Studying the temporal and vertical distributions of dust aerosols for the atmosphere of Zanjan

Level 2 data of Caliop space-borne lidar is used during 2006-2017 for 144 night overpass of Calipso satellite over Zanjan. It is seen that aerosol optical depth is increased during spring and summer. For example, maximum/minimum monthly-averaged AOD is 0.36/0.06 for August/December. The particulate depolarization ratio of data shows that dust is the dominant aerosol in the atmosphere of Zanjan. There is no relationship between AOD and surface wind speed. Also, based on the results of HYSPLIT backward trajectory model, the Tigris-Euphrates basin is the main dust source of the atmosphere of Zanjan. The parameter of horizontal visibility is not sharply decreased during dust events and it is accompanied by higher altitudes of recorded dust layers and therefore, one can conclude that dust particles have mainly external sources