Radiative Exchange in an Urban Street Canyon

Harman, Ian N.; Best, Martin; Belcher, Stephen E.

doi:10.1023/a:1026029822517

Cited by 106 publications

(117 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As shown in Figure 4 for two sets of material emissivity, the bulk emissivity values imply higher absorption and emission from the canyon tile (H/W > 0), than a flat surface. Note that Figure 4 is similar to Figure 4 in Harman et al (2004a). While this parametrization aims at representing the impact of long-wave exchange within the canyon box, urban emissivities are usually measured to be lower than other land-cover surfaces (Jin et al, 2005).…”

Section: Bulk Emissivitymentioning

confidence: 89%

“…The physics of the parametrization relies on the simplification of a four-facet single-layer model (Harman et al, 2004a, b;Harman and Belcher, 2006). In particular, radiative exchange within the canyon is formulated with an effective albedo and an effective emissivity (Harman et al, 2004a). Heat transfer relies on the formulation of effective roughness lengths for momentum and for heat (Harman et al, 2004b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Implementation of a new urban energy budget scheme in the MetUM. Part I: Description and idealized simulations

Porson

Clark

Harman

et al. 2010

Quart J Royal Meteoro Soc

117

View full text Add to dashboard Cite

Section: Bulk Emissivitymentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Implementation of a new urban energy budget scheme in the MetUM. Part I: Description and idealized simulations

Porson

Clark

Harman

et al. 2010

Quart J Royal Meteoro Soc

117

View full text Add to dashboard Cite

“…Although an infinite number of radiative reflections can be resolved analytically in a street canyon with homogeneous facets (Harman et al, 2004), extension of the algorithm to an urban canyon with subfacet heterogeneity (see Figure 1) is not trivial and involves expensive matrix operations with large dimensions. It has been verified that a two-reflection model is sufficient for typical urban surface temperatures and thermal properties (Wang, 2010) and is adopted in this article.…”

Section: Radiation Budgetsmentioning

confidence: 99%

“…. denotes the index of each subsurface of a facet; and F ij are the sky view factors computed as (Harman et al, 2004):…”

Section: Radiation Budgetsmentioning

confidence: 99%

A coupled energy transport and hydrological model for urban canopies evaluated using a wireless sensor network

Wang

Bou‐Zeid

Smith

2012

Quart J Royal Meteoro Soc

193

145

View full text Add to dashboard Cite

We propose a new surface exchange scheme coupling the transport of energy and water in urban canopies. The new model resolves the subfacet heterogeneity of urban surfaces, which is particularly useful for capturing surface exchange processes from vegetated urban surfaces, such as lawns or green roofs. We develop detailed urban hydrological models for surfaces consisting of either natural (soil and vegetation) or engineered materials with water-holding capacity. The coupling of energy and water transport enables us to parametrize surface evaporation from different urban facets including soils, vegetation and water-holding engineered surfaces. The new coupled model is evaluated using field measurement data obtained through a wireless sensor network deployed over the Princeton University campus. Comparison of model prediction and measured results shows that the proposed surface exchange scheme is able to predict widely varying surface temperatures for each subfacet with good accuracy. Different weather conditions and seasonal variability are found to have insignificant effect on the model performance. The new model is also able to capture the subsurface hydrological processes with reasonable accuracy, particularly for urban lawns. The proposed model is then applied to assess different mitigation strategies of the urban heat island effect.Key Words: urban canopy model; urban hydrology; urban heat island; land-atmosphere interaction; water-holding pavements

show abstract

“…By evaluating the exchange of diffuse radiation within an urban canyon, Harman et al [56] found that the averaged net radiative flux density from canyon facades decreases monotonically as the canyon aspect ratio increases. A climate measurement in Athens, Greece showed that a clear increase in cooling rates can be observed when decreasing aspect ratios [57].…”

Section: Aspect Ratiomentioning

confidence: 99%

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

et al. 2017

View full text Add to dashboard Cite

This paper presents a literature review on urban design indicators addressing the impact of urban geometry and vegetation on the outdoor thermal environment at the pedestrian level, as urban geometry and vegetation have been regarded as the most influential urban design factors that affect outdoor microclimate. The thermal balance concept is first introduced to elaborate how each component of energy fluxes is affected by the urban built environment, which helps to explore the underlying thermophysical mechanisms of how urban design modifies the outdoor thermal environment. The literature on numerous urban design descriptors addressing urban geometric characteristics is categorized into five groups in this paper according to the design features that the parameters entail, including land use intensity, building form, canyon geometry, space enclosure and descriptive characteristics. The literature on urban vegetation descriptors is reviewed together, followed by the combined effect of urban geometry and vegetation. This paper identifies a series of important urban design parameters and shows that the impact of design parameters on thermal environment varies with time, season, local climate and urban contexts. Contradictory impacts often occur between daytime and nighttime, or different seasons, which requests trade-offs to be achieved when proposing design strategies.

show abstract

Radiative Exchange in an Urban Street Canyon

Cited by 106 publications

References 18 publications

Implementation of a new urban energy budget scheme in the MetUM. Part I: Description and idealized simulations

Implementation of a new urban energy budget scheme in the MetUM. Part I: Description and idealized simulations

A coupled energy transport and hydrological model for urban canopies evaluated using a wireless sensor network

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

Contact Info

Product

Resources

About