Computational Simulation of the Atmospheric Chemistry of Alkanes

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A mechanism for the detailed atmospheric oxidation pathways of alkanes will be developed based on kinetic and mechanistic data determined from carefully designed laboratory chamber studies. Estimates of partitioning of product species between the gas and condensed phases will be made using an existing numerical module. The numerical predictions will be compared with the chamber studies to test parameters that must necessarily be estimated in the numerical modeling exercises. Once a satisfactory numerical mechanism has been developed, appropriate simplifications will be made to allow it to be implemented within a three-dimensional modeling framework. The latter will be applied to a number of real world situations including the South Coast Air Basin (SoCAB) in southern California, New England, the San Joaquin Valley, and St. Louis. A particular aspect of these simulations will be the ability of the model to reproduce the observed levels of secondary organic aerosol (SOA) generated. In each case a number of simulations will be generated to evaluate the hydrocarbon lumping schemes utilized, the impacts of alkane chemistry on SOA formation, and the specific molecular species present in the aerosol phase. Sensitivity to environmental variables such as temperature and humidity will also be examined. It is envisioned that the numerical modeling product of this research can also be used to help design future laboratory studies. This work will lead to improved numerical representations of atmospheric chemical processes which will eventually contribute to better predictions of the impacts of chemical species on air quality. Through better mechanistic understanding of atmospheric chemical processes, more reliable control strategies are possible. Educational aspects of this project include research experiences for undergraduate students and involvement of a female research scientist.