Impacts of the Biosphere on Global Tropospheric Chemistry and Climate

This research effort will investigate impacts of land use change on atmospheric composition with a primary focus on ozone (O3) and secondary organic aerosol (SOA) from pre-industrial (1850) to future conditions (2100). The responses of biogenic emissions, tropospheric composition, deposition, and feedbacks to changes in land use, vegetation, and anthropogenic emissions will be simulated with fully coupled biosphere-atmosphere model system (NCAR's Community Earth System Model, CESM). The current-generation scheme for SOA processing will be expanded to treat atmospheric aging and resulting functionalization and fragmentation. The new scheme will be tested against field observations and sensitivities to various poorly constrained factors will be quantified. The impacts of O3 damage to vegetation will be incorporated into the land model and the potential direct impacts of O3 on biogenic volatile organic compound (BVOC) emissions will be evaluated. Analysis of the impacts of historical land use change will focus primarily on the southeastern United States (US) where temperature trends have been tentatively attributed to changing vegetation and SOA. This part of the investigation will draw on results of the Southern Oxidant and Aerosol Study (SOAS) field campaign should it be funded. This effort will help resolve outstanding factors that control tropospheric concentrations of O3 and SOA.

The research will address social- and policy-related issues relevant to understanding major drivers of future air quality and associated impacts on public health. In addition, this effort will develop a next-generation scheme that explicitly evaluates the atmospheric aging of SOA for general application in global models. The research will support and contribute to the education of a graduate student and postdoctoral fellow. A graduate-level class will be developed to further explore biosphere-atmosphere interactions in the classroom setting. Finally, the research activities will be tied to an outreach project through the Boston Museum of Science in which undergraduate summer students will work on the museum's Current Science and Technology exhibits to bring atmospheric chemistry research to the public.