Parallel runs of a large air pollution model on a grid of Sun computers

Large-scale air pollution models can successfully be used in different environmental studies. These models are described mathematically by systems of partial differential equations. Splitting procedures followed by discretization of the spatial derivatives lead to several large systems of ordinary differential equations of order up to 80 millions. These systems have to be handled numerically at up to 250,000 time-steps. Furthermore, many scenarios are often to be run in order to study the dependence of the model results on the variation of some key parameters (as, for example, the emissions). Such huge computational tasks can successfully be treated only if: (i) fast and sufficiently accurate numerical methods are used and (ii) the models can efficiently be run on parallel computers. The mathematical description of a large-scale air pollution model will be discussed in this paper. The principles used in the selection of numerical methods and in the development of parallel codes will be described. Numerical results, which illustrate the ability of running the fine resolution versions of the model on Sun computers, will be given. Applications of the model in the solution of some environmental tasks will be presented. (C) 2004 IMACS. Published by Elsevier B.V. All rights reserved.