Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 3 4 2003 10.5194/acpd-3-3833-2003 http://www.atmos-chem-phys-discuss.net/3/3833/2003/ http://www.atmos-chem-phys-discuss.net/3/3833/2003/acpd-3-3833-2003.html http://www.atmos-chem-phys-discuss.net/3/3833/2003/acpd-3-3833-2003.pdf 3833 3867 2003-07-25 Simulation of ozone production in a complex circulation region using nested grids M. Taghavi S. Cautenet G. Foret Laboratoire de Météorologie Physique, OPGC-CNRS and Université Blaise Pascal, Aubière, France During ESCOMPTE precampaign (15 June to 10 July 2000), three days of intensive pollution (IOP0) have been observed and simulated. The comprehensive RAMS model, version 4.3, coupled online with a chemical module including 29 species, has been used to follow the chemistry of the zone polluted over southern France. This online method can be used because the code is paralleled and the SGI 3800 computer is very powerful. Two runs have been performed: run1 with one grid and run2 with two nested grids. The redistribution of simulated chemical species (ozone, carbon monoxide, sulphur dioxide and nitrogen oxides) was compared to aircraft measurements and surface stations. The 2-grid run has given substantially better results than the one-grid run only because the former takes the outer pollutants into account. This online method helps to explain dynamics and to retrieve the chemical species redistribution with a good agreement.