Conference Agenda

Climate change and urbanization transform life globally, with direct impacts on each other, yet they are rarely studied together across disciplines. The Synergy Grant urbisphere, funded by the European Research Council (ERC), aims to forecast feedbacks between climate and cities. With new synergies between four disciplines (spatial planning, remote sensing, modelling and ground-based observations), urbisphere incorporates city dynamics and human behaviour into climate forecasts/projections, focusing on within-city dynamics of peoples’ activities and how these can be up-scaled to cities globally. urbisphere is studying inter/intra-city form and function (demographics, mobility, climate adaptation and vulnerability planning typologies), exploring human/socio-economic vulnerability, exposure, risk perception, coping/adaptive measures to climatic stressors and settlement/building typologies.

urbisphere is developing new ways to represent city dynamics for weather/climate models. These models are informed by the urbisphere developed Earth Observation system, using space-borne/airborne sensors and ground based sensors with near real-time data transmission, processing, visualization and central archiving of data from 500+ sensors, including a network of ceilometers, scintillometers, Doppler wind lidars, flux towers combined with street-level and indoor sensors. Combined these measure the 3-dimensional state of the atmosphere and the surface. The sensors are being deployed through an annual cycle, with successful campaigns in Berlin (2021 - 2022) and Paris (2023 - 2024). The sensors are now being deployed in Bristol. These observations are providing both new understanding of urban surface-atmosphere processes and datasets for model evaluation at unprecedented detail. For example, the Berlin campaign helped understanding how an isolated city modifies the atmospheric boundary layer, the relation with human activity cycles and variations above and downwind of the city.

More information on urbisphere is available at: https://urbisphere.eu

The large abundance of materials absorbing short-wave radiation from the Sun and the concentration of people make cities particularly vulnerable to the heat island effect. Although the surface albedo and emissivity of the materials in the urban fabric are key quantitative properties for heat pollution mitigation strategies, these are often lacking citywide. Observing cities from space with high-spatial resolution optical and thermal-infrared sensors can circumvent the in-situ stations’ spatial and temporal coverage limitations.

However, the measurements from space correspond to information relative to a limited number of satellite acquisition geometry and spectral bands, which prevents the accurate computation of needed quantities such as urban albedo maps. In order to extrapolate satellite observations to any upward directions and to the whole spectral domain of interest, a physical model considering the complex 3D structure of urban environments is needed. This contribution describes the SuaBe project, which focuses on designing and implementing a fast, and robust algorithm, that uses the 3D radiative transfer code DART (https://dart.omp.eu/#/) to invert remote sensing images of cities as a 3D distribution of optical properties and temperature, using a geometric urban database. This approach enables us to obtain a 3D model of a city to simulate urban surface albedo and emissivity maps at any date as long as the optical properties of urban elements remain constant. These optical properties can be up-dated with the inversion of recently acquired satellite imagery.

As a case study, we will apply it to Brussels to retrieve surface albedo and emissivity maps at a neighbourhood scale. These results can be considered an asset to be used by urban planners and decision-makers to identify what urban areas should be considered priority candidates for an intervention to mitigate heat pollution, which in turn, shall allow authorities or civil organisations to maximise benefits from limited financial resources. Since the SuaBe’s methodology is based on a robust and rigorous physical model, it can be seamlessly implemented in any other city worldwide, provided that a geometric urban database is available.

Climate change increases stress on urban areas due to the rise in heat waves, which can threaten people’s wellbeing and even lives. Temperature is a crucial parameter in climate monitoring and Earth Observation (EO) systems. Advances in remote sensing technology have expanded opportunities for monitoring surface temperature from space. With numerous satellite thermal missions anticipated in the coming years, there is a pressing need for improved methods to retrieve surface temperatures for cities. While EO satellites are excellent for mapping Land Surface Temperature (LST), the unique properties and geometry of urban surfaces, along with the trade-off between temporal and spatial resolution, pose challenges in retrieving urban surface temperature (UST).

To this end, the EO4UTEMP project explored the use of EO data for monitoring UST from space. EO4UTEMP developed innovative methods and algorithms for producing detailed, accurate, and frequent UST products. A UST retrieval algorithm for high-resolution thermal sensors (e.g., Landsat, ASTER, ECOSTRESS, and the upcoming TRISHNA, LSTM, and SBG) includes emissivity corrections using ancillary information from external sources (e.g. urban surface cover information from Sentinel-2, Landsat) and spectral libraries. The algorithm accounts for the sensor’s viewing angle and considers the fraction of vertical urban facades in the UST retrieval, increasing the accuracy in retrievals. Combined with a thermal imagery downscaling approach, the UST retrieval algorithm allows for the use of low-resolution satellite thermal imagery, therefore increasing the frequency of UST observations. The EO4UTEMP methodology was evaluated using in-situ measured UST from meteorological station measurements in Heraklion, Greece, with a Mean Absolute Error (MAE) of up to 3.6 K for daytime and 1.4 K. The EO4UTEMP methodology is transferable and applicable to cities worldwide and the project showcases new technologies and tools to the EO community and promotes the use of EO data in urban meteorology.

