The objectives of this work focus on the development and formulation of an innovative numerical technique named SIS (semi-implicit symmetric) to solve ordinary differential equations with an application to atmospheric chemistry. Numerical analyses of the method are performed in detail showing a very good performance (stability, CPU time consuming, precision) when compared to the standard Gear's method (stiff option) The SIS method is used to generate a box photochemical model treating in detail diurnal variations of chemical species. The box model is respectively coupled to a one dimensional diffusive model and to a general circulation model with different chemicla mecanism . These 3 categories of models have been evaluated by comparing multiple sets of numerical results against existing measurements from stratospheric ballons, satellites and from the ground. Very good performance of all models is demonstrated, based on model-model and measurement-model comparison. The future application of the 3 dimensional model concern the comparison of measurements from UARS (satellite) with the model results.
