Eduardo P. Olaguer
The Dow Chemical Company
It has become increasingly necessary to account for global transport in determining exposure and risk due to the use of chemicals. Fast motions such as penetrating convection and tropospheric jets enhance the long-range transport of gaseous and particulate matter, allowing distant sources to contribute to local pollution. Moreover, environmental policy is tending towards a "one atmosphere" approach, which emphasizes the cross-linkages among urban and regional air quality, global tropospheric ozone pollution, stratospheric ozone depletion, climate change, and persistent organic pollutants. The Dow Circulation-Chemistry Model (DOWCCHEM) is an assessment tool designed to analyze such problems.
DOWCCHEM is a 3-D, 11-wave spectral, dynamical model of the atmosphere from 0-79 km coupled on-line to a grid, chemical transport model. It has a vertical grid resolution of about 1.2 km, and a horizontal grid resolution of 6 deg lat x 11.25 deg lon. The model employs a modified version of the global balance system of equations that conserves energy, while allowing for advection of zonal mean vorticity and temperature by the mean meridional circulation. It includes a detailed and fully interactive radiative transfer code, extensive inorganic and hydrocarbon chemistry (including the chemistry of acetone and other oxygenated compounds), an efficient parameterization for convection, and a fourth-order Bott advection scheme. Its highly efficient design yields a fast execution time of less than 1 minute on a single processor of a Compaq DS20 Alphaserver, thus making possible the detailed assessment of problems involving the long-range transport of short-lived compounds.