Aerosol Production in the Marine Boundary Layer Due to Emissions from DMS: Study Based on Theoretical Scenarios Guided by Field Campaign Data

The main sources of aerosols in the remote Marine Boundary Layer (MBL) are sea salt sources, non sea salt sources, and entrainment of free tropospheric aerosols. Non sea salt aerosols are mainly sulphate derived from the oxidation of gaseous DiMethyl Sulphide (DMS) produced in surface water.1 DMS is produced by phytoplankton and is estimated to account for approximately 25% of the total global gaseous sulphur released into the atmosphere.2 DMS can either be dissolved into aqueous-phase aerosols or oxidised to other gas-phase species which can contribute to aerosol formation, e.g. SO2, H2SO4, DiMethyl SulphOxide (DMSO), DiMethyl SulphOne (DMSO2), MethaneSulfInic Acid (MSIA) and Methane Sulphonic Acid (MSA). It has therefore been postulated3 that DMS emission from the oceans can produce new condensation nuclei and eventually Cloud Condensation Nuclei (CCN). Thus, DMS may have significant influence on the Earth’s radiation budget. In this paper, this DMS-postulate has been investigated for MBL conditions using the Chemistry-Aerosol-Cloud (CAC) model.4 The CAC model is a box model where the following processes are solved: