Lidar （Light detection and ranging） has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Ra...Lidar （Light detection and ranging） has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing.展开更多
Knowledge of the temporal-spatial distribution of water content in atmosphere and water phase change in cloud is important for atmospheric study. For this purpose, we have developed a high resolution full-spectrum wat...Knowledge of the temporal-spatial distribution of water content in atmosphere and water phase change in cloud is important for atmospheric study. For this purpose, we have developed a high resolution full-spectrum water Raman lidar that can collect Raman signals from ice, water droplets and water vapor simultaneously. A double-grating polychromator and a 32-channel photomultiplier-tube detector are used to obtain a spectral resolution of-0.19 nm in the full Raman spectrum range of water, Preliminary observations present the water Raman spectrum characteristics of both the mixed-phase cloud and humid air under cloudless condition.展开更多
Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important...Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and ＇real-time＇ Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.展开更多
This paper presents a Raman lidar for measuring tropospheric water vapor profiles over Hefei (31.9°N,117.17°E),China.Intercomparisons of water vapor mixing ratio obtained by this Raman lidar and GZZ-59 type ...This paper presents a Raman lidar for measuring tropospheric water vapor profiles over Hefei (31.9°N,117.17°E),China.Intercomparisons of water vapor mixing ratio obtained by this Raman lidar and GZZ-59 type radiosonde observations show the good agreements when relative humidity is higher than 20%.Typical vertical profiles and seasonal variations of water vapor mixing ratio distribution are reported.Many observation eases indicate that the high moisture layer corresponds to large aerosol scattering ratios in the lower troposphere.展开更多
采用Raman-Mie激光雷达探测了西安地区夏季气溶肢的光学特性,分析了消光系数、后向散射系数和雷达比在不同天气条件下的变化规律.实验结果表明,强降雨后,气溶肢消光系数在2-5 k m 范围内递减,并在5 k m 以上趋于稳定;相对于降雨前,降雨...采用Raman-Mie激光雷达探测了西安地区夏季气溶肢的光学特性,分析了消光系数、后向散射系数和雷达比在不同天气条件下的变化规律.实验结果表明,强降雨后,气溶肢消光系数在2-5 k m 范围内递减,并在5 k m 以上趋于稳定;相对于降雨前,降雨后低层气溶肢消光系数明显增大,而3 k m 以上高度范围内雷达比减小.这可能是由雨后气溶肢沉降、底层水汽密度增加所引起的.统计结果表明,晴天无云时,2-3 k m 范围内气溶肢的消光系数和雷达比均比较稳定,消光系数在0. 2-0. 3 km^-1之间,雷达比的平均值约为50 sr;3 -5 k m 范围内消光系数和雷达比均随高度递减;5-8 k m 范围内,消光系数和雷达比逐渐趋于稳定,消光系数和雷达比的平均值分别约为0.05 km^-1和20sr,表明此范围内仍有微量的气溶肢粒子存在.实验期间,水云的雷达比约为17 sr.展开更多
基金Project supported by National High Technology Development Program of China (Grant No 2002AA135030)
文摘Lidar （Light detection and ranging） has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing.
基金supported by the National Natural Science Foundation of China (Grant No. 40731055)
文摘Knowledge of the temporal-spatial distribution of water content in atmosphere and water phase change in cloud is important for atmospheric study. For this purpose, we have developed a high resolution full-spectrum water Raman lidar that can collect Raman signals from ice, water droplets and water vapor simultaneously. A double-grating polychromator and a 32-channel photomultiplier-tube detector are used to obtain a spectral resolution of-0.19 nm in the full Raman spectrum range of water, Preliminary observations present the water Raman spectrum characteristics of both the mixed-phase cloud and humid air under cloudless condition.
文摘Lidar （Light detection and ranging） system monitoring of the atmosphere is a novel and powerful technique tool. The Raman lidar is well established today as a leading research tool in the study of numerous important areas in the atmospheric sciences. In this paper, the principle of Raman lidar technique measurement CO2 concentration profile is presented and the errors caused by molecular and aerosol extinction for CO2 concentration profile measurement with Raman lidar are also presented. The standard atmosphere extinction profile and ＇real-time＇ Hefei area extinction profile are used to conduct correction and the corresponding results are yielded. Simulation results with standard atmosphere mode correction indicate that the errors caused by molecule and aerosol extinction should be counted for the reason that they could reach about 8 ppm and 5 ppm respectively. The relative error caused by Hefei area extinction correction could reach about 6%. The errors caused by the two components extinction influence could produce significant changes for CO2 concentration profile and need to be counted in data processing which could improve the measurement accuracies.
基金Supported by the National 863 High Technology Research and Development Project
文摘This paper presents a Raman lidar for measuring tropospheric water vapor profiles over Hefei (31.9°N,117.17°E),China.Intercomparisons of water vapor mixing ratio obtained by this Raman lidar and GZZ-59 type radiosonde observations show the good agreements when relative humidity is higher than 20%.Typical vertical profiles and seasonal variations of water vapor mixing ratio distribution are reported.Many observation eases indicate that the high moisture layer corresponds to large aerosol scattering ratios in the lower troposphere.
文摘采用Raman-Mie激光雷达探测了西安地区夏季气溶肢的光学特性,分析了消光系数、后向散射系数和雷达比在不同天气条件下的变化规律.实验结果表明,强降雨后,气溶肢消光系数在2-5 k m 范围内递减,并在5 k m 以上趋于稳定;相对于降雨前,降雨后低层气溶肢消光系数明显增大,而3 k m 以上高度范围内雷达比减小.这可能是由雨后气溶肢沉降、底层水汽密度增加所引起的.统计结果表明,晴天无云时,2-3 k m 范围内气溶肢的消光系数和雷达比均比较稳定,消光系数在0. 2-0. 3 km^-1之间,雷达比的平均值约为50 sr;3 -5 k m 范围内消光系数和雷达比均随高度递减;5-8 k m 范围内,消光系数和雷达比逐渐趋于稳定,消光系数和雷达比的平均值分别约为0.05 km^-1和20sr,表明此范围内仍有微量的气溶肢粒子存在.实验期间,水云的雷达比约为17 sr.
