Urban Heat Island Studies Using Satellite Imagery Coupled with Field Measurements: A Case Study from Chattanooga, TN

Urban and suburban areas experience elevated temperatures compared to their surrounding rural areas. This is well known as the urban heat island (UHI) effect, which is a common and an important effect of urbanization. The UHI effect is well known for the large cities around the world, and most of the recent studies were conducted there. UHI effects are less intense or less frequent in smaller urban areas compared to larger urban areas. However, this is not well understood since there is a significant lack of UHI effect studies on smaller cities. The city of Chattanooga, TN, is one of the fastest-growing cities in Tennessee. As urbanization continues in the greater Chattanooga area, it is very important to understand the possible UHI effect on sustainable development efforts in this area. Remote sensing technology has been used successfully to study the UHI effect for many large cities in the United States and the rest of the world. Using thermal images acquired by NASA’s Landsat‐8 satellite during the summers of 2018 and 2019, a recent study conducted in the Geological and Environmental Remote Sensing Laboratory at the University of Tennessee at Chattanooga found that the city of Chattanooga behaves like an UHI, and its effect is significant. Recently, we installed eight temperature-measuring stations across the city of Chattanooga, TN, to acquire air temperature at a 2‐m height from the ground. We have been acquiring temperature data every 10 min since March 2023. This study incorporated ground measured air temperature with the ongoing remote sensing-based study to better understand the UHI effect. The obtained results confirmed that the city of Chattanooga, TN, indeed behaves like an UHI. Both satellite-derived land surface temperature and direct air temperature measurements clearly captured the UHI effect, and their UHI profiles were comparable, with root mean square error values ranging from 5.0 to 7.5°F for different dates and 2.2 to 7.7°F for each station. While thermal images are particularly useful for mapping the spatial variation of UHI effects, air temperature measurements provide the advantage of capturing temporal variations throughout the day.