Experimental and Modeling Studies of Processes which govern the Marine Boundary Layer Aerosol.

Increasing awareness of the potential effects of aerosols on radiative transfer, both directly and indirectly through changes in cloud albedo, has thrust aerosols to the forefront of the climate-change debate. Aerosols are also of increasing importance because of their effect on satellite remote sensing and DoD electro-optical system performance. To predict aerosol effects it is necessary to understand and model the source, sink and transformation processes which govern the dynamics of the aerosol size and composition distributions. It is difficult to identify isolate, and measure such quantities as rate constants in the real atmosphere. Under the sponsorship of the NOPP, a study of aerosol processes, either known or thought to be important in the marine environment, was undertaken in Calspan's 600 cubic meter chamber. Seven organizations participated. The aerosol processes studied were: (1) the uptake of SO2 by sea-salt aerosol, (2) the change in the aerosol size distribution during cloud processing, (3) nucleation of aerosol particles from gas-phase reaction products, and (4) effect of organic material on cloud formation. Dynamic aerosol models which include these and other relevant processes are under development. The importance of the various physical and chemical processes on determining the evolution of the aerosol size distribution in the (atmospheric) marine boundary layer will be discusses as will some of the results from the NOPP Aerosol Processes Experiment and their impact on future models.