Urban Heat Island Mapping
Definition
Urban heat island (UHI) mapping quantifies how built areas are warmer than surrounding rural zones due to materials, geometry, and reduced evapotranspiration. Analysts combine land surface temperature from thermal imagery with air-temperature sensors, land cover (imperviousness, canopy), building footprints, and morphology metrics like sky-view factor. Day vs night cycles, humidity, and wind regimes are considered to distinguish heat storage from direct solar gain. Maps report intensity, hotspots, and drivers with uncertainty bands, guiding interventions that reduce harmful exposure.
Application
Public health prioritizes cooling centers and outreach. Urban forestry targets tree planting where shade reduces afternoon peaks. Transportation departments evaluate cool pavements and bus-stop shelters. Planners adjust zoning to require shade and reflective roofs. Developers use results to design courtyards and ventilation corridors that break heat build-up.
FAQ
Why does nighttime mapping matter as much as daytime?
Nighttime temperatures correlate strongly with health outcomes because bodies lack time to recover; stored heat in materials controls nights.
How can equity be embedded in UHI analysis?
Overlay heat with age, health, income, and AC prevalence; prioritize neighborhoods with high exposure and low adaptive capacity.
What pitfalls arise when using only satellite surface temperature?
Surface temperature and air temperature diverge under wind and humidity; complement with in-situ sensors or modeled air temps.
How do you measure intervention success over time?
Set baselines, monitor canopy growth and surface albedo, and compare heat metrics during similar weather using matched days and trend analysis.
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