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Hemispheric Transport of Air Pollution

Task Force on Hemispheric Transport of Air Pollution

Air pollution doesn’t stop at political boundaries but can at times be transported over several thousand kilometres and contribute to exceedances of air quality standards in downwind regions. Since 1979, an international convention on long-range transport of air pollution (CLRTAP) is in effect. A task force HTAP was founded in 2004 who created an assessment report in 2010. The information in this report is largely based on a set of model simulations performed by more than 20 different global chemistry transport models (see Fiore et al., 2009 for an overview of these experiments). IEK-8 operates the central data archive for this initiative and makes the HTAP model results available via their interoperable web service JOIN.

The animation below demonstrates the influence of individual emission regions on the distribution of carbon monoxide in the global atmosphere. Shown are results from the global chemistry climate model ECHAM5-MOZ for the year 2001. CO from European sources is labeled in green. This is mainly transported within the lower atmosphere towards Asia, but can also substantially pollute the Arctic region, especially in winter. CO from North American sources is labeled orange. This is also transported to the Arctic in winter and will be advected towards Europe during other times of the year; partially in the lower atmosphere and partially in the upper troposphere. Emissions from South Asia (blue) spread either east or westward, depending on season. This transport predominantly takes place at higher altitudes. East Asian CO (yellow) can significantly affect CO concentrations over North America, in particular in spring (partly covered by the blue cloud in the animation). There is only little influence of Asian CO on the Arctic region.


Fiore, A. M.; Dentener, F. J.; Wild, O.; et al. (2009): Multimodel estimates of intercontinental source-receptor relationships for ozone pollution, J. Geophys. Res., 114, doi: 10.1029/2008JD010816.