HR: 17:00h
AN: A24A-05    [Abstracts]
TI: Impact of biomass burning and biogenic emission on the evolution of Mexico City's air pollution plume
AU: * Tie, X
EM: xxtie@ucar.edu
AF: ACD/NCAR, P O Box 300, Boulder, CO 80303 United States
AU: Madronich, S
EM: sasha@ucar.edu
AF: ACD/NCAR, P O Box 300, Boulder, CO 80303 United States
AB: We use a newly developed regional chemical/transport model (WRF-Chem) to study the air pollutions in mega cities and their effect on surrounding areas. The model is based on a state of the art regional dynamical/transport model, the Weather Research Forecasting (WRF) model developed at NCAR in collaboration with other institutions. The model includes on-line calculation of dynamical inputs (winds, temperature, boundary layer, clouds etc.), transport (advective, diffusive, and convective), dry and wet deposition, gas phase chemistry, aerosol formation, radiation and photolysis rates, and surface emissions. The horizontal resolution of the model is flexible, ranging from a few km to several hundred km. In this study, we use a 6x6 km resolution located around Mexico City to study the air pollution inside the city and the impact of biomass burning and biogenic emissions on the chemical oxidants and ozone chemistry in the urban outflow plume. Mexico City is a highly polluted city, with NOx (NO2 + NO) and hydrocarbons (HCs) emissions resulting in locally high ozone concentrations (150-200 ppb peak values). The highly polluted city plume interacts strongly with the reactive emissions of the surrounding areas, esp. from vegetation and biomass burning. Biomass burning activity is highest in spring, and emits large amounts of NOx and CO. Vegetation emits a significant amount of HCs such as isoprene. After the city plume is transported into the surrounding areas, the polluted air is mixed with additional NOx and HCs emitted by biomass burning and vegetation. As a result, the ozone concentrations in the plume is significantly enhanced (20-30 %) at the far-end plume due to the NO emission of biomass burning, and is increased by 30-40 % at the near-end plume due to the biogenic emission of hydrocarbons.
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting