Fig. 1. A systematic framework of lidar

Fig. 2. Flow chart for estimating PM_2.5 and PM₁₀ mass concentrations with GRNN based on extinction coefficient and meteorological elements

Fig. 3. GRNN structure

Fig. 4. Result of four fold cross validation

Fig. 5. Validation of GRNN model. (a) Comparison between estimated and measured mass concentrations of PM_2.5 and PM₁₀; (b) correlation between estimated and measured mass concentration of PM_2.5; (c) correlation between estimated and measured mass concentration of PM₁₀

Fig. 6. Lidar observation location distribution map (dot A is the locations of polarimetric lidar for horizontal scanning)

Fig. 7. Average PM_2.5 mass concentration estimation under horizontal scanning in different periods on May 9, 2021

Fig. 8. Average PM₁₀ mass concentration estimation under horizontal scanning in different periods on May 9, 2021

Fig. 9. Change in hourly averages of PM_2.5 mass concentration, PM₁₀ mass concentration, temperature, relative humidity, wind direction and speed, and surface pressure in Pukou District on May 9, 2021

Fig. 10. Comparison between GRNN model estimated mass concentrations of PM_2.5 or PM₁₀ and measured values