ON THE FREQUENCY OF LONG-RANGE TRANSPORT EVENTS AT POINT-BARROW, ALASKA, 1983-1992

The Point Barrow, Alaska pollutant and meteorological data bases from the Climate Monitoring and Diagnostics Laboratory (CMDL) baseline station are evaluated for the first 120 days of each year between 1983 and 1992. The purpose of this study is to investigate whether a relationship between gaseous and aerosol pollutants during clean sector winds could be used to indicate periods of long-range transport of pollutants. Representative pollutant parameters used include carbon dioxide and aerosol light scattering (sigma(sp)), with methane, condensation nuclei, and black carbon used in support. Several interesting relationships emerge between the gases and sigma(sp) during long-range transport events: (1) the frequency of clean sector winds for most months is greater than 70%, with the range 31.6-92.8%; (2) high correlations between CO2 and sigma(sp) do not necessarily occur during long-range transport events, and the relationship between the two parameters is weak and erratic; (3) a considerable majority of transport periods occur in January and March, with the highest frequency in the AGASP measurement years 1983 and 1986, in some contrast to previous analysis using only haze as the pollution indicator; (4) pollution reaching surface monitors at Point Barrow most often originates from pooled air in the Arctic Basin, with no clear definition of more distant source regions.