Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima

We describe a broad resolution of the ‘‘Atlantic Parado’’ concerning the seasonal and geographic distribution of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan. – April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high-level transport to the west, with possible mixing over Africa. For the Jan. – March highest column-O 3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20– 50 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.