Seasonality of sulfur species (dimethyl sulfide, sulfate, and methanesulfonate) in Antarctica: Inland versus coastal regions

Abstract : To gain a better understanding of sulfate and methanesulfonate (MS−) signals recorded in central Antarctic ice cores in terms of past atmospheric changes, an atmospheric year-round study of these aerosols was performed in 2006 at the Concordia station (75°S, 123°E) located on the high Antarctic plateau. In addition, a year-round study of dimethyl sulfide (DMS), the gaseous precursor of sulfur aerosol, was conducted in 2007. The DMS mixing ratio remains below 1 pptv from October to January and exhibits a maximum of 10 pptv during the first half of winter (from April to July). Surprisingly, the well-marked maximum of sulfur aerosol recorded in January at coastal Antarctic sites is observed at Concordia for sulfate but not for MS− which peaks before and after sulfate in November and March, respectively. This first study of DMS and of its by-oxidation aerosol species conducted at inland Antarctica points out the complex coupling between transport and photochemistry of sulfur species over Antarctica. The findings highlight the complexity of the link between MS− ice core records extracted at high Antarctic plateau sites and DMS emissions from the Southern ocean.