Infrared radiative performance of urban trees: spatial distribution and interspecific comparison among ten species in the UK by in-situ spectroscopy

Abstract

Infrared radiative performance of urban trees: spatial distribution and interspecific comparison among ten species in the UK by in-situ spectroscopy. Building and Environment, 172. 106682.

In-situ spectroscopy and shortwave radiometry reveals spatial and temporal variation in the crown-level radiative performance of urban trees

“…We found that the spatial distribution of a tree's radiative performance varied with solar time and solar altitude, and that interspecific differences in tree radiative performance levels in the IR region were strongly dependent on leaf size in dense foliage (i.e. foliage with no obvious gaps and no concave shapes in tree crown contours) (Deng et al, 2020). Based on this previous work, the present study was designed with the following aims: i) to further identify the spatial distribution profile and temporal variation in tree radiative performance during the northern hemisphere summer by combining in-situ spectroscopy and spectroradiometry, ii) to elucidate the relationship between tree crown mean transflectance in the NIR (Near Infrared) region of 800 -900 nm and tree crown surface albedo by combining in-situ spectroscopy and shortwave radiometry, and iii) to examine whether temporal variation in the tree crown surface albedo varies across different species.…”

“…Generally, previous research into urban microclimate modelling and the development of urban tree planning strategies has used simplified approaches to assess tree radiative shading effects (Lee and Park, 2008;Wang, 2014;Upreti et al, 2017;Zhang et al, 2018;Eckmann et al, 2018;Simon et al, 2018). Tree crown surface albedo for a species is commonly assumed to be a constant in microclimate environment modelling (Eckmann et al, 2018) and in developing urban planning strategies (Zhang et al, 2018); however, temporal variation in tree crown transflectance throughout a day has been demonstrated (Deng et al, 2020). Therefore, to better understand urban tree radiative shading effects, the radiative performance within and between multiple tree species should be examined more closely, especially in the infrared (IR) region.…”

“…Previously, we established a methodology to characterise the IR radiative performance of urban trees by in-situ tree crown spectroscopy (Deng et al, 2019), and employed the method to solve two research questions (Deng et al, 2020): determining the spatial distribution of tree crown transflectance for individual trees, and identifying interspecific differences in tree radiative performance in the IR region. We found that the spatial distribution of a tree's radiative performance varied with solar time and solar altitude, and that interspecific differences in tree radiative performance levels in the IR region were strongly dependent on leaf size in dense foliage (i.e.…”

“…In the present study of tree crown transflectance across species, identical measuring instruments and test facilities were used as in our earlier work (Deng et al, 2020).…”

Evaluation of shade profiles while walking in urban environments: A case study from inner suburban Sydney, Australia

“…Tree-lined streets, alongside suburban parks or 'greenspaces', are included in a broad definition of natural environments [1] that are beneficial for human well-being [2]. In terms of physical well-being, urban treescapes can provide relief to pedestrians by improving thermal comfort and mitigating, on a local level, the urban heat island effect [3] [4]. However, measurements of shade at street level is still imprecise, particularly when it comes to tree shade and effects of diffuse reflected light from street structures [2] [5].…”