HR: 11:30h
AN: A32A-04 INVITED     [Abstracts]
TI: Chemical Processing Within And Above Forest Canopies
AU: * Fuentes, J D
EM: jf6s@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, 291 McCormick Road, Charlottesville, VA 22904 United States
AU: Wang, D
EM: Daniel.Wang@ec.gc.ca
AF: Environment Canada, Environmental Technology Center, 335 River Road South, Ottawa, ONT K1A 0H3 Canada
AU: Stockwell, W R
EM: William.Stockwell@dri.edu
AF: Howard University, 525 College Street, NW, Washington, DC 20059 United States
AB: Forests not only modify the disposition of actinic irradiance that governs photochemical processes inside canopies but also act as effective sinks and sources of reactive chemical species. In regions such as eastern North America, for example, forests emit a plethora of reactive hydrocarbons whose fluxes often exceed the anthropogenic emissions. In this presentation, the degree of chemical processing inside and just above forest canopies is reviewed for selected forest ecosystems under the influence of different regimes of nitrogen oxides. In situ gas flux measurements made within and above forest canopies will be presented and discussed. In addition, the key elements of a new one-dimensional photochemical model will be presented. The model includes an updated photochemical mechanism to investigate oxidant formation and estimate aerosol yields from hydrocarbon photooxidation processes taking place in the atmospheric column extending from the surface to the top of the convective boundary layer. Results from both field and theoretical studies indicate that substantial chemical transformation of reactive hydrocarbon species can occur within forest canopies. For instance, for hydrocarbons such as sesquiterpenes up to 50 percent of the locally emitted gases can react in the forest canopy during summertime daytime conditions. The actual amounts of chemical processing within forests depend on plant architecture, levels of atmospheric turbulence, and prevailing oxidant levels.
DE: 1610 Atmosphere (0315, 0325)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 3307 Boundary layer processes
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 3379 Turbulence (4490)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005