9625718 Pilinis Atmospheric aerosol particles consist of solid and liquid multicomponent phases. Some aerosol chemical constituents are sulfate, nitrate, ammonium, sodium, chloride, water, soot, organic matter, and dust. These species are not distributed evenly among particles of different sizes. As a result, the physical, chemical, and optical properties of particles of various sizes may differ. The nonhomogeneous distribution of chemical species within aerosol particles of different sizes are factors which currently introduce uncertainty into models which attempt to quantify direct forcing effects by atmospheric aerosols. Research conducted under this award will support the development of an aerosol model which accounts for the major processes that shape the size distribution and composition of atmospheric particles. Aerosol optical properties, including single scattering albedo, phase functions, asymmetry factors and upscatter fraction will be calculated for use in column radiative transfer models. The radiative transfer models will be used to calculate the direct aerosol forcing over shortwave and longwave radiation fields. The PI will evaluate the model by comparing model results with measured aerosol concentrations and aerosol optical properties. Once tested, the model will be used to estimate the effects of uncertainties in model input parameters to direct forcing due to aerosols. *** ATM-9625718
