手法を比較

	Urban Heat Island Analysis	Compactness Index
分野	Urban Studies	Urban Studies
系統	Process / pipeline	Process / pipeline
提唱年	1982	2010
提唱者	Tim R. Oke (energetic basis of the UHI)	Geographic shape-analysis tradition (Richardson, Cole; codified by Angel, Parent & Civco)
種類	Measurement of the temperature excess of urban areas relative to their rural surroundings	Geometric/morphological index of how compact a settlement footprint is
原典	Oke, T. R. (1982). The energetic basis of the urban heat island. Quarterly Journal of the Royal Meteorological Society, 108(455), 1–24.	Angel, S., Parent, J., & Civco, D. L. (2010). Ten compactness properties of circles: Measuring shape in geography. The Canadian Geographer, 54(4), 441–461.
別名	UHI Analysis, Urban Heat Island Intensity, Surface Urban Heat Island (SUHI) Analysis, Land Surface Temperature Differential	Shape Compactness Measure, Polsby-Popper Index, Richardson Compactness, Perimeter-Area Compactness
関連	4	4
概要	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.	A compactness index measures how compact the shape of a settlement, district, or built-up area is, almost always by comparing it to the circle — the most compact shape enclosing a given area. Classic indices such as the Polsby–Popper or Richardson ratio compare a polygon's area to its perimeter, while more elaborate measures compare interpoint distances or fitted circles, all returning a value of one for a perfect circle and falling toward zero as the shape becomes elongated, indented, or fragmented. Angel, Parent and Civco systematized these into a coherent family by showing that the circle is optimal on ten distinct geometric properties, clarifying which index answers which question.