| The atmospheric water vapor volume ratio is only 0.1%to 3%of the total air,but it is the most active gas in the atmosphere.The water vapor is also the most important greenhouse gas in the Earth's atmosphere,and in the global water cycle,weather system,atmospheric chemistry,etc.It plays a very important role.Raman lidar can detect the vertical profile of water vapor,and has the advantages of high detection accuracy,high temporal and spatial resolution,and continuous detection.However,the measurement results need to be calibrated.Existing calibration methods(such as radiosondes,GPS,microwave radiometers,etc.)cannot meet the current requirements for high-precision measurement of water vapor.At present,the calibration of water vapor Raman lidar has become a bottleneck restricting the widespread application of this technology;Traditional water vapor Raman lasers usually use high-energy water-cooled lasers,which have large volume and power consumption,which is not conducive to small integrated design.Water-cooled lasers need to be replaced with cooling water and xenon lamps frequently,which is inconvenient to maintain,which also limits the Raman laser radar.This paper focuses on the research of water vapor mixing ratio dual-wavelength self-calibration method and the development of all-solid-state Raman lidar system.The main contents are as follows:(1)Firstly,the characteristics of atmospheric water vapor and its importance are introduced.The distribution of atmospheric water vapor and its variation characteristics are summarized.The common methods of water vapor detection are summarized.The research progress of typical water vapor detection Raman lidar at Domestic and foreign is listed,and the physical parameters related to the Raman scattering mechanism and water vapor detection are introduced.The echo signal model of Raman laser radar water vapor detection system is established,and the numerical simulation results of water vapor mixing ratio are given.The simulation software of water vapor detection Raman lidar is designed to determine the technology of Raman lidar.The parameters and overall structure provide a reference for understanding the performance of detecting water vapor.(2)The dual-wavelength self-calibration method is discussed in detail:through the appropriate improvement of the water vapor Raman lidar,the water vapor molecular Raman channel can measure the Rayleigh scattering echo signal of the air molecule and the Raman scattering echo signal of the nitrogen molecule.The echo signal is scattered and an uncalibrated atmospheric nitrogen mixing ratio is calculated.3)Developed a highly integrated all-solid-state UV Raman lidar water vapor detection system,which can continuously measure the spatial and temporal distribution of water vapor day and night.The effective detection heights during day and night reach 2km and 5km respectively,and the water vapor mixing ratio measurement error Less than 10%.The all-solid-state design makes the lidar system very environmentally adaptable and easy to operate and maintain,making it ideal for long-term field measurements.The highly integrated design allows it to be mounted on a scanning fork for scanning and detecting the distribution of water vapor in the hemisphere sky.The dual-wavelength self-calibration lidar was used for the transmission calibration.The calibration results were compared with the radiosonde to further verify the applicability of the dual wavelength self-calibration method for different wavelengths.(4)A preliminary exploration of high-frequency all-solid-state water vapor Raman lidar technology was carried out,and the dual-wavelength self-calibration Raman lidar system was improved.The high-frequency all-solid-state dual-band laser was used instead of the original water-cooled Nd:YAG laser,and the high-speed photon counting card acquisition,initially obtained valid data,and verified that the high-repetition all-solid-state Raman lidar system scheme is feasible. |
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