Fig. 1. Schematic of combined detection using lidar and nephelometer

Fig. 2. Principle of coherent Doppler wind lidar

Fig. 3. Time-series comparison of Lidar backscatter intensity and horizontal visibility

Fig. 4. Fitting of horizontal visibility and lidar backscatter intensity

Fig. 5. Correlation plot of the results before and after calculating the residuals of estimated horizontal visibility and measured visibility from September 9 to October 1

Fig. 6. Relationship between visibility and lidar backscatter intensity under different relative humidity conditions

Fig. 7. Correlation graph between estimated horizontal visibility and measured visibility residual from October 2 to October 6

Fig. 8. The two models estimate the visibility timing diagram at 50 m and 100 m altitudes

Fig. 9. Visibility estimation errors at 50 m and 100 m compared with measured values

Fig. 10. Correlation plot of the results before and after calculating the residuals of estimated horizontal visibility and measuredvisibility，classified by humidity，from October 2 to October 6