Advancing air quality modeling through improved urban vegetation characterization and an enhanced understanding of biogenic sesquiterpene emissions

The goal of this master's project has been to improve urban fractional vegetation cover estimates for use in biogenic emissions models through the development of a low-cost and technologically modest technique, and to apply this technique to a case study. Though there are limitations involved in this approach, results of a validation exercise performed as part of this study suggest a high degree of agreement (∼95%) between this technique and a more rigorous/time-intensive method for determining fractional vegetation cover in urban areas. Findings from this study were incorporated into a biogenic emissions model for the Maricopa County Metropolitan area in Arizona, U.S.A., and results suggest significantly lower urban biogenic volatile organic compound emissions than have previously been predicted for the area. An additional focus of this project has been the compilation of a literature review focusing on the environmental controls governing the emission of sesquiterpenes (SQT) by terrestrial vegetation, for the purpose of better characterizing this important class of biogenic volatile organic compounds. This thesis is organized as follows: following a brief introduction (Chapter 1), Chapter 2 presents the results of a case study describing the development, implementation, and results associated with the urban fractional vegetation cover technique that I have developed. Chapter 3 summarizes many of the abiotic and biotic controls governing biogenic SQT emissions in the form of a literature review, and outlines numerous known SQT-emitting plant species as well as the quantities of SQT they have been observed to emit. Both Chapters 2 and 3 are intended to be stand-alone manuscripts for submission and (hopeful) publication in relevant peer-reviewed scholarly journals. Chapter 4 offers some brief concluding remarks based upon the findings presented in this document.