Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 15581-15592, 2016
https://doi.org/10.5194/acp-16-15581-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
16 Dec 2016
Projection of North Atlantic Oscillation and its effect on tracer transport
Sara Bacer1, Theodoros Christoudias2, and Andrea Pozzer1 1Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany
2Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia, Cyprus
Abstract. The North Atlantic Oscillation (NAO) plays an important role in the climate variability of the Northern Hemisphere, with significant consequences on long-range pollutant transport. We investigate the evolution of pollutant transport in the 21st century influenced by the NAO under a global climate change scenario. We use a free-running simulation performed by the ECHAM/MESSy Atmospheric Chemistry (EMAC) model coupled with the ocean general circulation model MPIOM, covering the period from 1950 until 2100. Similarly to other works, the model shows a future northeastward shift of the NAO centres of action and a weak positive trend of the NAO index (over 150 years). Moreover, we find that NAO trends (computed over periods shorter than 30 years) will continue to oscillate between positive and negative values in the future. To investigate the NAO effects on transport we consider carbon monoxide tracers with exponential decay and constant interannual emissions. We find that at the end of the century, the south-western Mediterranean and northern Africa will, during positive NAO phases, see higher pollutant concentrations with respect to the past, while a wider part of northern Europe will, during positive NAO phases, see lower pollutant concentrations. Such results are confirmed by the changes observed in the future for tracer concentration and vertically integrated tracer transport, differentiating the cases of “high NAO” and “low NAO” events.

Citation: Bacer, S., Christoudias, T., and Pozzer, A.: Projection of North Atlantic Oscillation and its effect on tracer transport, Atmos. Chem. Phys., 16, 15581-15592, https://doi.org/10.5194/acp-16-15581-2016, 2016.
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Short summary
We investigate the influence of the North Atlantic Oscillation on atmospheric pollutant transport in the 21st century under a global climate-change scenario, using a coupled atmosphere–chemistry–ocean general circulation model. We find that, at the end of the century, the south-western Mediterranean and northern Africa will see higher pollutant concentrations during positive NAO phases with respect to the past, while a wider part of north Europe will see lower pollutant concentrations.
We investigate the influence of the North Atlantic Oscillation on atmospheric pollutant...
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