title: A Multi-Year Aerosol Characterization for the Greater Tehran Area Using Satellite, Surface, and Modeling Data.
abstract: This study reports a multi-year (2000-2009) aerosol characterization for metropolitan Tehran and surrounding areas using multiple datasets (Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR), Total Ozone Mapping Spectrometer (TOMS), Goddard Ozone Chemistry Aerosol Radiation and Transport (GOCART), and surface and upper air data from local stations). Monthly trends in aerosol characteristics are examined in the context of the local meteorology, regional and local emission sources, and air mass back-trajectory data. Dust strongly affects the region during the late spring and summer months (May-August) when aerosol optical depth (AOD) is at its peak and precipitation accumulation is at a minimum. In addition, the peak AOD that occurs in July is further enhanced by a substantial number of seasonal wildfires in upwind regions. Conversely, AOD is at a minimum during winter; however, reduced mixing heights and a stagnant lower atmosphere trap local aerosol emissions near the surface and lead to significant reductions in visibility within Tehran. The unique meteorology and topographic setting makes wintertime visibility and surface aerosol concentrations particularly sensitive to local anthropogenic sources and is evident in the noteworthy improvement in visibility observed on weekends. Scavenging of aerosol due to precipitation is evident during the winter when aconsistent increase in surface visibility and concurrent decrease in AOD is observed in the days after rain compared with the days immediately before rain.
authors.affiliation: Department of Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Ewan
authors.initials: E
authors.lastname: Crosbie
authors.affiliation: Department of Atmospheric Sciences, University of Arizona, Tucson, AZ 85721, USA ; Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Armin
authors.initials: A
authors.lastname: Sorooshian
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Negar Abolhassani
authors.initials: NA
authors.lastname: Monfared
authors.affiliation: Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Taylor
authors.initials: T
authors.lastname: Shingler
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, Irvine, CA 92697, USA.
authors.forename: Omid
authors.initials: O
authors.lastname: Esmaili
keywords: Iran; MISR; MODIS; aerosol; visibility; wet scavenging
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