大气污染物垂直廓线扫描差分吸收光谱方法研究

Study on Scanning Differential Optical Absorption Spectroscopy for Monitoring Vertical Profiles of Atmospheric Pollutant

差分光学吸收光谱法(DOAS)已经成为测量大气痕量气体含量的常用方法,该方法灵敏度高,可同时监测多种大气痕量气体。提出了应用差分吸收光谱方法监测大气痕量气体垂直分布,结合放置数套角反射器的近地层高塔,研制出扫描长光程差分吸收光谱(扫描LP-DOAS)系统。应用此系统于2007年夏季对北京城市重要大气污染物NO_2的垂直分布进行了外场监测,准确获得了NO_2沿各光路的积分浓度,确定了系统在各光路的检测限和系统总的测量误差。基于垂直廓线模型,成功反演了NO_2的垂直廓线和垂直梯度。研究结果表明扫描LP-DOAS技术监测城市大气近地层痕量气体垂直分布的可行性。

Differential optical absorption spectroscopy （DOAS） has become a widely used simulataneous detection of atmospheric trace gases with low detection limits. DOAS method method for the is proposed for monitoring the vertical distribution of atmospheric trace gases . Based on DOAS technique and a high tower with angle-reflectors, the scanning long-path（LP）-DOAS system is developed . Field observations of vertical distribution of NO2 was performed by using the scanning LP-DOAS system in the summer of 2007. The NO2 concentrations along three light paths were accurately measured, and the detection limits along three light paths and the total systematic error were obtained. The vertical profiles and vertical gradient of NO2 were successfully retrieved by using the vertical profiles model. The results indicate that the scanning LP-DOAS system can perform vertical observations of trace gases in the urban boundary layer.