The North Atlantic Oscillation controls air pollution transport to the Arctic

S. Eckhardt (1) , A. Stohl (1) , S. Beirle (2) , N. Spichtinger (1) , P. James (1) , C. Forster (1) , C. Junker (3) , T. Wagner (2) , U. Platt (2) , S. G. Jennings (3)

1 Department of Ecology
2 IUP - Institute of Environmental Physics [Bremen]
3 Department of Experimental Physics

This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 1-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 NO₂ vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO₂ transport and reduced NO₂ 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.

Domaines: Océan, Atmosphère

S. Eckhardt, A. Stohl, S. Beirle, N. Spichtinger, P. James, et al.. The North Atlantic Oscillation controls air pollution transport to the Arctic. Atmospheric Chemistry and Physics Discussions, 2003, 3 (3), pp.3222-3240. ⟨hal-00301108⟩