Abstract
Local aerodynamic roughness parameters (zero-plane displacement, zd, and aerodynamic roughness length, z0) are determined for an urban park and a suburban neighbourhood with a new morphometric parameterisation that includes vegetation. Inter-seasonal analysis at the urban park demonstrates zd determined with two anemometric methods is responsive to vegetation state and is 1–4 m greater during leaf-on periods. The seasonal change and directional variability in the magnitude of zd is reproduced by the morphometric methods, which also indicate z0 can be more than halved during leaf-on periods. In the suburban neighbourhood during leaf-on, the anemometric and morphometric methods have similar directional variability for both zd and z0. Wind speeds at approximately 3 times the average roughness-element height are estimated most accurately when using a morphometric method which considers roughness-element height variability. Inclusion of vegetation in the morphometric parameterisation improves wind-speed estimation in all cases. Results indicate that the influence of both vegetation and roughness-element height variability are important for accurate determination of local aerodynamic parameters and the associated wind-speed estimates.
Highlights
Theservices of urban vegetation are both context and scale specific, cannot be generalised (Salmond et al 2016)
It is imperative that the understanding of the physical implications of urban vegetation is improved across micro, local, and regional scales
This extends beyond urban parks and vegetation in street canyons – as the edges of cities are approached vegetation may become the most prominent roughness elements (e.g. Giometto et al 2017, Kent et al 2017a)
Summary
The (dis)services of urban vegetation are both context and scale specific, cannot be generalised (Salmond et al 2016). Gill et al 2007; Landry and Chakraborty 2009; Roy et al 2012; Andersson-Sköld et al 2015; Kremer et al 2015; Salmond et al 2016; Ward and Grimmond 2017). It is imperative that the understanding of the physical implications of urban vegetation is improved across micro-, local-, and regional scales. This extends beyond urban parks and vegetation in street canyons – as the edges of cities are approached vegetation may become the most prominent roughness elements This extends beyond urban parks and vegetation in street canyons – as the edges of cities are approached vegetation may become the most prominent roughness elements (e.g. Giometto et al 2017, Kent et al 2017a)
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