Densely built cities with a low percentage of green areas are sensitive to heat waves due to air temperatures in the core of the city significantly higher than in the surrounding rural areas. When these high temperatures coincide with low wind speeds and high humidity, the population might be put under thermal stress with dramatic consequences. The metropolitan areas that are the most prone to heat waves are called Urban Heat Islands (UHI).

The project "Urban Heat Islands and Urban Thermography" aims principally at defining, designing, developing, verifying, validating and demonstrating a set of services that integrate satellite observations with ground weather stations into urban meteorological and climate models for a better prevention of UHI impacts during summer heat waves, a reduction of the heat wave risk in metropolitan areas, and a better implementation of energy efficiency policies in European cities.

The project has a threefold objective:

• Firstly, the assimilation of satellite Remote Sensing observations (principally but not only Thermal Infrared bands) with urban ground stations (Temperature, Relative Humidity and Wind Speed) into urban meteorological and climate modelling to help the mitigation of UHI impact (through appropriate alert system) and to reduce the risk (through dedicated urban land planning).
• Secondly, the study of the energy balance of the cities for a better response to the urban energy efficiency policies.
• Thirdly, the study of a dedicated TIR satellite mission with high spatial resolution and revisiting time for a more adequate provision of Land Surface Temperature (LST) retrievals in the metropolitan areas of European cities.

The ultimate objective of the project is, through a better understanding of the conditioning factors that drive urban climates, to be in a position to predict and mitigate the spatial and temporal variability of Urban Heat Islands in metropolitan areas and their effect on the local population most at risk.

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Email: marc.paganini@esa.int