| The concentration of sulfur dioxide in the atmosphere is one of the important indexs for measuring atmospheric pollution.It is necessary to conduct high-precision and high-temporal resolution detection.The development of lidar technology provides an effective tool for the detection of polluting gases.Under the support of the APSOS(Atmospheric Profiling Synthetic Observation System)led by Academician Lu Daren of the Institute of Atmospheric Physics,Chinese Academy of Sciences,we developed a sulfur dioxide differential absorption lidar system.Using this lidar system,the distribution of sulfur dioxide near the ground(0.3-3.Okm)was obtained.The detection results are comparable with those of the surface meteorological department,and the detection accuracy can reach ±2 ppb.This article can be divided into three parts,the main research content is as follows:(1)The first part is the literature review part,mainly including chapters 1 to 2.Taking the doctoral thesis as the main line,a large number of domestic and foreign related literatures have been read.Firstly,the physical and chemical properties,hazards,and source distribution of sulfur dioxide in the atmosphere have been summarized.Common methods for detecting sulfur dioxide gas concentrations have been described,and the necessity for the development of this topic has been described.Secondly,the physical basis of laser atmospheric detection and the common types,applications and development trends of lidar are introduced.The above work has laid a foundation for the development of a vehicle-borne sulfur dioxide differential absorption lidar system.(2)The second part is to introduce the detailed development work of the vehicle-borne sulfur dioxide differential absorption lidar system,mainly including Chapters 3-7.This part is also the main part of my work during the doctoral period.Firstly,the theoretical basis of the system is introduced.Then,with the knowledge of lidar,the overall design of the system is performed.Secondly,the sub-systems of this vehicle-borne lidar system are introduced in detail.Two high-energy solid-state lasers are used to pump narrow linewidth dye lasers to obtain strong absorption wavelengths?on=300.05nm and weak absorption wavelengths ?off=301.50nm.The two laser beams pass through the combination of the polarization beam combiner and the beam expander of the 12-fold beam expander,and are collimated and transmitted coaxially with the telescope into the atmosphere.The backscattered echo signal is received by a 350mm near-Newtonian telescope and then passed through a conducting fiber into the subsequent light path,where it is attenuated by the subsequent light path and the filter finally reaches the photomultiplier tube.The photomultiplier tube converts the optical signal into an electrical signal,which is then collected by a data acquisition card and used to invert the distribution profile of sulfur dioxide.Finally,the vehicle-borne shelter for carrying the entire radar system was introduced in detail,and its vibration modes and stability were analyzed.(3)The third part is the data processing and analysis results of the laser radar system,mainly including Chapters 8-9.After the completion of the development of the onboard sulfur dioxide differential absorption laser radar system,we conducted a large number of field tests,and obtained a large number of valid data,and analyzed the experimental results and the stability of the entire system.Chapter 8 mainly introduces the anti-jamming scheme of the laser radar system,the processing and inversion of raw data,and the preliminary detection results with error analysis.Chapter 9 first gives some typical detection results,such as daytime detection results,detection and locking of typical pollution sources;based on previous detection data,the stability,integration time,and detection accuracy of the system are also analyzed;then we give the triple-wavelength dual The preliminary detection results of the differential absorption lidar and the detection data of the Yangbajing area in Tibet. |
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