Abstract
Influence of lateral and top boundary conditions on regional air quality prediction: A multiscale study coupling regional and global chemical transport models
Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa, USA
Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa, USA
Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa, USA
Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa, USA
Geophysical Fluid Dynamics Laboratory, NOAA, Princeton, New Jersey, USA
NASA Langley Research Center, Hampton, Virginia, USA
NASA Langley Research Center, Hampton, Virginia, USA
National Center for Atmospheric Research, Boulder, Colorado, USA
Carolina Environmental Program, University of North Carolina, Chapel Hill, North Carolina, USA
NASA Langley Research Center, Hampton, Virginia, USA
NASA Langley Research Center, Hampton, Virginia, USA
Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA
Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
National Center for Atmospheric Research, Boulder, Colorado, USA
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA
Argonne National Laboratory, Argonne, Illinois, USA
Department of Meteorology, Pennsylvania State University, University Park, Pennsylvania, USA
The sensitivity of regional air quality model to various lateral and top boundary conditions is studied at 2 scales: a 60 km domain covering the whole USA and a 12 km domain over northeastern USA. Three global models (MOZART-NCAR, MOZART-GFDL and RAQMS) are used to drive the STEM-2K3 regional model with time-varied lateral and top boundary conditions (BCs). The regional simulations with different global BCs are examined using ICARTT aircraft measurements performed in the summer of 2004, and the simulations are shown to be sensitive to the boundary conditions from the global models, especially for relatively long-lived species, like CO and O3. Differences in the mean CO concentrations from three different global-model boundary conditions are as large as 40 ppbv, and the effects of the BCs on CO are shown to be important throughout the troposphere, even near surface. Top boundary conditions show strong effect on O3 predictions above 4 km. Over certain model grids, the model's sensitivity to BCs is found to depend not only on the distance from the domain's top and lateral boundaries, downwind/upwind situation, but also on regional emissions and species properties. The near-surface prediction over polluted area is usually not as sensitive to the variation of BCs, but to the magnitude of their background concentrations. We also test the sensitivity of model to temporal and spatial variations of the BCs by comparing the simulations with time-varied BCs to the corresponding simulations with time-mean and profile BCs. Removing the time variation of BCs leads to a significant bias on the variation prediction and sometime causes the bias in predicted mean values. The effect of model resolution on the BC sensitivity is also studied.
Received 16 May 2006; accepted 8 January 2007; published 25 April 2007.
Citation: (2007), Influence of lateral and top boundary conditions on regional air quality prediction: A multiscale study coupling regional and global chemical transport models, J. Geophys. Res., 112, D10S18, doi:10.1029/2006JD007515.
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