Modelling marine CCN

Introduction Conclusions References Tables Figures Back Close Print Version Interactive Discussion Abstract Introduction Conclusions References Tables Figures Back Close Print Version Interactive Discussion Abstract The concentration of cloud condensation nuclei (CCN) in the marine boundary layer (MBL) was estimated from dimethyl sulfide (DMS) flux, seasalt (SS) emission, and aerosols entrained from the free troposphere (FT). Only under clean air conditions, did the nucleation of DMS derived sulfur (DMS CCN) contribute significantly to the MBL 5 CCN. The accommodation coefficient for sulfuric acid mass transfer was found to be a very important parameter in the modeling the contribution of DMS to MBL CCN. The relationship between seawater DMS and MBL CCN was found to be non-linear mainly due to the transfer processes of sulfuric acid onto aerosols. In addition, seasalt derived CCN (SS CCN) and entrained CCN from the FT (FT CCN) affected the MBL 10 CCN directly, by supplying CCN, and indirectly, by behaving as an efficient sink for sulfuric acid. The SS CCN explained more than 50% of the total predicted MBL CCN when wind speeds were moderate and high. Seasalt and FT CCN may often be more efficient sources of MBL CCN than DMS.