物理学报2017，Vol.66Issue(9)：81-89,9.DOI:10.7498/aps.66.090704
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 NO2
摘要
Abstract
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 spec-trometer (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 wave-length 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 μm 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 etticiency. 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 optimum acquisition time of 1000 s. Concentrations of NO2 are recorded and compared with data from a long path different optical absorption spectroscopy instrument, and the results show good agreement with each other. The linear correlation coetticient R2 is 0.86 in a slope of 0.92 with an offset of ?0.402 ppb. The IBBCEAS system is deployed on an airborne platform, and the detection limit is 95 ppt (1σ) with a time resolution of 2 s. The profile of tropospheric NO2 by airborne observation is obtained over Shijiazhuang in Northern China. IBBCEAS system in the airborne platform shows good stability.关键词
非相干宽带腔增强吸收光谱/机载/对流层NO2廓线Key words
incoherent broadband cavity enhanced absorption spectrometer/airborne/troposphere NO2profile引用本文复制引用
梁帅西,刘建国,刘文清,秦敏,段俊,方武,李昂,徐晋,卢雪,唐科,谢品华..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[J].物理学报,2017,66(9):81-89,9.基金项目
国家自然科学基金(批准号: 91544104, 41571130023, 61275151)和国家高技术研究发展计划(批准号: 2014AA06A508)资助的 课题.Project supported by the National Natural Science Foundation of China (Grant Nos. 91544104, 41571130023, 61275151)and the National High Technology Research and Development Program of China (Grant No. 2014AA06A508). （批准号: 91544104, 41571130023, 61275151）
