The objective of this project is to obtain quantitative cloud condensation nuclei (CCN) data at Palmer Station, Antarctica, using a CCN spectrometer of the principal investigator's own design. The project is integrated with a study of tropospheric sulfur chemistry in order to examine the climatic negative feedback mechanism involving atmospheric CCN and the emission of dimethylsulfide (DMS) from oceanic phytoplankton. DMS is oxidized and converted to CCN in the atmosphere, with the increased concentration of CCN leading to more extensive marine stratus clouds. The increased cloud cover, because it reflects a greater proportion of the incoming solar radiation, is hypothesized to produce large-scale atmospheric cooling. The net cooling and the reduced solar radiation at the surface reduce the oceanic phytoplankton population and the rate of DMS emission. The remote location of Palmer Station, and the establishment of the two-year study of atmospheric sulfur chemistry offers a unique opportunity to study quantitative relationships, not only between CCN and DMS, but also with other transient and stable sulfur compounds such as non-sea salt sulfates, methane sulfonate, and sulfuric acid, as well as dry aerosols and sea salt particles.
