The Importance of the Representation of DMS Oxidation in Global Chemistry‐Climate Simulations

Erik Hans Hoffmann,Anne Kubin,Ina Tegen,Hartmut Herrmann,Bernd Heinold

doi:10.1029/2021gl094068

Erik Hans Hoffmann, Anne Kubin + Show 3 more

Open Access

https://doi.org/10.1029/2021gl094068

Copy DOI

Abstract

AbstractThe oxidation of dimethyl sulfide (DMS) is key for the natural sulfate aerosol formation and its climate impact. Multiphase chemistry is an important oxidation pathway but neglected in current chemistry‐climate models. Here, the DMS chemistry in the aerosol‐chemistry‐climate model ECHAM‐HAMMOZ is extended to include multiphase methane sulfonic acid (MSA) formation in deliquesced aerosol particles, parameterized by reactive uptake. First simulations agree well with observed gas‐phase MSA concentrations. The implemented formation pathways are quantified to contribute up to 60% to the sulfate aerosol burden over the Southern Ocean and Arctic/Antarctic regions. While globally the impact on the aerosol radiative forcing almost levels off, a significantly more positive solar radiative forcing of up to +0.1 W m−2 is computed in the Arctic (>60°N). The findings imply the need of both further laboratory and model studies on the atmospheric multiphase oxidation of DMS.

Highlights

Oceans cover 70% of Earth's surface and are the primary source of atmospheric water vapor and various marine aerosols
Highest methane sulfonic acid (MSA) concentrations are modeled between 0° and 30°S, which is related to the interplay of high modeled dimethyl sulfide (DMS) emissions together with strong photochemistry
The results suggest that the negative radiative forcing (RF) of natural aerosol in the Arctic may be overestimated unless a more sophisticated representation of DMS oxidation is considered

Summary

Introduction

Oceans cover 70% of Earth's surface and are the primary source of atmospheric water vapor and various marine aerosols. Mass fluxes from the ocean surface into the atmosphere have considerable impact on cloud formation and climate. Main photochemical stable oxidation products of DMS are SO2, H2SO4 and methane sulfonic acid (MSA). These products are known to contribute to new particle formation and growth of existing particles (e.g., Kerminen & Wexler, 1997; O'Dowd & de Leeuw, 2007; Zhang, Khalizov, et al, 2012). DMS oxidation heavily impacts natural aerosol population and abundance of cloud condensation nuclei (CCN). The importance of DMS oxidation for climate led to the formulation of the highly debated CLAW hypothesis (Carslaw et al, 2010; Charlson et al, 1987; Quinn & Bates, 2011)

Methods

Results

Conclusion