Rapid intercontinental air pollution transport associated with a meteorological bomb

[摘要] Intercontinental transport (ICT) of trace substances normally occurs on timescales ranging from a few days to several weeks.In this paper an extraordinary episode in November 2001 is presented, where pollution transport across the North Atlantic took only about one day.The transport mechanism, termed here an intercontinental pollution express highway because ofthe high wind speeds, was exceptional, as it involved an explosively generated cyclone, a so-called meteorological"bomb''. To the authors' knowledge, this is the first study describing pollution transport in a bomb.The discovery of this event was based on tracer transport model calculations and satellite measurements ofNO₂, a species with a relatively short lifetime in the atmosphere, which could be transported that far only because ofthe high wind speeds produced by the bomb. A 15-year transport climatology shows that intercontinental express highways are about four times more frequentin winter than in summer, in agreement with bomb climatologies. The climatology furthermore suggests that intercontinental express highways may be important for the budget ofshort-lived substances in the remote troposphere. For instance, for a substance with a lifetime of1 day, express highways may be responsible for about two thirds of the totalICT. We roughly estimate that express highways connecting North America with Europe enhance the averageNO_x mixing ratios over Europe, due to North American emissions, by about2-3 pptv in winter.

[学科分类] 大气科学