A three-dimensional study of the tropospheric sulfur cycle

摘要: The global tropospheric distributions of seven important sulfur species were simulated with a three-dimensional chemistry-transport model (IMAGES). Surface emission and deposition velocity maps established for use as lower boundary conditions in the model. While anthropogenic SO2 emissions are by far largest source northern midlatitudes, reduced compounds, notably dimethyl sulfide (DMS) predominate over most remote areas. Simulations performed present-day (∼ 1985) atmosphere. calculated compared available observations. results found to be generally within factor (at most) 2–3 long-term Comparison campaign measurements is more difficult, mostly due strong dependence concentrations on local meteorological conditions. results, however, indicate need future refinements, especially respect biogenic estimates parameterization cloud processes. A sensitivity study presented discuss uncertainties related several parameters (the decoupling wet scavenging convective transport soluble species, volcanoes velocities). Results also discussed terms budgets variables Around 125 Tg S/yr non-sea-salt (nss) compounds (DMS, CS2, H2S, COS, SO2) injected into balance mainly maintained nss-sulfates dry deposition, (94% total deposition). It that DMS oxidation represents main contribution chemical production (80% sources), major sink provided in-cloud (90% sinks), under assumption all incorporated clouds oxidized. annual sulfates reaches 3 g S m−2 yr−1 Europe North America, while it usually than 0.5 parts world. Estimations lifetimes 0.9 day DMS, 4 days 2.2 0.6 SO2, 0.18 DMSO, 6.1 MSA, 4.7 nss-sulfates.