In this article, the author discusses how LANDSAT TM satellite data and GIS software were used to map micro-urban heat islands in a portion of Dallas, Texas. Unsupervised classifications were performed on a LANDSAT sub-scene to extract tree cover information which was merged with TM data to make a map showing the location of micro-urban heat islands and wooded areas. Heat islands are generally described as urban areas that produce higher than background surface temperatures associated with rural surroundings. Major factors leading to the formation of heat islands include; the effects of street canyon geometry on radiation, the effects of thermal properties on heat storage release, and waste heat from residential and other buildings.
The study area within Dallas is named White Rock Lake. It contains both older and newer residential neighborhoods, major highways, shopping centers, a warehouse district, wooded areas, and a large lake, providing variable land cover with contrasting thermal regimes. The methodology for mapping out the area involves LANDSAT TM processing and classification, thermal map generation, and GIS merging and final map production.
In the figure above, the hot spots in the White Rock Lake area exist as heat island patterns with the warmest temperatures in the center and coolest temperatures around the edges.
After examining the maps, it was noted that hot spots throughout this urban area were radiative in nature. The hottest areas were where land use was associated with impervious cover such as a large warehouse district, asphalt parking lots and roads, and a large number of apartment complexes. Also, new neighborhoods were significantly warmer than older neighborhoods. The coolest areas were those with heavy tree cover, including the forested park just north of the lake.
LINK TO THE ARTICLE: http://www.sciencedirect.com/science/article/pii/0098300495000335
Aniello Cathy, Morgan Ken, Busbey Arthur, and Newland Leo (1994). Mapping Micro-Urban Heat Islands Using LANDSAT TM And A GIS. Computers & Geoscience. Vol. 21, No.8.