DEVELOPMENT OF A MODELLING CHAIN FROM CONTINENTAL TO URBAN SCALE APPLIED OVER ITALY

The recent implementation of a modelling system interfacing the meteorological chain GLOBO-BOLAM-MOLOCH with the LES building-resolving model PALM-4U is presented. For the accurate modelling of the urban climate and air quality, a detailed local environment description and realistic meteorological boundary conditions are needed. Our current efforts are aimed at (i) preparing detailed static drivers for the region of interest, with a special focus on the buildings and vegetation characterization, and (ii) implementing the dynamic drivers by using the regional meteorological model MOLOCH as boundary conditions. Preliminary applications of the system regarded a 1-km squared area in the city of Bologna (“Bolognina” case study), characterized by a high presence of public and private greenery, and the city center of Catania (“CT Digital-twin” case study), where the focus is on resolving the flow in built environment and assessing the impact of emissions from the streets. For both experiments, the meteorological boundary conditions were provided by the convection-permitting MOLOCH model. For Bolognina, to compile the static driver, we adopted various data sources, including remote sensing, municipal data collections and open data. For private trees, a specific census was carried out. This led to the creation of a geodatabase of public and private trees with detailed information including more than 5000 elements. For CT-Digital twin, the static input files include the DEM data of the buildings in the area and the relative road graph classified according to OpenStreetMap. Our preliminary findings pointed out: in Bolognina case study, the extremely detailed information on the urban vegetation, down to the single tree, allowed testing and assessing NBS (Natural-Based Solutions) strategies in urban context. Such modelling system proved to be a suitable tool for testing natural mitigation strategies in urban context and for evaluating their effectiveness; in CT Digital-twin test, we were able to provide a demo on the potentiality of this modelling approach for the implementation of digital twins of urban environments. The fields output from the modelling system can be used to assess different scenarios of air quality and human comfort depending, for instance, on emission-reduction strategies. This, leads to useful guidelines for urban planners and decision makers in devising specific mitigation plans for their cities.