Arctic Air Pollution: Insights from Recent Airborne and Ground-Based Observations

Recent airborne and ground-based field studies in the Arctic have brought new measurement and modeling capabilities to bear on the long-studied issue of pollution in the Arctic troposphere. Combined with long-term monitoring at surface sites, these measurements show that layers of pollution and biomass burning smoke are often found aloft where they are decoupled from the surface layer. In contrast, the pronounced seasonal cycle in gas- and particulate-phase pollutants observed at the surface sites is typical of the diffuse pollution present in the background troposphere in the Arctic (with occasional maxima from intense, discrete pollution episodes). The varied sources and composition of dense aerosol hazes found above the surface are similar to those observed elsewhere in the northern midlatitudes, and are not unique to the Arctic. In spring 2008, deposition of aerosol particles to the snow and ice surface of the Arctic was observed to occur from the near-surface layer rather than from the dense hazes above the surface. Major uncertainties remain in quantifying the mechanisms and rates of aerosol transport to and deposition within the Arctic and the relationship between the atmospheric and cryospheric loadings of soot.