Urban Heat Island Characterization with Airborne Thermal Infrared Hyperspectral Imaging

The higher concentration of man-made objects like asphalt pavement and concrete structures within urban areas lead to the formation of subareas known as urban heat islands (UHI), where the ambient temperature is significantly higher. Having a good understanding of this problem is critical for better urban development. Thermal infrared (TIR, 8-12 μm) remote sensing is often used to localize UHI. However, surface temperature measurement using conventional broadband TIR sensors cannot account for the spectral emissivity properties of the materials leading to erroneous surface temperature estimates. In this work, airborne TIR hyperspectral imaging (HSI) was carried out on urban areas at high spectral resolution. The thermodynamic temperature maps obtained after temperature-emissivity separation (TES) display sharper thermal contrast associated with UHI, making their identification easier. A chemical map of quartz (SiO2), a material used in the fabrication of many buildings and roads, highlights the close association between UHI and manmade objects.