Modeling of Aerosol Chemical and Optical Properties Based on Marine Boundary Layer Measurements During ACE 1

DJ Coffman, PK Quinn, and DS Covert (NOAA/PMEL, Seattle, WA 98115; 206-526-6892; email:

Goals of the first Aerosol Characterization Experiment (ACE 1) include 1) using closure experiments to reduce uncertainties associated with the measurement and calculation of aerosol chemical, physical, and optical properties and 2) determining the effect of aerosol chemical and physical properties on aerosol optical properties in a remote marine atmosphere. Both of these goals have been addressed through the development of chemical and optical models of the aerosol which are based on measured aerosol chemical mass size distributions and number size distributions. The aerosol measurements serving as model input data were made onboard the NOAA ship Discoverer. The chemical model, which assumes thermodynamic equilibrium, is designed to calculate the aerosol density and refractive index as a function of particle size. This information is then used in an optical model to calculate the scattering and backscattering by the aerosol as a whole and by the non-seasalt sulfate and seasalt aerosol components. Details of the model calculations will be given and results will be presented. These results will include aerosol density and refractive index as a function of size for different air mass regimes along with the corresponding non-seasalt sulfate and seasalt aerosol component scattering and backscattering coefficients. In addition, calculated scattering and backscattering coefficients for the aerosol as a whole will be compared to those measured with an integrating nephelometer.