手法を比較

	Sky View Factor Analysis	Urban Heat Island Analysis
分野	Urban Studies	Urban Studies
系統	Process / pipeline	Process / pipeline
提唱年	1981	1982
提唱者	Timothy R. Oke (urban-climate application)	Tim R. Oke (energetic basis of the UHI)
種類	Pipeline for computing the fraction of visible sky from a point in urban geometry	Measurement of the temperature excess of urban areas relative to their rural surroundings
原典	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.	Oke, T. R. (1982). The energetic basis of the urban heat island. Quarterly Journal of the Royal Meteorological Society, 108(455), 1–24.
別名	SVF Analysis, Sky View Factor Mapping, Sky Openness Analysis, Skyview Factor	UHI Analysis, Urban Heat Island Intensity, Surface Urban Heat Island (SUHI) Analysis, Land Surface Temperature Differential
関連	4	4
概要	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.	Urban heat island (UHI) analysis quantifies how much warmer cities are than the rural land around them, a difference driven by impervious surfaces, reduced vegetation, waste heat, and street-canyon geometry that traps radiation. The intensity of the effect is defined simply as the urban-minus-rural temperature differential, a framework given its physical, energy-balance foundation by Tim Oke in 1982. Modern analysis increasingly maps the surface UHI from thermal satellite imagery, converting radiance to brightness temperature and then to land surface temperature so the heat island can be observed continuously across an entire metropolitan area rather than at a few weather stations.