ANALYSIS OF LONG-RANGE TRANSPORT EVENTS AT ALERT, NORTHWEST-TERRITORIES, DURING THE POLAR SUNRISE EXPERIMENT

In situ measurements of carbon dioxide, methane, black carbon, peroxya cetylnitrate, condensation nuclei, and radon were made from the Canadi an Baseline Atmospheric Monitoring Observatory at Alert, Northwest Ter ritories, Canada (82 degrees 28'N, 62 degrees 30'W) during the ''Polar Sunrise Experiment'' (January 16 to April 20, 1992). The time series of methane, carbon dioxide, peroxyacetylnitrate, and black carbon were frequently highly correlated during January and February during well- defined episodes lasting from 2 to 5 days. This is consistent with dat a from earlier years. Shortly after polar sunrise, the temporal variab ility in both trace gases and aerosols diminished. Using a definition of black carbon concentrations exceeding 100 ng m(-3), 11 long-range t ransport episodes were defined. Lagrangian 5-day back trajectories alo ng with the concentration data were classified into six geographical s ectors to characterize the major episodes. The winter variability is r elated to synoptic meteorology, weak vertical mixing, and rapid air ma ss transport originating from Siberian and/or European source regions. Measurements of the radon daughter (Rn-222) activity in the atmospher e were used to further explore the transport of continental material a cross the Arctic basin.