Fig. 1. Distribution and classification of observation sites

Fig. 2. Variations of PM_2.5 (a), O₃ (b), temperature (c), pressure (d), wind speed (e) and relative humidity(f) during the monitoring period (April 16-22, 2018)

Fig. 3. Statistics of times of exceeding the standard of hourly ozone mass concentration value

Fig. 4. Pollution status at environmental monitoring stations during 16-22 April, 2018

Fig. 5. Meteorology and ground observation map during 18-21 April, 2018

Fig. 6. [in Chinese]

Fig. 7. Mean profiles of optical parameters at 02:11 on 19th April, 2018. (a) Extinction coefficient; (b) backscattering coefficient;(c) depolarization ratio; (d) color ratio

Fig. 8. Aerosol distribution at 12:51 on 19th April, 2018

Fig. 9. Mean profiles of optical parameters at 12:51 on 19th April, 2018. (a) Extinction coefficient; (b) backscattering coefficient;(c) depolarization ratio; (d) color ratio

Fig. 10. 24 h HYSPLIT backward trajectory. (a) 02:00 a.m. on the 19th; (b) 13:00 p.m. on the 19th

Fig. 11. Relationship between the hourly average mass concentration of PM_2.5 and wind direction (a), ozone and wind direction (b)