The North Atlantic Oscillation controls air pollution transport to the Arctic

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Eckhardt, S., Stohl, A., Beirle, S., Spichtinger, N., James, P., Forster, C., Junker, C., Wagner, T., Platt, U., Jennings, S. G.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Arctic; Arctic pollution; black carbon; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.5194/acp-3-1769-2003; https://www.atmos-chem-phys.net/3/1769/2003/

This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 15-year model simulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North Atlantic Oscillation (NAO) exerts a strong control on the pollution transport into the Arctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about 70% (30%) during high phases of the NAO (in the following referred to as NAO + ) compared to its low phases (NAO - ). This is mainly due to great differences in the pathways of European pollution during NAO + and NAO - phases, respectively, but reinforced by North American pollution, which is also enhanced in the Arctic during NAO + phases. In contrast, Asian pollution in the Arctic does not significantly depend on the NAO phase. The model results are confirmed using remotely-sensed NO 2 vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO 2 transport and reduced NO 2 outflow into the North Atlantic from Central Europe during NAO + phases. Surface measurements of carbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels during NAO + phases