Dear Colleagues,

Green Infrastructures such as urban forests, green parks, corridors, roofs and walls play an essential role as nature-based solutions to circumvent the current and future extreme events affecting urban areas, with particular attention to air pollution. Therefore, understanding the overall perturbations exerted by Green Infrastructures is essential to assess their impacts on the urban microclimate and on all the physical and chemical dispersion processes. This requires accurate measurements, complemented by distinct available tools, such as numerical and physical models, able to model the exchanges within the urban atmospheric boundary layer. Computational Fluid Dynamics (CFD) models have been applied to simulate the turbulent flow dynamics and the dispersion of atmospheric pollutants within the urban surface layer. CFD models usually account for the morphological characteristics of the urban environment, being able to simulate the perturbations caused by the urban obstacles to the flow dynamics. In particular, CFD models allow simulating the impact of urban vegetation on air pollution, mainly considering the effects of trees and shrubs induced by the mechanical drag of trees or by mechanisms of deposition and filtration. Still, up to now, most of the available studies have been performed over urban-like geometries, through idealized configurations. Although the effects of Green Infrastructures on urban atmospheric dynamics have been widely studied, deeper knowledge is still required focused on the overall perturbations induced by trees on the microclimate and, consequently, on the air pollution dispersion. Despite several contributions available from outdoor measurements, wind tunnel measurements, an extensive database on idealized street canyons and several CFD studies, the current understanding of turbulent flow dynamics within and around vegetation is not sufficient, denoting local increases and decreases in wind speed and turbulence, depending on several parameters (e.g., characteristics of vegetation, urban morphology and meteorological conditions). Therefore, there is a current knowledge gap, which motivates this Special Issue, linked with the need to contribute to improve the knowledge of the effects of green infrastructures on the microclimate at a very local scale and, consequently, on-air pollutant dispersion patterns.

The current Special Issue aims to foster the scientific knowledge on the microclimate and air pollution in urban areas, evaluating the benefits of Green Infrastructures as effective and innovative solutions to increase resilience of cities towards an urban sustainable development in line with the Sustainable Development Goals adopted by the United Nations. Assessing the benefits of Green Infrastructures in urban areas strongly aligns with the Sustainability journal’s scope considering its crosscutting axis of environmental, cultural, economic, and social sustainability. The main objective of the Special Issue is to evaluate the impact of distinct Green Infrastructures on the urban microclimate and air quality, in recent past, current and future climates.     

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

• Impacts of GI on air quality using CFD models
• Impacts of GI on air quality or/and microclimate using measurements
• Assessment of GI impacts using physical modeling
• Impacts of GI on air quality using regional/ mesoscale models
• Impacts of GI on pedestrian comfort
• Impacts of GI on thermal comfort
• Benefits of GI in adapting urban areas to climate change

We look forward to receiving your contributions.

Dr. Vera Rodrigues
Dr. Sandra Rafael
Guest Editors

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• nature-based solutions
• urban environment
• air quality
• CFD modelling
• wind tunnel
• mesoscale models
• thermal comfort
• pedestrian comfort
• future climate scenarios