HR: 1340h
AN: A33D-1557    [Abstracts]
TI: Calculations of the Chemical Composition of the Sacramento Urban Plume
AU: * Perez, I M
EM: imperez@berkeley.edu
AF: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, United States
AU: Cohen, R C
EM: cohen@cchem.berkeley.edu
AF: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, United States
AB: Recent measurements within the Sacramento urban plume have provided a detailed benchmark for testing our understanding of tropospheric chemistry. Available measurements include a wide suite of VOC and BVOC, NO_y,i, O₃, and CO at the source and at a receptor site five hours downwind. Further, the meteorology in the region is extremely regular making it possible to evaluate effects of temperature or day-of-week patterns with a single season of measurements. Here we use a Lagrangian model representing transport from Granite Bay, a suburb at the eastern edge of Sacramento, to the University of California Blodgett Forest Research Station (UC- BFRS). The model represents chemistry based on MCM v3.1 along with mixing and dilution. The model is initiated with concentrations of NO_x, peroxynitrates, alkyl and multifunctional nitrates, HNO₃, VOCs and O₃ based on measurements at the edge of the Sacramento suburban sprawl east of the city. Biogenic VOC emissions throughout the transect are included. The outputs of the model are compared with ozone measurements at Cool three hours downwind, and detailed measurements of VOC, the speciation of the nitrogen oxides and O₃ at UC-BFRS, 5 hours downwind of the Sacramento suburbs in the center of the Mountain counties air basin. The comparisons indicate 1) O₃ at UC-BFRS and Cool is largely driven by the combination of rural biogenic emissions and urban NO_x emissions, 2) that OH is underestimated by standard chemical models, 3) that partitioning of NO_y is dominated by peroxy and other multifunctional nitrates that are not represented in standard chemical models and which have a strong impact on how much NO₂ is available for ozone production. We also investigate model representation of temperature and weekend/weekday effects.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting