CL2.8 | Urban climate, urban biometeorology, and science tools for cities
EDI
Urban climate, urban biometeorology, and science tools for cities
Convener: Daniel FennerECSECS | Co-conveners: Hendrik Wouters, Natalie TheeuwesECSECS, Matei Georgescu, Gaby LangendijkECSECS, Dragan MiloševićECSECS, Valentina VitaliECSECS
Orals
| Tue, 25 Apr, 08:30–12:30 (CEST), 14:00–18:00 (CEST)
 
Room F1, Wed, 26 Apr, 08:30–10:15 (CEST)
 
Room F1
Posters on site
| Attendance Wed, 26 Apr, 10:45–12:30 (CEST)
 
Hall X5
Posters virtual
| Attendance Wed, 26 Apr, 10:45–12:30 (CEST)
 
vHall CL
Orals |
Tue, 08:30
Wed, 10:45
Wed, 10:45
Urban areas play a fundamental role in local to large-scale planetary processes, via modification of heat, moisture, and chemical budgets. With urbanization continuing globally it is essential to recognize the consequences of landscape conversion to the built environment. Given the capabilities of cities to serve as first responders to global change, considerable efforts are currently being dedicated across many cities to monitor and understand urban atmospheric dynamics. Further, various adaptation and mitigation strategies aimed to offset impacts of rapidly expanding urban environments and influences of large-scale greenhouse gas emissions are being developed, implemented, and their effectiveness evaluated.
This session solicits submissions from both the observational and modelling communities. Submissions covering urban atmospheric and landscape dynamics, processes and impacts owing to urban-induced climate change, the efficacy of various strategies to reduce such impacts, human-biometeorological investigations in urban settings, and techniques highlighting how cities are already using novel science data and products that facilitate planning and policies on urban adaptation to and mitigation of the effects of climate change are welcome. Emerging topics including, but not limited to, citizen science, crowdsourcing, and urban-climate informatics are highly encouraged.

Orals: Tue, 25 Apr | Room F1

Chairpersons: Daniel Fenner, Valentina Vitali, Hendrik Wouters
08:30–08:35
Multi-scale observations and crowdsourcing
08:35–08:45
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EGU23-8591
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ECS
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On-site presentation
Tania Sharmin, Simon Lannon, and Adrian Chappell

This study explores the spatiotemporal variations in Land Surface Temperature (LST) and vegetation indices in relation to Local Climate Zone (LCZ) classification in a coastal, temperate climate city across multiple seasons. The study focuses on Cardiff, the capital and largest city of Wales, located only 2.4 km from the sea. The findings of this study extend our scientific understanding of the interrelations between LST and morphological and surface properties of the built environment and urban vegetation for various LCZ classes in Cardiff. Results showed a significant variation in Surface Urban Heat Island (SUHI) intensity in spring, summer, and winter. LST and Normalised Difference Vegetation Index (NDVI) were found to vary significantly across the LCZ classes demonstrating their association with the local urban form and morphology. For built-up areas, LCZ classes with lower vegetation cover and higher building density showed higher LST. For natural areas, LCZ F (Bare soil or sand) had higher LST than LCZ A (Dense trees). The high-density, built-up LCZ classes have a greater UHI compared to the natural classes. In addition, the results showed that LST and NDVI are significantly affected by the morphological and surface properties for each LCZ classes. Building surface fraction, impervious surface fraction and surface admittance were found to have a positive correlation with LST. Sky View Factor, surface albedo and pervious surface fraction, on the other hand, showed a negative correlation with LST. Opposite associations were found with the NDVI. Urban planners and designers will find the study useful to develop heat mitigation strategies while planning, designing, or improvising the new and existing urban areas in Cardiff. In addition, the LCZ map produced in this study for Cardiff using local expert knowledge will enable international comparison and testing of proven climate change adaptation and mitigation techniques for similar urban areas.

How to cite: Sharmin, T., Lannon, S., and Chappell, A.: Spatio-temporal variability of land surface temperature and vegetation indices within Local Climate Zone classes in Cardiff, Wales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8591, https://doi.org/10.5194/egusphere-egu23-8591, 2023.

08:45–08:55
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EGU23-15292
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ECS
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Virtual presentation
Xu Zhang, Josep Roca Cladera, and Blanca Arellano Ramos

The inverse S function can not only fit the spatial attenuation of construction land density, but also fit the spatial attenuation characteristics of various urban characteristics. Therefore, we assume that the inverse S-function curve is also applicable to the spatial variation law of urban LST. We hope to conduct an inverse S function model fitting analysis of the surface temperature of the three major cities in Beijing, Tianjin, Hebei, China's capital economic circle in 2001 and 2020 in winter, summer, day and night in eight periods to verify that they all conform to the characteristics of the function curve, and use the fitting parameters to analyze the urban development process and its impact on the thermal environment.

First, we draw concentric circles at intervals of 1KM from the center points of the three cities, and then extract the land surface temperature (LST) of each circle and process it dimensionlessly. Finally, the inverse S function model is fitted to all LST data, and the expression of the inverse S function is as follows. And combined with the characteristics of LST, the fitting parameters in the function are given corresponding meanings.

Analyzing the results of fitting parameters, LST conforms to the law of the reverse S-curve model in most cases.

Since the LST in the most periods can be simulated by the inverse S model, it is proved that their change law is that they first decrease slowly with the increase of the radius of the concentric circle, then decrease rapidly, and finally decelerate to zero.

The fit parameter "a" controls the slope of the curve. The larger "a" is, the faster the curve decays, indicating that the urban thermal environment is more compact.

The "a" of each city of winter is greater than that of summer.

Except for the smallest "a" in winter night in Beijing in 2020, the "a" in summer in 2001 was the smallest in other cities. The distribution of urban thermal environment in this period is the most scattered.

The "a" results for Beijing and Tianjin are similar every time, but Beijing has a wider range of values. Tianjin's is generally larger than them.

The fitting parameter "c" is the mean value of surface temperature at the city fringes.

The most cities are distributed between 0 and 0.2.

Only Tianjin Xiaye in 2020 reached 0.53. It shows that the temperature around Tianjin is on the high side during this period.

The fitting parameter "D" reflects the radius of the urban thermal environment.

The "D" of each city sample has increased to varying degrees, indicating that the urban high-temperature thermal environment has also expanded.

The thermal environment radii of Beijing and Shijiazhuang are the smallest at night in winter, while Tianjin is the smallest at night in summer.

The fastest growth rate was during summer nights, with each city adding more than 10 kilometers.

The slowest growth in Beijing is during the daytime in summer, while that in Tianjin and Shijiazhuang is during the night in winter.

How to cite: Zhang, X., Roca Cladera, J., and Arellano Ramos, B.: Research on the effect of urban territorial expansion on thermal environment using the inverse S-function curve- Taking Beijing-Tianjin-Hebei China Capital Economic Circle as an Example, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15292, https://doi.org/10.5194/egusphere-egu23-15292, 2023.

08:55–09:05
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EGU23-16489
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ECS
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On-site presentation
Hantian Wu and Bo Huang

Urban anthropogenic heat has a direct impact on urban climate. However, due to a warm feedback loop, the attributions of urban anthropogenic heat in urban area are unclear. This research carried out an attribution analysis of anthropogenic heat index (AHI) derived from remote sensing over global 1386 cities to investigate the contribution of 13 environmental variables to global urban anthropogenic heat based on GEE environment. 13 independent variables are categorized the groups of human activities, land morphology, vegetation, climate and atmospheric environment on anthropogenic heat. The results show that although human activities are considered as the main source of the anthropogenic heat, other factors have more impacts on the anthropogenic heat pattern in the urban area due to the feedback loop of urban thermal environment. Climate played a leading role in the impacts on anthropogenic heat with a contribution rate of 30-50% in most background contexts. The impact rate of human activities and landforms on anthropogenic heat accounts for 20% in most background scenarios. The findings of this research can contribute to the solution of mitigating urban anthropogenic heat and expanded the research scope of urban anthropogenic heat in the urban area.

How to cite: Wu, H. and Huang, B.: Attributes analysis of global urban anthropogenic heat index with multi-sources remote sensing data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16489, https://doi.org/10.5194/egusphere-egu23-16489, 2023.

09:05–09:15
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EGU23-290
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ECS
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On-site presentation
Matej Žgela and Ivana Herceg Bulić

There is often a lack of meteorological stations in cities, which makes it difficult to examine their microclimate. Alternatively, it is possible to get around this by fixing measuring instruments on bicycles and traversing through the city to observe spatial patterns in the urban canopy layer. The "traverse" approach enables insight into the spatial variation of air temperature in relation to urban form.

In this research, air temperature measurements were carried out using bicycles and an IoT MF-300 instrument with a synchronized GPS receiver and a temperature probe under different weather conditions throughout 2021 and 2022 in Zagreb, Croatia. The GPS receiver's high sensitivity and position accuracy allowed measurements in places like urban canyons and dense foliage environments. The routes were carefully designed to pass through morphologically diverse parts of Zagreb to emphasize the heat characteristics of the city's microclimate. We specifically analysed the spatial distribution of air temperature and land surface temperature (LST) during a heat wave event on the 24th of June 2021. On that day mobile measurements were conducted between 10:30 and 11:15 AM local time to match the LST measurements of the Landsat-8 satellite that overpassed Zagreb at approximately 10:45 AM. Additional measurements were carried out in other seasons and at different times of the day.

Results show thermal differences between surface types and urban forms. During a heat wave event, air temperatures reached up to 35 °C, and LST was above 40 °C, which are high temperatures considering the time of measurement. However, mobile measurements showed that city parks can be even 3 °C cooler compared to densely built-up city areas. Due to the high response time of the instrument, the effect of microscale city properties, such as tree lines, was also observed. These results indicate the cooling effect of green areas in Zagreb and the importance of their preservation for heat load reduction and mitigation of the negative effects of the urban heat island.

How to cite: Žgela, M. and Herceg Bulić, I.: Urban heat load assessment in Zagreb, Croatia: a multi-scale analysis using mobile measurements and satellite imagery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-290, https://doi.org/10.5194/egusphere-egu23-290, 2023.

09:15–09:25
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EGU23-1476
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On-site presentation
Moritz Burger, Moritz Gubler, and Stefan Brönnimann

Detailed knowledge about the intra-urban air temperature variability within a city is crucial for the implementation of adaptation strategies to counteract the negative effects of urban heat stress. Various methods to model urban-rural temperature differences exist, but they often only cover certain periods (heatwave, hot day) or meteorological conditions (sunny and calm) due to computational limitations or limited data availability. Land use regressions, which are usually based on fine scaled measurements and high resolution spatiotemporal data, are one promising method to overcome those limitations and to conduct daily urban temperature fields.

In the city of Bern, Switzerland, a very dense urban temperature network (about 1 station per 1.5 km2) is operated since summer 2018. With that detailed information on temperature and publicly available land use and meteorological data, different land use regression types with a differing degree of complexity were tested in the recent past. One main outcome of the application of the method in Bern is an urban temperature dataset that covers the temperature distribution of all nights of the metropolitan area of the summers 2007 to 2022 with a resolution of 50 meters. In this talk, we would like to present the different models applied in Bern, analyze the potential of land use regression approaches in urban climate studies, and discuss possible applications of the dataset regarding urban planning and heat stress studies.

How to cite: Burger, M., Gubler, M., and Brönnimann, S.: Modeling daily urban temperature fields using land use regression approaches, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1476, https://doi.org/10.5194/egusphere-egu23-1476, 2023.

09:25–09:35
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EGU23-10461
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ECS
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Virtual presentation
Marzie Naserikia, Melissa A. Hart, Negin Nazarian, Benjamin Bechtel, and Kerry A. Nice

Urban heat is a local scale warming effect associated with urban areas where most of the world's population live. Due to the scarcity of air temperature (Ta) data, urban heat studies have been mostly focused on Land Surface Temperature (LST) extracted from satellite imagery and a quantitative understanding of how LST interacts with Ta within a city is still lacking. Using crowdsourced weather station data in Sydney, Australia, combined with high resolution satellite images and urban datasets (such as Local Climate Zone (LCZ) and building-level urban data), we explore the interaction between Ta and LST, and their intra-urban variabilities during different seasons. We found that LST and Ta have different characteristics and their dependency varies by season and LCZ. When exploring the relationship between Ta, LST, and variables describing the urban structure, such as building fraction, the correlation between LST and urban structure was stronger and more seasonal dependent than the Ta-urban form relationship. Moreover, stronger correlations between LST and Ta were observed in the less built-up areas within the city. We also found that the determinants of LST variability are different from the contributing factors of Ta. These findings provide new insights for quantitatively investigating surface and canopy urban heat and their relationship with land cover, providing fit-for-purpose information to mitigate the adverse effects of urban overheating at local and global scales. 

How to cite: Naserikia, M., Hart, M. A., Nazarian, N., Bechtel, B., and Nice, K. A.: Understanding within-city interaction between surface and air temperatures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10461, https://doi.org/10.5194/egusphere-egu23-10461, 2023.

09:35–09:45
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EGU23-2658
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ECS
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Highlight
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Virtual presentation
AI for urban climate: an EO-based approach for high-resolution mapping of human exposure to heatwaves
(withdrawn)
Ana Oliveira, Rita Cunha, Vasco Leal, Manuel Galamba, Giovanni Buroni, and Guilherme Eugénio
09:45–09:55
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EGU23-14110
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Virtual presentation
Timothy D. Mitchell and Matthew J. Fry
Crowdsourced observations have the potential to bring a step-change in urban climatology. This rapid prototyping project explores their potential for improving the standard observed grids, and the likely consequences for urban climate services. Basic quality control procedures are applied to WOW, Davis, Netatmo and Met Office sites around Manchester (UK), and site records of daily minimum and maximum temperatures are built. These are interpolated onto a set of daily observed grids of temperature for Manchester at 1km resolution for summer (JJA) 2020, thus obtaining a crowdsourced alternative to HadUK-Grid. The number of tropical nights (minimum > 20 degrees) is counted in these two gridded products. This provides the baseline for a current climate service for partners in local government that projects possible future changes in heat hazards. Thus the comparison of the standard and crowdsourced products gives some insight into the potential for observations from citizen science to improve gridded observations, an observed hazard metric, future projections of that metric, and so influence public policy decisions related to extreme heat.

How to cite: Mitchell, T. D. and Fry, M. J.: The use of crowdsourced observations to build climate grids and assess urban heat hazard., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14110, https://doi.org/10.5194/egusphere-egu23-14110, 2023.

09:55–10:05
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EGU23-7886
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ECS
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Highlight
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On-site presentation
Esther Peerlings and Gert-Jan Steeneveld

Due to climate change and urbanization, the world's population is increasingly exposed to extreme heat, posing a threat to public health. Despite people spending ~90% of their time indoors, heat effects in buildings have been studied far less than outdoor heat island effects. This study aims to observe, understand and model the behaviour of indoor air temperatures (Tin) during summer heat. As a proof of concept, we present and analyse up to 27 years of individual Tin timeseries of seven citizen weather stations (CWS) across the Netherlands. First, we find that typically Tin increases slower, but also cools down slower than Tout with a lag difference of ~130 minutes in the diurnal cycle. We demonstrate that nocturnal indoor human thermal comfort (HTC) can be worse than outdoor HTC even for days after a heatwave.

Second, to model Tin behaviour, we simulate six-hour changes in Tin behaviour with a physics-based statistical model by Vant-Hull et al. (2018) that has an outdoor conduction, indoor conduction and solar transfer component. Preliminary results of this computationally-fast model for each of the seven houses are promising, showing on average a R-squared of 0.74 and a root mean squared error of 0.13 K. Third, in the next research steps, we are also interested in how Tin may evolve due to climate change. We will study this by converting the Tin measurements to 2050 and 2085 values based on the Royal Netherlands Meteorological Institute 2014 climate scenarios (or 2023 if available).

Finally, we will scale up our proof-of-concept analyses to 100 indoor CWS placed in Amsterdam. The participating households receive a CWS for three years to measure their indoor climate – temperature, relative humidity, CO2 concentrations – in the bedroom and living room. Based on our insights, we will make recommendations for climate-sensitive urban design to reduce indoor heat stress.

How to cite: Peerlings, E. and Steeneveld, G.-J.: Hot weather impacts on urban indoor air temperature assessed through citizen science observations in the Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7886, https://doi.org/10.5194/egusphere-egu23-7886, 2023.

