Estimate of global atmospheric organic aerosol from oxidation of biogenic hydrocarbons

The results from a series of outdoor chamber experiments establishing the a tmospheric aerosol-forming potential of fourteen terpenoid hydrocarbons hav e been used to estimate the annual amount of secondary organic aerosol form ed globally from compounds emitted by vegetation. Hydroxyl radical, ozone, and nitrate radical oxidation each contribute to aerosol formation in full- photooxidation experiments; because oxidation by nitrate radical under ambi ent, remote conditions is likely to be negligible, parameters describing ae rosol formation from hydroxyl radical and ozone reaction only are developed . Chamber results, temporally and spatially resolved, compound-specific est imates of biogenic hydrocarbon emissions, and hydroxyl radical and ozone fi elds are combined to lead to an estimate for atmospheric secondary organic aerosol formed annually from biogenic precursors of 18.5 Tg, a number small er than the previously published estimate of 30-270 Tg [Andreae and Crutzen , 1997].