Sources, Chemistry and Fate of Volatile Methylated Sulfur in Southern Ocean and Antarctic Atmospheres

Volatile methylated sulfur (VMS) gases from ocean biology help form sulfate particles that can seed clouds, especially over the Southern Ocean and Antarctica, where climate impacts are highly uncertain and measurements are limited. This thesis measures key VMS gases, mainly dimethyl sulfide (DMS) and methanethiol (MeSH), using high resolution instruments at Kennaook/Cape Grim (Tasmania) and on a Southern Ocean-Antarctic research voyage in early 2024. It shows MeSH is widespread in clean marine air (about 10–55 ppt) and can make up around 40% of total VMS. Over the open ocean, MeSH and DMS usually vary together, but near the Antarctic coast and ice-edge that link often weakens. This means models should not assume DMS always predicts MeSH; they need separate, region-aware estimates to improve cloud and climate predictions.