detection efficiency of the superconducting detector is obviously improved.4.Based on the developed lidar system,the proposed carbon dioxide flux calculation model was verified.The lidar captures the CO2 plume emitted by the industrial area,and the two-dimensional distribution of the concentration of carbon dioxide shows that the plume spread trend corresponds to the wind direction.Diurnal and diurnal cycle characteristics of CO2 concentration in different regions were observed,especially large emissions at night in industrial areas were observed.The horizontal net flux of CO2 in three representative carbon source and carbon sink regions was calculated,and the carbon sinks and carbon sources determined according to the calculation results were in good agreement with the actual situation of the region.The experiments verified that the measurement of the horizontal net flux can effectively realize the traceability of carbon dioxide. |