10:05–10:15
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EGU23-14781
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Highlight
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On-site presentation
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Martial Haeffelin, Simone Kotthaus, Sophie Bastin, Sophie Bouffies-Cloché, Chris Cantrell, Andreas Christen, Jean-Charles Dupont, Gilles Foret, Valérie Gros, Aude Lemonsu, Juliette Leymarie, Fabienne Lohou, Malika Madelin, Valéry Masson, Vincent Michoud, Jeremy Price, Michel Ramonet, Jean-Francois Ribaud, Karine Sartelet, and Jean Wurtz and the PANAME team

The Paris region (France) is increasingly the focus of urban atmospheric research. Numerous national and international research projects have chosen Europe’s largest metropolitan region as their study area to better understand and predict critical hazards (incl. heat, air pollution, thunderstorms) in the context of a changing climate. Located on rather flat terrain in continental, mid-latitude climates, the densely populated Paris region is very suitable for the evaluation of urban processes in numerical simulations at different scales. The European research infrastructures ACTRIS and ICOS are developing strategies for the improved operational monitoring of air pollution and greenhouse gas budgets, respectively. Various research projects are conducting fundamental process studies and model developments to investigate the dynamics and chemistry of the urban atmosphere and its interactions with the rural surroundings and regional-scale flow to better quantify associated health risks and inform sustainable planning.

In addition to numerous modelling activities (chemistry-transport, numerical weather prediction, climate projections), diverse atmospheric observations are collected. These include dense surface station networks, turbulent flux towers, and ground-based atmospheric remote sensing to monitor the atmospheric boundary layer. This multi-project context motivates the pooling of resources.

To facilitate efficient project synergy and to optimise the coordination of the individual experimental campaigns, the PANAME initiative (https://paname.aeris-data.fr/) was established. PANAME provides a framework to optimise the design of the Paris region measurement network and helps to standardise the operations. A professional, multi-disciplinary data portal is developed at the French AERIS atmospheric data centre to host the PANAME observations and model results. Here, data are collected and formatted, standardised advanced products are derived from the diverse sensor networks and high-quality visualisations are generated in near real-time. The presentation will provide an overview on the scientific objectives of the on-going projects, the deployment of measurements and simulation tools, and the data portal design.

 

How to cite: Haeffelin, M., Kotthaus, S., Bastin, S., Bouffies-Cloché, S., Cantrell, C., Christen, A., Dupont, J.-C., Foret, G., Gros, V., Lemonsu, A., Leymarie, J., Lohou, F., Madelin, M., Masson, V., Michoud, V., Price, J., Ramonet, M., Ribaud, J.-F., Sartelet, K., and Wurtz, J. and the PANAME team: PANAME – Project synergy of atmospheric research in the Paris region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14781, https://doi.org/10.5194/egusphere-egu23-14781, 2023.

Coffee break
Chairpersons: Matthias Demuzere, Daniel Fenner, Gaby Langendijk
Model development and evaluation
10:45–10:55
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EGU23-16480
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ECS
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On-site presentation
Jérémy Bernard, Fredrik Lindberg, and Sandro Oswald

The wind speed varies significantly within a neighborhood due to building and vegetation size and position. A good estimation of these spatial variations is useful for several applications (outdoor thermal comfort, air pollution, building energy consumption and thermal comfort, etc.) but might be time-consuming using Computational Fluid Dynamic tools and difficult to produce for non experts.

URock is a Python library that has been developped within UMEP, a city-based climate service tool integrated as plug-in in the free and open source QGIS software. It is based on the Röckle approach already used in non open source softwares such as QUIC-URB and SkyHelios: first an initial wind field is set according to empirical laws derived from wind tunnel observations; second the mass air flow is balanced minimizing the modifications of the initial wind field. This method is less accurate than traditional CFD method but quicker and simple to implement for non specialists. This work presents the evaluation of URock against wind tunnel observations.

Acknowledgement

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 896069.

 

How to cite: Bernard, J., Lindberg, F., and Oswald, S.: Quick calculation of wind field in urban area within a free and open source GIS: evaluation of the URock model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16480, https://doi.org/10.5194/egusphere-egu23-16480, 2023.

10:55–11:05
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EGU23-3458
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ECS
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On-site presentation
Maximilian May, Simone Wald, and Sanam N. Vardag

During the last decade, atmospheric measurement networks in urban areas have become important drivers for global pollution and greenhouse gas (GHG) mitigation. For city stakeholders to effectively plan GHG emissions mitigation measures and to monitor changes in emissions, GHG concentration data both, from measurements and simulations on high resolution, are required, but still lacking in most cities. The accurate simulation of high-resolution dispersion in urban areas enables the interpretation of concentration measurements as well as quantitative estimates of local emissions in an inverse modelling framework.

High-resolution dispersion simulations on neighborhood scale are generally computationally costly, preventing the analysis of long time periods. To overcome this limitation, we use the coupled GRAMM/GRAL model which is computationally efficient due to a ‘catalogue approach’. GRAMM/GRAL is composed of the mesoscale model GRAMM, solving the Reynolds Averaged Navier Stokes equations for an outer domain (resolution 100 m), and the computational fluid dynamics model GRAL for an inner domain (resolution 10 m). We run GRAMM for 1008 different wind situations differing in synoptic wind forcing and stability class. GRAL is initialized by the GRAMM fields and calculates wind fields taking the flow around buildings into account.  A time series of hourly, 10 m resolved wind fields and concentrations can be obtained by matching catalogued, simulated wind fields with measurement of a local wind measurement network (‘catalogue approach’).

Here, we evaluate the GRAMM/GRAL model in the urban area of Heidelberg for 12 months. 14 wind measurement stations within the inner GRAL domain enable a thorough evaluation of GRAL for yearly time periods and for a 12x12 km2 area under challenging topography. Our evaluation also includes wind profile measurements (up to 200 m) from a LIDAR. We find good agreement between modelled and simulated wind directions. Wind speeds can be simulated with an overall root-mean square difference of about 1 ms-1 and a mean bias of about -0.3 ms-1. Measurement sites with poorer model representation are located in the forest or the outer domain with coarser resolution. We conclude that GRAMM/GRAL is capable of simulating high-resolution wind fields in urban areas of complex topography. We showcase first dispersion simulations for carbon dioxide in Heidelberg.

How to cite: May, M., Wald, S., and Vardag, S. N.: Comprehensive analysis of high-resolution dispersion simulations in urban area using the GRAMM/GRAL model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3458, https://doi.org/10.5194/egusphere-egu23-3458, 2023.

11:05–11:15
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EGU23-7691
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ECS
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On-site presentation
Albert König, Markus Pichler, and Dirk Muschalla

The mitigation of urban microclimatic deficiencies as a result of the urbanized environment receives increasing attention by cities, municipalities and the planning community. Priority areas for the implementation of multi-beneficial climate change adaptation measures and the development of mitigation plans need to be identified. Therefore modelling methods producing good results while only requiring moderate data input and computational effort are needed for the widespread application in planning processes. In this study, we test the rapid fine-scale methodology for simulating urban bioclimatic conditions in a 2D environment that was previously introduced by Back et al. (Back et al., 2021). The original methodology uses high resolution land cover classification (Hiscock et al., 2021) from multi-spectral aerial imagery, digital elevation data, and a vector layer of buildings to calculate land surface temperature (LST), mean radiant temperature (MRT), and the Universal Thermal Climate Index (UTCI). We apply this methodology to the rural municipality of Feldbach, Austria, using commercially and openly available satellite imagery. The simulated data is validated against the publicly available monitoring data from the WegenerNet climate station networks (Fuchsberger et al., 2022), which provides high spatial and temporal resolution measurements. The results are evaluated regarding the agreement of relative spatial differences of the simulated variables with the observed data. To be suitable for the identification of priority areas for the implementation of climate change adaptation measures, the methodology is expected to accurately reflect the spatial variability of the simulated variables.

Project supported by ESA Network of Resources Initiative.

Back, Y., Bach, P. M., Jasper-Tönnies, A., Rauch, W., & Kleidorfer, M. (2021). A rapid fine-scale approach to modelling urban bioclimatic conditions. Science of The Total Environment, 756, 143732. https://doi.org/10.1016/j.scitotenv.2020.143732

Fuchsberger, J., Kirchengast, G., Bichler, C., Leuprecht, A., & Kabas, T. (2022). WegenerNet climate station network Level 2 data [Text/csv,application/x-netcdf]. Wegener Center for Climate and Global Change, University of Graz. https://doi.org/10.25364/WEGC/WPS7.1:2022.1

Hiscock, O. H., Back, Y., Kleidorfer, M., & Urich, C. (2021). A GIS-based Land Cover Classification Approach Suitable for Fine‐scale Urban Water Management. Water Resources Management, 35(4), 1339–1352. https://doi.org/10.1007/s11269-021-02790-x

How to cite: König, A., Pichler, M., and Muschalla, D.: Validation of a 2D modelling approach for urban microclimatic conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7691, https://doi.org/10.5194/egusphere-egu23-7691, 2023.

11:15–11:25
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EGU23-15015
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ECS
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On-site presentation
Eva Späte, Leyla Sungur, Johann Schneider, Wolfgang Babel, and Christoph K Thomas

Urban areas are known to be exposed to higher temperatures than rural areas making urban citizens particularly vulnerable to extreme heat events. Large eddy simulation (LES) models can simulate micrometeorological heat transport and mixing processes by directly resolving large-scale turbulence. These models can be used to simulate urban development strategies aiming at mitigating the adverse effects of heat waves in cities by analyzing their influence on urban microclimate. Despite their use in formulating recommendations for city planning, these models are often not validated with observed meteorological data. We here present results from conducting a model-observation comparison for a mid-size city in Germany. Model simulations were computed with the LES model PALM4U run at two different resolutions (Δx,y,z = 5 and 20 m) and evaluated against observations from a network of microweather stations for a heat wave in 2019 reaching maximum near-surface air temperatures of 37 °C.

During daytime, differences between observed and modeled near-surface air temperatures were small (-3.8 to 1.1 K, mean = 0.9 K), but much larger during night-time and the early morning transition. The latter findings can be explained by an overestimated modeled ground heat flux resupplying too much energy offsetting the radiative cooling leading to overestimated modeled air temperatures by up to +9 K (mean = 5.3 K). Further, results showed that in areas where the actual urban structure is reproduced well by the model resolution, differences between observed and modeled wind speeds were lower. Our findings indicate that a spatial resolution smaller than the mean building height produce more accurate model results for wind speeds. Many differences in model-observation intercomparison are explained by an overestimated modeled turbulent kinetic energy (TKE) causing inflated turbulent mixing in the air, which leads to distorted model output particularly for the urban nocturnal boundary layer.

How to cite: Späte, E., Sungur, L., Schneider, J., Babel, W., and Thomas, C. K.: Simulating an extreme heat event in a mid-sized city in Europe: validating and analyzing the relevance of spatial resolution in the urban LES model PALM4U with an observation network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15015, https://doi.org/10.5194/egusphere-egu23-15015, 2023.

11:25–11:35
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EGU23-1326
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On-site presentation
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Dieter Scherer, Katharina Scherber, Ute Fehrenbach, Fred Meier, Marco Otto, Benjamin Schmidt, Ralf Steikert, and Achim Holtmann

During heat waves, urban dwellers are exposed to elevated temperatures, especially during night-time when urban heat island (UHI) effects are most intense. Climate change is expected to further increase heat-stress hazards. There are only few studies that have investigated how UHI effects interfere with heat waves. Here, we present results from a sensitivity study in which we analyse non-linear effects of elevated meso-scale temperature forcing on micro-scale atmospheric processes. The study employs the large eddy simulation model PALM-4U. The ‘Tempelhofer Feld’ in Berlin, Germany, the largest park within the city, was used as study area. Starting point was a 24 h (plus 6 h spin-up) control simulation followed by a scenario simulation in which all temperature variables, not only air temperature, were increased by 1 K. The control simulation was configured to represent a real weather situation in an idealized form. Grid spacing was set to 10 m horizontally and 2 m vertically to resolve buildings and trees. A residential area to the east of the airport was simulated with a higher horizontal grid resolution of 2 m to investigate micro-scale atmospheric processes in more detail. The results show that the micro-scale response of near-surface air temperature to elevated meso-scale temperature forcing is not constant throughout the day with lower values during day-time and higher values during night-time, particularly in the early evening. In both simulations, the night-time inversion over the park continues into the settlement above the roof level. The study shows that there are weak non-linear effects leading to an amplification of the UHI during night-time. However, as linear effects dominate, adaptation measures with regard to heat stress may be planned on the basis of current weather and climate conditions, additionally documented by observational data, and subsequently evaluated by urban climate monitoring.

How to cite: Scherer, D., Scherber, K., Fehrenbach, U., Meier, F., Otto, M., Schmidt, B., Steikert, R., and Holtmann, A.: Sensitivity of micro-scale atmospheric processes in a city quarter of Berlin, Germany on elevated meso-scale temperature forcing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1326, https://doi.org/10.5194/egusphere-egu23-1326, 2023.

11:35–11:45
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EGU23-3249
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ECS
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On-site presentation
Arnaud Forster, Valéry Masson, and Clotilde Augros

Climate change and a rapidly increasing urban population make cities more vulnerable to hazardous weather events. The need for a better understanding of meteorological processes and an improvement of the weather prediction system in an urban environment is crucial to mitigate these impacts and protect the population. 

The “Paris Olympics” international Research and Demonstration Project, endorsed by WMO, aims at improving meteorological research in urban meteorological processes and weather forecasting systems at 100m resolution. It mainly focuses on extreme weather events in urban areas such as urban heat islands and thunderstorms. Several study cases have been proposed. They are golden cases observed during the PANAME2022 field campaign in Paris and they represent interesting weather situations to test numerical weather prediction capacities.

The objective of this study is to investigate through the selected cases, the influence of Paris’s urban environment on thunderstorms. An ensemble of hectometric simulations is built using the Meso-NH research atmospheric model initialized and forced by the members of the AROME-EPS ensemble prediction system which has a 1.3 km horizontal resolution. For each case, two sets of ensemble simulations are performed; to identify the main processes driving the interactions between urban environment and thunderstorms: one with a fine-scale surface description of the city (using a multi-layer urban scheme) and another one where the urban surface is replaced with vegetation.

The first results show that it remains challenging to correctly simulate the location of thunderstorms. Nevertheless, the ensemble technique combined with urban and non-urban city description is effective to discriminate random effects from real trends on  the urban environment impacts on thunderstorms.

How to cite: Forster, A., Masson, V., and Augros, C.: Study of the urban effect of Paris on several thunderstorm cases in 2022, using hectometric ensemble simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3249, https://doi.org/10.5194/egusphere-egu23-3249, 2023.

11:45–11:55
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EGU23-10849
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ECS
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On-site presentation
Pratiman Patel, Song Chen, Anurag Dipankar, Matthias Roth, Humphrey Lean, Hugh Zhang, and Aurel Moise

Increasing urbanization and its implication for human health, outdoor thermal comfort, air quality or energy consumption necessitate a need for high-resolution urban modelling. In this study, we evaluate uSINGV, a coupled urban-atmosphere research model used by the Singapore Meteorological Service, for four clear-day over Singapore using two different spatial resolutions of 300 and 100 m, respectively. The model is modified to incorporate urban morphology and land use/land cover datasets which are based on European Space Agency climate change initiative data (ESA CCI) at 300 and local datasets at 100 m spatial resolution. The evaluation is carried out for near-surface variables such as temperature, specific humidity, wind speed, and turbulent surface fluxes using Kling-Gupta efficiency (KGE'), root mean square error (RMSE) and mean absolute error (MAE) as model evaluation metrics. Results suggest that temperature and specific humidity are similar for 300 m and 100 m spatial resolution. On the other hand, for 100 m (300 m), the 10 m wind speed has a KGE’ of 0.45 (0.15), RMSE of 0.69 (1.42) m/s, and MAE of 0.55 (1.26) m/s, hence showing improvements from 300 to 100 m spatial resolution. In addition, sensible heat flux for 100 m resolution simulations is closer to observations, while latent heat flux is overestimated. Overall, uSINGV is able to produce reliable simulations at 100 m spatial resolution, thereby showing promise for improved understanding of detailed urban climate processes.

