Climate and Emission Changes Contributing to Changes in Near-surface Ozone in Europe over the Coming Decades: Results from Model Studies

摘要

We used an off-line, regional, model of atmospheric transport and chemistry to investigate current and future levels of near-surface ozone and accumulated ozone exposure over a threshold of 40 ppb(v) (AOT40) in Europe. To describe the current situation and enable an evaluation of the model's performance we simulated a number of years around 2000. To assess changes in ozone concentrations due to possible emission changes in Europe, the model was run with the meteorology of the early 2000s and precursor emissions from a set of Clean Air for Europe (CAFE) emissions scenarios. By extrapolation of the observed increase in near-surface O_3 at coastal locations in northwest Europe we constructed model boundaries that were used to simulate the impact of increasing hemispheric background in 2020. To assess changes in ozone concentrations due to climate change, the model was run with recent (2000) emissions but using meteorology from a regional climate model simulating a control (1961-1990) and a future (2021-2050) climate. The results indicate that climate change will have a small impact on ozone concentrations and AOT40 in the Nordic countries. Changes in hemispheric background concentrations and changes in precursor emissions in Europe will have a larger effect on ozone in Northern Europe. The situation is quite different in southern Europe, where climate change is expected to result in a very large increase in near-surface ozone concentrations.