Production and loss of methanesulfonate and non-sea salt sulfate in the equatorial Pacific marine boundary layer

Abstract

The concentrations of aerosol methanesulfonate (MSA) and non-sea salt sulfate (NSS) were measured in the remote Pacific marine boundary layer (MBL) at Christmas Island. Distinct diurnal variations were observed. Large-particle dry deposition may account for 10-20% of the observed nighttime decrease, with entrainment of cleaner free tropospheric air responsible for the rest. A simple model suggests that NSS and MSA were produced at rates of about 74 and 6 ppt per day, respectively. Between 30 and 40% of the daily dimethylsulfide flux forms NSS and 3% forms MSA. -from Authors