Investigations of Global Chemistry-Climate Interactions and Organic Aerosol Using Atmospheric Modeling

Citation

Pye, Havala Olson Taylor (2011) Investigations of Global Chemistry-Climate Interactions and Organic Aerosol Using Atmospheric Modeling. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/WCT5-RM26. https://resolver.caltech.edu/CaltechTHESIS:08172010-150049831

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Abstract

Aerosol, or particulate matter (PM), is an important component of the atmosphere responsible for negative health impacts, environmental degradation, reductions in visibility, and climate change. In this work, the global chemical transport model, GEOS-Chem, is used as a tool to examine chemistry-climate interactions and organic aerosols.

GEOS-Chem is used to simulate present-day (year 2000) and future (year 2050) sulfate, nitrate, and ammonium aerosols and investigate the potential effects of changes in climate and emissions on global budgets and U.S. air quality. Changes in a number of meteorological parameters, such as temperature and precipitation, are potentially important for aerosols and could lead to increases or decreases in PM concentrations. Although projected changes in sulfate and nitrate precursor emissions favor lower PM concentrations over the U.S., projected increases in ammonia emissions could result in higher nitrate concentrations.

The organic aerosol simulation in GEOS-Chem is updated to include aerosol from primary semivolatile organic compounds (SVOCS), intermediate volatility compounds (IVOCs), NO_x dependent terpene aerosol, and aerosol from isoprene + NO₃ reaction. SVOCs are identified as the largest global source of organic aerosol even though their atmospheric transformation is highly uncertain and emissions are probably underestimated. As a result of significant nighttime terpene emissions, fast reaction of monoterpenes with the nitrate radical, and high aerosol yields from NO₃ oxidation, biogenic hydrocarbons reacting with the nitrate radical are expected to be a major contributor to surface level aerosol concentrations in anthropogenically influenced areas such as the United States. Globally, 69 to 88 Tg/yr of aerosol is predicted to be produced annually, approximately 22 to 24 Tg/yr of which is from biogenic hydrocarbons.

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• Investigations of Global Chemistry-Climate Interactions and Organic Aerosol Using Atmospheric Modeling. (deposited 16 Sep 2010 21:02) [Currently Displayed]

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