An efficient chemical systems modelling approach 1

56 Systems of stiff chemical reactions are often associated with atmospheric chemistry modelling, which plays a very important 57 role in the studies of stratospheric ozone depletion, tropospheric air pollution problems, and future chemistry-climate feedbacks 58 and interactions. This paper revisits an open-source stiff system solver SVODE and presents its efficient use in modelling different 59 levels of complexity of a range of chemical systems. The chemical systems discussed here are the Lotka–Volterra (predator–prey) 60 model, the Brusselator model, the Oregonator model, and the Lorenz model. The first two models consist of two variables, while 61 the remaining two models consist of three variables. Finally, an application of this modelling approach to a generalised organic/NOx 62 mechanism for characterising air pollution development is presented. Since the SVODE is an open-source code, and the simulations 63 were run on a Linux PC (with g77 compiler), all results discussed in this paper can be easily reproduced. Most importantly, the 64 approach shown here can be readily extended to other larger scale applications such as the three-dimensional air pollution modelling. 65  2002 Published by Elsevier Science Ltd.