How to cite: Patel, P., Chen, S., Dipankar, A., Roth, M., Lean, H., Zhang, H., and Moise, A.: Comparison of 300 m and 100 m uSINGV clear-day simulations for Singapore, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10849, https://doi.org/10.5194/egusphere-egu23-10849, 2023.

11:55–12:05
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EGU23-14169
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Highlight
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On-site presentation
Nadège Blond, Florentin Breton, Alice Micolier, and Maxence Mendez

The urban environment and climate change are essential factors to consider for applications involving urban planning and human health. Although these factors influence estimations of energy consumption and thermal comfort, buildings in France are still generally designed and renovated without accounting for these specific conditions but by considering present rural weather conditions. The first objective of this study is to develop an approach to explore building design and renovation choices while accounting for the urban environment and climate change. The second objective is to find which design and renovation choices are relevant to improve thermal comfort and reduce energy consumption (and therefore GHG emissions).

First, we use observations and simulations of weather conditions in several cities of France (representing different climatic zones), for the present and future climate (2050), to analyze urban conditions and estimate energy consumption. Second, we run building simulations for rural and urban situations, and for present and future climate conditions, to investigate the effect of the urban environment and climate change on the operation of buildings, and the effect of building scenarios on the urban climate.

How to cite: Blond, N., Breton, F., Micolier, A., and Mendez, M.: A modeling approach to address building energy consumption and thermal comfort under urban climate change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14169, https://doi.org/10.5194/egusphere-egu23-14169, 2023.

12:05–12:15
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EGU23-5473
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ECS
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Virtual presentation
Giandomenico Vurro, Katiana Constantinidou, and Panos Hadjinicolaou

Climate change is posing a significant strain on society. The fast urbanization process, in addition to population growth and the constant rise in anthropogenic greenhouse gas emissions, exacerbates climate-induced phenomena. In this background, the EMME region, a climate change hotspot, emerges for its high vulnerability to climate change impacts. Taking advantage of the improvements made in urban parameterization and modeling, and given the lack of works that focus on this region integrating advanced urban parameterization schemes, this work adopts the Weather Research and Forecasting (WRF) model coupled with different urban canopy models (UCMs), to evaluate their performance using Local Climate Zones (LCZs) as land use classification. In particular, we applied three parameterization schemes: 1) Bulk parameterization, 2) Building Effect Parameterization (BEP), and 3) Building Energy Model coupled with BEP (BEP+BEM) over the city of Nicosia (Cyprus) at 1 km2 horizontal resolution for the period 27th of July to 5th of August 2021. This way, we aim to capture a better representation of the finer spatial and temporal distribution of the heatwave that occurred during that period, leading to a peak temperature of 44.3 °C on the 4th of August. These three simulations were compared with observations provided by the Department of Meteorology. The Modified IGBP MODIS-NOAH land use classification is adopted for the whole domain. At the same time, the LCZs classify the land cover into 10 classes based on the urban and thermal features of the Nicosia domain.

How to cite: Vurro, G., Constantinidou, K., and Hadjinicolaou, P.: Comparison of urban canopy models (UCMs) over the area of Nicosia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5473, https://doi.org/10.5194/egusphere-egu23-5473, 2023.

12:15–12:25
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EGU23-15513
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On-site presentation
Csilla Gal

This study summarizes the inter-comparison of three urban canopy models that are able to derive local-scale urban air temperature from rural atmospheric data and urban land use and built form characteristics at an hourly resolution. The focus of this presentation are the findings of the sensitivity analysis and the lessons learned in the process. The evaluated models are the Urban Weather Generator (UWG), the Vertical City Weather Generator (VCWG), the Surface Urban Energy and Water Balance Scheme (SUEWS). The evaluation is done against a two-week-long air temperature and relative humidity measurement conducted in the neighborhood of Újlipótváros in Budapest, Hungary. 
 
The study found a good agreement between modeled and observed air temperature values with a root mean square error (RMSE) remaining between 1–2ºC when calculated for the entire period. However, when separated per day- and nighttime, as well as per cyclonic and anticyclonic periods, the RMSE of the models increased up to 2–3ºC—particularly when calculated for nighttime and/or for anticyclonic periods. The sensitivity analyses shed light on additional shortcomings in the models. It revealed UWG’s low sensitivity to trees and vegetation. In this regard, especially the presence of trees in the urban canopy were not captured by the model. The analysis also found discrepancies regarding VCWG’s model physics, as the model responded to the increase in shortwave radiative forcing with decreasing air temperatures. The study will conclude with a set of recommendations for model developers and users.

How to cite: Gal, C.: A model inter-comparison and sensitivity analysis of three urban canopy models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15513, https://doi.org/10.5194/egusphere-egu23-15513, 2023.

12:25–12:30
Lunch break
Chairpersons: Daniel Fenner, Dragan Milošević, Gaby Langendijk
Climate change, mitigation, and adaptation
14:00–14:10
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EGU23-12497
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ECS
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On-site presentation
Robert Hrițac, Lucian Sfîcă, Iuliana-Gabriela Breabăn, and Vlad-Alexandru Amihăesei

Snowfall and snow depth are important elements of the climate system which can have a significant impact on the transport sector, local economy, water resources and local thermal regime.

This study aims to identify the future trends of snowfall and snow depth in the most important urban areas in Romania, based on high-resolution regional climate models (RCM) data, made available through the EURO-CORDEX, and bias-corrected RCM simulations available în the RoCliB dataset. Ten different regional climate models with a target resolution of 10 km and two emission scenarios were considered, namely the moderate (RCP4.5) and business-as-usual (RCP8.5) scenarios. The study covers the interval from 2021 to 2100.

In order to predict the future snow depth, snow cover duration and snowfall amounts based on the available parameters from the RCM simulations, it was necessary to identify the complex relationship between snowfall, snow melting, temperature and precipitation. In order to do this, we first extracted the ERA5 reanalysis data from 1981 to 2020 for each urban area, and then employed a Bayesian Regularized Neural Network (BRNN). The resulting model was used to predict the future variables for all major urban areas in Romania.

A general trend of decreasing snowfall amounts, mean snow depth and snow cover duration was observed for all analyzed areas and for both emission scenarios. Important regional variations were also observed, with some areas no significant change for the 2021 – 2050 interval compared to the observation period, which could be explained mostly by the increasing winter precipitation predicted by the RCM simulation. The results also showed an increased possibility of some years virtually lacking any snow cover and snowfall precipitation, especially after 2050 in the business-as-usual scenario (RCP8.5). However, an increased variability was also observed, with extreme snowfall events remaining possible even in the latter half of the study interval.

How to cite: Hrițac, R., Sfîcă, L., Breabăn, I.-G., and Amihăesei, V.-A.: The expected effect of climate change on snowfall amounts and snow depth in the major urban areas of Romania, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12497, https://doi.org/10.5194/egusphere-egu23-12497, 2023.

14:10–14:20
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EGU23-16349
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Highlight
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On-site presentation
Josep Roca, Blanca Arellano, and Xu Zhang

According to NASA's temperature record, Earth in 2021 was about 1.1 degrees Celsius warmer than the late 19th century average, the start of the industrial revolution. The rate of Global Warming (GW), however, differs across different regions of the planet. The Mediterranean is one of the "hotspots" of climate change, with more prominent temperature increases throughout the 20th and 21st centuries (Giorgi 2006). Since the mid-20th century, the average temperature over the Mediterranean has been increasing above the global average. The recent temperature record reveals an annual mean temperature for the entire basin that is approximately 0.4°C above the global mean (Lange 2021). This increase is even higher on the Spanish coast, which has experienced increases of more than 2°C (Arellano 2022).

The aim of this paper is to analyze the warming process in the main Spanish urban areas since unified records were kept in the early 1970s. For this purpose, the evolution experienced by temperatures between 1971 and 2022 in 21 meteorological stations representative of all the Spanish Autonomous Communities is analyzed. Barcelona, Madrid, Valencia, Zaragoza, Seville, Malaga, Bilbao, Valladolid, Ciudad Real, Badajoz, Asturias, Corunya, Ourense, Murcia, Logroño, Palma de Mallorca, Las Palmas de Gran Canaria and Santa Cruz de Tenerife, are studied.

The results show that, if on a global scale temperatures have risen 0.94°C since 1971, the increase in the main cities of peninsular Spain has been 2.17°C. And 2022 will be the warmest year on record. The research carried out differentiates the evolution experienced by maximum and minimum temperatures, showing that the continental influence is mainly manifested in the increase of maximum temperatures, while in the area of Mediterranean influence, the increase of minimum temperatures is more pronounced. On the other hand, the Cantabrian and Atlantic coasts, as well as, above all, the Canary Islands, show less pronounced increases, below 2°C.

The study also presents the heat and cold waves (Serra 2022) experienced by the cities studied. Diurnal heat waves (DHW) have increased from 0.6 per year per weather station in the decade 1971-1980, to 1.71 in 1981-1990, 1.81 in 1991-2000, 2.72 in 2001-2010, and 3.84 in 2011-2020. 2022, with 7.11 DHW per station, is the year with the highest number of diurnal heat waves in the entire series. Regarding nocturnal heat waves (NHW) they have increased from 0.47 per station per year in the decade 1971-1980, to 1.53 (1981-1990), 1.57 (1991-2000), 3.55 (2001-2010), and 4.63 (2011-2020). Again 2022 is the year with the highest number of NHW, with 7.61 per weather station.

2022 appears, therefore, as the warmest year since records have been kept, and the one in which a greater number of NHW has been experienced.

How to cite: Roca, J., Arellano, B., and Zhang, X.: Global Warming in Spanish Cities (1971-2022), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16349, https://doi.org/10.5194/egusphere-egu23-16349, 2023.

14:20–14:30
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EGU23-12896
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ECS
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On-site presentation
Francesca Casale, Wenchuang Zhang, and Daniele Bocchiola

Poli-HE, a coupled hydrological-energy budget model was developed to simulate the surface water, and energy fluxes between soil and shallow atmospheric boundary for the city of Milano, Northern Italy. So doing, we describe the urban heat island effect, i.e. differences in land surface temperature (LST) between paved/urban, and green/natural areas, i.e. parks, and suburban agricultural patches.

Energy and water balance equations are linked through soil water content (W), and latent heat flux (LE), calculated as a function of the LST. W in turn drives (actual) evapotranspiration, thus driving (water) mass balance. Input variables were used from i) meteorological stations, air temperature (Ta), net radiation (Rn), rainfall (R), and ii) satellite images, giving leaf area index (LAI) and land surface temperature were used for model tuning.

The results show large differences in LST between urban/green areas, high during summer, viz 3-4 °C, lower in winter, viz 0.3°C. During 2010-2021 max surface temperature in Milano was +37.3°C in urban areas, and to +33.6°C in the green areas.

The model was then used for future projections of LST, using outputs of the Global Circulation Model EC-Earth3.0, constrained to shared socio-economic pathways SSP1-2.6 and SSP5-8.5 of the CMIP6. We analysed near (2030-2041), medium (2050-2061) and long-term (2080-2091). On average in the city of Milano, LST is projected between +0.14°C (SSP 2.6 in the medium-term), and +6.35°C (SSP 8.5 in the long-term). The jump of LST between urban/green areas would reduce against average increase of air temperature, and LST, i.e. large increase of air temperature will be less and less dampened by the present green area cover.

How to cite: Casale, F., Zhang, W., and Bocchiola, D.: Urban heat island under climate change. The case study of Milano, Italy., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12896, https://doi.org/10.5194/egusphere-egu23-12896, 2023.

14:30–14:40
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EGU23-5207
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ECS
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On-site presentation
Marijana Boras, Matej Žgela, and Ivana Herceg Bulić

In this study, land use/land cover changes were examined to investigate their impact on the urban heat load of the City of Dubrovnik in the present and future climate. Dubrovnik is situated in the Mediterranean, which has been referenced as one of the most responsive regions to climate change. Therefore, it is crucial to investigate the effects of different substrates on the heat load and its possible mitigation. Firstly, urban heat load, in the current morphology of the city, is investigated in the present and future climate conditions by using data observed at the local meteorological station and data obtained from regional climate models of the EURO-CORDEX initiative. Also, the urban climate model MUKLIMO_3 is utilized to obtain the spatial distribution of the heat load. Climate indices based on measured data (summer days and tropical nights) show that the heat load has been increasing in the last 50 years. The spatial distribution of the heat load in the City of Dubrovnik in the present climate indicates that the highest heat load is in the public and residential parts of the city. Furthermore, during the nighttime, heat load decreases with a reduction in the density of buildings. Climate indices obtained by simulations of the model MUKLIMO_3 for future climate scenarios (rcp4.5 and rcp8.5) show that the heat load will increase in the entire city domain, with the strongest increase in its urbanized parts. In this study, the impact of modifications in land use/land cover (like changes in the fraction of buildings, impervious surfaces, vegetation and albedo of the roofs) on the heat load are examined. It is demonstrated that these changes will decrease the heat load to some extent. However, the impact is locally limited and significantly smaller than the contribution of global warming. Therefore, land use/land cover changes can mitigate the urban heat load. However, even more comprehensive interventions cannot eliminate the overall increase in the urban heat load due to global warming.   

How to cite: Boras, M., Žgela, M., and Herceg Bulić, I.: Impact of land use/land cover changes on the urban heat load - a case study for the city of Dubrovnik, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5207, https://doi.org/10.5194/egusphere-egu23-5207, 2023.

14:40–14:50
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EGU23-14056
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ECS
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On-site presentation
Florentin Breton

Territories are complex environments with many issues at stake. The issues of human health and energy consumption for instance are linked to local weather and climate change. Despite the scientific and societal developments of the last decades, some of the physical and social processes of territorial climate change are still not well understood, and the implementation of mitigation and adaptation is slow. The following studies address these aspects of processes, mitigation, and adaptation, based on different methods in climate and social sciences.

The first study investigates the seasonality of weather conditions in Europe by using classification approaches (weather types, local analogues) on climate observations, simulations and projections. Simulations are close on average to the observed variability, winter conditions decrease while summer conditions increase, and Mediterranean seasonality expands Northwest while Scandinavian seasonality declines. 

The second study investigates the social perception of climate change and the acceptability of territorial options (mitigation, adaptation) by inhabitants and decision-makers, based on field interviews and foresight activities in the Gulf of Morbihan (France). A strong territorial seasonality (climate, socio-economy) and a complex role of climate change are found, as well as general agreement between local experiences and scientific knowledge. Despite divergent visions among inhabitants, two long-term scenarios and about twenty short-term actions emerged from foresight activities.

A third study investigates the effect of urban parameters on city temperature, and how urban planning options can optimize thermal comfort and reduce energy consumption and GHG emissions, based on urban climate observations and simulations. The city size drives urban warming, followed by urban fraction but building heights can cool the city depending on the season. Model adjustment and sensitivity simulations are presented for the urban planning approach.

How to cite: Breton, F.: Territorial climate change: understanding, mitigating and adapting, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14056, https://doi.org/10.5194/egusphere-egu23-14056, 2023.

14:50–15:00
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EGU23-848
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ECS
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On-site presentation
Matteo Carollo, Ilaria Butera, and Roberto Revelli

The population growth and its concentration within cities, on the one hand lead to an increment of water demand and on the other hand affect the urban water cycle with frequent urban flood events associated to rain extreme events. New approaches to the water management are currently being developed where a role is assigned to rain water harvesting (RWH). RWH provides water for non-potable uses (private and public, indoor and outdoor), reducing water consumption. Moreover, RWH allows to partially retain water on site, reducing the probability of failures of the sewerage system during heavy rain events.

These positive effects are easily evaluable at a building scale when well-known behavioral models are used, while the evaluation becomes often more complex at an urban scale, due to the lack of characteristics and demographic data about all the buildings in the city. In our work, we consider RWH impact at the urban scale, by means of the representative building concept.

We focus on several hypothetical retrofitting scenarios for the residential buildings of Turin (Italy): 1) domestic use of rainwater (e.g., toilet flushing and the washing machine), where buildings are independent of each other, and 2) two public uses of rainwater (the irrigation of public green areas and street washing), for which we have hypothesized that the rainwater collection takes place at a district scale. We estimate a reduction of 42% in the non-potable water consumption for domestic use (values vary across the municipal districts from 29% to 62%, according to the characteristics of the buildings), while for irrigation and street washing, that require a lower amount of water, about 80% of the water can be provided by RWH. The highest reduction of the flow peak conveyed to the sewerage system during extreme storms is reached in the domestic use scenario (about 60%, quite constant across the city), while for public uses the retention capacity is very low.

