Abstract
Ozone has been observed in elevated concentrations by satellites over hitherto believed "background" areas. There is meteorological evidence, that these ozone "plumes" over the Atlantic ocean originate from biomass fires on the African continent. Therefore we have investigated ozone and assumed precursor compounds over African regions. The measurements revealed large photosmog layers in altitudes between 1.5 and 4 km. Both chemical and meteorological evidence point to savanna fires as sources located up to several thousand km upwind.