SUMMERTIME AEROSOL MEASUREMENTS IN THE ROSS SEA REGION OF ANTARCTICA

The physical and chemical characteristics of atmospheric aerosol were determined at a site remote from anthropogenic influences, on the edge of the Antarctic continent. The number concentration (0.12-3.12-mu-m diameter) ranged between 9 and 90 cm-3 and the corresponding mass between 0.1 and 3.7-mu-g m-3. The concentration of sulphate in two filter samples was 0.29 and 0.48-mu-g m-3. Size distributions at the site were remarkably invariant. The two major factors affecting the size distribution and concentration were occurrence of precipitation and atmospheric stability, respectively. Modes in the volume distribution occurred at about 0.2 and 2.0-mu-m diameter. The smallest particles < 0.1-mu-m diameter were composed entirely of sulphur species whereas particles above about 0.5-mu-m diameter consisted mainly of sea-salt minerals. Similarities in size distribution and composition were observed between aerosols < 0.5-mu-m diameter collected in this study and those sampled in the free troposphere of the Southwest Pacific.