Assessment of dimethyl sulfide atmospheric oxidation mechanisms, used in both box models and global models, through the comparison with previous experiments

Dimethyl sulfide (DMS), which originates from phytoplankton, is the major natural source of sulfur compounds in the atmosphere. The oxidation products of DMS can form aerosols, which contribute to the formation of clouds, making them important for rain and the radiative balance of the planet. Additionally, due to DMS naturally occurring above oceans, an oxidation product of DMS, methanesulfonic acid (MSA), has been used to determine sea ice extent in ice cores up to 300 years in the past. However, due to gaps in the oxidation pathway of DMS, there are large uncertainties in the modelling of MSA formation. The aim of this work is to reduce the uncertainties in the DMS oxidation pathway, improving the modelling of the major products.

This project uses the KPP wrapper, BOXMOX, to compare box model outputs to chamber experiments from Albu et al. [1], Arsene et al. [2] and Ye et al. [3]. This comparison allows for an assessment of a near-explicit mechanism used in box models (the Master Chemical Mechanism) and a reduced mechanism useful for global models (CRI-Strat) regarding DMS oxidation in both low and high NO_x environments. This work presents the outcomes from this assessment and recommendations for the mechanisms to improve their modelling of DMS oxidation.

[1] Albu, M.; Barnes, I.; Becker, K. H.; Patroescu-Klotz, I.; Benter, T.; Mocanu, R. In Simulation and Assessment of Chemical Processes in a Multiphase Environment, Barnes, I., Kharytonov, M. M., Eds.; Springer Science: Dortdrecht, 2008, pp 501–513.   

[2] Arsene, C.; Barnes, I.; Becker, K. H.; Mocanu, R. Atmos. Environ. 2001, 35, 3769–3780.

[3] Ye, Q.; Goss, M. B.; Krechmer, J. E.; Majluf, F.; Zaytsev, A.; Li, Y.; Roscioli, J. R.; Canagaratna, M.; Keutsch, F. N.; Heald, C. L.; Kroll, J. H. Atmos. Chem. Phys., 2022, 22, 16003–16015.