Finally, our estimations based on historical rainfall series are examined against different climate change scenarios.

 

How to cite: Carollo, M., Butera, I., and Revelli, R.: Rainwater harvesting potential: the Turin case for an analysis at the urban scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-848, https://doi.org/10.5194/egusphere-egu23-848, 2023.

15:00–15:10
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EGU23-13652
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ECS
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On-site presentation
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Ivo Suter, Saskia Drossaart van Dusseldorp, and Julien G. Anet

Residents of urban areas are disproportionately affected by heat stress due to the combination of global warming and increasing urbanisation[1]. This not only affects the quality of life, but also poses a significant health risk and has been shown to lead to increased mortality rates[2]. However, due to the complex nature of urban climate, the impact of such interventions can vary depending on the local conditions and are thus hard to predict.

Figure 1) Left: Image of the misting system. Right: Locations of the misting system (blue circle) and the nearby measuring stations. Station 110 serves as a reference. Left photo from Tabea Vogel, https://www.stadt-zuerich.ch/ted/de/index/gsz/aktuell/aktuelle-projekte/Nebelwolke-Turbinenplatz.html, accessed: 04.01.2023. Right aerial image from www.geo.admin.ch, Swiss federal authorities.

In this study a real-world implementation of a spray mist cooling system in the city of Zurich is investigated. A ring carrying 180 high pressure nozzles was installed on a public square, as shown in figure 1a. Studies on spray mist cooling are scarce and inconclusive, as it depends on various operational, environmental and experimental factors[3]. State-of-the-art measuring stations[4] have been deployed for continuous measurements of temperature, humidity and other parameters during summer 2022, as shown in figure 1b. The measurements showed a weak cooling effect that was most pronounced south of the cloud, as shown in figure 2. A mean effect of -0.7°C was measured, with the strongest cooling of up to -2.5°C. The impact of the cloud was most pronounced at 25°C. A dependency on relative humidity and wind direction was measured, with the largest effect measured at low relative humidity downwind of the misting system. Outside of the operational hours no temperature difference was observed.

Figure 2) Mean difference between the mean temperatures of the measurement sites and the reference station from 12 July to 26 September during operating hours

The field experiment supports model development as an ideal case for model validation. The effect of the misting systems on heat and moisture fluxes have been implemented into the urban LES model PALM[1]. The parameterised cooling system in PALM was then used to investigate variations in placement, weather conditions and amount of sprayed water.

[1] Keith Oleson u. a., „Interactions between urbanization, heat stress, and climate change“, Climatic Change 129 (1. April 2013), https://doi.org/10.1007/s10584-013-0936-8.

[2] Sally Howard und Geetanjali Krishna, „How Hot Weather Kills: The Rising Public Health Dangers of Extreme Heat“, BMJ 378 (14. Juli 2022): o1741, https://doi.org/10.1136/bmj.o1741.

[3] Giulia Ulpiani, „Water Mist Spray for Outdoor Cooling: A Systematic Review of Technologies, Methods and Impacts“, Applied Energy 254 (November 2019): 113647, https://doi.org/10.1016/j.apenergy.2019.113647.

[4] BARANI DESIGN Technologies, „MeteoHelix IoT Pro Datasheet“, 18. August 2022, https://www.baranidesign.com/meteohelix-pro-weather-station.

[5] Maronga et al., Geosci. Model Dev., 13, 1335–1372, https://doi.org/10.5194/gmd-13-1335-2020, 2020

How to cite: Suter, I., Drossaart van Dusseldorp, S., and Anet, J. G.: From observations to modeling: Investigating the heat mitigation potential of public spray mist cooling in Zurich, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13652, https://doi.org/10.5194/egusphere-egu23-13652, 2023.

15:10–15:20
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EGU23-11806
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ECS
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On-site presentation
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Nils Eingrüber, Karl Schneider, and Wolfgang Korres

Extreme heat events are becoming more frequent in urban areas, and the magnitude of the urban heat island effect is increasing. Thus, adaptation of cities to climate change is a major challenge in urban planning. The summer of 2022 was the hottest summer in Germany on record. It was characterized by prolonged drought periods and low water levels in many rivers like the Rhine. For our urban study area in the city of Cologne (Germany), temperatures of more than 40°C were measured on several days, which is associated with excessive heat stress and health risks for the affected population. Significant small-scale temperature differences can be determined within cities for such heat events showing local effects and potentials for local adaptation and participation in climate change mitigation. As heat waves predominantly occur during radiation intensive and low-exchange weather conditions with limited or no advective air flow, microscale temperature differences can be traced back to the following most relevant processes: (1) differences in radiation absorption due to the albedo of urban surfaces, (2) shading effects by vegetation or buildings, (3 ) heat storage capacity and emissivity of materials, and (4) cooling effects through evapotranspiration of green infrastructures, urban water bodies, green facades or roofs. The aim of this study is to identify and explain small-scale microclimatic differences within a 16-hectare research area in the city of Cologne. Air temperature differences in a pedestrian level for two parallel streets with the same orientation and significant differences in terms of street width and greenery are analysed. We used the 3D ENVI-met model to simulate the urban microclimate of our study area with a spatial resolution of 1m² for the three hottest consecutive days which show the maximum 72-hour mean temperature in 2022 (July 18th-20th). The simulation results are validated using a densely distributed microclimate measurement network of 36 NETATMO low-cost sensors. The accuracy of these citizen science measurements is checked by three recalibration runs under laboratory conditions and direct comparisons with research-grade meteorological sensors in the field. The sensors show a high long-term stability and consistency with a measurement error less than one tenth of a Kelvin. ENVI-met model outputs and measurements are in very good agreement and show a high correlation. Thus, cause and effect relationships explaining the microclimatic conditions and its local deviations between the two selected streets can be made with high confidence during this heat wave in July 2022. Significant temperature differences of several Kelvin were identified when comparing the narrow, vegetation-free street canyon with the parallel broader street characterized by green front gardens, a double avenue of street trees and several facade greenings. Measured and modelled results show that local climate change adaptation measures can be highly effective in mitigating urban heat stress. In further steps, model scenarios will be developed to simulate and assess the potentials of various heat mitigation strategies in our study area in order to improve thermal outdoor comfort in cities with an increasing frequency of heat waves with over 40°C due to global warming.

How to cite: Eingrüber, N., Schneider, K., and Korres, W.: Evaluation of microclimatic variations and adaptation effects in a central European city during the most excessive heat wave in summer 2022 by ENVI-met modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11806, https://doi.org/10.5194/egusphere-egu23-11806, 2023.

15:20–15:30
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EGU23-15871
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ECS
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On-site presentation
Modelling assessment of the potential of adaptation measures to mitigate urban heat in future climate conditions
(withdrawn)
Anastasios Polydoros, Constantinos Cartalis, Vasiliki Kotroni, Kostantinos Lavouvardos, Ilias Agathangelidis, Christos Giannaros, Maria Saliari, and Elisavet Galanaki
15:30–15:40
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EGU23-12500
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Highlight
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On-site presentation
Chi-Yung Francis Tam, Tobi Eniolu Morakinyo, Gerald Mills, Ziqian Wang, Chenxi Hu, Ga Ming Cheng, and Renguang Wu

The dual forcing of climate change and rapidly urban development on heat waves over the Greater Bay Area (GBA), China and Lagos, Nigeria are investigated by multi-scale numerical simulation with the Weather Research and Forecasting (WRF) model coupled with single-layer urban canopy model. Heat stress cases are dynamical downscaled for the GBA and Lagos, under different scenarios. Three experiments are designed: For the first one, historical climate background derived from ERA5 reanalysis data will be utilized as boundary conditions for WRF, and present urban information is used. For the second experiment, future projected climate forcing using CMIP6 is incorporated into ERA5, with present urban information used. For the third experiment, both future climate and future urban landuse data (2050) will be utilized. Model outputs will then serve as boundary conditions for the ENVI-met model, which simulates microclimate conditions and provides details about heat stress at the street scale in two megacities. Based on our previous work, both urbanization and climate change lead to near-future temperature rise over the GBA, with the intensity of extreme heat events greatly enhanced due to their joint effects. This study is envisaged to provide invaluable urban climate information for climate change risk identification, prediction, mitigation and adaptation, by assessing how global warming, future urbanization, and their dual forcing affect heat stress at the city scale with model. Results related to future heat waves will provide useful information to policy maker about climate-sensitive urban planning, nature-based mitigation strategies and public policies making in the future.

How to cite: Tam, C.-Y. F., Morakinyo, T. E., Mills, G., Wang, Z., Hu, C., Cheng, G. M., and Wu, R.: Investigating global warming and future urbanization impacts on heat stress inmegacities- a multi-scalemodeling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12500, https://doi.org/10.5194/egusphere-egu23-12500, 2023.

15:40–15:45
Coffee break
Chairpersons: Dragan Milošević, Daniel Fenner, Hendrik Wouters
16:15–16:35
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EGU23-6042
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solicited
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Highlight
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Virtual presentation
Leena Järvi, Joyson Ahongshangbam, Minttu Havu, Hei Shing Lee, Jesse Soininen, Esko Karvinen, Anni Karvonen, and Liisa Kulmala

Urban green areas have multiple benefits extending from heat mitigation and carbon sinks to human well-being. Due to their multi-benefits, they are an attractive natural solution to aid climate change adaptation and mitigation. In cities of Helsinki and Tampere located in Finland, intensive observations and modelling of urban water and carbon dioxide (CO2) fluxes have taken place to improve our understanding of the functioning and carbon sequestration potential of different urban green areas and provide science-based evidence for decision-makers on how urban green areas should be planned and constructed to maximize their climate benefits.

Extensive eco-physiological observations were collected from different vegetation types (urban forest, park, garden, and street vegetation) in Helsinki during summers 2020-2022. The observations were made in the vicinity of the ICOS Associated Ecosystem Station FI-Kmp where eddy covariance (EC) measurements presenting the ecosystem level are conducted. The measurements included photosynthesis, sap flow, soil respiration, phenology, fine root growth, meteorology and soil properties. FI-Kmp represents mixed land use and vegetation, and to get more information of the behavior of lawns, additional EC measurements were conducted over urban lawn in the city of Espoo in 2021-2022. The observations are complemented by ecosystem modelling using SUEWS (Surface Urban Energy and Water balance Scheme). SUEWS is used to examine the impact of different urban green area planning options on carbon sinks and storages with focus on the city of Tampere. 

This work will highlight some of the findings made so far and provide examples on the carbon and water fluxes in different urban green areas. We also demonstrate how science-based knowledge can aid decision-making concerning urban green areas.

How to cite: Järvi, L., Ahongshangbam, J., Havu, M., Lee, H. S., Soininen, J., Karvinen, E., Karvonen, A., and Kulmala, L.: Observations and modelling of urban carbon and water fluxes to aid cities in climate mitigation and adaptation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6042, https://doi.org/10.5194/egusphere-egu23-6042, 2023.

Science tools and services for scientists and cities
16:35–16:45
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EGU23-7111
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Highlight
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On-site presentation
Fredrik Lindberg, Jeremy Bernard, Nils Wallenberg, Oskar Bäcklin, Jessika Lönn, Sofia Thorsson, and Karzo Kalori

The Urban Multi-scale Environmental Predictor (UMEP) is a city based climate service tool that facilitate user-friendly open source capabilities to combine models and tools essential for climate simulations. The tool is designed for a broad range of users, both within academia as well as practitioners and non-expert users. UMEP is available as a plugin in QGIS, a free and open source geographic information system (GIS) available on all common platforms. One main purpose with UMEP is to include pre-processing of geo- and weather data, process calculations as well as post-processing and visualisation in the same tool.

Recent developments in UMEP enables creation of all essential input variables required to generate high-resolution raster grid of common human thermal comfort indices such as Physiological Equivalent Temperate (PET), Universal Thermal Comfort Index (UTCI), Comfort Formula (COMFA) etc. This work presents initial results and methodology used to compute these indices within UMEP. Examples of workflow throughout the process, all the way to the final result, will be presented and discussed.

Acknowledgement
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 896069.

How to cite: Lindberg, F., Bernard, J., Wallenberg, N., Bäcklin, O., Lönn, J., Thorsson, S., and Kalori, K.: Modelling spatial variation of thermal comfort indices in urban settings performed within an open source GIS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7111, https://doi.org/10.5194/egusphere-egu23-7111, 2023.

16:45–16:55
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EGU23-1546
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Highlight
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On-site presentation
Matthias Demuzere, Jonas Kittner, Mathew Lipson, and Ting Sun

In recent years it has become increasingly evident that the solutions to climate changes, both mitigation
and adaptation, must pay greater attention to the places where most people on the planet live. Moreover,
the demand for weather services at urban scales is increasing in line with the ability to model
atmospheric processes at these finer scales; these advances could herald more resilient cities with the
evidence to support planning and design at appropriate time scales. In this context, the lack of
information on urban landscapes and the dearth of urban observations represent a major obstacle to
progress.
This work explores the possibility to create the scientific infrastructure needed to incorporate climate
knowledge into urban decision-making quickly. By combining globally available but locally appropriate
datasets (global map of LCZs, ERA5, Copernicus global land cover layers) and cloud computing (Google
Earth Engine), we created a seamless, holistic and user-friendly SUPY-based urban modelling framework
that can be applied anywhere at any time. Results are evaluated using the Urban Plumber flux tower
observations and a large unique database crowdsourced weather-station observations. The wider
purpose of the project is to develop a pathway to the creation of a universal ‘toolbox’ for baselining
climate-related data for use in any city.

How to cite: Demuzere, M., Kittner, J., Lipson, M., and Sun, T.: Urban climate modelling, anywhere, at any time, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1546, https://doi.org/10.5194/egusphere-egu23-1546, 2023.

16:55–17:05
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EGU23-12118
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On-site presentation
Stefan Horn and Janek Zimmer

The aim of the project CityCLIM is the development of a suite of services for the urban environment interesting for citizens and city administrations. The core of the CityCLIM services consists of a model chain to provide an operational weather forecast with an outstanding cell size of 100m for an area covering a whole city for a time span of up to three days. Therefore, the already operational SuperHD model by Meteologix is used to drive the new UltraHD model, which is a fully compressible large eddy simulation model including a two-moment microphysics parameterization. The UltraHD model was designed to use GPUs as the computational platform and is implemented using OpenCL. Surface orography and mountains were implemented using an immersed boundary layer approach and the model uses three-dimensional boundary conditions from the 1km SuperHD model. During the CityCLIM project further extensions for the UltraHD will be the implementation of a soil model for heat and moisture fluxes, a canopy layer to better represent vegetation fluxes and urban surface characteristics and a three-dimensional radiative transport code using raytracing for the short and a longwave band.

The developed CityCLIM services target at two different groups, the citizens within a city and the city administrations.

Services focused on the citizens are the Heat Wave Information and Warning Service, the Climate Information Service, the Pollution Information Service and the Citizen Weather Sensation Service. Except the Climate Information Service, the services will be based on operational everyday forecasts using the SuperHD and the GPU based UltraHD LES model chain. The Climate Information Service will be an extensive collection of climate and weather related parameters from available reanalysis models and measurement data on the Meteologix web portal. The Pollution Information Service will include aerosol compounds (PM10, PM2.5) and atmospheric trace gases (NOx, O3). With the added equations the computational effort for the UltraHD is significantly higher.

The administrative services consist of identification services for heat islands, city air flow and pollution areas within the city and simulation and mitigation strategies services. For the identification services a collection of many operational UltraHD model runs are analyzed for hot spots within a city and areas which are more sensitive to extreme weather conditions can be identified. The simulation and mitigation strategies services use manipulated input fields like orography and land use for recalculations for selected days. Those will be performed on demand and can be compared to previous simulations. This will provide insight in the effects of certain climate mitigation strategies and can be used as a testbed for large scale city planning.

To verify the results and to improve the initial model fields, high resolution measurement data is necessary. Therefore, the CityCLIM consortium installs additional weather stations within the pilot city regions and additional citizen science data will be collected. Earth observation data is extensively used, to characterize the surface of the city area with respect to land use and vegetation state and to compare model results like land surface temperature and soil moisture.

How to cite: Horn, S. and Zimmer, J.: CityCLIM – From an operational city weather forecast to a suite of services addressing the urban environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12118, https://doi.org/10.5194/egusphere-egu23-12118, 2023.

