Fig. 1. Absorption spectra of some trace gases

Fig. 2. VOCs concentration measured by FTIR in 2018

Fig. 3. FAGE system in a field campaign (upper left is the whole, upper right is the sampling port, lower right is the laser light source part)

Fig. 4. HO_x free radical concentration by FAGE in 2018

Fig. 5. Space-time distribution of particles detected by lidar. (a) Beijing; (b) Baodi; (c) Shijiazhuang; (d) Langfang; (e) Xingtai; (f) Cangzhou; (g) Xinxiang; (h) Jining

Fig. 6. Algae concentration

Fig. 7. Different soil types in the range of 315--320 nm spectrum