Dynamic Biogenic Emissions for the Marine Background Aerosol

Tuesday, May 13, 2014 - 07:00
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The ocean transfers numerous gaseous and condensed precursors into the global aerosol system, influencing boundary layer reflectivity over a majority of the planetary surface. The most variable and active substances involved are of biotic origin, including byproduct gases of the marine organosulfur cycle and carbon chain macromolecules within the detrital organic pool. Dimethyl sulfide, proteins, polysaccharides, lipids, humics and many permutations from within this list are all intimately involved. A unique program will be described which cuts across the DOE systems modeling community and undertakes global scale simulation for the collective marine aerosol source material. We seek through inter-laboratory collaborations to represent chemical oceanographic and atmospheric science points of view simultaneously. Marine-to-troposphere biogeochemical interactivity is thus built into our approach, so that climate feedbacks and uncertainties may be assessed as they are manifested through the aerosol direct and indirect effects. We construct a unified model for the organic metabolism of phytoplankton and heterotrophic bacteria, then superimpose the resulting chemical resolution onto distributions of the global dissolved organic matter. Individual compound volatilities and surfactant properties are estimated based on laboratory physical chemistry studies, and speciated fluxes into the atmosphere are computed for wind and bubble driven transfer. We are now closing coupled loops into the chemistry of the modal aerosol, for dimethyl sulfide and the dominant classes of biomacromolecule. Strategies and early results from our effort will be outlined.

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