HR: 0800h
AN: A31B-0827    [Abstracts]
TI: Evolution of Particulates and Aerosol Direct Radiative Forcing in the vicinity of Mexico City
AU: * Fast, J D
EM: jerome.fast@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, K9-30, Richland, WA 99352 United States
AU: Barnard, J C
EM: james.barnard@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, K9-30, Richland, WA 99352 United States
AB: During March of 2006, several field campaigns as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) will be conducted in central Mexico to better understand the evolution of ozone and particulates originating from anthropogenic emissions in Mexico City. Several research aircraft will be sampling over the city and up to several hundred kilometers downwind of city and two surface measurements sites will be located ~10 and ~40 kilometers northeast of Mexico City. In this study, the chemistry version of the Weather Research and Forecasting model, WRF-chem, is used as a pre-field campaign tool to better understand the transport pathways of particulates and aerosol direct radiative forcing downwind of Mexico City. The aerosol-radiative feedback processes implemented in WRF-chem employ Mie theory and the predicted size distribution of aerosol number and composition to determine the aerosol optical depth, single scattering albedo, and asymmetry factor used in the shortwave radiation scheme. Simulations that employed a 2 km grid spacing over central Mexico were conducted for periods of March 1997 and April 2003 when meteorological, radiation, and particulate measurements were collected in Mexico City during prior field campaigns. The predicted transport pathways of particulates associated with different synoptic conditions, particularly for those cases with transport northeast of Mexico City, are put in the context of the proposed aircraft sampling strategies for U.S. DOE's Megacity Aerosol Experiment in Mexico City (MAX-Mex) 2006 field campaign. The predicted aerosol optical depth and shortwave radiation are compared to measured values in the city and the spatial distribution of aerosol direct radiative forcing over and downwind of the city is quantified.
UR: http://www.pnl.gov/atmos_sciences/Jdf/wrfchem.html
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005