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We present a first description and evaluation of GEOS-CHEM, a global three-dimensional (3-D) model of tropospheric chemistry driven by assimilated meteorological observations from the Goddard Earth Observing System (GEOS) of the NASA Data Assimilation Office (DAO). The model is applied to a 1-year simulation of tropospheric ozone-NO •-hydrocarbon chemistry(More)
[1] We use a global three-dimensional coupled oxidant-aerosol model (GEOS-CHEM) to estimate natural and transboundary pollution influences on sulfate-nitrate-ammonium aerosol concentrations in the United States. This work is motivated in part by the Regional Haze Rule of the U.S. Environmental Protection Agency (EPA), which requires immediate action to(More)
[1] We use a global 3-D model of atmospheric mercury (GEOS-Chem) to interpret worldwide observations of total gaseous mercury (TGM) and reactive gaseous mercury (RGM) in terms of the constraints they provide on the chemical cycling and deposition of mercury. Our simulation including a global mercury source of 7000 Mg yr À1 and a TGM lifetime of 0.8 years(More)
We analyze the Asian outflow of CO, ozone, and nitrogen oxides (NO x) to the Pacific in spring by using the GEOS-CHEM global three-dimensional model of tropospheric chemistry and simulating the Pacific Exploratory Mission-West (PEM-West B) aircraft mission in February-March 1994. The GEOS-CHEM model uses assimilated meteorological fields from the NASA(More)
[1] The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February–April 2001). The model is used also to place the TRACE-P observations in an interannual(More)
[1] Observations indicate that ozone (O 3) concentrations in surface air over the United States in summer contain a 20–45 ppbv background contribution, presumably reflecting transport from outside the North American boundary layer. We use a three-dimensional global model of tropospheric chemistry driven by assimilated meteorological observations to(More)
[1] The U.S. Environmental Protection Agency (EPA) presently uses a 40 ppbv background O 3 level as a baseline in its O 3 risk assessments. This background is defined as those concentrations that would exist in the absence of North American emissions. Lefohn et al. [2001] have argued that frequent occurrences of O 3 concentrations above 50–60 ppbv at remote(More)
[1] We present a model study of carbon monoxide for 1988–1997 using the GEOS-Chem 3-D model driven by assimilated meteorological data, with time-varying emissions from biomass burning and from fossil fuel and industry, overhead ozone columns, and methane. The hydroxyl radical is calculated interactively using a chemical parameterization to capture chemical(More)
The Regional Haze Rule of the U.S. Environmental Protection Agency mandates reduction in U.S. anthropogenic emissions to achieve linear improvement of visibility in wilderness areas over the 2004-2018 period toward an endpoint of natural visibility conditions by 2064. Linear improvement is to apply to the mean visibility on the statistically 20% worst days,(More)
[1] We present a retrieval of tropospheric nitrogen dioxide (NO 2) columns from the Global Ozone Monitoring Experiment (GOME) satellite instrument that improves in several ways over previous retrievals, especially in the accounting of Rayleigh and cloud scattering. Slant columns, which are directly fitted without low-pass filtering or spectral smoothing,(More)