9610051 Rood The primary objective of this project is to provide reliable experimental and modeled results describing the ambient aerosols' light scattering properties and composition. This project is part of the North Atlantic Regional Aerosol Characterization Experiment (ACE-2) which will be conducted in June and July, 1997, over the subtropical Northeastern Atlantic Ocean as an international collaborative effort. The main objectives of ACE-2 are to study the properties of atmospheric aerosols relevant to radiative forcing and climate using aircraft, ship-board, and ground-based measurements. Measurements will be performed with in-situ rapid response aerosol sampling instrumentation for a six-week period at a ground-based station at Sagres, Portugal. Aerosol light scattering properties will be obtained with controlled relative humidity nephelometry performed by University of Illinois personnel. Aerosol particle composition, aerosol particle size distribution, and hygroscopic growth measurements will be performed by collaborators from the Desert Research Institute, University of Washington, Seattle, and Institute of Tropospheric Research, Leipzig. Further analyses of the in-situ particle measurements and aerosol composition will be performed with recently developed thermodynamic models in collaboration with Dr. C. Pilinis, University of Miami. Measurements and models will be integrated to describe the ambient aerosol's light scattering coefficients and their dependence on controlled relative humidity, wavelength of light, direction of light scattered, and particle composition.
