A CFD study on the effectiveness of trees to disperse road traffic emissions at a city scale

Jeanjean, Antoine; Hinchliffe, G.; McMullan, W. A.; Monks, Paul S.; Leigh, R. J.

doi:10.1016/j.atmosenv.2015.08.003

Cited by 127 publications

(83 citation statements)

References 20 publications

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“…), microclimate (Ren, Ng & Katzschner ), atmospheric pollution (Jeanjean et al . ), climate change (Gaffin, Rosenzweig & Kong ), sociology (Watkins et al . ), and politics (Heynen ).…”

Section: Discussionmentioning

confidence: 99%

“…Finer grained maps derived using what may be considered more 'scale appropriate' data (i.e. with spatial resolutions finer than 10 m) provide one solution to this problem (Pu 2011;Pu & Landry 2012;Jeanjean et al 2015). However, to date these data have been exploited principally to assess the extent of greenspace rather than its structural composition, and to deliver two-dimensional data, or at best two-and-a-half dimensional data (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

et al. 2017

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Summary Urban greenspace has a major impact on human health and quality of life, and thus the way in which such green infrastructure is constructed, managed and maintained is of critical importance. A range of studies have demonstrated the relationship between the areal coverage and distribution of vegetation and the provision of multiple urban ecosystem services. It is not known how sensitive findings are to the spatial resolution of the underlying data relative to the grain size of urban land cover heterogeneity. Moreover, little is known about the three‐dimensional (3D) structure of urban vegetation and delivery of services, and addressing such questions is limited by the availability of data describing canopy structure from the tree tops to the ground. Waveform airborne laser scanning (lidar) offers a new way of capturing 3D data describing vegetation structure. We generated voxels (volumetric pixels) from waveform lidar (1·5 m resolution), differentiated vegetation layers using height as a determinant, and computed statistics on surface cover, volume and volume density per stratum. We then used a range of widely available remote sensing products with varying spatial resolution (1 to 100 m) to map the same greenspace, and compared results to those from the waveform lidar survey. We focused on data from three urban zones in the UK with distinct patterns of vegetation cover. We found −3%, +7·5% and +26·1% differences in green surface cover compared with, respectively, town planning maps (<10 m resolution), national land cover maps (25 m) and European land cover maps (100 m). There were differences of −59·1%, +12·4% and −2·4% in tree cover compared with global (30 m resolution), European (25 m) and national (1 m) estimates. Waveform lidar captured sub‐canopy structure and detected empty spaces in the understorey which contributed a 16% bias in the total green volume derived from non‐waveform lidar observations. We conclude that waveform lidar has a key role to play in estimating important quantitative metrics of urban green infrastructure, which is important because urban greenspace is highly fragmented and shows high levels of spatial and volumetric heterogeneity.

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“…), microclimate (Ren, Ng & Katzschner ), atmospheric pollution (Jeanjean et al . ), climate change (Gaffin, Rosenzweig & Kong ), sociology (Watkins et al . ), and politics (Heynen ).…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

et al. 2017

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“…The evaluation of the reduction of pollution by urban forest in the Leicester City Center (UK) demonstrates that trees reduce concentration of ambient vehicular pollutants, at pedestrian height, on average by 7% [71]. To know the dispersion of air pollutants, a group of researchers from the Aarhus University developed Operational Street Pollution Model (OSPM) which elaborated the behavior of air masses in the street canyons, taking into account the impact of wind resulting in higher concentrations of pollutants in the leeward side than in windward ones [72].…”

