We discuss the implementation of an off-line air quality model (AQM). More precisely, how to design a code for an AQM that runs efficiently on a variety of computer platforms. We implemented our ideas in an AQM benchmark and we show the performance of this benchmark on the different architectural paradigms. A second subject of the paper is the I/O performance of the Cray~T3E for an off-line model. We implemented the required I/O in different ways and show that none of these results in a truly scalable I/O.

MATHEMATICAL SOFTWARE (acm G.4), PHYSICAL SCIENCES AND ENGINEERING (acm J.2), Partial Differential Equations (acm G.1.8)
Explicit machine computation and programs (not the theory of computation or programming) (msc 92-04), Parallel computation (msc 65Y05), Method of lines (msc 65M20)
Modelling, Analysis and Simulation [MAS]
Computational Dynamics

Blom, J.G, Lioen, W.M, & Verwer, J.G. (1998). HPCN and air quality modeling. Modelling, Analysis and Simulation [MAS]. CWI.