The North Atlantic Oscillation controls air pollution transport to the Arctic

[摘要] This paper studies the interannual variability of pollution pathways fromnorthern hemisphere (NH) continents into the Arctic. Using a 15-year modelsimulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North AtlanticOscillation (NAO) exerts a strong control on the pollution transport into theArctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about70% (30%) during high phases of the NAO (in the following referred to asNAO⁺) compared to its low phases (NAO^-). This is mainly due to greatdifferences in the pathways of European pollution during NAO⁺ andNAO^- phases, respectively, but reinforced by North American pollution, which isalso enhanced in the Arctic during NAO⁺ phases. In contrast, Asianpollution in the Arctic does not significantly depend on the NAO phase. Themodel results are confirmed using remotely-sensed NO₂ vertical atmosphericcolumns obtained from seven years of satellite measurements, which show enhanced northwardNO₂ transport and reduced NO₂ outflow into the NorthAtlantic from Central Europe during NAO⁺ phases. Surface measurements ofcarbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels duringNAO⁺ phases

[学科分类] 大气科学