拉曼差分法探测大气中的臭氧

Monitoring O_3 in Atmosphere by Raman-Differentiai Absorption Method

介绍了拉曼差分法测量对流层底部污染物O_3的基本原理。计算和研究了N_2,O_2的拉曼光谱强度分布特征,利用O_3对N_2,O_2紫外波段拉曼散射光的不同吸收特性,推导出O_3浓度反演公式;设计了拉曼差分激光雷达(Raman-DIAL)系统,该系统采用双通道分别接收N_2和O_2对紫外266 nm激光的拉曼散射光,通过拉曼差分法反演大气中O_3浓度。分析了激光雷达系统噪声的来源,对双通道滤光片提出了相应的要求;分析了大气中污染物SO_2,NO_2在紫外波段的吸收特性对拉曼差分法测量O_3的影响及造成的相对误差;利用差分激光雷达AML-2测得的O_3数据模拟了拉曼差分激光雷达系统N_2与O_2的拉曼信号,从而证实了该方法探测对流层底部大气臭氧含量垂直分布的可行性。

Raman-differential absorption method was introduced for monitoring ozone concentration in the bottom of troposphere. The intensity of the Raman spectra of N2 and O2 was analyzed and calculated. The retrieving equation of ozone＇s concentration was presented based on the different absorption of ozone to the Raman spectra of N2and O2 in ultraviolet （UV）. A Raman-differential absorption lidar system was designed. The system collected Raman scattering signals of N2 and O2 by two channels, and concentration of ozone can be retrieved by these pairs of signals. The specifications of interference filters in two channels were presented by analyzing the sources of noises. The influences and relative errors of monitoring ozone in this method were analyzed, because SO2 and NO2 also absorb Raman scattering signals of N2, O2 in UV. Finally, vibrational Raman signals of N2 and O2 were simulated by the ozone data which monitored by AML-2 differential absorption lidar （made in Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences）. The simulation results indicate that Raman-differential absorption method is feasible for monitoring ozone concentration in low atmosphere.