The influence of African air pollution on regional and global tropospheric ozone

[摘要] We investigate the influence of African biomass burning, biogenic, lightningand anthropogenic emissions on the tropospheric ozone over Africa andglobally using a coupled global chemistry climate model. Our model studiesindicate that surface ozone concentration may rise by up to 50 ppbv in theburning region during the biomass burning seasons. Biogenic emissions yieldbetween 5–30 ppbv increase in the near surface ozone concentration overtropical Africa. The impact of lightning on surface ozone is negligible,while anthropogenic emissions yield a maximum of 7 ppbv increase in theannual-mean surface ozone concentration over Nigeria, South Africa and Egypt.Our results show that biogenic emissions are the most important Africanemission source affecting total tropospheric ozone. The influence of each ofthe African emissions on the global tropospheric ozone burden (TOB) of384 Tg yields about 9.5 Tg, 19.6 Tg, 9.0 Tg and 4.7 Tg for biomassburning, biogenic, lightning and anthropogenic emissions emitted in Africarespectively. The impact of each of these emission categories on African TOBof 33 Tg is 2.5 Tg, 4.1 Tg, 1.75 Tg and 0.89 Tg respectively,which together represents about 28% of the total TOB calculated over Africa.Our model calculations also suggest that more than 70% of the troposphericozone produced by each of the African emissions is found outside thecontinent, thus exerting a noticeable influence on a large part of thetropical troposphere. Apart from the Atlantic and Indian Ocean, Latin Americaexperiences the largest impact of African emissions, followed by Oceania, theMiddle East, Southeast and south-central Asia, northern North America (i.e.the United States and Canada), Europe and north-central Asia, for all theemission categories.

[学科分类] 大气科学