Study on Atmospheric Temperature and Water-Vapor Mixing Ratio Based on Raman Lidar

Raman lidar has been designed by the Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, which measures atmospheric temperature, water vapor, and aerosol simultaneously. A high-performance spectroscopic box that utilizes multicavity interference filters, mounted sequentially at small angles of incidence, is used to separate the lidar return signals at different wavelengths, and to extract the signals with high efficiency. The external experiments are carried out for simultaneous detection of atmospheric temperature, water vapor, under clear and hazy weather conditions. The vertical profiles of temperature, water vapor are analyzed. The results show that for an integration time of 5 min and laser energy of 200 mJ, the mean deviation between measurements obtained by lidar and radiosonde is small, and the overall trend is similar. The temperature inversion layer is found in the low troposphere. The statistical temperature error for nighttime is below 1 K up to a height of 6. 2 km under clear weather conditions, and up to a height of 2. 5 km under slightly hazy weather conditions, with 5 min of observation time. Moreover, the relative error in water vapor detection process mostly does not exceed 5% up to 4 km, and is well below 20% up to 7. 5 km. Continuous observations verify the reliability of Raman lidar to achieve real-time measurement of atmospheric parameters in the troposphere.