Measurements of the Aerosol Light-Scattering Coefficient at Ambient and 85% Relative Humidity on the ONR Pelican During ACE-2

Associated with the renewal of funding in 2002, and the successful attainment of several of the studies early goals, the current goals of the study have been modified and now include the interaction of marine aerosols with marine boundary layer (MBL) clouds. New goals include: 1) assessment of the relative impacts of purely meteorological and aerosol factors on cloud albedo, 2) determination of the impact of very large CCN on cloud albedo, 3) assessment of the impact of cloud processing on aerosol light scattering, and 4) explore, observationally, the impact of organics on CCN activation in MBL clouds. Additionally, the more general goal of assessing the impact of organics on aerosol hygroscopicity has been retained and, indeed, expanded to include an element of aerosol-cloud interaction. On the other hand, we have curtailed our exploration of the hygroscopicity-organic composition relationship using the POEM code since our work suggests that it is premature to attempt this until measurement of the aerosol size distribution in the super-micron size range is better established.