Grant: Discovery Grants Program - Individual

Cities, home to an increasing majority of the world's population, create important modifications to the surface and atmosphere. These changes result in distinct urban climates that affect local weather, the health of urban residents, demand for building energy, the livability of cities and the export of pollutants and greenhouse gases to larger scale climates. The temperatures of urban surfaces are a key component of urban climate because they represent a solution to the surface energy budget - the inputs and outputs of heat at the surface that control local climates. Thus, accurate measurement of urban surface temperatures is critical for understanding the processes that create urban climates, assessing risk, and informing climate mitigation and adaption efforts. Thermal remote sensing provides an attractive means of observing surface temperatures over the complex urban surface where access can be difficult and spatial variability is large. However, these sensors view only a portion of the entire three-dimensional urban surface. When the spatial resolution of the sensor is larger than the surface structure, the microscale temperature variations that arise due to surface structure and variability of surface properties result in a directionally varying temperature at the remote sensor. This directional variation is referred to as thermal anisotropy and poses a significant challenge because it means that such measurements are biased and therefore limited in their applicability to represent urban surface climates. The overall objective of this program of research is to better understand how to use thermal remote sensing to obtain representative urban surface temperatures and to apply measurements and modeling of urban surface temperature to improve our understanding of urban climates. It will characterize urban thermal anisotropy and develop models to correct for thermal anisotropy at a range of scales for urban areas. It seeks to develop a better understanding of how thermal remote sensing at different scales can provide temperature measurements relevant to the needs of Canadians: better characterization of the thermal conditions in our cities, including heat loading on urban residents and on buildings, evaluating models of urban climate, tracking changes in our urban climate over time and assessing urban heat mitigation strategies such as cool surfaces and tree cover.