Export of Ozone and Precursors from Europe and Impacts on Air Quality, Climate and Ecosystems

This project will quantify the impacts of processes that control export of pollution from Europe on air quality, climate and ecosystems. These processes currently lack observational constraint, and our understanding is largely based on model simulations. We will conduct the first studies of European pollution export constrained by extensive aircraft and satellite observations, and quantify air quality and climate impacts. We will also quantify the role of ozone pollution from Europe in reducing CO2 uptake to European and Siberian forest, due to its harmful effects on vegetation. This will be compared with the direct climate impact of European ozone as a greenhouse gas. This will also allow quantification of a reduction in the effectiveness of CO2 emission cuts due to ozone limitation of carbon uptake to the biosphere, which is of urgent interest to policy makers and governments. Ozone is a pollutant in the lower atmosphere, which is not emitted directly, but is formed in the atmosphere by sunlight-driven chemical reactions acting on nitrogen oxides emitted from high-temperature fuel combustion (primarily motor vehicles, power plants, biomass burning) and volatile organic compounds, emitted from both man-made and natural sources. Ozone is a strong oxidant and a greenhouse gas in the lower atmosphere, and its concentrations have increased markedly since pre-industrial times. It is harmful to human health, and also damages vegetation. This leads to substantial reductions in crop yields, and also results in a reduction in the ability of vegetation to take up CO2 from the atmosphere - meaning it may result in further 'indirect' greenhouse warming. Export of pollution from the major continents in controlled by transfer of pollutants from the surface boundary layer (BL) to the overlying large-scale free troposphere (FT), where it can be transported over 1000s km. Over North America and Asia this 'venting' of the BL is controlled largely by fronts associated with low-pressure weather systems, however over central Europe these are much less frequent. Processes controlling European pollution export are much less well understood, and our lack of understanding is exacerbated by a lack of observations in regions downstream from Europe (mainly Arctic, Siberia and over the Mediterranean basin). Our approach will be to use new observations from aircraft experiments over the Arctic and Siberia, satellites and numerical models to quantify the roles of dynamic and chemical processes in controlling ozone pollution export from Europe. We will investigate how these processes determine the air quality and climate impacts of European ozone precursor emissions. In addition, we will determine how anthropogenic and natural processes interact to affect these processes, and quantify the impact of European ozone pollution on CO2 uptake to European and Siberian vegetation. We will finally quantify how these processes may change under future climate (year 2050).