Abstract: Based on the visibility data at atmospheric composition monitoring station of Anshan from June 2010 to May 2011, the relationship between visibility and meteorological elements such as mass concentrations of PM10, PM2.5, PM1.0, wind speed, precipitation intensity and aerosol optical depth (AOD) were analyzed. The results indicate that the monthly average visibility is in an increasing trend after August, reaches a peak in November and then drops significantly and gets the lowest value in February; it is in a substantial increase after March, while it is in a slight decrease in summer. The ratios of PM2.5 to PM10 and PM1.0 to PM10 have a negative correlation with the visibility, namely, the higher the visibility is, the lower two ratios are, and the decreasing trend of PM1.0/PM10 is significant. Thus, it suggests that particles affecting the visibility are mainly fine particles. The trends of the average wind speed and visibility are basically the same, while the trend of average wind is in a negative correlation with those of PM2.5/PM10 and PM1.0/PM10. The average visibility decreases with the increase of precipitation intensity. The average visibility in the days before the precipitation day and after the precipitation day is more than that in the precipitation day, and their change values and change rates increase with the increase of precipitation intensity. It can be seen by the change of the Angstrom exponent that pollutant particles impacting the visibility in Anshan are more stable as a whole. It is a significant negative correlation between visibility and AOD.

Key words: Visibility, PM, Precipitation intensity, Aersol optical depth (AOD)