HR: 09:15h
AN: B31C-06    [Abstracts]
TI: Understanding urban atmospheric CO$_{2}$: Challenges and Opportunities
AU: * Pataki, D E
EM: dpataki@uci.edu
AF: UC Irvine, Dept. of Earth System Science, Irvine, CA 92697-3100 United States
AU: Ehleringer, J R
EM: ehleringer@biology.utah.edu
AF: University of Utah, Dept. of Biology, Salt Lake City, UT 84112 United States
AU: Forster, C B
EM: forster@arch.utah.edu
AF: University of Utah, College of Architecture and Planning, Salt Lake City, UT 84112
AU: Klewicki, J C
EM: klewicki@mech.utah.edu
AF: University of Utah, Dept. of Mechanical Engineering, Salt Lake City, UT 84112 United States
AU: Pardyjak, E R
EM: pardyjak@eng.utah.edu
AF: University of Utah, Dept. of Mechanical Engineering, Salt Lake City, UT 84112 United States
AU: Peterson, R E
EM: rpeterson@eng.utah.edu
AF: University of Utah, Dept. of Chemical and Fuels Engineering, Salt Lake City, UT 84112 United States
AU: Steenburgh, W J
EM: jimsteen@met.utah.edu
AF: University of Utah, Dept. of Meteorology, Salt Lake City, UT 84112 United States
AU: Tyler, B J
EM: bonniet@eng.utah.edu
AF: University of Utah, Dept. of Chemical and Fuels Engineering, Salt Lake City, UT 84112 United States
AB: Many studies have shown that atmospheric CO$_{2}$ concentrations are elevated far above ambient levels in cities due to strong local sources. Measurements of urban atmospheric CO2 mixing ratio, its isotopic composition, and its sources and sinks provide opportunities to understand the local carbon cycle and biogeochemistry of cities, which is increasingly important in studies of regional and global change as well as urban sustainability and planning. In an ongoing project in the Salt Lake Valley, Utah, measurements of CO$_{2}$ mixing ratio and the isotopic composition of CO$_{2}$ have shown that vehicle exhaust significantly elevates CO$_{2}$ mixing ratios above ambient, particularly in the wintertime when temperature inversions create stable conditions. Natural gas combustion also makes a large contribution to CO$_{2}$ mixing ratio in the winter, but becomes negligible in the summer. However, the urban "forest" in the Salt Lake Valley plays an active role in influencing CO$_{2}$ mixing ratio during the spring, summer, and fall through photosynthesis and respiration. Atmospheric CO$_{2}$ measurements in the Salt Lake Valley are also useful in that they correlate with air pollutants such as aerosols, particularly in the wintertime when CO$_{2}$ sources are dominated by combustion. The relationship between CO$_{2}$ mixing ratio and other pollutants varies as a function of fuel source (natural gas versus gasoline) and meteorological variables that affect atmospheric chemistry of reactive compounds; therefore, these relationships provide additional information about sources and sinks for atmospheric constituents. Finally, CO$_{2}$ is a stable atmospheric tracer in that it does not undergo chemical transformations in the atmosphere. Measurements in the Salt Lake Valley showed that the temporal and spatial distribution of CO$_{2}$ in the wintertime may provide information about atmospheric transport during complex cold pools events if mixing ratios are monitored at multiple locations. These results suggest that studies of the processes and controls on land-atmosphere exchange of CO$_{2}$ are warranted in human-dominated, urban systems as well as more "pristine" natural ecosystems.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
DE: 0345 Pollution--urban and regional (0305)
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting