The Flemish Region in northern Belgium suffers from air pollution levels that rank among the highest in Europe. At the same time, the effects of global climate change are increasingly being experienced in Flanders. In view of climate and air quality policy support, atmospheric models are crucial tools as they are able to provide prognoses and scenarios, and to date, particularly 3-D prognostic computer models are the best available instruments. However, these models are often limited to academic research purposes and are rarely run for sufficiently long periods to be of relevance for policy makers due to their complexity and computation intensive character.
The objective of the CLIMAQS research project is to substantially improve and verify existing 3-D regional prognostic atmospheric grid models and to develop strategies for their effective implementation as policy support tools in the areas of climate change impacts and urban/regional air pollution in Flanders. Therefore, a very broad and generic knowledge platform in advanced atmospheric modelling will be developed, building on available expertise in Flanders. The project is a co-operation of VITO, the Dept. of Geography and the Dept. of Applied Science of the K.U.Leuven and the Dept. of Bioscience Engineering of the UA.
In the first phase of the project, models for the regional and local scale secondary aerosol formation, the hydrologic cycle, and the biosphere-atmosphere-interaction processes will be improved. Moreover, data assimilation techniques will be implemented for certain hydrologic parameters and atmospheric trace gas and particle concentrations. Therefore, a dynamic biosphere scheme will be integrated in a regional climate model, allowing vegetation to interactively grow and decay following atmospheric conditions representative for future climates. The resulting improved regional climate modelling capacities are not only valuable in their own right, they will also benefit significantly to improved air quality modelling. At the local scale, i.e., that of a city quarter, a building and vegetation resolving modelling approach will be applied at a spatial resolution of metres. The 3-D terrain features will be reconstructed from high-resolution stereo-mode satellite imagery and will be employed to initialise model runs. The work will concentrate on implementing and testing a numerical representation of mainly traffic related pollutants like PM10, PM2.5 and NO2. In addition, special attention will be given to the harmful ultrafine fraction of particles, the dynamics affecting their size distribution and their interaction with plants.
In the second phase, the focus will be on enhancing the applicability of the considered models for policy support purposes and on demonstrating their potential through case studies. So, following model coupling, code optimisation and parallelising, the final phase will be committed to performing policy relevant demonstration activities. These will consider specific case studies with local scale modelling in support of pollution mitigation strategies. At the same time, long term (~ 10 years) regional climate impact and air quality simulations will be carried out at resolutions down to a few kilometres covering the Flemish Region, both for current and future climate.
The Dept. of Bioscience Engineering of the UA will develop numerical modules in the existing FORUG model to simulate (i) the impact of ambient atmospheric conditions and ozone (O3), sulfur dioxide (SO2) and nitrogen oxides (NOx) on physiological vegetation dynamics and (ii) the emissions of BVOC's (biogenic volatile organic compounds) in terms of meteorological conditions and phenology, for trees, grassland and crops. Next, an existing deterministic plant model in ENVI-Met will be expanded to simulate the exchange of pollutants (deposition, uptake and leaching by leaves) and the physiological consequences of air pollutants. Therefore, intensive measuring campaigns are currently being set up in capital cities in Flanders to assess plant-pollutant interactions, for different tree species and in high spatio-temporal resolution. Finally, by means of case studies in the cities of Ghent and Hasselt, the benefits of realistic scenarios of urban green design will be assessed for local air quality and climate, with the extended ENVI-Met model. Urban green scenarios such as the creation of additional public park, the planting of hedges along busy streets, the creation of green roofs and a change in urban tree species, will be selected in collaboration with the cities involved.