【摘要】 发光二极管（LED）发射光谱窄限制了差分吸收光谱反演波段，难以实现多种气体的同时测量。采用光纤束组合两种紫外LED形成组合式LED宽带光源，应用于DOAS系统实现大气SO₂和O₃的同步探测。光谱分析显示两种LED灯谱在280～295 nm处发生叠加，275～301 nm有明显的灯结构。该灯结构会随着双峰光强比增加而增强，同时向短波方向漂移。实际测量时，外界环境改变会引起两个LED光谱各自独立变化，且二者发射光谱波段内大气消光存在差异。这将导致大气吸收光谱的双峰光强比不断变化，且与灯谱不一致，二者相除难以抵消灯结构。光谱反演结果显示宽带光源灯结构为参考谱参与拟合无法较好地扣除干扰。为扣除测量时LED光谱独立变化对光谱反演的影响，提出采用各LED独立灯结构作为参考谱参与拟合，结果显示SO₂和O₃拟合残差分别由1%、 6‰降低至4‰左右，扣除效果较好。该方法与避开干扰结构相比，拓宽了SO₂和O₃的反演波段，SO₂和O₃吸收峰分别增加了1.75倍和1倍，平均拟合误差分别降低了67.5%和37.3%,测量精度明显提高。SO₂和O₃测量结果与同时段同地区的传统氙灯长光程DOAS系统比较，结果显示二者保持较高一致性，相关性系数R高于95%。结果表明DOAS反演时组合式LED宽带光源灯结构可以通过各LED独立的灯结构来拟合扣除。更多还原

【Abstract】 The narrow emission spectrum of light emitting diode（LED） limits differential optical absorption spectroscopy（DOAS）retrieval range, and it is not easy to realize simultaneous measurement of various gases. In this paper, two kinds of ultraviolet LEDs are combined to form a combined LED broadband light source, which is applied to DOAS to simultaneously detect atmospheric SO₂ and O₃. The spectral analysis shows that their spectrum is superimposed in 280～295 nm and has an obvious lamp structure in 275～301 nm. The structure enhances and drifts to the shortwave direction with the increase of the dual-peak light intensity ratio. During actual measurement, the LED spectrum will change independentlydue to the environmental conditions. Moreover, atmospheric extinction is different in their emission spectral bands. Therefore, the dual-peak light intensity ratio ofthe atmospheric spectrum will change continuously and is inconsistent with the lamp spectrum. It is not easy to offset the lamp structure by dividing the two.The spectrum retrieval results show that the combined lamp structure as a reference spectrum can not fit well with the interference structure. In order to remove the influence of independent LED spectrum changes on spectrum retrieval during measurement, it is proposed to use each LED lamp structure as a reference spectrum to participate in the fitting. The fitting residuals of SO₂ and O₃ are reduced from 1% and 6‰ to about 4‰, respectively, and the interference structure is well removed.Compared with evading interference structure, the retrieval range of SO₂ and O₃ is broadened, and the number of SO₂ and O₃ absorption peaks in the retrieval range is increased by 1.75 and 1 time, respectively. The average fit errors of SO₂ and O₃ are reduced by 67.5% and 37.3% respectively. The measurement accuracy is significantly improved. The measuremens are compared with the SO₂ and O₃ levels measured by the traditional xenon lamp long path DOAS system. The comparison shows excellent agreements with Pearson correlation coefficients（R） of SO₂ and O₃ measurements above 95%. The results demonstrate that the lamp structure of a combined LED broadband light source can be fitted by the independent lamp structure of each LED in DOAS retrieval.更多还原