Urban heat island map

Satellite-derived urban heat island map reveals thermal differences between cities and rural areas, essential for climate studies and urban planning.

About this subject

Urban heat islands (UHI) are phenomena where metropolitan areas experience significantly higher temperatures than their rural surroundings. This effect occurs due to the replacement of natural surfaces with materials like asphalt, concrete, and dark roofing, which absorb and retain heat. Additionally, lack of vegetation reduces cooling through evapotranspiration. Satellites such as Landsat and MODIS (Moderate Resolution Imaging Spectroradiometer) capture land surface temperature with spatial resolutions ranging from 30 meters to 1 kilometer, enabling detailed UHI maps. These data undergo atmospheric correction and calibration algorithms, resulting in images that highlight the hottest spots within cities.

In Brazil, cities like São Paulo and Rio de Janeiro suffer from strong UHI. Studies show central São Paulo can be up to 6 °C hotter than peripheral green areas. Satellite mapping assists local governments in identifying critical zones and implementing solutions such as green roofs, permeable pavements, and tree planting. In 2023, Rio de Janeiro's Cidade + Verde program used thermal imagery to prioritize tree planting in the most affected neighborhoods.

Globally, UHIs intensify heatwaves, increase energy consumption for cooling, and exacerbate respiratory illnesses. With climate change, the frequency and intensity of these events are expected to rise. UHI maps are vital tools for urban planners and policymakers, helping create more resilient and sustainable cities with better quality of life.

Frequently Asked Questions

What is an urban heat island?

It is a phenomenon where urban areas experience higher temperatures than nearby rural areas, caused by replacement of natural surfaces with heat-absorbing materials like asphalt and concrete, and reduced vegetation.

How do satellites map urban heat islands?

Satellites with thermal infrared sensors, such as Landsat and MODIS, measure land surface temperature. The data is processed to create maps highlighting thermal differences between urban and rural areas.

How do urban heat islands affect health?

They intensify heatwaves, increasing risks of heatstroke, dehydration, and worsening respiratory and cardiovascular diseases. They also elevate air pollution by favoring ground-level ozone formation.