WP 4: Megacity air quality

Overview and background

The main objective of WP4 is to improve our ability to simulate multiscale transport and transformation processes of air pollutants in megacities. Major research needs on this topic include: detailed and more reliable air quality assessments; improved source apportionment; exposure pattern analysis in selected megacity areas and quantification of the pollution burden for sensitive population groups; and quantifying potential links between urban air quality, meteorology and climate change. Mesoscale models need to be enhanced with novel physical and chemical parameterisations that are specifically adapted to the urban environment. Improved versions of both simpler and sophisticated models need to be formulated, so that integrated tools, such as that to be developed in WP7, will be versatile enough to be applicable for process analysis by scientists, as well as for assessments and mitigation option analysis by local authorities and policy makers, especially towards minimising the urban air pollution risks for susceptible populations. All of these needs will be addressed in WP4 through the methodology described below.

Methodology and advancement beyond the state-of-the-art

The current state-of-the-art is largely defined by the knowledge and results gained from other relevant projects addressing the issue of urban AQ assessment and exposure analysis, such as FUMAPEX, OSCAR, SAPPHIRE, Urban Exposure and BOND. WP4 will build upon this expertise. We will continue to investigate the role of advanced parameterisations for realistically describing the physical and chemical processes in the urban atmospheric sublayer, for which a significant research effort on has been invested in the past for the sake of adjusting the parameterisation of global and mesoscale NWP models to urban areas. Furthermore, going beyond this, particular emphasis will be given in the representation of scale interaction processes by the integration of different scale models (street, local and mesoscale) including the advanced "urbanised" parameterisations into the modelling tools. The current proposal will also carry forward the analysis of meteorological patterns leading to urban air pollution episodes conducted, for example, within FUMAPEX, by the development of suitable indicators linking particular meteorological conditions/parameters to increased air pollution levels in the urban area. These indicators will constitute a particularly useful tool for regulators in suggesting effective policies and mitigation measures. Finally, a combination of modelling and analysis of observations data in WP4 will allow both the quality assurance of the new parameterisations as well as the verification of input emissions.

To meet the needs of various users, WP4 will lead to a multiscale approach for urban air quality analyses using advanced modelling tools capable of simulating concentration patterns in megacities. For this purpose, the contribution of all major pollution sources will be considered, taking into account various physical and chemical processes which are characteristic for urban environments. For addressing the aims and objectives of WP4 the following steps will form a suitable methodology:
  • Develop, implement and evaluate a multiscale zooming approach based on the parameterisations developed in WP2. This will be taken on in two separate tasks, one focused on advanced physical parameterisations (developed in WP2), and the other on new findings from chemical laboratory work, as a basis for developing physical and chemical parameterisations for describing and quantifying pathways of stressors' fate through dispersion, transformation, transport and removal processes.
  • Describe and quantify the feedback interaction between megacity air quality and meteorology, by investigating the effect of increased pollutant concentrations on the urban meteorology, as well as the influence of meteorological patterns on air pollution. The effect of specific meteorological patterns in the development of urban air pollution episodes and the development of relevant indicators will be investigated. This information can be then used in WP8 for assessments relevant to policy purposes. Apart from describing feedback mechanisms of direct relevance to WP2, this task will allow assessing how increased urban scale air pollution indirectly affects regional climate (relevance to WP6).
  • Identify and quantify the impact caused by the main individual local emission sources, including both mobile and stationary sources. This task will be carried out in cooperation with WP1, as the appropriate generation of emission data is particularly important in any source apportionment analysis. The results will reveal which pollution sources are mainly responsible for poor urban scale air quality, thus being of direct relevance to WP8.
  • Analyse and explain the role of urban meteorology, land use and urban structure, and population spatial distribution and time use on the observed exposure patterns, and develop advanced methods for producing assessments of both personal and population exposure, and dose/intake estimates, based on the source apportionment exercise planned in collaboration with WPs 1 and 3. The resulting methodology will be applied in selected target cities, using as input the computed spatial concentration and population density distributions, as well as the modelling results from the first tasks.

  • FP7 EC MEGAPOLI, 2008-2011