Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 5 2004 10.5194/acpd-4-6379-2004 http://www.atmos-chem-phys-discuss.net/4/6379/2004/ http://www.atmos-chem-phys-discuss.net/4/6379/2004/acpd-4-6379-2004.html http://www.atmos-chem-phys-discuss.net/4/6379/2004/acpd-4-6379-2004.pdf 6379 6430 2004-10-07 Parametric sensitivity and uncertainty analysis of dimethylsulfide oxidation in the remote marine boundary layer D. D. Lucas ddlucas@alum.mit.edu R. G. Prinn Department of Earth, Atmospheric, and Planetary Sciences, MIT, Cambridge, MA 02139, USA Present address: Frontier Research Center for Global Change, Yokohama, Japan A study of the current significant uncertainties in dimethylsulfide (DMS) gas-phase chemistry provides insight into additional research needed to decrease these uncertainties. The DMS oxidation cycle in the remote marine boundary layer is simulated using a diurnally-varying box model with 56 uncertain chemical and physical parameters. Two analytical methods (direct integration and probabilistic collocation) are used to determine the most influential parameters (sensitivity analysis) and sources of uncertainty (uncertainty analysis) affecting the concentrations of DMS, SO₂, methanesulfonic acid (MSA), and H₂SO₄. The key parameters identified by the sensitivity analysis are associated with DMS emissions, mixing in to and out of the boundary layer, heterogeneous removal of soluble sulfur-containing compounds, and the DMS+OH addition and abstraction reactions. MSA and H₂SO₄ are also sensitive to the rate constants of numerous other reactions, which limits the effectiveness of mechanism reduction techniques. Propagating the parameter uncertainties through the model leads to concentrations that are uncertain by factors of 1.8 to 3.0. The main sources of uncertainty are from DMS emissions and heterogeneous scavenging. Uncertain chemical rate constants, however, collectively account for up to 50–60% of the net uncertainties in MSA and H₂SO₄. The concentration uncertainties are also calculated at different temperatures, where they vary mainly due to temperature-dependent chemistry. With changing temperature, the uncertainties of DMS and SO₂ remain steady, while the uncertainties of MSA and H₂SO₄ vary by factors of 2 to 4.