Microscale air quality modelling refers to air quality modelling at high spatial resolution (typically down to a scale in the order of one meter), usually focused on urban environments. This type of modelling applications is more and more used in the AAQD policy context, driven by the fact that more and more exceedances occur at local hotspots which require high spatial resolution for understanding their causes and setting up specific and localized measures to mitigate the problem. The focus points of this working group are thus:

• 1 Testing the robustness of approaches to retrieve annual averaged concentrations (and other AAQD statistics such as percentiles), in particular by assessing the importance of meteorology: e.g. understanding differences between unsteady full year simulations vs scenario (wind sector) approach.
• 2 Specifying simulation requirements in terms of input data (e.g., microscale emission inventories, meteorological data) and observation datasets for validation.
• 3 Providing guidance for microscale model applications in the context of the AAQD, e.g. derivation of exceedance situation indicators, spatial representativeness area of monitoring stations, ... (link with WG8)