Delineation of biogenic S and SO2 in the growth of sulfate aerosols by isotope apportionment

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Weather and climate predictions lack fundamental information to link nanoscale aerosols, which are suspended liquids or solids, to precipitation processes that would allow models to better predict rain and snowfall at local and global scales. Models for weather and climate need to incorporate microphysical and chemical details about the atmosphere, and characteristics of aerosols, that influence the initiation of precipitation. This proposal aims to bridge a gap in our knowledge of processes governing precipitation by identifying characteristics of aerosols responsible for initiating and sustaining rain and snowfall.***Aerosol sulfate is a key piece of the puzzle and its source and role in precipitation formation and cloud characteristics are essential to understand and improve rainfall prediction. Aerosol sulfate is the dominant atmospheric compound contributing to aerosols that lead to cloud formation, and it affects how long clouds last and how bright they are. Both of these properties of clouds in turn influence the scattering of incident solar radiation and therefore, are important components in the radiation budget and climate. Of course clouds are also an important factor in weather events and precipitation.***Emissions and processes leading to aerosol and cloud formation are fundamental: the ability of aerosols to absorb water, coagulate and grow, parameters that affect the lifetime of sulfur compounds and cloud and precipitation properties, differs substantially, depending on the source of the aerosol. Reduced sulfur gases produced in large quantity over the remote marine atmosphere from biogenic emissions are considered to be a major factor contributing to sulfate aerosols and cloud formation in remote environments. Cloud and precipitation formation in the Arctic are particularly important to understand: as the ocean warms and ice cover declines, air-sea exchange of biogenic gases that participate in short and longwave radiation feedbacks, increase. Identifying the linkages between micro (aerosols) and macro-scale (clouds, sea ice) properties affecting cloud formation, persistence and the likelihood of precipitation is essential to improving our ability to predict the strength and magnitude of climate variation and local meteorological precipitation extremes. ********