PIXE analysis of south pole aerosol

Abstract

The Geophysical Monitoring tor Climatic Change (GMCC) program of the National Oceanic and Atmospheric Administration (NOAA) operates an atmospheric monitoring observatory at Amundsen-Scott Station, South Pole. Long-term measurements of carbon dioxide, ozone, aerosols, and other background pollutants are obtained to understand their possible effects on the earth's climate. The aerosol measurement program consists of the continuous measurement of condensation nucleus (CN) concentration and aerosol scattering extinction coefficient ( σ sp ). During 1982 Nuclepore-filter aerosol samples were taken with 8-h time resolution for analysis by the proton induced X-ray emission (PIXE) technique. A time series of sodium, chlorine, and sulfur concentrations shows that the sulfur and CN records are similar and that the sodium, chlorine, and σ sp records are similar. Episodes of sodium are measured at the ground in the austral winter and are apparently caused by large-scale transport from coastal regions and vertical transport to the surface during times of surface warming and weakening of the surface temperature inversion. These episodes are characterized by increases in sodium concentration, CI/Na ratio, σ sp , and particle size, and decreases in nonseasalt sulfur concentration, suggesting a decrease in atmospheric acidity with a displacement of sulfuric acid aerosol. An analysis of back trajectories suggests transport times of several days from the Antarctic coast.