Extreme heat events pose a growing threat to urban populations, with rising temperatures linked to increased mortality. In response, the development of advanced tools becomes imperative for effective mitigation and real-time management of heat-related mortality. This work presents a novel approach leveraging digital twin (DT) concept to estimate mortality associated with extreme heat events, offering both long-term projections and real-time insights for heatwave management. The work is being implemented within the framework of CARMINE project (Climate-Resilient Development Pathways in Metropolitan Regions of Europe).

The DT on heat health risk will serve as a human mortality estimator, employing a Machine Learning model trained on diverse urban indicators to predict heat-related mortality occurrences during summer months and heatwave events. This research establishes digital coupling, facilitating seamless connections between disparate data sources essential for mortality estimation. Key datasets for this utilization include high resolution urban scale modeling coupled with near-real time data incorporating natural (including Nature-based Solutions – NbS) and built environment features, real-time satellite-derived temperatures, weather forecasts, Copernicus C3S, mortality records, socio-economic data and demographics. The latter are among the prime variables to condition population vulnerability and thus the fatality of future heatwaves and to dictate policies to strengthen resilience.

Protocols for accessing datasets and ensuring data security, including user authentication mechanisms, are integral components of the DT.

By integrating advanced modeling techniques with real-time data streams and urban indicators, the proposed DT offers a comprehensive solution for proactive heatwave management. The ability to forecast heat-related mortality enables policymakers and public health authorities to implement targeted interventions, including NbS, asses their performance through the DT, and allocate resources effectively, ultimately enhancing urban resilience to extreme heat events. Furthermore, this initiative will coordinate with the flagship initiative of DestinE to increase its impact and scaling up.

Funded by the European Union (GA 101137851).

For EU policies to be efficiently planned, there is a need for a continental, harmonized, multitemporal and highly detailed indicator on soil sealing that allows the monitoring of the location and the degree of impacts. The European Copernicus Land Monitoring Service has been producing datasets on imperviousness every 3 years since 2006, which are the only high-resolution datasets that enable European wide monitoring. However, after the 2015 reporting year, the input for the production of the imperviousness dataset was switched from mixed inputs to the European Sentinel satellites. While this led to an improvement in the spatial detail from 20 m to 10 m, the change in the input dataset also resulted in a break in the time series as the 2018 update was not comparable to the previous reference years. In addition, the European Copernicus Land Monitoring Service has been producing a new dataset from 2018 onward entitled the CORINE Land Cover (CLC)+ Back Bone which also include a sealed area thematic class. When comparing both datasets with sampled reference data, it appears that the imperviousness dataset substantially underestimates sealed areas at European level. However. The CLC+ dataset only started to be available from 2018 and currently does not include any change layer. To address these issues, we present a harmonized and bias-corrected continental soil sealing combined dataset for Europe for the entire observation period. This new dataset has been validated to be the best current dataset for monitoring imperviousness and soil sealing impacts as a direct input for European policies. Finally, recommendations for future updates and validation of imperviousness degree monitoring geospatial products are given.

Soil sealing – also called imperviousness – is defined as a change in the nature of the soil leading to its impermeability. Soil sealing has several impacts on the environment, especially in urban areas and local climate, influencing heat exchange and soil permeability; soil sealing monitoring is crucial for the Mediterranean coastal areas, where soil degradation combined with drought and fires contributes to desertification.

Some artificial features like buildings, paved roads, paved parking lots, and other artifacts can be considered to have a long duration. In general, these land cover types are referred to as permanent soil sealing because the probability of coming back to natural use is low. Other land cover features included in the definition of soil sealing can be considered reversible. For them, the probability of coming back to natural use is higher. The land cover classes that are included in the reversible soil sealing have been defined with the users of the project, and include solar panels, construction site in early stage, mines and quarries, long-term plastic-covered soil in agricultural areas (e.g., non-paved greenhouses).

The project Mediterranean Soil Sealing, promoted by the European Space Agency (ESA) in the frame of the EO Science for Society – Mediterranean Regional Initiative, aims to provide specific products related to soil sealing and its degree over the Mediterranean coastal areas by exploiting EO data with an innovative methodology capable to optimize and scale-up their use with other non-EO data. The project started in March 2021 and the final products are available in 2024. The project team is led by Planetek Italia, and composed by ISPRA and CLS.

The targeted products are high-resolution maps of the degree of soil sealing over the Mediterranean coastal areas (within 20km from the coast) for the 2018-2022, at yearly temporal resolution with a targeted spatial resolution of 10m.

The involvement of stakeholders and end-users is an essential element of the project. Since from the early stage of the proposal, efforts have been made to reach a diversity of users and stakeholders; the presence of ISPRA in the consortium is a plus for the project in this sense.

Users are grouped into classes: municipalities; sub-national agencies or local governmental institution; national institutions and research centers; regional institutions (EEA) and international (UN).