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ABSTRACT
A better understanding of the urban heat island (UHI) effect can be facilitated by ac-curately measuring urban geometry. One commonly utilized approach is to calculate the sky-view factor (SVF), which represents the proportion of the sky visible from a given location. The overall purpose of this study is to assess the spatial distribution of SVF values for various land use classes in Athens, GA. Since fish-eye lens imagery can effectively capture the complex nature of the urban canyon, I used a simplistic photographic methodology. I took fish-eye photographs within four land use classes (downtown, commercial, residential and rural/open space) and used graphics soft-ware to calculate the SVF values from the imagery. It was discovered that the lowest SVF values were located close to the urban core in the residential and downtown areas while the highest values were observed in the more peripheral commercial and rural/open space areas. These results suggest that an UHI could potentially exist in downtown Athens.
Key Words: urban heat island, sky-view factor, fish-eye photography, Athens (GA)
INTRODUCTION
Urban surface geometry has a significant but complex influence on the urban atmo-sphere. The taller buildings characteristic of urbanized areas often act to restrict out going long-wave radiation, which can thwart nocturnal cooling and contribute to an urban heat island (UHI) effect (Oke 1981). The UHI phenomenon is important because it partially explains why cities can sometimes experience higher temperatures when com-pared with the surrounding countryside (Coutts et al. 2007). High levels of urban heating have been linked to poor urban air quality (Sarrat et al. 2006) as well as altered precipitation (Shepherd 2006) and snowmelt patterns (Todhunter et al. 1992; Semá deni- Davies & Bengtsson 1998). Furthermore, as the areal extent of cities expands (Lang & Knox 2009), the impact of urban landscapes and the subsequent UHI effect may no longer be confined to just the urban core, but spread to more suburban regions (Stone et al. 2010; Stone and Rodgers 2001).
Consequently, a better understanding of the UHI effect can be facilitated by accurately measuring urban geometry. One commonly utilized approach is to calculate the sky-view factor (SVF), which can be simply defined as "a measure of the degree to which the sky is obscured by the surroundings for...