Section: Green Infrastructure Directed To Phytoremediationmentioning

confidence: 99%

Air Phytoremediation

Gawroński

Gawrońska

2017

Phytoremediation

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Air pollution presently is a challenge fo-r many areas of the world. Plants are higher organisms that can best deal with this problem despite the fact often in the air is a mixture of pollutants of different origin and toxicity. The world of plants is very diverse and well adopted to changes in the environment, including air. This large biodiversity allowed to select species with a very high tolerance, which are the base for the discipline known as phytoremediation. All plants during their presence in the environment run the process of phytoremediation, but some species tolerate a very high concentration of selected pollutants. Moreover, they are able to uptake/ accumulate and next to degrade/detoxify in order to make them less harmful. Tolerant plant species can be found in very extreme conditions but for phytoremediation are useful plant species which besides being cultivatable, produce a large leaf area and biomass. Urban areas often contribute in creating high polluted sites as street canyons, road crossing, bus stops, and surrounding of heavy traffic freeway. In all these places, air pollution can be mitigated by the presence of selected plant species. Additionally, agronomic practices allow to maintain them on a polluted site and to form them in configuration for optimal deposition of pollutants. Air phytoremediation in urban areas, where at present men spend most of the time, is strongly desired and hard to overestimate if environment and human health and well-being are the prospect.

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“…Resolving three-dimensional distributions of wind flow and gas concentration in the modelling domain on small scales makes them an attractive choice compared to Lagrangian dispersion models (Leelőssy et al, 2014). The CFD model presented in this study has previously been evaluated by a comparison exercise against a wind tunnel experiment (Jeanjean et al, 2015) and measurements from an urban monitoring station . As a result of this comparison it was shown that a model accuracy of 30 to 40 % can be achieved.…”

Section: Cfd Modelmentioning

confidence: 99%

CH<sub>4</sub> emission estimates from an active landfill site inferred from a combined approach of CFD modelling and in situ FTIR measurements

et al. 2017

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Abstract. Globally, the waste sector contributes to nearly a fifth of anthropogenic methane emitted to the atmosphere and is the second largest source of methane in the UK. In recent years great improvements to reduce those emissions have been achieved by the installation of methane recovery systems at landfill sites, and subsequently methane emissions reported in national emission inventories have been reduced. Nevertheless, methane emissions of landfills remain uncertain and quantification of emission fluxes is essential to verify reported emission inventories and to monitor changes in emissions. Here we present a new approach for methane emission quantification from a complex source such as a landfill site by applying a computational fluid dynamics (CFD) model to calibrated in situ measurements of methane as part of a field campaign at a landfill site near Ipswich, UK, in August 2014. The methane distribution for different meteorological scenarios is calculated with the CFD model and compared to methane mole fractions measured by an in situ Fourier-transform infrared (FTIR) spectrometer downwind of the prevailing wind direction. Assuming emissions only from the active site, a mean daytime flux of 0.83 mg m −2 s −1 , corresponding to a spatially integrated emission of 53.3 kg h −1 , was estimated. The addition of a secondary source area adjacent to the active site, where some methane hotspots were observed, improved the agreement between the simulated and measured methane distribution. As a result, the flux from the active site was reduced slightly to 0.71 mg m −2 s −1 (45.6 kg h −1 ), and at the same time an additional flux of 0.32 mg m −2 s −1 (30.4 kg h −1 ) was found from the secondary source area. This highlights the capability of our method to distinguish between different emission areas of the landfill site, which can provide more detailed information about emission source apportionment compared to other methods deriving bulk emissions.

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A CFD study on the effectiveness of trees to disperse road traffic emissions at a city scale

Cited by 127 publications

References 20 publications

Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

Air Phytoremediation

CH<sub>4</sub> emission estimates from an active landfill site inferred from a combined approach of CFD modelling and in situ FTIR measurements

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A CFD study on the effectiveness of trees to disperse road traffic emissions at a city scale

Cited by 127 publications

References 20 publications

Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

Improving models of urban greenspace: from vegetation surface cover to volumetric survey, using waveform laser scanning

Air Phytoremediation

CH&lt;sub&gt;4&lt;/sub&gt; emission estimates from an active landfill site inferred from a combined approach of CFD modelling and in situ FTIR measurements

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Product

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CH<sub>4</sub> emission estimates from an active landfill site inferred from a combined approach of CFD modelling and in situ FTIR measurements