基于Raman激光雷达反演大气污染气体浓度几种方法

Method for Retrieving Pollution Gas Concentration from Raman Lidar Return

Raman激光雷达是探测大气污染气体的一种重要方法,雷达回波反演是其中的重要步骤,反演的关键在于正确得到透过率指数因子。以消光系数为中心的三个方案,介绍了目前已普遍采用的方法、应用532 nm大气消光系数间接求取α(1λ,z)和α(2λ,z)。提出了两种新方法:(1)采用拉曼波长与待测气体相近的参考气体,α(1λ,z)=α(2λ,z);(2)借助1λ和2λ的Mie-Rayleigh散射回波求取指数因子。

Raman lidar is an important tool for the detection of atmosphere pollution, and inversion for lidar returns is an importam process. The key for inversion is to get transmission exponential function exp [∫0^R[α（λ1 ,z） -α（λz ,z）] . Three methods with extinction coefficient as the center are presented. First, 532 nm atmospheric extinction coefficient was used to indirectly obtain α（λ1, z） and α（λ2, z）, This method has been used generally by people. Two new methods were proposed： 1, reference gas with approximate Raman wavelength is used so that α（λ1 ,z）=α（λ2 ,z）. 2, Mie-Rayleigh scattered return with wavelength λ1 or λ2 is used to compute exp [∫0^R[α（λ1 ,z） -α（λz ,z）].