Gianluca Pappaccogli1, Lorenzo Giovannini2, Dino Zardi2
1 Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bolzano, Italy
2 Atmospheric Physics Group – Department of Civil, Environmental and Mechanical Engineering – University of Trento, Trento, Italy
The city of Bolzano is located in the north-eastern Italian Alps, in a basin at the crossing of three valleys. Climatic conditions in the city are tightly connected with the complex topography of the surrounding area, influencing in particular the flow field, mainly characterized by daily-periodic up- and down-valley winds from tributary valleys, especially in the warm season. The present work aims at assessing the role of vegetation solutions in the urban area in such a complex environment, in view of providing a basis for planning sustainable development policies in the city. Such policies aim at an efficient use of environmental resources (including energy), and at improving the quality of the urban environment, mitigating undesirable urbanization effects. For this purpose, high-resolution simulations with the Weather Research and Forecasting (WRF) model coupled with an advanced urban parameterization scheme were carried out over the city of Bolzano, focusing in particular on the impact of different mitigation strategies, involving use of vegetation, on climatic conditions. Fine-scale parameters quantifying urban morphology (e. g. building plan and area fraction, average and distribution of building height) and spatial vegetation distribution were evaluated, to provide high-resolution input datasets for the urban parameterization scheme. Model results were first validated by means of comparison with data from a network of permanent conventional weather stations in the area. Then, the impact of the vegetation was estimated both at the city and at the microclimatic scale, investigating the thermal characteristics of the Urban Canopy Layer (UCL).
Keywords: urban meteorology, urban vegetation, mesoscale modeling, WRF, urban parameterizations