机载腔增强吸收光谱系统应用于大气NO2空间高时间分辨率测量  

Airborne cavity enhanced absorption spectroscopy for high time resolution measurements of atmospheric NO_2

作　　者：梁帅西 秦敏[1] 段俊[1] 方武[1] 李昂[1] 徐晋[1] 卢雪[1,2] 唐科[1,2] 谢品华[1,2,3] 刘建国[1,2,3] 刘文清[1,2,3] 

机构地区：[1]中国科学院合肥物质科学研究院,中国科学院安徽光学精密机械研究所,环境光学与技术重点实验室,合肥230031 [2]中国科学技术大学,合肥230026 [3]中国科学院区域大气环境研究卓越创新中心,厦门361021

出　　处：《物理学报》2017年第9期74-81,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:91544104,41571130023,61275151);国家高技术研究发展计划(批准号:2014AA06A508)资助的课题~~

摘　　要：介绍了一套用于机载平台测量的非相干宽带腔增强吸收光谱(IBBCEAS)系统,并应用于实际大气NO_2空间分布的高时间分辨率观测.为满足机载测量中对时间分辨率的需求,系统采用离轴抛物面镜代替消色差透镜提高光学耦合效率;并运用Allan方差,对系统性能进行了分析.通过腔增强吸收光谱系统与长光程吸收光谱系统对实际大气NO_2的对比测试,两者线性相关系数R^2达到0.86.将IBBCEAS系统应用于机载平台,在时间分辨率为2 s的情况下,探测限达到95 ppt(1σ).通过机载观测,获得了华北地区石家庄等地上空对流层大气NO_2的廓线信息.Nitrogen dioxide （NO2） is an important trace gas in the troposphere and plays a vital role in many aspects of the chemistry of the atmosphere. Accurate measurement of NO2 is the primary step to understand its role in atmospheric chemistry and to establish effective pollution prevention policies. Relatively few measurements of the NO2 profile in troposphere by using point-type instruments with high temporal resolution have been carried out in China. Due to the relatively poor measurement environment on airborne platform, the measurement system requires good anti-vibration ability, stability and environmental adaptability. A home-built incoherent broadband cavity enhanced absorption spectrometer （IBBCEAS） on the airborne platform is presented in this paper, and applied to high temporal resolution observations of the actual atmospheric NO2 spatial distribution. According to the strong absorption of NO2 in a wavelength range from 449 nm to 470 nm, we choose a high=power 457 nm light-emitting diode （LED） as a light source. A Peltier is used to control LED temperature and to stabilize the LED temperature at （20 ± 0.1）℃. The pure PFA material optical cavity and sampling tube are used to reduce wall loss. And we choose the highly reflecting mirrors （reflectivity R 〉 0.9999@440-450 nm） to improve the effective optical path. A 2 pm filter is used at the inlet of instru- ment to remove most of the particulate matter in the sample flows, which reduce the effect of particulate matter on the effective path length. In order to meet the requirement for time resolution in airborne measurement, we use an off-axis paraboloic mirror instead of an achromatic lens to improve the optical coupling efficiency. The reflectivity of the highly reflecting mirror is calibrated by the difference in Rayleigh scattering between He and N2. And the optimum averaging time of the IBBCEAS instrument is confirmed to be 1000 s by the Allan variance analysis. Detection limit （1σ） of 10 ppt for NO2 is achieved with an optimu

关 键 词：非相干宽带腔增强吸收光谱 机载 对流层NO2廓线 

分 类 号：X87[环境科学与工程—环境工程] TH74[机械工程—光学工程]