Southern Africa - a giant natural photochemical reactor

Abstract

The analogy of a ‘giant natural photochemical reactor’ is extended in this paper to the central and southern African tropics, where tropospheric ozone enhancement occurs over a vast geographical area from the Congo to South Africa, and over a long period of time, from June to October. Maximum regional ozone enhancement in September occurs between 10º - 20ºS over Zambia and Zimbabwe, which is designated as the core of the ‘photochemical reactor’. Features that contribute towards the ‘giant natural photochemical reactor’ are abundant sources of ozone precursors (biomass burning, lightning, biogenic and urban-industrial sources), and meteorological conditions that promote anticyclonic recirculation on a subhemispheric scale.