An interpretation of trace gas correlations during Barrow, Alaska, winter dark periods, 1986-1997

Positive correlations among CO, CO2, and CH4 during winter-spring have been observed at Barrow, Alaska, for many years. We examine these, as well as negative correlations between O-3 and these gases, during the winter dark period. Because biogenic and photochemical processes are limited within this environment, we believe that pollution is driving these relationships. The dearth of mixing processes within the Arctic basin, the strong stability of the winter boundary layer, and lack of sunlight (and hence low OH) contribute to the winter-spring maxima in CO, CO2, and CH4. We hypothesize that the negative correlation of O-3 with these gases is the result of O-3 titration by NO and NO2 (NOX) in industrial plumes, which leads to the destruction of one to two molecules of O-3 per NO emitted. Using the empirical slopes of O-3/CO2 and O-3/CO determined from 12 years of Barrow data, we derived emission factors, Delta NOX/Delta CO2 and Delta NOX/Delta CO, assuming -1.5 O-3/NO because of titration. Comparing these with published emission factors for NOX, CO2, and CO from industrial processes, we found good agreement. This pollution signature is regionally widespread, although air parcels transported from the direction of Siberia have the highest mixing ratios of pollutant gases. Possible scenarios leading to these trace gas relationships are explored.