Large scale exploitation of satellite data for the assessment of urban surface temperatures

Increased heat stress on urban areas due to rising heat waves is threatening people’s lives and well-being. Temperature is a crucial parameter in climate monitoring and advances in remote sensing technology have expanded opportunities for monitoring surface temperature from space. With numerous thermal satellite missions anticipated in the coming years, there is an urgent need to improve methods for retrieving surface temperatures in cities. While Earth Observation (EO) satellites excel for Land Surface Temperature (LST) retrieval, urban surface properties and geometry, along with the trade-off between temporal and spatial resolution, complicate urban surface temperature (UST) retrieval. This study explored combined use of EO data for monitoring detailed, accurate, and frequent UST. EO4UTEMP is a Living Planet fellowship project exploiting satellite data for the assessment of urban surface temperatures. A UST retrieval algorithm is developed, including emissivity corrections that account for the third dimension of the urban surface. Coupled with a thermal imagery downscaling approach, the UST retrieval algorithm is increasing the UST observation frequency. The methodology was assessed against in-situ UST measurements in Heraklion, Greece, achieving a Mean Absolute Error of 3.6 K during the day. The methodology is transferable to cities worldwide, showcasing new technologies and promoting EO data use in urban meteorology.