应用多光路主动差分光学吸收光谱仪观测大气污染物的空间分布

研制了一套具有4条测量光路的主动差分光学吸收光谱仪(DOAS)系统,以一盏短孤氙灯为4台集成一体的发射/接收望远镜提供光源,可同时发射4条相互独立的测量光路,4台望远镜的角度可分别独立调整以对准不同位置的角反射镜,光路之间的最大发散角可达28°.为测试仪器性能,使4条光路测量同一区域内的NO₂浓度. 对4条光路的测量结果进行相互对比,任意两条光路的相关系数均在0.97以上,测得NO₂的体积分数平均差异小于10^-9, 表明结果具有良好的一致性 关键词： 差分光学吸收光谱 2')" href="#">NO₂ 2')" href="#">SO₂ 大气污染

Observation on the spatial distribution of air pollutants by active multi-axis differential optical absorption spectroscopy

An active 4-axis differential optical absorption spectroscopy system is developed in the project. The system has 4 telescopes integrated together that can simultaneously project and receive 4 independent light beams for measurement. The 4 beams share one xenon short-arc lamp as the light source. Each telescope can be adjusted individually to point to different reflectors. The angle between different beams can be adjusted up to 28°. A test is conducted on the system with four beams setting to measure the concentration of NO₂ in the same area. The comparison shows good consistency between measurement data from different beams: the correlation coefficient (R²) between the data from any two beams is no less than 0.97 and the average difference between different beams is below 1×10^-9. The long-term observations on the vertical distributions of NO₂ and SO₂ around Fudan University reveal the average feature of its daily variation: the concentration of NO₂ shows a variation of double-peak in a day, the 2 peaks occur in the early morning and the evening respectively, while the valleys occur in the afternoon and the wee hours; the layer of 44—66 m has the highest NO₂ concentration, while the layer of 66—88 m the lowest; during the nighttime, inter-layer difference of NO₂ concentration is higher than that during the daytime and can be as high as 17×10^-9; the concentration of SO₂ shows a variation of single-peak in a day, the peak occurs in the forenoon; the vertical distribution of SO₂ is relatively even, with the inter-layer difference below 3×10^-9.