17:05–17:15
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EGU23-1976
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Highlight
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On-site presentation
Nektarios Chrysoulakis, David Ludlow, Zina Mitraka, Giorgos Somarakis, Zaheer Khan, Dirk Lauwaet, Hans Hooyberghs, Efrén Feliu, Daniel Navarro, Christian Feigenwinter, Anne Holsten, Tomas Soukup, Mario Dohr, Mattia Marconcini, and Birgitte Holt Andersen

A major challenge for the urban community is the exploitation of Earth Observation intelligence in managing in the multidimensional nature of urban sustainability towards enhancing urban resilience, particularly in relation to the challenges of climate change. This study presents the ways in which the H2020 funded project CURE (Copernicus for Urban Resilience in Europe) synergistically exploited Copernicus Core Services to develop cross-cutting applications supporting urban resilience. CURE provided the urban planning community with spatially disaggregated environmental intelligence at a local scale, as well as a proof-of-concept that urban planning and management strategies development enhancing the resilience of cities can be supported by Copernicus Core Services. Here, we demonstrate the technical operational feasibility of an umbrella cross-cutting system on urban resilience, consisting of 11 specific applications. These use Copernicus core products from at least two services each as main input information, reflect the main urban sustainability dimensions and are relevant to user needs, which were identified based on a strong stakeholders’ engagement. As a result, CURE is built on Data and Information Access Services (DIAS), as a system integrating these cross-cutting applications, capable of supporting downstream services across Europe, enabling its incorporation into operational Copernicus products portfolio in the future and also addressing its economic feasibility. For more information on CURE: http://cure-copernicus.eu

How to cite: Chrysoulakis, N., Ludlow, D., Mitraka, Z., Somarakis, G., Khan, Z., Lauwaet, D., Hooyberghs, H., Feliu, E., Navarro, D., Feigenwinter, C., Holsten, A., Soukup, T., Dohr, M., Marconcini, M., and Holt Andersen, B.: Copernicus for Urban Resilience in Europe: Final results from the CURE project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1976, https://doi.org/10.5194/egusphere-egu23-1976, 2023.

Urban thermal comfort and heat stress
17:15–17:25
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EGU23-573
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Virtual presentation
Modeling outdoor thermal comfort in waterfront urban fabric in a touristic city: Viña del Mar
(withdrawn)
Luz Cárdenas-Jirón and Andreas Matzarakis
17:25–17:35
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EGU23-197
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ECS
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On-site presentation
Cláudia Reis, André Nouri, and António Lopes

Today’s urban areas are excessive heat sources. The urbanization process has led to the development of positive temperature anomalies, called Urban Heat Islands (UHI). The future climate projections add an increasingly concern to the already heated and polluted urban environments, especially the increase in air temperature and in the frequency, intensity and duration of heat wave events. Hence, the degradation of the thermal conditions is already affecting human thermo-physiological comfort (TC) and health. In this investigation the UHI effect in Lisbon was detailed analyzed according to different thermal seasons (created based on the annual cycle of maximum and minimum air temperatures) and meteorological conditions, these later grouped into Local Weather Types (LWT). Over 60 000 hourly air temperature grids between 2008 and 2014 with a spatial resolution of 100m were extracted from the Copernicus Earth Observation Program. The UHI was calculated based on the widely used land use/land cover scheme, Local Climate Zones (LCZ). Furthermore, the UHI daily cycle by LWT and LCZ was also analyzed. Results show that on rainy conditions with higher cloud coverage the UHI effect is less pronounced (median intensity close to 0ºC), while on sunny conditions with weak to moderate winds and almost no clouds, especially very cold winter days and very hot summer days, median UHI reach 1.5ºC. The analysis of the UHI daily cycle proves that the UHI effect is mainly a nighttime phenomenon, while during the morning a slight Urban Cool Island (UCI) appears on most LWT. However, the analysis of UHI’s patterns and intensities only shows and compares the distribution of air temperature across different land uses, but the human body’s thermal sensation depends not only on air temperature, but also on wind, humidity, and radiation fluxes Therefore, the TC on 163 days between 2008 and 2014 from a particular LWT (the hottest summer days) was modeled in Lisbon. Thirteen microscale samples were selected according to the LCZ scheme, and 2 different TC indices based on the heat balance of the human body (Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI)) and Mean Radiant Temperature (MRT) were modeled during the day (12:00 to 15:00h) and night (00:00 to 03:00h) on a freely available and user-friendly software (SkyHelios v. 1.5). Results depict a moderate heat stress on LCZ A during the day (average PET/UTCI/MRT of 34ºC, 32ºC and 45ºC respectively) while the  sun-exposed and poorly ventilated areas on the remaining samples registered higher PET, UTCI (strong to extreme heat stress) and MRT values. During the night, PET results present a slight cold stress in all samples, while UTCI simulations show no thermal stress. This investigation will ultimately help to identify critical areas in the city that need interventions on surface materials, urban morphology, urban greenery and anthropogenic heat emissions in order to mitigate extreme heat conditions and its health risks associated.

How to cite: Reis, C., Nouri, A., and Lopes, A.: Urban Heat Island and thermo-physiological stress by Local Weather Types in Lisbon, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-197, https://doi.org/10.5194/egusphere-egu23-197, 2023.

17:35–17:45
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EGU23-7133
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On-site presentation
Sorin Cheval, Alexandru Dumitrescu, Dana Micu, Irina Onțel, Monica-Gabriela Paraschiv, and Gabriel Simion

Climate and climate-related hazards are growing threats to our cities, as a result of the twin challenges derived from the warming climate and urban expansion. Accountable development strategies must take into consideration the safety of the urban population, including its vulnerability and exposure to different hazards. The evaluation of risks related to heat hazards is a priority for urban municipalities, especially in big cities where the urban heat island intensity is significant. For example, the urban perimeter of Bucharest (Romania) is 2 - 3°C warmer than the 5 km buffer of the rural neighborhood, as an average of the land surface temperature (LST) over the summer months.

This research explores the risk associated with the heat hazard occurring over Bucharest due to vulnerabilities derived from different urban elements, such as population, land cover-land use, local climate zones, and characteristics of the buildings. The analysis covers the period 2013-2022, and the outputs are delivered at 100-m spatial resolution. The heat hazards were derived from LST retrieved from high-resolution imagery (i.e. Landsat 8) data using emissivity estimation, and the urban risk was calculated based on several variables related to demographics and built environment, considering their influence on the vulnerability to heat hazard. The Heat Hazard-Risk was computed using a risk matrix approach, as a product between the heat hazard and vulnerability, and the results inform the level of Census Administrative Units (CAU).

The results show that the heat hazard is more frequent during the warm season, and especially in June-July-August, when the average daily LST exceeds 40°C over the largest part of the city. The land cover characteristics and the LCZ have a significant influence on the LST values and generate adverse impacts on health, economic activities, and the environment.

As regards the demographic profile, this study examines the consequent risk derived from (a) population size (i.e. number of inhabitants and density), (b) age (i.e. younger and older people), and (c) density of people in the same dwelling.

This study has been partly funded by the project Synergies between Urban Heat Island and Heat Wave Risks in Romania: Climate Change Challenges and Adaptation Options (SynUHI) PN-III-P4-PCE-2021-1695.

How to cite: Cheval, S., Dumitrescu, A., Micu, D., Onțel, I., Paraschiv, M.-G., and Simion, G.: Heat hazard and risk assessment in urban areas. Case study of Bucharest (Romania), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7133, https://doi.org/10.5194/egusphere-egu23-7133, 2023.

17:45–17:55
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EGU23-6962
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On-site presentation
Dominik Kortschak, Andrea Damm, Heinz Gallaun, Michael Kernitzkyi, Judith Köberl, and Manuel Strohmaier

Climate change is causing temperatures around the globe to rise, leading to an increase in hot days and nights and a rise in the frequency and intensity of heat waves. High temperatures represent one of the key factors causing heat stress, which is affecting human health. Examples include the mega heat wave in August 2003 that took more than 70,000 lives across Europe or the unprecedented heat in 2018 with more than 100,000 heat-related deaths in the EU. Spatial exposure to heat stress varies, with urban areas usually heating up much stronger than their rural surroundings (urban heat island effect). With progressing global warming, the importance of spatially monitoring and predicting urban heat stress over large areas to prevent heat-associated morbidity and mortality is thus rising. For this purpose, thermal data obtained by satellites may represent a valuable alternative or addition to in-situ observations and climate modelling, which both show several advantages, but also shortcomings in terms of spatial coverage (in-situ), data needs (climate modelling) and costs.

One of the main challenges for the use of satellite thermal data for urban heat stress monitoring is to convert the obtained land surface temperature (LST) into air temperature (AT), since satellites only provide information on the former whereas the latter is needed as input for most heat stress indicators. In our presentation, we will address this challenge with emphasis on urban regions. Two main strands of methods are used in the literature for converting LST into AT. First, data driven methods that use the empirical relationship between in-situ observations of AT from weather stations and LST data from satellites. These methods usually work well for individual stations, but the transferability of the relationship to different locations is typically limited. In addition, especially for methods based on machine learning techniques, a significant amount of data is needed for model calibration. The second type of methods comprises physical models. They typically make use of the energy balance to estimate AT from LST. These models show the advantage of better transferability but need additional input data besides LST. Moreover, physical methods are often designed for applications in rural areas, which may differ from the situation in cities. We apply different methods to derive AT from LST in urban regions and discuss their suitability to monitor and predict urban heat stress based on satellite thermal data.

How to cite: Kortschak, D., Damm, A., Gallaun, H., Kernitzkyi, M., Köberl, J., and Strohmaier, M.: Towards a satellite based long-term monitoring and prediction of urban heat stress, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6962, https://doi.org/10.5194/egusphere-egu23-6962, 2023.

17:55–18:00

Orals: Wed, 26 Apr | Room F1

Chairpersons: Valentina Vitali, Dragan Milošević, Hendrik Wouters
Urban trees, urban green, and nature-based solutions
08:30–08:40
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EGU23-14239
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ECS
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On-site presentation
Francesco Busca, María Teresa Gómez-Villarino, and Roberto Revelli

Urban green infrastructures are considered useful tools to mitigate air pollution, increase the resistance of cities to climate change, optimize energy consumption expenses and promote the integral management of economic, social and cultural development, according to a "sustainable cooperation". However, there are few studies that quantitatively support this contribution and there is also a lack of knowledge about which species are the most suitable for an urban area in order to improve air quality.  

Therefore, the research project proposes to analyze the improvement of air quality and the contribution to reducing the effects of climate change by trees of an entire urban area. i-Tree Eco software and the inventory of the urban trees of the Madrid Municipality of Boadilla del Monte, with which the project has been developed, have been used. Results about air pollutants reduction have been compared with the Municipality's emissions in order to see how urban greenery helps to the improvement of air quality. Finally, an annual monetary estimation of the Ecosystem Services (ES) offered by the urban trees of the city has been made through the software, then compared with the annual costs (planting, maintenance, removal) agreed with the Municipality of Boadilla, reaching a Cost-Benefit Analysis representative of the contribution given by urban green areas to the surroundings. 

How to cite: Busca, F., Gómez-Villarino, M. T., and Revelli, R.: Influence of urban trees on the climate change adaptation in Boadilla del Monte (Spain), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14239, https://doi.org/10.5194/egusphere-egu23-14239, 2023.

08:40–08:50
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EGU23-5192
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ECS
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On-site presentation
Markus Anys and Markus Weiler

The rapid expansion of impermeable surfaces in cities has a major impact on hydrology and meteorology. The infiltration of rainwater is reduced resulting in more overland flow with higher peak flows, but also reduced evapotranspiration and hence higher sensible heat flux. Urban trees are becoming more important as stormwater management or climate adaptation tools. The rainfall interception of trees already reduces overland flow generation and increases latent heat flux. An in-situ field experiment to measure throughfall on the common urban trees Acer platanoides (Norway maple) and Tilia cordata (small-leaved lime) was conducted to determine the interception of solitary trees on urban sites with different degrees of surface sealing and shading from surrounding buildings in the city of Freiburg, Germany. The influence of rainfall characteristics and tree morphological traits on interception behaviour was investigated with eight trees per species. 76 recorded rainfall events were evaluated from April to September 2021. The recorded interception rates were much higher compared to typical values in forests. Average interception rates were higher for T. cordata (70.29 ± 6.56%) than for A. platanoides (54.76 ± 10.29%). The average interception loss of the recorded events per tree was 2.58 ± 0.60 mm and 3.73 ± 0.29 mm for A. platanoides and T. cordata, respectively. For both tree species, significant linear correlations were found between the relative interception values and other factors like rainfall characteristics, the leaf area index (LAI), and the plant area index (PAI) (adj.R2 > 0.45). Compared to A. platanoides, T. cordata showed significant relationships between several tree morphological parameters (CR, CPA, CC, CV, LAD, PAD) and the relative interception values (adj.R2 > 0.43). The lowest LAI of both tree species were observed at sites with highest degree of surface sealing (tree pits), which also impacts the interception process. Our results provide a better understanding of the interception process of solitary trees for different urban settings. However, further field experiments with various tree species need to be conducted in order to obtain a larger database for simplified applications in modelling approaches and to support urban planners in managing stormwater runoff and adapt to climate change.

How to cite: Anys, M. and Weiler, M.: Urban influences on rainfall interception of different tree species, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5192, https://doi.org/10.5194/egusphere-egu23-5192, 2023.

08:50–09:00
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EGU23-1877
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ECS
|
Virtual presentation
Urbanization-induced vegetation cover loss and its impact on urban heat island and carbon emission in Kolkata megacity region, India.
(withdrawn)
Manob Das, Arijit Das, and Paulo Pereira
09:00–09:10
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EGU23-2185
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ECS
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On-site presentation
Aisha Javed, Yerin Yun, Jaewon Hur, Junho Yeom, and Youkyung Han

Vegetations play an important role in the management of physical activities and the public health of urban residents. However, with the rapid urbanization in the world, vegetation regions are changing constantly. In order to prevent the decrease in vegetation areas, constant vegetation monitoring is required. In this study, we performed vegetation extraction and vegetation change monitoring in very high-resolution (VHR) satellite imagery through deep learning-based techniques. To this end, two deep learning networks (i.e., DeepLabV3-plus, and deeply supervised image fusion network (DSIFN)) were used for vegetation extraction and change detection, respectively. Firstly, the two networks were trained on the two datasets each for their respective purpose. Then, a DSIFN was tested to detect all the changes occurring in VHR bitemporal satellite images. Moreover, the binary vegetation maps from bitemporal images were independently generated by using DeepLabv3-plus. Later, the vegetation maps and the change detection result were combined to figure out the change tendency related to vegetation. To show the effectiveness of the proposed method, an accuracy assessment was carried out. The proposed method can be used to determine the amount of change occurring within a period in the vegetation of urban areas.

How to cite: Javed, A., Yun, Y., Hur, J., Yeom, J., and Han, Y.: Deep Learning-Based Vegetation Extraction and Vegetation Change Monitoring by using Very High-Resolution Satellite Imagery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2185, https://doi.org/10.5194/egusphere-egu23-2185, 2023.

09:10–09:20
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EGU23-1367
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ECS
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Virtual presentation
Ricard Segura, Carme Estruch, Alba Badia, Sergi Ventura, E. Scott Krayenhoff, and Gara Villalba

The Mediterranean basin is expected to experience an increase in intensity and frequency of heat wave events. Additionally, heat peaks are exacerbated by the low albedo of urban materials and the heat island effect of urban areas. To reduce heat-related discomfort and health risks, urban planners aim to implement green infrastructures to regulate temperatures thanks to their transpiration cooling effect. For example, the Metropolitan Area of Barcelona (AMB) has created a metropolitan network of “climate shelters”, which are public spaces (both indoor and outdoor) where urban dwellers can find better climatic conditions. Urban parks can be considered “climate shelters” if two requirements are met: the NDVI of the vegetation is higher than 0.4 and the extension of the park is bigger than 0.5 ha. However, given the dense urban edification and space limitation, we wanted to explore the thermal regulation capacity of smaller urban parks which are easier to implement. In this study, we present the results of a micrometeorological measurement campaign to assess the temporal and spatial variations of thermal comfort in parks of different sizes in the AMB during a heatwave episode in July 2022. The goals of this study are to determine the impact on human biometeorology of urban design in the construction of urban parks for facing heatwave episodes and to check the classification requirements for the “climate shelters”.

