Abstract

A more detailed study to identify types of aerosol can help to better understand the sources and effects of aerosols. In this paper, a number of optical properties of aerosols have been investigated for each season to classify aerosol types during 2010-2014 over Zanjan, a city in Iran. Using AERosol RObotic NETwork (AERONET) data, aerosols were classified applying multiple clustering techniques. Both fine and coarse mode particles were observed in seasonal average of Aerosol Volume Size Distribution (AVSD). Single Scattering Albedo (SSA) variations reveal the presence of scattring aerosols like dust in all seasons especially in the spring and summer. Also it illustrates the dominance of absorbing type aerosols in the winter. The maximum value of the phase function was detected in the summer and in small scattering angle which can be due to the presence of coarse mode particles. In addition, low values of phase function at angles bigger than 10 are due to the presence of fine mode particles. The scatter plot of Aerosol Optical Depth (AOD) versus Angstrom Exponent (AE) is one of the most effective methods to find aerosol types. The graph shows presence of dust in the spring and summer in the atmosphere of Zanjan. Also the presence of BC and Industrial aerosols occur in all seasons. another method consisting of plotting SSA versus Extinction Angstrom Exponent (EAE), illustrate that dust is abundant in the spring and summer. Moreover, in the falls and winters smoke and mixed aerosols are plentiful. However, industrial aerosols and polluted dust are permanent in all seasons. Finally, The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) aerosol subtype profiles show the dominance of dust and polluted dust in the spring and summer. Although in the fall and winter polluted dust and smoke exist in the area, too. Keywords: AERONET; Angstrom Exponent; Aerosol Optical Depth; Single Scattering Albedo; Aerosol Volume Size Distribution; Phase function.