OZONE PRODUCTION DUE TO EMISSIONS FROM VEGETATION BURNING

Ozone has been observed in elevated concentrations by satellites over areas previously believed to be 'background'. There is meteorological evidence, that these ozone 'plumes' found over the Atlantic Ocean orig inate from vegetation fires on the African continent. In a previous st udy (DECAFE-88), we have investigated ozone and assumed precursor comp ounds over African tropical forest regions. Our measurements revealed large photosmog layers at altitudes from 1.5 to 4 km. Both chemical an d meteorological evidence point to savanna fires up to several thousan d km upwind as sources. Here we describe ozone mixing ratios observed over western Africa and compare ozone production ratios from different field measurement campaigns related to vegetation burning. We find th at air masses containing photosmog 'ingredients' require several days to develop their oxidation potential, similar to what is known from ai r polluted by emissions from fossil fuel burning. Finally, we estimate the global ozone production due to vegetation fires and conclude that this source is comparable in strength to the stratospheric input.