Ozone isopleths for Mexico City using CBM4 within AQUAMI R. Munoz-Ledo", J.R. Varela*, C. Reyes-Lopez",

AQUAMI is a microcomputer based software package which includes a module to account for photochemical process taking place in the atmosphere; when coupled to kinetic mechanisms as the so-called CBM4, it allows the calculation of pollu- tants concentration in a system containing NO% and HCTs. From such calculations the so-called Isopleths, which are level curves representing the maximum Ozone concentra- tion in terms of NO* and HC's concentrations at the beginning of the solar day, may be constructed. Such curves have been widely used for the analysis of "scenarios'" in various cities through out the world. In this work we describe the use of CBM4 within AQUAMI and a parametrization to simulate local conditions, as actinic flux, for Mexico City so that Ozone isopleths may be obtained. CBM4 has been selected as the chemical model since it is faster than the so-called CBM-X model and although the latter includes more reactions, CBM4 has those which arc relevant for the present work; it should be pointed out that the resulting computer program can be handled by an IBM compatible personal computer involving small CPU times, which is important since several simulations are required for each isopleth. The simulation is done for irradiation conditions at several months of the year, keeping the same patterns for pollutant emissions.