| 12 Feb 2026
An advanced modelling study on the role of dimethyl sulfide in new particle formation in the pristine marine boundary layer
Abstract. New particle formation (NPF) enhances the concentration of cloud condensation nuclei (CCN) over the oceans, thereby affecting the radiative balance and, consequently, Earth’s climate. The literature suggest that marine NPF predominantly occurs in the free troposphere, as the extensive surface area of sea spray aerosols and limited precursor gases suppress NPF in the marine boundary layer (MBL). However, such interpretations do not fully account for the observations on nucleation and Aitken-mode particles within the MBL. Here, we demonstrate how natural emissions of dimethyl sulfide (DMS) and NH3 can drive H2SO4–NH3-derived NPF in the MBL during cloud-free conditions following precipitation events. The newly formed particles manage to grow into the upper Aitken and accumulation mode size range within 3–4 days, with the potential to act as CCN. Through extensive sensitivity runs, we show that DMS-derived NPF and growth exhibits a non-linear response to variations in air temperature and wind speed, whereas their response to changes in sea surface temperature, precipitation rate, and DMS surface ocean concentration remains approximately linear. Sporadic cloud cover is shown to suppress NPF. Finally, we report new rate coefficients and reaction pathways for the OH-initiated oxidation of methane sulphinic acid (MSIA) and assess key uncertainties in the DMS oxidation mechanism, illustrating their impact on the formation and growth of DMS-derived aerosol particles in the MBL.
The present work provides a comprehensive and systematic analysis of how DMS-derived new particle formation (NPF) and subsequent growth respond to varying meteorological conditions within the marine boundary layer. The results clearly demonstrate that DMS-derived NPF and growth occur only under a limited set of conditions, specifically, cloud-free periods following moderate to heavy precipitation, despite a wide range of meteorological and environmental parameters. In addition, the study identifies priority areas for future research on gas-phase DMS oxidation chemistry, based on detailed quantum chemical calculations and sensitivity analyses. This represents an important step toward addressing the role of DMS in clouds and climate.
I recommend publication after the authors address the minor concerns outlined below.
General comments:
Throughout Section 3.2: My primary concern is the lack of model evaluation against field observations. For example, the modeled DMS concentrations, ranging from 200 ppt (Line 448) to 2 ppb (Line 559), are substantially higher than typical observed values, which are mostly below 300 ppt and rarely exceed 500 ppt in the summertime Southern Ocean (e.g., Figure 8 of Kang et al., 2025). Similarly, the modeled SO2 concentrations (100–500 ppt; Lines 386–387) are considerably higher than observations, which are generally below 50 ppt (Figure S3 of Kang et al., 2025). I recognize that this is a modeling study aimed at qualitatively demonstrating how DMS-derived NPF responds to different environmental conditions. However, these large discrepancies between model results and observations raise concerns about the reliability of the conclusions. I suggest that the authors discuss the possible reasons for the overestimation of atmospheric sulfur species and assess its potential impact on their conclusions.
Section 3.2.1 and 3.2.4, and Figure 3: Is it correct that the SST sensitivity tests were conducted with a fixed air temperature of 283 K? It is somewhat difficult to envision scenarios in which air temperature and sea surface temperature vary independently, although I appreciate the value of isolating the sensitivity to individual parameters. If feasible, I suggest performing additional sensitivity tests in which both air temperature and SST are varied simultaneously by the same amount. Would their effects on PN concentrations offset each other, or does one parameter exert a stronger control on PN concentrations?
Line 148-161 and Line 379-391: The rapid cloud uptake of HPMTF (Novak et al., 2021) is not considered in this model. Given the importance of this process in suppressing gas-phase SO₂ formation, I recommend that the authors conduct an additional sensitivity test including this process to ensure that it does not affect their conclusions. References such as Fung et al. (2022) and Tashmim et al. (2024) may be useful for constraining the rate constants. Alternatively, the authors should justify why this process is not included.
