Parameterization of Aerosol Size of Organic and Secondary Inorganic Aerosol for Efficient Representation of Global Aerosol Optical Properties

HAIHUI ZHU, Randall Martin, Betty Croft, Shixian Zhai, Liam Bindle, Inderjeet Singh, Jeffrey R. Pierce, Chi Li, Deepangsu Chatterjee, Washington University in St. Louis

     Abstract Number: 64
     Working Group: Aerosol Physical Chemistry and Microphysics

Abstract
Accurate representation of aerosol optical properties is essential for modeling and remote sensing of atmospheric aerosols. Although aerosol optical properties are strongly influenced by the aerosol size distribution, atmospheric models seldom use an aerosol microphysics scheme because of the computational demand. Computationally efficient parameterizations are needed. In this study, aircraft measurements over the United States (DISCOVER-AQ) and South Korea (KORUS-AQ), are interpreted with a global chemical transport model (GEOS-Chem) to investigate the variation in aerosol size when organic matter (OM) and sulfate-nitrate-ammonium (SNA) are the dominant components. Measurements exhibit a strong correlation (r = 0.82) between aerosol size and the sum of OM and SNA mass (M_SNAOM). A global microphysical model (GEOS-Chem-TOMAS) simulation indicates that M_SNAOM, and the ratio between the two components (OM/SNA) are the major indicators for SNA and OM aerosol size. A parameterization of effective radius (R_eff) for SNA and OM aerosol is proposed, which is highly consistent with GEOS-Chem-TOMAS simulated Reff (R² = 0.72, slope = 0.99). Thus, this parameterization offers a computationally efficient method to represent aerosol size in atmospheric models.