Abstract
Abstract. We examined the influence of the North Atlantic Oscillation (NAO) on the atmospheric dispersion of pollution by computing the emission, transport and removal of idealized insoluble gaseous and water-soluble aerosol tracers, tagged by the continent of origin. We simulated a period of 50 yr (1960–2010), using the ECHAM5/MESSy1 atmospheric chemistry (EMAC) general circulation model. The model accounts for anthropogenic, biogenic and biomass burning sources, removal of trace gases through OH oxidation, and precipitation, sedimentation and deposition of aerosols. The model is shown to reproduce the observed spatial features of the NAO, moisture transports and precipitation. During high NAO phase seasons the axis of maximum westerly North American trace gas transports extends relatively far to the north and east over Europe. The NAO phase is significantly correlated with North American insoluble gas and soluble aerosol tracer concentrations over the northwestern Atlantic Ocean and across northern Europe, and with European trace gases and aerosols over Africa and north of the Arctic circle. We find a strong anti-correlation between the phase of the NAO and European pollutant gas concentration over western and central Europe.
Highlights
The North Atlantic Oscillation (NAO) is a major recurring large-scale pattern of interannual variability in the atmospheric circulation of the Northern Hemisphere
Eckhardt et al (2003) have studied the control that the NAO exerts over pathways of pollution transport towards the Arctic simulating fixed lifetime passive tracers over 15 yr and found that there is a strong relation between the NAO and surface concentrations of carbon monoxide (CO) in the Arctic, most pronounced during winter and spring
In the present paper we study the emission and transport of tagged idealised tracers, with the characteristics of carbon monoxide (CO) and aerosols in the atmosphere, simulated over a 50 yr period to include several positive and negative NAO phases in order to deduce robust patterns, using the ECHAM5/MESSy1 Atmospheric Chemistry (EMAC) climate model
Summary
The North Atlantic Oscillation (NAO) is a major recurring large-scale pattern of interannual variability in the atmospheric circulation of the Northern Hemisphere. Eckhardt et al (2003) have studied the control that the NAO exerts over pathways of pollution transport towards the Arctic simulating fixed lifetime passive tracers over 15 yr and found that there is a strong relation between the NAO and surface concentrations of carbon monoxide (CO) in the Arctic, most pronounced during winter and spring. In the present paper we study the emission and transport of tagged idealised tracers, with the characteristics of carbon monoxide (CO) and aerosols in the atmosphere, simulated over a 50 yr period to include several positive and negative NAO phases in order to deduce robust patterns, using the ECHAM5/MESSy1 Atmospheric Chemistry (EMAC) climate model.
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