Using a mobile human-biometeorological weather station (MaRTy cart), we registered the microclimatic factors affecting thermal exposure at different points inside and outside the parks. From the microclimatic measurements we derived the Universal Thermal Climate Index (UTCI). Additional characterization of the measurement points consisted in sky-view-factor estimations and 360o vegetation and impervious view factors. Throughout the campaign period and measurement hours (14:00, 15:00 and 20:00 LT), the UTCI varied between 29.5 oC (moderate heat stress) and 41.9 oC (very strong heat stress). During the early afternoon, when air temperatures and heat stress are higher, the UTCI is lower inside of the parks, by a difference that ranges from 1.0 oC to 3.2 oC. The sky-view-factor is responsible for 43 to 58% of the observed variability in the UTCI, pointing out the importance of tree shadowing inside the parks. Air temperature has also a clear influence on thermal comfort, explaining between 17 and 50% of the UTCI variability. Although air temperature reductions in smaller parks are not as significant as in the “climate shelter” park, there are vegetation zones inside the smaller parks with comparable reductions in the UTCI. The results show that small parks can provide thermal comfort in similar capacity as bigger parks classified as “climate shelters”.

How to cite: Segura, R., Estruch, C., Badia, A., Ventura, S., Krayenhoff, E. S., and Villalba, G.: Evaluating the impact of urban parks on the thermal comfort during a heat wave episode in a Mediterranean city, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1367, https://doi.org/10.5194/egusphere-egu23-1367, 2023.

09:20–09:30
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EGU23-11913
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ECS
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On-site presentation
Bakul Budhiraja and Jennifer McKinley

Urbanization causes modifications in the urban climate of a city due to increase in impervious fraction and lack of evapotranspiration. The rise of extreme heatwave events due to climate change is causing concern for the cities effected by the urban heat island. Europe Union has recommended using Nature based solutions as a solution for multiple urban issues including the mitigation of urban heat. The UPSURGE project aims to use nature-based solutions for regenerative development in five demonstration cities. The five cities are based in different climate zones, consists of single to multiple demonstration sites, and are deploying various Nature based solutions based on the key city challenges.  The cities include Belfast, Breda, Budapest, Maribor, and Katowice. The demonstration sites are being Co-designed with multiple stakeholders to address the local concerns, diversity of voices to encompass perspectives and include citizens to address the longevity of Nature based solutions. The static and mobile sensors are being deployed to build a baseline and measure the effect of Nature based solutions. The cities have selected Nature based solutions varying from green roof, green wall, raingardens, Miyawaki forest, agroecology community gardens, rewilded zones, climate arboretum, meadows, water gardens. The work aims to model the effect of different Nature based solutions on the canopy urban heat island. The urban parameterization of the cities is done using local climate zone classification scheme. The advanced research Weather Research Forecast model is used to model the canopy urban heat island during the heatwave of July 2022. The WRF model is run for 7 days on three domains, 10 km, 5 km and 1 km horizontal resolution using six hourly data from ECMWF. The performance of the model has been assessed by analysing temperature, wind speed, relative humidity and surface level pressure considering their effect on local urban heat stress. The results showcase the importance of using actual urban morphology values in Weather Research Forecast to accurately simulate near-surface variables. The Weather Research Forecast simulations shows the presence of urban heat island and depicts the effect of deploying the various Nature based solutions across cities.

How to cite: Budhiraja, B. and McKinley, J.: Modelling the effect of Nature based solutions on urban heat island using the Local Climate Zone scheme in Weather Research Forecast model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11913, https://doi.org/10.5194/egusphere-egu23-11913, 2023.

09:30–09:40
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EGU23-9178
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Highlight
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On-site presentation
Marianne Bügelmayer-Blaschek, Martin Schneider, Tanja Tötzer, Michael Friesenecker, Thomas Thaler, Antonia Schneider, Michael Getzner, Sebastian Seebauer, Claudia Hahn, and Maja Zuvela-Aloise

Since almost half of the world’s population lives in cities and another third in settlements with similar characteristics, the current and future impacts of climate change in cities is of greatest importance. The characteristics of urban environments (reduced long-wave emissions towards the sky due to the blockage effect of the surrounding buildings, construction materials, anthropogenic heat production, lack of green and blue infrastructure) further increase ambient temperatures and cause urban heat islands. Nature-based solutions (NbS) have widely been investigated as a remedy to this challenge, which is quickly worsening due to the combined effects of climate change and the rapid densification of urban settlements. NbS cover a wide scope of measures such as planting roadside trees, greening facades or roofs, re-naturalizing rivers or unsealing of parking spaces to allow rainwater to penetrate and enable evapotranspiration. Yet, the widespread implementation of NbS often meets political, social, legal, financial or spatial barriers. 

In the presented study we combine interdisciplinary expertise from natural to social and economic sciences and a wide range of methods to evaluate and illustrate, exemplarily for the city of Vienna, how urban areas can implement NbS and overcome the aforementioned barriers. Therefore, (1) a list of possible NbS is compiled; (2), their performance is quantified through numerical micro-climate simulations, (3) their impact and potential trade-offs applying a socio-spatial analysis and survey, (4) individual preferences and willingness to pay are analyzed for a representative sample of 2,181 Viennese residents using a choice experiment, and finally, (5) a consolidated list of NbS is validated within policy workshops.

Using this approach we find that substantially transforming an existing quarter by implementing green and blue infrastructure, as well as technical solutions (e.g. sun blinds) may reduce the ambient air temperature by up to 2°C and the mean radiant temperature on some surfaces by up to 45°C, with natural measures being more effective than technical ones. Implementing these measures within the whole city of Vienna may yield a similar temperature effect. The socio-spatial vulnerability assessment identifies few areas where a strong overrepresentation of vulnerable age groups, low-income residents and housing vulnerabilities coincide.  In the city of Vienna, green gentrification owing to rising housing prices for already vulnerable groups thus seems to be very limited, especially as long-standing social housing policies and a rather strict regulation of the private housing markets lead to comparatively stable rent levels. The choice experiment shows a substantial willingness to pay for NbS, suggesting that Viennese citizens would financially support the implementation and maintenance of extensive greening measures. However, the politicians fear the conflicts with the citizens and other political parties as well as stakeholders. Stakeholders from the city authorities map potential physical and legal barriers for local implementation, such as building codes, administrative procedures for permits and inspections, or conflicts over scarce public space.

How to cite: Bügelmayer-Blaschek, M., Schneider, M., Tötzer, T., Friesenecker, M., Thaler, T., Schneider, A., Getzner, M., Seebauer, S., Hahn, C., and Zuvela-Aloise, M.: Climate resilience of the City of Vienna: social impact of Nature-based Solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9178, https://doi.org/10.5194/egusphere-egu23-9178, 2023.

09:40–10:15

Posters on site: Wed, 26 Apr, 10:45–12:30 | Hall X5

Chairpersons: Daniel Fenner, Valentina Vitali, Dragan Milošević
X5.267
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EGU23-13816
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ECS
Marvin Plein, Gregor Feigel, Matthias Zeeman, Ferdinand Briegel, Carsten Dormann, and Andreas Christen

Exposure and vulnerabilities to heat stress are concentrated in cities, yet exhibit large intra-urban variability. However, existing Weather Sensor Networks (WSNs) that monitor relevant meteorological conditions are typically installed at a much coarser resolution and generally do not cover canopy-layer conditions in cities. There are few examples of fine urban-scale massive sensor networks at street-level, however, they rarely provide any data beyond air temperature and humidity needed to assess, map and calculate thermal comfort, and many street-level networks often lack the real-time data transmission and quality control procedures necessary for real-time communication.

Here, we present a customizable two-tiered WSN setup, coupled with a quality and data processing chain, to quantify, map and communicate heat exposure data and resolve intra-urban variabilities in real-time. The hierarchical urban canopy-layer network developed for long-term monitoring of thermal comfort conditions (and also heavy precipitation and wind storm impacts) in the city of Freiburg, Germany, consists of two different station systems that are integrated into public street lights at a uniform height of 3 m a.g.l. Thirteen “tier I stations“ are strategically placed in representative built-up and rural areas. They are equipped with a ClimaVUE 50 all-in-one weather sensor (precipitation, wind, radiation, temperature, humidity, pressure) and a Black Globe Sensor (both from Campbell Scientific, Inc.) which enables real-time thermal comfort calculations such as the Physiologically Equivalent Temperature (PET) or the Universal Thermal Climate Index (UTCI). Tier I stations feature a custom-built multi-purpose logger which is controlled by a Raspberry Pi Zero running a custom remote control software and GSM data transmission. This allows for a highly flexible setup that can easily be expanded to include additional sensors (e.g. air quality) in the future. In addition, 35 commercial “tier II stations“ (LoRAIN, Pessl Instruments GmbH) measure air temperature, humidity and precipitation and transmit data over NB-IoT.  These tier II stations significantly increase the spatial density of the WSN at a lower cost per site. In addition to urban street-light mounted locations, an additional eight sites in non-built-up locations capture areas with predominantly rural and natural land cover, with selected stations specifically measuring cold-air drainage channels into the city.

With measuring and transmission intervals of one and five minutes, respectively, one major purpose of this WSN is to develop machine learning routines for data quality control and quality assessment in real-time and downscaling thermal comfort data from tier II to tier I stations and areas not covered by stations. Moreover, the WSN will provide input and validation data for numerical high-resolution modelling of urban heat exposure. Real-time visualizations inform researchers, city officials and the general public with instantaneous and historical data at neighborhood-scale. 

How to cite: Plein, M., Feigel, G., Zeeman, M., Briegel, F., Dormann, C., and Christen, A.: A sensor network for real-time monitoring and modelling of street-level heat exposure in Freiburg, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13816, https://doi.org/10.5194/egusphere-egu23-13816, 2023.

X5.268
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EGU23-2898
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ECS
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Sarah Berk, Manoj Joshi, Peer Nowack, and Clare Goodess

The Surface Urban Heat Island (SUHI), known as the difference in land surface temperature (LST) created by the presence of a city, is impacted by both the climate and morphology of the city in question. Subsequently, a changing climate would be expected to result in consequences for characteristics of the SUHI. Modelling the future climate of cities remains a challenge as resolution of global climate models is too coarse to capture the scale of a city, and regional climate models are computationally expensive. In order to address these issues, statistical models can be used. Using a dataset of cities selected based on similar characteristics such as population, variation of elevation within the city and surrounding area, and proximity to water bodies, satellite data is used to quantify the SUHI magnitude. A statistical model is fitted to current observations using predictive variables based on climate. The model shows promising performance for the majority of cities in the dataset and results are discussed.  

How to cite: Berk, S., Joshi, M., Nowack, P., and Goodess, C.: How will the Surface Urban Heat Island respond to changes in climate?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2898, https://doi.org/10.5194/egusphere-egu23-2898, 2023.

X5.269
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EGU23-6825
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ECS
Stefanel-Claudiu Cretu, Lucian Sfica, Vlad-Alexandru Amihaesei, Iuliana-Gabriela Breaban, and Pavel Ichim

Urban Heat Island (UHI) is caused by inadvertent climate modification due to human spatial concentration, being generally defined as the difference in temperature between urban areas and their rural surroundings. However, seen at fine spatial resolution, the heat island seems rather to look like an archipelago of hot spots delimited by colder areas. This study analyses the Surface Urban Heat Islands (UHISurf) of 16 cities located in Romania’s North-East Development Region for the identification of these hot and cold spots.

For each city, in order to identify UHISurf’s hot and cold-spots, Landsat series of satellites were used due to their potential to provide Land Surface Temperature (LST) product at a high spatial resolution, which is commonly required for micro or local scale studies. For this purpose, LST is derived from the Landsat 4, 5, 7, and 8 (1988-2021), collection 1 (using the Statistical Mono-Window algorithm), implemented in Google Earth Engine platform.

For hot /cold spots identification, Hot Spot Analysis (Getis-Ord Gi*) tool from ArcGIS Pro 3.0 was used. This tool calculates the Getis-Ord Gi* statistic for each feature in a dataset by looking at each feature within the context of neighboring features. To be classified as a statistically significant hot spot, a feature will have a high value and has to be surrounded by other features with high values. The local sum for a feature and its neighbors is compared proportionally to the sum of all features and a statistically significant z-score results. The larger the z-score is (positive), the more intense the clustering of high values defined as hot spots. The smaller the z-score is (negative), the more intense the clustering of cold spots. When the False Discovery Rate (FDR) correction is applied, statistical significance is adjusted to account for multiple testing and spatial dependency.

This procedure was applied for each of 16th cities, summing up 10900 images which cover an area of 2526,8 km2. LST is strongly controlled by surface properties (radiative, thermal, geometric, moisture and aerodynamic), these giving a greater surface temperature variability compared to air temperature, particularly during the day. Inside the identified hot spots, the LST is with 8-10C higher than the mean of UHISurf LST. Generally, light industrial, warehouses and transportation infrastructure (airports) are often relatively hot-spots, while cold-spots, are obviously more heavily vegetated areas, water bodies and areas of well-watered vegetation, but their futures are related to each city characteristics. The obtained results are designated to be used as the main assessment of urban heat island, delivering for stakeholder a clear image of the target regions inside the cities for the policies dedicated to the mitigation of the urban heat island effect.

How to cite: Cretu, S.-C., Sfica, L., Amihaesei, V.-A., Breaban, I.-G., and Ichim, P.: Identification of hot/cold spots inside the Surface Urban Heat Island of the main cities in North-Eastern Romania using Landsat imagery, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6825, https://doi.org/10.5194/egusphere-egu23-6825, 2023.

X5.270
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EGU23-566
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ECS
The impact of land use and land cover changes on land surface temperature in the first ring of Suceava Metropolitan Area
(withdrawn)
Vasilică-Dănuț Horodnic, Dumitru Mihăilă, Vasile Efros, Petruț-Ionel Bistricean, Alin Prisacariu, and Liliana Gina Lazurca (Andrei)
X5.271
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EGU23-5328
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ECS
The Assessment of the air temperature distribution in the Suceava - North-East Romania Metropolitan Agglomeration (2019-2021)
(withdrawn)
Alin Prisăcariu, Dumitru Mihăilă, Petruţ-Ionel Bistricean, Vasilică-Dănuţ Horodnic, and Liliana-Gina Lazurca (Andrei)
X5.272
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EGU23-9878
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ECS
Jelena Dunjic, Stevan Savić, and Dragan Milošević

Intensive urbanization and climate change are issues that are affecting majority of the urban areas around the world. Traditional artificial materials that are dominant in most of the cities are enhancing thermal stress that is very pronounced in the summertime especially in urban areas.  Different local and micro locations develop their own specific thermal conditions according to type of the materials that are dominant in the area. Green areas can contribute to improving thermal conditions of the area, but there is few in situ measurements to support those statements.

The main aim of the study is to investigate if there are intra- and inter-urban differences or similarities in thermal conditions in cities of different sizes and climate types. Micro-climate conditions (Ta, RH, v and Tg, 1 min. temporal resolution) were assessed using the in situ measurements with Kestrel 5400 Heat Stress Trackers in urban areas during the summer period. The measurement campaigns were conducted in five cities located in three Balkan countries: Serbia (Belgrade and Novi Sad), Bosnia and Herzegovina (Banja Luka and Trebinje), and Slovenia (Ljubljana). The first results indicate that there are significant differences in micro-climatological conditions of different local climate zones within the cities, which confirms that there are intra- and inter-urban differences within the cities and are related to the level of urbanization and presence of natural areas. For example, in Belgrade measurements show that differences in air temperature between densely built-up areas (LCZs 2 and 8) and green areas (LCZs A and B) are up to 7 ºC. Significant differences among the same LCZ are also recorded, depending on the level of shade provided by the urban configuration. Similar results are recorded in other cities where the measurements were performed. The results also show that shade and short- and long-wave radiation plays the most important role when it comes to reducing the outdoor thermal stress. The results are in good accordance with the previous studies that also reported more comfortable conditions in less built-up local climate zones with higher amount of greenery. This kind of assessments contribute to creating more sustainable urban environments that are resilient to climate change and increased thermal stress and extreme events in urban areas.

How to cite: Dunjic, J., Savić, S., and Milošević, D.: Comparison of thermal conditions in different intra- and inter-urban structures of different Balkan cities during the summer period, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9878, https://doi.org/10.5194/egusphere-egu23-9878, 2023.

