Rapid determination of canyon geometry parameters for use in surface radiation budgets

Chapman, Lee; Thornes, John E.; Bradley, Andrew V.

doi:10.1007/s007040170036

Cited by 75 publications

(58 citation statements)

References 11 publications

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“…Several authors discuss the time-consuming process of gathering spatial sky view information and the development of mobile continuous measurement techniques (Postgård 2000;Chapman et al 2001a;Bradley et al 2001;Grimmond et al 2001). The energy exchange surface is basically the ground surface and to make mobile data collection possible a fish-eye camera lens needs to be mounted on some kind of vehicle, i.e., above ground level.…”

Section: Sky View Factor At Ground Level or At Sensor Heightmentioning

confidence: 99%

“…The SVF is naturally not the sole parameter that explains the air temperature pattern in an urban area. Neither is the SVF sufficient to describe the effect of canyon geometry during daytime at locations with an obstructed sky hemisphere when shade and the blocking of direct sun radiation may be a problem (Oke et al 1991;Chapman et al 2001a). …”

Section: Parameters Important For Air Temperaturementioning

confidence: 99%

“…The SVF expresses the ratio between radiation received by a planar surface and that from the entire hemispheric radiating environment (Watson & Johnson 1987). Parameters such as anthropogenic heat release and thermal properties of material are related to the intensity of the T u-r but simulations show that the SVF alone can produce a T u-r with a magnitude of 7 • C (Oke 1981;Oke et al 1991;Chapman et al 2001a). For low wind speeds the intensity of the T u-r is a function of the city centre's SVF, a relationship which is explained when it is noted that the development of the T u-r at night is partly due to long-wave radiation losses in the city (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Different methods have also been used to express urban geometry or calculate the SVF. It has been calculated as height/width ratio (Oke 1981;Johnson & Watson 1984), graphically (Watson & Johnson 1987), from fish-eye photographs (Steyn 1980;Bärring et al 1985;Holmer et al 2000;Chapman et al 2001a;Grimmond et al 2001), with the aid of a three-dimensional (3-D) building database , and recently using GPS receivers and satellite data (Chapman et al 2002). Fish-eye photographs have the advantage of the 3-D perspective as opposed to the 2-D SVF factors derived from height/width ratios or, in asymmetric canyons, the multiple calculations due to segmentations of the hemisphere (Bradley et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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Sky view factor analysis – implications for urban air temperature differences

Svensson¹

2004

Meteorological Applications

228

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Section: Sky View Factor At Ground Level or At Sensor Heightmentioning

confidence: 99%

Section: Parameters Important For Air Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sky view factor analysis – implications for urban air temperature differences

Svensson¹

2004

Meteorological Applications

228

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“…Several efforts have also been made to improve the computations and make them faster and more effective so that more photographs could be processed in a shorter time (e.g. Holmer et al, 2001;Chapman et al, 2001;Grimmond et al, 2001). Due to the development of new techniques and the increased availability of spatial data in various digital formats, new geometrical parameters such as the weighted volumetric compactness that characterize the volume, structure and thermodynamic role of buildings have been derived (Unger, 2006).…”

Section: Introductionmentioning

confidence: 99%

Modelling the urban climate using a local governmental geo‐database

Lindberg

2007

Meteorological Applications

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ABSTRACT:In this study, local government digital spatial data are used to describe urban geometry and analyse spatial variations of the urban climate within the central areas of Göteborg, Sweden. A high-resolution raster digital elevation model (1 m pixel resolution) consisting of building structures and ground heights is derived from a local government geodatabase, as well as land use patterns and artificial heat sources. Parameters such as the sky view factor (SVF) and daily averages of solar radiation are calculated. Results obtained from the model are compared with intra-urban air temperature variations which are derived from mobile measurements, as well as surface temperature variations derived from thermal infrared images. Results show that high-resolution digital elevation models in raster format are very useful sources of data for the investigation of intra-urban temperature variations. Results also show that the areal mean of SVF correlates with intra-urban air temperature variations to a higher degree than SVF that is taken from a point source location. The correlation between the modelled SVF and surface temperature is high during both spring and winter. Adding information about daily averages of global radiation for the spring measurement causes the correlation between SVF and surface temperature variations to increase.

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Sky view factor analysis of street canyons and its implications for daytime intra‐urban air temperature differentials in high‐rise, high‐density urban areas of Hong Kong: a GIS‐based simulation approach

Chen¹,

Ng²,

An³

et al. 2010

Intl Journal of Climatology

337

121

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Hong Kong is a high-density sub-tropical city with 7 million people living in an urban area of just over 260 km 2 . Tall and closely packed buildings are the common urban morphology. How the urban geometry influences the microclimate in summer daytime is a primary planning concern. The sky view factor (SVF) has been commonly used to indicate the impact of urban geometry on air temperature differences in cities. However, only limited discussions in this aspect have been addressed for daytime course in high-rise and high-density urban environment such as Hong Kong. This paper firstly provides a comprehensive review of SVF analysis in urban climatology studies and then presents a simulation approach to investigate the role of SVF in determining summer daytime intra-urban air temperature differences in urban Hong Kong. An ArcGIS-embedded computer program is developed for calculating continuous SVF values for an entire urban environment and an SVF map is generated. The result is evaluated against meteorological data observed in field measurements. The regression analysis shows that the spatial average of SVF values has a close negative relationship with daytime intra-urban temperature differences. The study indicates that SVF is a significant factor for understanding the microthermal climate in Hong Kong's street canyons. The paper further raises discussions on the application of SVF analysis to urban planning. The study demonstrates that the SVF analysis is a useful and effective tool for planners and urban climatologists conducting studies on high-rise and high-density sub-tropical cities. The understanding can provide support for the development of planning standards and good practice.

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Rapid determination of canyon geometry parameters for use in surface radiation budgets

Cited by 75 publications

References 11 publications

Sky view factor analysis – implications for urban air temperature differences

Sky view factor analysis – implications for urban air temperature differences

Modelling the urban climate using a local governmental geo‐database

Sky view factor analysis of street canyons and its implications for daytime intra‐urban air temperature differentials in high‐rise, high‐density urban areas of Hong Kong: a GIS‐based simulation approach

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