Publication Type:Journal Article
Source:Geophysical Research Letters, Volume 30, Issue 22, p.2136 (2003)
Keywords:Aerosols, Aerosols and particles, Troposphere: composition and chemistry
Tropospheric distributions of H2SO4-H2O binary nucleation rates are calculated from a 3D model with DMS chemistry. Two mechanisms are used that include and exclude an SO2-independent H2SO4 production path. In the lower troposphere, the SO2-independent path generates extra H2SO4 and, consequently, much higher aerosol nucleation rates. However, these rates are less than 10−5 particles cm−3 s−1 in most of the lower troposphere, which indicates that DMS oxidation does not lead to appreciable aerosol formation there. In the upper troposphere, binary nucleation is fairly insensitive to the mechanism differences, with both yielding rates that exceed 1 particle cm−3 s−1 in the upper tropics. These large upper tropospheric nucleation rates imply that the DMS cycle may have served as an important source of aerosols to the troposphere and stratosphere during preindustrial and volcanically-quiescent periods, or during modern periods in clean marine regions where anthropogenic SO2 and H2SO4 are relatively low.