Line 763-766 (and 20-26): This recommendation for future work would benefit from rephrasing in light of both the results of the present study and existing observational evidence. As summarized in Kerminen et al. (2018) (their Section 3.2.4) and Zheng et al. (2021), the prevailing view that “NPF is rare in the marine boundary layer” is based on the limited number of observed NPF events relative to the substantial body of field observations across various regions and seasons, particularly at the surface level. The present study, which shows that DMS-derived NPF occurs only under a limited set of conditions, is consistent with these observational findings from a theoretical perspective. I am not convinced that simply deploying long-term, station-based observations would be sufficient to demonstrate the influence of MBL NPF on CCN concentrations. A more critical question is where within the MBL such conditions are met. At a minimum, new observational efforts should target locations with favorable conditions (e.g., frequent cloud-free periods) and be combined with detailed air-mass history analyses to determine whether such events occur near the surface or aloft.
Figure 1: The placement of the DMS + BrO pathway is potentially misleading. In the current scheme, this pathway appears to be categorized under the abstraction pathway, which is not consistent with chemical terminology. In an abstraction pathway, oxidants remove an H atom from a methyl group of DMS, whereas in an addition pathway, oxidants form a bond with the central sulfur atom of DMS in the initial reaction step. Please see Barnes et al. (2006, their Section 2.3.8) for a detailed discussion of this mechanism. The initial product of the DMS + BrO reaction is generally assumed to be the (CH3)2S–OBr adduct. In addition, the DMS + Cl reaction can proceed via both abstraction and addition pathways (see also Barnes et al., 2006, Section 2.3.2). These pathways are treated separately in the present model (Nr G4 and G5 in Table S1). Please check whether the flux value reported for DMS + Cl in Figure 1 (2.2 × 103) corresponds solely to the abstraction pathway.
Technical comments:
Line 48, 327 and more: “metrological” may be a typo of “meteorological”. Please check throughout the manuscript.
Line 268, 352, 356, and more: “continues” may be a typo of “continued” or “continuous”. Please check throughout the manuscript.
Line 464: “As a results, …” -> “As a result, …”
Line 759: “formation SA” -> “formation of SA”
Line 763: Delete one “to” from “the scientific community to to provide…”.
References:
Barnes, Ian, Jens Hjorth, and Nikos Mihalopoulos. (2006) “Dimethyl Sulfide and Dimethyl Sulfoxide and Their Oxidation in the Atmosphere.” Chemical Reviews 106 (3): 940–75. https://doi.org/10.1021/cr020529+.
Fung, Ka Ming, Colette L. Heald, Jesse H. Kroll, et al. (2022) “Exploring Dimethyl Sulfide (DMS) Oxidation and Implications for Global Aerosol Radiative Forcing.” Atmospheric Chemistry and Physics 22 (2): 1549–73. https://doi.org/10.5194/acp-22-1549-2022.
Kang, Litai, Roger Marchand, Po-Lun Ma, et al. (2025) “Impacts of DMS Emissions and Chemistry on E3SMv2 Simulated Cloud Droplet Numbers and Aerosol Concentrations Over the Southern Ocean.” Journal of Advances in Modeling Earth Systems 17 (5): e2024MS004683. https://doi.org/10.1029/2024MS004683.
Kerminen, Veli-Matti, Xuemeng Chen, Ville Vakkari, Tuukka Petäjä, Markku Kulmala, and Federico Bianchi. (2018) “Atmospheric New Particle Formation and Growth: Review of Field Observations.” Environmental Research Letters 13 (10): 103003. https://doi.org/10.1088/1748-9326/aadf3c.
Novak, Gordon A., Charles H. Fite, Christopher D. Holmes, et al. (2021) “Rapid Cloud Removal of Dimethyl Sulfide Oxidation Products Limits SO2 and Cloud Condensation Nuclei Production in the Marine Atmosphere.” Proceedings of the National Academy of Sciences 118 (42): e2110472118. https://doi.org/10.1073/pnas.2110472118.
Tashmim, Linia, William C. Porter, Qianjie Chen, et al. (2024) “Contribution of Expanded Marine Sulfur Chemistry to the Seasonal Variability of Dimethyl Sulfide Oxidation Products and Size-Resolved Sulfate Aerosol.” Atmospheric Chemistry and Physics 24 (6): 3379–403. https://doi.org/10.5194/acp-24-3379-2024.
Zheng, Guangjie, Yang Wang, Robert Wood, et al. (2021) “New Particle Formation in the Remote Marine Boundary Layer.” Nature Communications 12 (1): 527. https://doi.org/10.1038/s41467-020-20773-1.