Monday, February 15, 2016

Mapping Micro-Urban Heat Islands

Heat Islands are becoming more prevalent as cities continue to grow. Typically in urban areas, heat islands are sections within the geography that produce a higher surface temperature than those associated with surrounding rural areas and radiate heat from the center point with the highest temperature. Factors that contribute to the development of these islands include street canyons (a street with buildings on either side that create a valley or canyon between the structures), thermal effects of heat storage and release from the ground and synthetic materials of man-made structures, and waste heat from buildings and residential areas. In this study, to detect the presence of heat islands in Dallas, Texas, satellite images of tree coverage are compared to a map of average heat spectrum of the city. Lack of trees correlate to higher temperatures and suggest that heat islands are a direct result from tree loss. Older neighborhoods with mature trees support this claim, with an average of 5 degrees Fahrenheit lower than newer neighborhoods with younger trees and less shade coverage. Areas such as parking lots and warehouse districts were the hottest, ranging 2-8 degrees Fahrenheit warmer than rural areas in the same region. The findings of this study support an initiative to restore tree coverage to decrease CO2 emissions within Dallas and propose installing small banks of dense tree coverage.

Map of canopy cover (white) and micro-urban heat islands (black)

Aniello, C., Morgan, K., Busbey, A., & Newland, L. (1995). Mapping micro-urban heat islands using Landsat TM and a GIS. Computers & Geosciences21(8), 965-969.

I have acted with honesty and integrity in producing this work and am unaware of anyone who has not. Mattie Cryer


  1. This is a really interesting connection between trees and urban heat islands -- I wonder if the other factors influencing the creation of heat islands (street canyons, man-made structures, and waste heat) could be so easily mapped as well. Is the connection of these factors to heat islands less clear than is seen with trees?

  2. It would be interesting to see a heat island map from a city like Sacramento, that has a high density of trees and how that correlates to having a nice cool temperature.

  3. Tree coverage in a city not only reduces heat islands and CO2, it also has psychological benefits for people and provides habitat for urban animals. But neighborhoods with lots of trees tend to have large yards and would probably sprawl much more than an more compact apartment with few trees. I don't know of any simple way to map the advantages and disadvantages, but it would be interesting to compare those additional factors as well.