Statistics of aerosol extinction coefficient profiles and optical depth using lidar measurement over Lanzhou, China since 2005-2008

The aerosol extinction coefficient profiles and optical depth over Lanzhou in China were observed under no precipitation and dust free condition using the micropulse lidar CE370-2 from September 2005 to July 2008. The statistics of the variations of monthly average aerosol optical depth (AOD) and daily average AOD, frequency distribution of daily average AOD, and the seasonal variation of aerosol vertical distribution were analyzed based on the observation data. The results showed that the daily average AOD of Main Observatory and City Observatory was 87.8% and 78.2% ranged below 0.4 respectively with similar frequency distribution patterns. The AOD in autumn and winter were larger than that in spring and summer, and AOD in suburb was in certain extent smaller than that in city of Lanzhou. Aerosol existed in the layer below 4 km, and its extinction coefficient decreased with increasing of height.

► Lidar observation of aerosol was carried out in Lanzhou, China. ► Cloud discrimination was applied in lidar retrieval algorithm. ► Aerosol existed below 4 km, and most of AOD were smaller than 0.4. ► AOD in autumn and winter were larger than in spring and summer. ► AOD in city was larger than in suburb, their frequency distributions were similar.