Extreme heat episodes in cities, which are becoming increasingly intense, frequent and prolonged, pose a threat to both the environment and the health of citizens. Counteracting these effects requires not only understanding their causes, but also designing strategies to adapt to the changing climate conditions resulting from global warming.
Given that the spatiotemporal dynamics of surface temperature are closely related to land cover-very heterogeneous in urban areas-and atmospheric conditions, the study conducted by the team from the University of Valencia (UV) has collected data from the ECOSTRESS and Landsat satellites to monitor, at very high resolution, the land surface temperature (LST) in the city of Valencia (Spain). From a selection of 17 representative images during July and August 2022 and 2023, they have been able to monitor both the temperature and surface urban heat islands (SUHI), that is, the city’s hot spots or critical areas. This has resulted in the creation of the first high-resolution map of local climate zones for the city of Valencia, which has become a model for climate studies in Mediterranean cities.
Published in the International Journal of Applied Earth Observation and Geoinformation (Elsevier), the study samples urban surface temperatures by zones-tracked on a 10-metre scale-and by time zones-day and night; it delimits heat islands and provides valuable information for urban and environmental policymakers to effectively address problems associated with extreme weather.
The study details the specificity of each area according to the ’local climate zones - LCZ’ classification scheme, a guide that provides urban planners and architects with a novel perspective on the influence of land cover on the thermal dynamics of the urban environment. "Policymakers should closely monitor the buildings and surfaces most affected during heat waves and propose corresponding mitigation measures to improve the environment", comments José Antonio Sobrino, professor of Earth Physics and Thermodynamics at the UV, and principal investigator of this work conducted by the Global Change Unit (UCG) of the Image Processing Laboratory (IPL) at the University of Valencia.
The results indicate which types of buildings experience greater heat intensity and identify particularly hot spots; they provide evidence of the relationship between the presence of vegetation and night-time cooling and allow us to deduce, for example, that the low heat dissipation capacity of compact, high-rise buildings leads to a higher heat effect during the night.
