Mechanistic, sensitivity, and uncertainty studies of the atmospheric oxidation of dimethylsulfide

The global-scale emissions and reactivity of dimethylsulfide (CH3SCH3, DMS) make it an integral component in the atmospheric sulfur cycle. DMS is rapidly oxidized in the atmosphere by a complex gas-phase mechanism involving many species and reactions. The resulting oxidized sulfur-bearing products are hygroscopic and interact with aerosols through condensation and secondary aerosol formation. Predictions of the impacts of DMS chemistry on aerosols and climate are inhibited by the poorly understood DMS oxidation mechanism. This thesis diagnoses the gas-phase connections between DMS and its oxidation products by simulating comprehensive DMS chemistry (approximately 50 reactions and 30 species) using three atmospheric models of varying size and complexity. A diurnally-varying box model of the DMS cycle in the remote marine boundary layer is used to identify important DMS-related parameters and propagate parameter uncertainties to the sulfur-containing species. This analysis shows that the concentrations of DMS and sulfur dioxide (SO2) are sensitive to relatively few parameters. Moreover, the concentrations of DMS and SO2 are found to have factor of 2 uncertainties caused primarily (more than 60% of the variance) by uncertainties in DMS emissions and heterogeneous removal, respectively. In contrast, the concentrations of other products, such as sulfuric acid (H2SO4) and methanesulfonic acid (CH3SO3H, MSA), are found to be sensitive to many parameters and have larger uncertainties (factors of 2 to 7) resulting from multiple uncertain chemical and non-photochemical processes. The DMS oxidation mechanism is quantitatively assessed using a one-dimensional column model constrained by high-frequency aircraft measurements from the

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Lucas, Donald David, 1969-

Advisor dc:contributor.advisor

• Ronald G. Primm.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29759

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29759