Long-Range Tropospheric Transport of Pollution Aerosols into the Alaskan Arctic

Abstract

Noncrustal vanadium and manganese are used as chemical tracers for pollution-derived aerosols (collected over a period of four years in the near-surface air at Barrow, Alaska), in order to investigate tropospheric long-range transport of anthropogenic pollution from midlatitudes to the Alaskan Arctic. The analysis is based upon subjectively identifying characteristic transport pathway types using daily circumpolar weather maps. The transport occurs when the midlatitudinal and Arctic atmospheric circulations manifest quasi-persistent circulation patterns. Rapid transport of aerosols, on the order of 7?10 days, is dominated by quasi-stationary anticyclones and takes place along their peripheries where pressure gradients are relatively strong. The seasonal variation in concentration of the Arctic pollution-derived aerosol is related to the seasonal variation in the occurrence and position of midlatitude blocking anticyclones, of the Arctic anticyclone and of the Asiatic anticyclone. The positions of the major anticyclonic centers and their seasonal variation are responsible for the fact that different source regions contribute to the pollution-derived aerosol during different times of the year. Central Eurasian sources contribute predominantly during winter, Western Eurasian sources during spring, whereas North American and Far Eastern sources contribute little to the Arctic pollution aerosols collected in Alaska.