X5.273
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EGU23-17349
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Highlight
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Andrei Covaci, Thomas Vergauwen, Sara Top, Steven Caluwaerts, and Lesley De Cruz

Traditional weather stations monitor the weather above short grass, which is a standardized environment. Such an environment is far from representative of where most people live. Moreover, despite advances in urban climate modelling, even state-of-the-art weather forecasts and climate scenarios do not account for the hyperlocal influence of land cover on meteorological variables.

To bridge this gap, we have constructed several machine learning models to translate 2-meter temperature measurements from standardized to different rural and urban environments. The input features of these models are the land cover fractions: impervious, green and water around a target station, and the interpolated open-field 2-meter temperature and wind values at the target location. The target feature for these models is the temperature data from the Flemish crowd-sourced VLINDER-network, which consists of calibrated stations positioned in unconventional locations. These models were trained on data from a limited set of VLINDER-stations and evaluated on unseen data of previously used and unused VLINDER-stations. We found that a random forest model yields the best results and had the highest interpretability of how the features interacted with the model. The results of the simple artificial neural networks are not robust, making these models less reliable.

We explore the addition of more features related to the urban environment such as building height, sky view factor and variables related to radiation. Finally, we investigate how to prevent possible overfitting due to insufficient variation in the land cover in the training data by including other data sources.

How to cite: Covaci, A., Vergauwen, T., Top, S., Caluwaerts, S., and De Cruz, L.: Machine learning-based emulation of land cover effects at sub-hectometric scale using crowd-sourced weather observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17349, https://doi.org/10.5194/egusphere-egu23-17349, 2023.

X5.274
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EGU23-4451
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ECS
Zitong Wen, Lu Zhuo, Qin Wang, and Dawei Han

The increasing frequency of heatwave events poses new threats to the health of urban residents. This effect can be exacerbated by the urban heat island (UHI) phenomenon. Air temperature is widely utilised in public health to quantify and analyse nonaccidental mortality attributable to heatwaves in urban areas throughout the world. Therefore, monitoring air temperature at the city level is important for identifying high-risk areas during heatwaves. However, measuring the spatial distribution patterns of air temperature in urban areas is challenging due to the lack of weather stations. The coarse spatial resolution of existing global and regional climate models is insufficient to detect the changes in microclimates, especially in complex-topography areas. In this study, a downscaling method for acquiring the 1-km hourly daytime air temperature data is proposed. It aims to produce a regression model by adopting Genetic Programming (GP) algorithm to estimate air temperature. Using multi-source datasets is considered to combine the advantages of spatial and temporal resolution from different datasets. This research used six weather stations from UK Met Office to assess the regression model obtained from seven satellite- and model-based products. The products consist of six satellite-based datasets retrieved from Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), Terra MODIS, Shuttle Radar Topography Mission (SRTM) and Landsat 8, and one model-based dataset from the newly released ERA5-Land produced by the European Centre for Medium Range Weather Forecasts (ECMWF). The study demonstrates the potential of the proposed model in retrieving high-resolution urban air temperature. The regression model validation showed good results with an R-squared value of 0.992, an RMSE of 0.001 °C, an MAE of 0.322 °C and an NSE of 0.989. The novelty of the study is threefold: (a) unlike previous studies that only estimated the spatial distribution patterns of maximum daily temperatures in urban areas, this study is the first to produce estimations at a one-hour time granularity; (b) it innovatively combines multi-source datasets with GP algorithm to explore possible downscaling models; and (c) it makes the model more reflective of the temperature distribution of extremely hot days than others considering that the regression model is obtained based on data during heatwaves. This study provides a general framework for obtaining hourly air temperature data in urban areas, which could provide theoretical support for heatwave-related decisions. Simultaneously, it can help public health scholars improve the estimation process of mortality caused by heatwave events.

How to cite: Wen, Z., Zhuo, L., Wang, Q., and Han, D.: Estimating air temperature with high spatio-temporal resolution in urban areas during heatwaves using genetic programming algorithm combined with multi-source datasets, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4451, https://doi.org/10.5194/egusphere-egu23-4451, 2023.

X5.275
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EGU23-13342
Daiane Brondani, Umberto Giostra, and Luca Mortarini

Air pollution from traffic is one of the leading causes of disease and premature death, potentially affecting all human body organs, depending on exposure to polluting sources. Among the main harmful agents to human health are fine particulate materials (PMs), such as PM 10 μm, PM 2.5 μmand PM 1 μm. The finest particulates, like PM 2.5 μm and PM 1 μm, are easily inhaled, causing respiratory problems such as irritation in the airways, coughing or difficulty breathing, worsening asthma, developing chronic bronchitis, irregular heartbeat, non-fatal heart attacks, premature death in people with heart disease, decreased lung function, contributing to the developing lung cancer. 

In addition, transported by the wind and then deposited in soil or water, the fine particulate contributes to the alteration of their acidity and nutrients, causing damage to forests and agricultural plantations. 

The present study investigates the ability of non-porous (concrete, glass) and porous (vegetation) barriers to attenuate the dispersion of fine particulate from roadway traffic. Large Eddy Simulations combined with observational data are used to evaluate the effectiveness of the different barriers in reducing the particulate concentration downwind from the roadway. Different types of barriers, different distances between the road and the barrier, and different barrier heights are simulated with PALM - 4U. The simulated concentration fields are compared to the Marche Region (Italy) measurements.

How to cite: Brondani, D., Giostra, U., and Mortarini, L.: Estimating the effect of roadside barriers in reducing PMs concentration with  PALM - 4U, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13342, https://doi.org/10.5194/egusphere-egu23-13342, 2023.

X5.276
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EGU23-6744
Fengqi Cui, Rafiq Hamdi, Piet Termonia, and Philippe De Maeyer

The coexistence of urban heat islands (UHIs) and heatwaves (HWs) enhances the stress on human society. However, how UHIs responds to the HWs and the interaction mechanisms between the UHIs and HWs in historical period and under different global warming levels (GWL) 1.5 ºC and 2 ºC scenarios are still elusive. In this study, the regional climate model ALARO-SURFEX (incorporated with LCZs) will be firstly used to estimate the historical interactions between the UHI and HW and the contribution of urbanization to the HWs in Beijing. The intensifying impact of three HWs (daytime HW, nighttime HWs, compound HW) on the UHI will be analyzed, and its energy mechanism will also be revealed. Secondly, the ensembled EAS-CORDEX data calibrated by adding hourly urban signatures will be used to force the offline SURFEX model to project the future urban climate in Beijing. The HW duration, frequency, and intensity will be estimated, and the UHI intensity and pattern will be investigated before, during, and after three kinds of HWs under different warming levels (GWL1.5 and GWL2). Understanding the interaction mechanisms of HWs and UHIs, as well as projecting for HWs and UHIs under the Paris Agreement, would be beneficial for stakeholders and city planners in developing future local adaptation policies.

How to cite: Cui, F., Hamdi, R., Termonia, P., and De Maeyer, P.: The interactions between the summer urban heat islands and heatwaves in Beijing: from past to future, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6744, https://doi.org/10.5194/egusphere-egu23-6744, 2023.

X5.277
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EGU23-4305
SLUCM-BEM: a parameterisation for dynamic anthropogenic heat and electricity consumption for WRF-Urban
(withdrawn)
Yuya Takane, Yukihiro Kikegawa, Ko Nakajima, and Hiroyuki Kusaka
X5.278
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EGU23-9022
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ECS
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Chiara Ghielmini, Francesco S.R. Pausata, Daniel Argüeso, and Razib Vhuiyan

Cities can have a significant impact on local microclimate. Higher temperatures that often characterise urban fabric can influence other meteorological parameters, such as precipitation. In this study, we investigated how the urban heat island (UHI) of Kuala Lumpur impacts rainfall through a set of sensitivity studies performed with the Weather Research and Forecasting (WRF) model. Many studies have already pointed out that the UHI can increase local rainfall, but they disregarded the city heterogeneity to large extent. Here, we investigated the effect of the city on precipitation incorporating different representations of the urban landscape. We performed three simulations with different urban land cover: 1) without city (control experiment) 2) with the urban terrain represented homogeneously and 3) with the urban land represented heterogeneously with the surface classification in the 11 categories of the Local Climate Zone (LCZ) system. We observed that the consideration of the city of Kuala Lumpur in the simulations results in a localised increase in mean annual precipitation and mean intense precipitation within the boundaries of the urban area. However, in the case of the homogeneous representation of the city, the increase is more pronounced than in the case of the heterogeneously represented city. In the former case, the increases also occur over a larger area and the impacts propagate more strongly into the upper layers of the atmosphere. Thus, a more realistic representation of the city and its heterogeneities limits the urban-induced effects on precipitation.

How to cite: Ghielmini, C., Pausata, F. S. R., Argüeso, D., and Vhuiyan, R.: On the evaluation of different WRF urban canopy schemes for the study of precipitation related to urban heat island in Kuala Lumpur, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9022, https://doi.org/10.5194/egusphere-egu23-9022, 2023.

X5.279
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EGU23-8044
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ECS
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Laura Tams, Björn Kluge, and Eva Nora Paton

Current shifts in rainfall and temperature regimes towards dryer and hotter periods in central Europe have caused substantial water stress for urban trees.  To be able to adapt water supply to urban trees under a changing climate,  a quantification of evapotranspiration and water availability becomes necessary and is at the same time, very challenging in the heavily modified urban environments. Both processes are influenced by soil sealing and complex shading patterns of the surrounding street canyon.  

For five urban street trees in the city center of Berlin, evapotranspiration rates and water availability was monitored in a field campaign (sapflow measurement and soil moisture in different depth) during the vegetation period of 2022. The monitoring results were then used to test a hydrological urban tree model with an integrated shading model which specifically takes into account the shading and sealing variability of the surrounding built environment.

Both measured and modelled data a  show that potential evapotranspiration rates were significantly larger for trees with full sun exposure compared to shaded trees. At sites with full sun exposure, the increased evapotranspiration also reduced soil moisture content faster; at the same time measured actual evapotranspiration was reduced by up to 2/3 during water stress periods.

In conclusion, the comparison showed that our model is a promising option to obtain information on water availability and to improve water management for urban trees under different shading and sealing environments in heavily modified cities. The tool will be further developed to be used by local authorities and practitioners to identify water shortage periods and hot spots  within the city to optimize irrigation efforts.

Key words: urban trees, evapotranspiration (ET), water availability, water stress, water management,  urban environment, shading

How to cite: Tams, L., Kluge, B., and Paton, E. N.: Urban tree water demand: Comparison of modeling results to measured sapflow and soil moisture data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8044, https://doi.org/10.5194/egusphere-egu23-8044, 2023.

X5.280
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EGU23-1872
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Highlight
Stevan Savić, Dragan Milošević, Jelena Dunjić, Hrvoje Krstić, and Ivan Šećerov

To improve the urban environment in general and contribute to the greening of urban areas in the cities of Central and Southeastern Europe, an international project was implemented in the period 2019-2022. The GReENERGY project is an international/cross-border project that is implemented in Europe, with the aim to improve the environmental conditions in cities, i.e., in this case, the urban areas of Novi Sad (Serbia) and Osijek (Croatia). Therefore, the activities of the GReENERGY project aim to: a) encourage the production and consumption of green energy through the installation of new solar power plants in public buildings, and reduce the energy consumption from conventional sources that are the major emitters of CO2; b) highlight the installation of vertical and horizontal greenery (green roofs and walls) on public facilities as one of the nature-based solutions (NBS) that ensure increased energy efficiency of buildings; and c) help preserve the urban ecosystem and improve outdoor thermal comfort conditions on a microscale.

The microclimate monitoring during the summer period and on hot days around a public building in Novi Sad (School for primary and secondary education “Milan Petrović”) showed that the thermal conditions are mainly driven by a combination of direct sunlight exposure or the presence of tree/building shadows. In our case, the differences in globe temperature (Tg) range from 6 °C to 10 °C during daytime at the micro-scale. A noticeable cooling effect caused by horizontal/vertical green areas is present during the night and based on datasets from our network this cooling effect is about 2 °C in Tg values.

Finally, thanks to the GReENERGY project the AWS network was installed around the public building in Novi Sad, and further monitoring, analysis and research of datasets from the network and current microclimate conditions in Novi Sad is supported by a new regional project financed by Autonomous Province of Vojvodina (regional government).

Finally, thanks to the GReENERGY project, an AWS network was installed around a public building in Novi Sad, and further monitoring, analysis and research of datasets from the network and current microclimate conditions in Novi Sad is supported by a new regional project financed by the Autonomous Province of Vojvodina (regional government).

Acknowledgement: The research was supported by the project entitled: "Improving the environment in Vojvodina in order to adapt to climate change and reduce the risk of natural disasters" (no. 142-451-3161/2022-01) financed by the Autonomous Province of Vojvodina.

How to cite: Savić, S., Milošević, D., Dunjić, J., Krstić, H., and Šećerov, I.: Greening the cities – Improving micro-scale thermal conditions and enhancing sustainable urban environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1872, https://doi.org/10.5194/egusphere-egu23-1872, 2023.

X5.281
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EGU23-2135
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Highlight
Leiqiu Hu and Qi Li

Urbanization has continued growing dramatically in the past few decades, as more than half of the global population live in urban areas. The alternation of surface materials and morphologic characteristics in urban areas and anthropogenic emissions from daily activities have been evident with a considerable influence on a wide spectrum of local climate, hydrologic cycles, and ecologic patterns. Decades of research efforts have enlightened our physical understanding of the impacts of LULC on urban climates. In addition, such knowledge has provided a scientific basis for adaptation and mitigation strategies in cities to counteract the risks associated with adverse climate effects. Examples include the adoption of high albedo roofs and pavements to alleviate heat stress and harnessing the evapotranspirative cooling power of urban greenspace and blue space (water bodies, including lakes, rivers, etc.) to provide a more comfortable thermal environment. Building on multiple-year dense observations from the ground networks and high-resolution spaceborne thermal measurements, this presentation will discuss the heat mitigation capacity of nature-based cooling infrastructures, such as green space and blue space.   Specifically, we will compare the thermal benefits of different cooling infrastructures, and how their spatial organization, and coverage yield different diurnal effects at both the microclimate scale and the city scale. The study shed light on their individual and interactive effects under different meteorological conditions, which offers new insights into the cooling benefit of excising urban amenities under various synoptical conditions, including extreme heat events. The findings provide critical information support to invest in future natural-based cooling amenities in cities as the heat threats grow dramatically on a global scale. 

How to cite: Hu, L. and Li, Q.: Greenspace, bluespace, and their interactive influence on urban  thermal environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2135, https://doi.org/10.5194/egusphere-egu23-2135, 2023.

X5.282
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EGU23-6927
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ECS
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Jonathan Simon, Christoph Beck, Joachim Rathmann, Elisabeth André, Linda Becker, Yekta Can, Alexander Heimerl, Bhargavi Mahesh, Nicolas Rohleder, and Andreas Seiderer

Urban forests are a proven human health resource, as they restore the physical and mental health of the human body and mind. They have a positive impact on air quality and thermal conditions by reducing concentrations of gaseous and particulate pollutants and lowering air temperature, respectively. In addition, urban forests provide several important ecosystem services, including those associated with human health. Different human-place concepts, show that a close connection of humans to their natural environment is an important determinant of people's well-being. Urban forests, however, vary based on e.g., tree species composition, structure, age and diameter of trees, canopy cover, number and density of canopy layers, abundance of plant species, dead wood, visibility distance, and light conditions. In any human-centered approach, these physical forest characteristics cannot be considered independently of subjective human perception.

Thus, besides answering the question of whether different urban/peri-urban forest and open land structures are associated with different local and human bioclimatic characteristics, another major objective of the project is to collect, digitize, process, model and assess data on human physiological effects gathered during field experiments and walking studies in selected study regions within the city and the urban forest of Augsburg, Germany. Thus, the overarching research question of our study is whether "climatic" forest types are also "human physiological" and "therapeutic" forest types.

The thermal properties of the study regions will be modelled with the microclimatic model ENVI-met and validated against field measurements of climate variables like air temperature, relative humidity, and wind conditions. If successful, this will allow the calculation of further bioclimatological thermal indices such as physiological equivalent temperature (PET), predicted mean vote (PMV) or universal thermal climate index (UTCI) and the development of silvicultural scenarios. Data on physiological effects on humans will be collected during monitored thermal walks along predefined routes in and near-by the study regions, where participants will be equipped with wearable electronic devices that collect physiological data, such as heart activity. Stress levels of participants along the routes will be assessed by saliva-cortisol probes. Questionnaires will be used to collect sociodemographic data and data on participants perceived thermal and visual sensations during the walks. Subjective thermal sensations will be compared to objectively derived thermal indices based on the model results and mobile measurements taken simultaneously with the thermal walks.

