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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D21305, doi:10.1029/2005JD006721, 2006

Evolution of ozone, particulates, and aerosol direct radiative forcing in the vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model

Jerome D. Fast

Pacific Northwest National Laboratory, Richland, Washington, USA


William I. Gustafson Jr.

Pacific Northwest National Laboratory, Richland, Washington, USA


Richard C. Easter

Pacific Northwest National Laboratory, Richland, Washington, USA


Rahul A. Zaveri

Pacific Northwest National Laboratory, Richland, Washington, USA


James C. Barnard

Pacific Northwest National Laboratory, Richland, Washington, USA


Elaine G. Chapman

Pacific Northwest National Laboratory, Richland, Washington, USA


Georg A. Grell

Cooperative Institute for Research and Environmental Sciences, University of Colorado, Boulder, Colorado, USA


Steven E. Peckham

Cooperative Institute for Research and Environmental Sciences, University of Colorado, Boulder, Colorado, USA


Abstract

A new fully coupled meteorology-chemistry-aerosol model is used to simulate the urban- to regional-scale variations in trace gases, particulates, and aerosol direct radiative forcing in the vicinity of Houston over a 5 day summer period. Model performance is evaluated using a wide range of meteorological, chemistry, and particulate measurements obtained during the 2000 Texas Air Quality Study. The predicted trace gas and particulate distributions were qualitatively similar to the surface and aircraft measurements with considerable spatial variations resulting from urban, power plant, and industrial sources of primary pollutants. Sulfate, organic carbon, and other inorganics were the largest constituents of the predicted particulates. The predicted shortwave radiation was 30 to 40 W m−2 closer to the observations when the aerosol optical properties were incorporated into the shortwave radiation scheme; however, the predicted hourly aerosol radiative forcing was still underestimated by 10 to 50 W m−2. The predicted aerosol radiative forcing was larger over Houston and the industrial ship channel than over the rural areas, consistent with surface measurements. The differences between the observed and simulated aerosol radiative forcing resulted from transport errors, relative humidity errors in the upper convective boundary layer that affect aerosol water content, secondary organic aerosols that were not yet included in the model, and uncertainties in the primary particulate emission rates. The current model was run in a predictive mode and demonstrates the challenges of accurately simulating all of the meteorological, chemical, and aerosol parameters over urban to regional scales that can affect aerosol radiative forcing.

Received 28 September 2005; accepted 2 August 2006; published 11 November 2006.

Keywords: particulate; aerosol radiative forcing; modeling.

Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 0345 Atmospheric Composition and Structure: Pollution: urban and regional (0305, 0478, 4251); 0360 Atmospheric Composition and Structure: Radiation: transmission and scattering.

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Citation: Fast, J. D., W. I. Gustafson Jr., R. C. Easter, R. A. Zaveri, J. C. Barnard, E. G. Chapman, G. A. Grell, and S. E. Peckham (2006), Evolution of ozone, particulates, and aerosol direct radiative forcing in the vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model, J. Geophys. Res., 111, D21305, doi:10.1029/2005JD006721.