Modélisation à haute résolution du transport de polluants à longue distance

Antoine Auby 1
1 TROPO - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : Air pollution can be transported between continents by large-scale atmospheric dynamics, where it can impact climate and regional air quality far from emission regions. During transport, concentrations in polluted plumes are affected by mixing with the background. Impacts of longrange pollution on climate and air quality are usually quantified using global Eulerian models, that tend to overestimate mixing due to their low resolution. This induces errors in the simulated export of pollutants, and in the reaction rates due to the non-linearity of atmospheric chemistry. This thesis aims to better understand and quantify mixing of pollutant plumes in the free troposphere during long-range transport, and its representation in numerical models. It focuses on the Arctic, which is a region vulnerable to climate change, and where greenhouse gases and aerosol distributions are strongly influenced by transport of pollution from mid-latitudes. The work focuses on three case studies of transport into the Arctic troposphere during the POLARCAT campaign, in summer 2008. Results include estimates of the intensity of mixing in the Arctic troposphere, which was found to be lower than in mid-latitudes. The results also show that a Lagrangian modelling approach is able to reproduce the variability in observed concentrations in aged plumes, to simulate the transport of small-scale structures, and to evaluate the variability of ozone evolution in pollutant plumes due to differences in mixing scenarios. The model results are also used to assess pollutant transport simulated by global models in the Arctic, and to define the resolution neeeded for more accurate simulations. Overall, the results highlight the necessity to combine Lagrangian and Eulerian approaches to improve the representation of long-range pollution transport in numerical models.
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Submitted on : Tuesday, September 25, 2012 - 2:58:36 PM
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Antoine Auby. Modélisation à haute résolution du transport de polluants à longue distance. Sciences de l'environnement. Université Pierre et Marie Curie - Paris VI, 2012. Français. ⟨tel-00735198⟩

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