Increasing Ozone over the Atlantic Ocean

Ship-borne ozone (O 3 ) measurements over the Atlantic Ocean during the period from 1977 to 2002 show that O 3 trends in the northern mid-latitudes are small. In contrast, remarkably large O 3 trends occur at low latitudes and in the Southern Hemisphere, where near-surface O 3 has increased by up to a factor of 2. The likely cause is the substantial increase of anthropogenic emissions of nitrogen oxides (NO x ) associated with energy use in Africa, which has added to NO x from biomass burning and natural sources.