手法を比較

	Urban Canyon Analysis	Sky View Factor Analysis
分野	Urban Studies	Urban Studies
系統	Process / pipeline	Process / pipeline
提唱年	1988	1981
提唱者	Timothy R. Oke	Timothy R. Oke (urban-climate application)
種類	Pipeline for characterising street-canyon geometry and its microclimatic effects	Pipeline for computing the fraction of visible sky from a point in urban geometry
原典	Oke, T. R. (1988). Street design and urban canopy layer climate. Energy and Buildings, 11(1-3), 103–113.	Oke, T. R. (1981). Canyon geometry and the nocturnal urban heat island: comparison of scale model and field observations. Journal of Climatology, 1(3), 237–254.
別名	Street Canyon Analysis, Canyon Aspect Ratio Analysis, Urban Canopy Layer Analysis, H/W Ratio Analysis	SVF Analysis, Sky View Factor Mapping, Sky Openness Analysis, Skyview Factor
関連	4	4
概要	Urban canyon analysis characterises a street flanked by buildings as a 'canyon' and studies how its geometry — chiefly the ratio of building height to street width — governs airflow, radiation, temperature, and pollutant dispersion within it. The single most important descriptor is the aspect ratio H/W, which determines whether wind skims over the top, recirculates inside, or interacts between adjacent canyons. The framework was set out by Timothy Oke's 1988 paper on street design and the urban canopy layer, which tied canyon geometry to the microclimate of the air below roof level.	Sky view factor (SVF) analysis quantifies the fraction of the overlying hemisphere of sky that is visible from a given point on the ground, ranging from 1.0 in a wide-open field to near 0 at the bottom of a deep, narrow street canyon. It is a central geometric descriptor in urban climatology because the amount of visible sky governs how much longwave radiation a surface can lose at night, directly shaping the urban heat island. The measure was put on a rigorous footing by Timothy Oke's 1981 work linking canyon geometry to nocturnal urban warming.