Parametric sensitivity and uncertainty analysis of dimethylsulfide oxidation in the remote marine boundary layer
Résumé
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.
Domaines
Océan, Atmosphère
Origine : Accord explicite pour ce dépôt
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