基于CW-CRDS的大气甲烷浓度直接测量方法研究

Study on Direct Measurement Method of Atmospheric Methane Concentration Based on CW-CRDS

腔衰荡光谱技术(CRDS)具有高灵敏度、高精度、高光谱分辨率,适合痕量气体检测。但是,其在被用于测量大气甲烷浓度时,需要对大气样本进行预处理,否则会受到其他气体吸收特性和气溶胶消光特性干扰,影响测量精度。本文针对这个问题,提出了一种基于CW-CRDS的直接测量大气甲烷浓度的方法,利用可调谐激光器进行光谱扫描,在同时测量大气中水汽、二氧化碳吸收系数和多种粒径气溶胶颗粒消光系数的基础上,结合波长校正法,提高了在环境大气中无预处理条件下的大气甲烷测量准确性。

The Cavity Ring Down Spectroscopy(CRDS)is a direct absorption spectroscopy technology with high sensitivity,high precision and high spectral resolution,which is suitable for the trace gas detection.However,there is a problem that atmospheric samples need to be pretreated when it is used to measure the atmospheric methane concentration.Otherwise,it will be interfered by other gas absorption characteristics and aerosol extinction characteristics,which will affect the measurement accuracy.Aiming at this problem,this paper proposes a method of directly measuring atmospheric methane concentration based on CW-CRDS,which uses a tunable laser for spectral scanning.On the basis of simultaneously measuring the absorption coefficients of water vapor and carbon dioxide and the extinction coefficients of aerosol particles with various particle sizes in the atmosphere,combined with the wavelength correction method,the accuracy of atmospheric methane measurement without pretreatment in the ambient atmosphere is improved.