THE ROLE OF CONVECTIVE PROCESSES OVER THE ZAIRE-CONGO BASIN TO THE SOUTHERN HEMISPHERIC OZONE MAXIMUM

During October, satellite measurements show that there is a region of elevated tropospheric ozone over the tropical southern Atlantic Ocean. The cause of the high ozone concentrations has been related to biomas s burning in South America and Africa. In this paper, we present evide nce from satellite sources, European Center for Medium-Range Weather F orecast analyses, and a mesoscale simulation during October, suggestin g that afternoon and evening deep convection in central Africa is resp onsible for some of the abnormally high concentrations of ozone in the Tropical South Atlantic which extend southeast over southern Africa i nto the Indian Ocean. The mechanisms for enhancing tropospheric O-3 in cludes (1) the removal of ozone, NOx, and hydrocarbon rich air from fi res in eastern Africa within the planetary boundary layer to the middl e and upper troposphere by deep convection; (2) the production of NOx from lightning associated with mesoscale convective systems and the su bsequent photochemical production of O-3, and (3) the entrainment of O -3 rich air from the lower stratosphere into the upper troposphere by deep convection. During the next few years an international field camp aign in central Africa (the experiment for regional sources and sinks of oxidants-EXPRESSO), global lightning data, and the launch of the Tr opical Rainfall Measuring Mission (TRMM) will help to identify the rel ative importance of each of the processes over central Africa that cou ld be responsible for high O-3 concentrations over the tropical south Atlantic.