Measurements of bioclimatic parameters, human physiological responses, hormone releases, and the recording of subjective well-being as well as subjective perceptions of environmental variables allow for a comprehensive analysis of positive human-environment relationships in urban forests. Thus, a qualitative and quantitative assessment of recreational effects, differentiated by different forest structures, bioclimatic parameters, and social groups, can be comprehensively presented.

How to cite: Simon, J., Beck, C., Rathmann, J., André, E., Becker, L., Can, Y., Heimerl, A., Mahesh, B., Rohleder, N., and Seiderer, A.: Climate and health effects of different urban forest structures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6927, https://doi.org/10.5194/egusphere-egu23-6927, 2023.

X5.283
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EGU23-8092
Andreas Hoy and Karl Gutbrod

Grey infrastructures like buildings, roads and parking lots relate to surface sealing, lack of ventilation and anthropogenic heat – leading to effects like urban heat (UHI) and dry islands (= higher temperatures and lower relative humidity), and impact surface runoff during precipitation events. Hence, urban climate conditions differ significantly from their rural surroundings, demanding more granular data to quantify the effect city space has on weather parameters. However, observations and weather forecasts are usually made for rural areas, representative for a larger area – not for spaces where most people live, work and sleep. While a lot of data indeed exist for urban areas already – e.g., from satellites, radar stations and climate models – they all need calibration from measurements, in the city itself.

Tallinn is the European Green Capital 2023. While it strives making green spaces more accessible for its people, grey infrastructure development is continuing and even expanding, sustaining and increasing the city’s urban heat and dry islands. On the other hand, Tallinn is conserving and investing in green infrastructure, like turning an old railway track into a green corridor and publicly open space (the so-called “Pollinator Highway”). This corridor connects living quarters of Tallinn`s outskirts with central areas and supports social inclusion by passing through diverse socio-economic districts.

We created a concept to show the value of this green corridor for urban climate conditions. In May 2022, SEI Tallinn set up a network of 18 weather sensors measuring temperature, relative humidity and precipitation. The majority of stations are placed in green (5), urban green (5) and urban grey (5) spaces in the vicinity of the “Pollinator Highway”, with two more nearby the sea (to quantify land-sea-wind effects) and one near the official weather station. Data are open access, and live measurements publicly accessible.

In this contribution, we evaluate the results of 10 months of measurements, with a spatiotemporal focus on how and where Tallinn’s UHI enhances the impacts of heat and mitigates cold waves. With the data presented in this contribution, we make urban climate challenges visible and climate communication more relevant to people, show the climatic value of green compared to grey city spaces (especially during heat waves) to municipal decision-makers and Tallinn’s citizens, determine the effect of the sea on Tallinn's climate and how it shapes Tallinn`s UHI, and finally support climate resilience and tailored adaptation solutions.

How to cite: Hoy, A. and Gutbrod, K.: Showing the value of green spaces from a climate perspective: a weather sensor network for city spaces in Tallinn, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8092, https://doi.org/10.5194/egusphere-egu23-8092, 2023.

X5.284
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EGU23-9316
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Highlight
Thomas Nehls, Laura Tams, and Cristina Sousa Coutinho Calheiros

Green roofs are promoted to deliver climate regulation and urban heat island mitigation and many more. Ecosystem services of green roofs are discussed generally positively, but their footprint from production and demolition processes have not been fully addressed. In this study, a life cycle analysis (LCA) was conducted to assess the possibility of creating of a carbon-neutral green roof and to evaluate and compare the global warming potential (GWP) of two green roofs: 1) a conventional green roof (GR-c) with expanded clay, pumice, and compost in the substrate and a polypropylene drainage, and 2) an eco-friendly green roof (GR-a) with recycled bricks and compost in the substrate and a cork drainage. The LCA refers to a functional unit (FU) of a 218 m2 green roof (substrate depth of 9 cm; lifespan of 40 years). The results showed that the use of a brick substrate can reduce the GWP to 3139 kg of CO2 eq/FU (- 50%) and the use of cork drainage to 441 kg of CO2 eq/FU (- 69%). Apart from production, demolition is a key process  to be improved in future, accounting for 32% (GR-c) and 55% (GR-a) of the GWP. Once produced, a green roof can take up 783 gCO2/(m2⋅a) because of plant uptake. To become CO2-neutral, a GR-c and GR-a would have to last 88 and 53 years, respectively. Furthermore, the GWP was influenced by green roof maintenance and plant CO2 uptake. We conclude that recycled bricks and cork are promising green roof materials.

How to cite: Nehls, T., Tams, L., and Calheiros, C. S. C.: Rethinking green roofs- natural and recycled materials improve their carbon footprint, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9316, https://doi.org/10.5194/egusphere-egu23-9316, 2023.

X5.285
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EGU23-9050
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ECS
Evaluating the cooling potential of green walls and green roofs in Central European cities
(withdrawn)
Dragan Milosevic, Bernhard Pucher, Stevan Savic, Jelena Dunjic, and Günter Langergraber
X5.287
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EGU23-10965
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ECS
Jeongseop Lee, Dongwon Ko, and Sanghyun Kim

Climate change frequently generated extreme meteorologic event. The temperature difference between urban and its adjacent rural area had been defined as Urban Heat Island(UHI). The UHI during nighttime associated with high humidity condition introduces inconvenient living condition during Monsoon season. The generation of rainfall event and intensity of UHI had been known to counter reciprocal due to the apparent rainfall disturbance to vertical temperature profile. The hydro-meteorological data collected during summer season between 2013 and 2022 was used to evaluate the UHI intensity in Busan, South Korea. The impact of rainfall generation pattern was analyzed to configure the relationship rainfall and nighttime UHI. The results were derived that the temperature difference showed the characteristics of each year rather than the regular form.

How to cite: Lee, J., Ko, D., and Kim, S.: Nighttime Urban Heat Island with rainfall impact during monsoon season in South Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10965, https://doi.org/10.5194/egusphere-egu23-10965, 2023.

X5.288
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EGU23-9892
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ECS
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Highlight
Wan Ting Katty Huang, Pierre Masselot, Elie Bou-Zeid, Simone Fatichi, Athanasios Paschalis, Ting Sun, Antonio Gasparrini, and Gabriele Manoli

Ambient temperatures have an impact on human health, with unfavourably warm and cold conditions both associated with elevated mortality risk. By modulating the temperature in urban environments, urban heat islands (UHIs) can therefore both amplify the impact of heat and offer protection against cold weather. In this study, we quantify the impact of UHI on human mortality at 500m resolution for 85 European cities using air temperature simulations and age-dependent epidemiological temperature-mortality relationships for each city. On an annual basis, UHIs have weak net protective effects for most cities examined. This is due to the prevalence of cold to mild days in these cities when an increase in temperature is associated with slight reductions in mortality risk. On a daily basis, however, UHIs induce the greatest impact during heat extreme days, with a median of 39% increase in risk compared to a 7% reduction during cold extreme days. A valuation of such mortality risk reveals that the annual cost of UHI-related heat mortality is comparable to air pollution-related mortality costs as well as transit costs. Cities with Arid climates and Temperate Dry Summer climates in Southern Europe tend to experience the greatest protective UHI effects during cold extreme weather and the least adverse effect during heat extremes, while cities with Cold climates in Eastern and Northern Europe tend to benefit the least during cold extremes. Annually, the net impact of UHI is most strongly correlated with each city’s vulnerability to heat and cold and the ratio of warm vs. cold days in a year.

How to cite: Huang, W. T. K., Masselot, P., Bou-Zeid, E., Fatichi, S., Paschalis, A., Sun, T., Gasparrini, A., and Manoli, G.: Assessing the impact of urban heat islands on the risks and costs of temperature-related mortality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9892, https://doi.org/10.5194/egusphere-egu23-9892, 2023.

X5.289
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EGU23-8820
Biometeorological risk assessment due to thermal extremes in Suceava - NE Romania
(withdrawn)
Dumitru Mihăilă, Petruț-Ionel Bistricean, Alin Prisacariu, Emilian-Viorel Mihăilă, Mihaela Țiculeanu (Cirlică), and Sînziana Călina Silișteanu
X5.290
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EGU23-11123
Biometeorological risk assessed by ITU in Suceava metropolitan agglomeration - NE Romania
(withdrawn)
Petrut - Ionel Bistricean, Dumitru Mihăilă, Alin Prisacariu, Emilian-Viorel Mihăilă, Vasilică Dănuț Horodnic, Liliana Gina Lazurca (Andrei), and Mihaela Țiculeanu (Ciurlică)
X5.291
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EGU23-13594
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ECS
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Siwoo Lee, Cheolhee Yoo, Jungho Im, Dongjin Cho, Yeonsu Lee, and Dukwon Bae

The transformation of natural land cover into impermeable materials is a common definition of urbanization. However, it should be noted that vertical growth caused by urban renewal has been disregarded, while the horizontal expansion of urban areas has been widely studied. Understanding dynamic land cover change and its impact focusing on the thermal environment is essential for the sustainable management of urban areas. Therefore, the objective of this study is to propose a simple yet effective urban thermal environment investigation strategy that responds to dynamic land cover transformation. The study area is Suwon, Republic of Korea, where the city has recently been experiencing the most extreme urbanization along with explosive population growth. We designed a three-step approach: 1) extraction of temporal local climate zone (LCZ) to monitor the change in land cover due to urban growth over the period 2004 and 2021, 2) retrieval of high spatial-resolution land surface temperature (LST) using artificial intelligence to observe surface energy flux in heterogeneous urban area in detail, and 3) apply the filtering analysis method, which only uses the pixels classified with a higher confidence level, based on deep learning probabilistic approach to reduce the uncertainty of LCZ classification. To construct the temporal LCZ maps with a 30 m spatial resolution and retrieve the downscaled LSTs (DLSTs) with a corresponding spatial resolution, Landsat series satellites, Shuttle Radar Topography Mission (SRTM), and land cover map produced by Ministry of Environment were used. We obtained the following results: First, the overall accuracy (OA) of the LCZ classification was higher than 90% in both 2004 and 2021. Second, the average coefficient of determination (R2) and root mean square error (RMSE) of the DLSTs were greater than 0.9 and less than 1 °C, respectively. Third, through our suggested urban thermal environment investigation strategy, this study could find that the results of LST changes were clearly varied by building height and compactness changes. Especially, change of low-rise building to mid-rise building increased LST significantly. With these findings, we solidly believe the suggested strategy facilitates advanced urban climate studies.

How to cite: Lee, S., Yoo, C., Im, J., Cho, D., Lee, Y., and Bae, D.: An innovative method to investigate the altering urban thermal environment by dynamic land cover change: A case study of Suwon, Republic of Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13594, https://doi.org/10.5194/egusphere-egu23-13594, 2023.

X5.292
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EGU23-15799
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ECS
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Highlight
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Tom Wood, Hadi Arbabi, and Martin Mayfield

The global human population is projected to grow to between 8.9 billion and 12.4 billion by the end of the 21st century, with the proportion of the population living in cities projected to increase to 85% (OECD, 2015; UN, 2022). More than 80% of current global gross domestic product (GDP) is generated in cities (World Bank, 2020), demonstrating the importance of urban environments to the global economy and human flourishing. Urban infrastructure systems, such as energy networks, water supply and wastewater treatment, transport, communications, waste disposal and other utilities, are vulnerable to climate change impacts. It is therefore vital that the full range of potential climate change impacts on urban areas are understood.

Low-risk, high-consequence (LRHC) extreme climate change (ECC) events represent a severe threat to many aspects of human society. Existing literature tends to focus on average climate responses projected by climate models and emphasises the most likely scenarios based on a probabilistic approach. The impact of LRHC extreme and worst case scenarios has not received as much attention (Kemp et al., 2022). This includes impacts on urban and peri-urban infrastructure systems, regional and global supply chains, population displacement and migration, food, water and energy security and associated consequences such as increased conflict. While the likelihood of worst-case ECC effects by current assessment is low (IPCC, 2021), there remains significant uncertainty regarding potential climate tipping points that may cascade, trigger feedbacks and lead to runaway climate change (Lenton et al., 2019), even if global temperature increase is restricted to 1.5°C - 2°C (Armstrong McKay et al., 2022) which is growing more unlikely (Liu and Raftery, 2021). The potentially existential impacts of such scenarios necessitates that we exercise the precautionary principle (Sutton, 2019) and “explore the boundaries of plausibility” (Shepherd et al, 2018).

In this study we present synthesised evidence from the most extreme estimates of climate change effects such as extreme temperatures, precipitation, flooding, drought, wildfire, storms and sea-level rise from ECC scenarios, assessing the potential worst-case impacts on urban systems with a focus on heterogeneous regional impacts and the potential need for significant pre-emptive adaptation efforts. Global cities are ranked according to their potential vulnerability to ECC impacts with the aim of identifying cities where critical infrastructure is at risk of failure and what ECC effects they are likely to experience. We highlight gaps in current understanding and the need to focus research in this area while outlining a research agenda to explore ECC effects on urban infrastructure, including case studies of infrastructure systems in cities identified as vulnerable, with the aim of generating evidence for use in policy development.

 

References:

Armstrong McKay et al.. (2022). https://doi.org/10.1126/science.abn7950

IPCC, (2021) doi:10.1017/9781009157896

Kemp, et al (2022). https://doi.org/10.1073/pnas.2108146119

Lenton, T. M., et al., (2019). https://doi.org/10.1038/d41586-019-03595-0

Liu, P. R., & Raftery, A. E. (2021). https://doi.org/10.1038/s43247-021-00097-8

Shepherd, T. G. (2019). https://doi.org/10.1098/rspa.2019.0013

Sutton, R. T. (2019). https://doi.org/10.1175/BAMS-D-18-0280.1

How to cite: Wood, T., Arbabi, H., and Mayfield, M.: Extreme Climate Change Impacts on Urban Infrastructure and Support Systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15799, https://doi.org/10.5194/egusphere-egu23-15799, 2023.

Posters virtual: Wed, 26 Apr, 10:45–12:30 | vHall CL

Chairpersons: Hendrik Wouters, Gaby Langendijk, Dragan Milošević
vCL.3
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EGU23-2638
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ECS
Nistor Alina, Nistor Bogdan, Mihăilă Dumitru, Bistricean Petruț-Ionel, Sfica Lucian, and Emandi Elena Maria

Argument. The bioclimate is one of the most important life factors for humans, influencing a multitude of states, reactions, attitudes, actions and human activities. In the context of the regional warming of the atmosphere, in the conditions where the warming of the atmosphere of the cities of the region is faster and considering that in the cities of Suceava, Botoșani, Piatra Neamț, Iași, Bacău, Vaslui, Focșani and Galaţi there are 1,469,929 inhabitants, this study is necessary and fills a gap in scientific research with the information it brings.

Objectives. Having temperature and humidity data series from 10 stations in the 8 cities for the interval January 1, 2009 - December 31, 2022, we bring to the knowledge plan the temporal and spatial coordinates of the ITU for the Moldova region, with the attention focused on the days of the warm season in which ITU was above the thresholds of 66 (the lower limit of the alert threshold) and 80 units (the lower limit of the bio-meteorological discomfort threshold). The objectives of the study are:

  • i) outlining the differences and similarities of the multiannual, annual and daily regime of the ITU, with the identification and determination of the frequency of occurrence of temporal entities in which the value increase exceeded the threshold of 66, respectively 80 units,
  • ii) the identification of critical intervals from year and day in which the thermo-hygrometric complex can put man in difficulty, iii) finding some explanations related to the spatiality and temporality of the ITU, focusing on the positional, dimensional-urbanistic and synoptic factors, for the cases where the ITU has passed the threshold of 66/80 units.

Results. From all the processed time series, it emerged that the ITU can exceed the daily threshold of 66 units in the April - October interval. The highest frequency of days with ITU above 66 units is reached at all stations during summer days. ITU went up to over 80 units almost exclusively on summer days, most frequently in big cities (Iași - 9.8%, Galați - 2.9%).In the other cities, the ITU passing over 80 units is almost statistically insignificant at the daily level (in Suceava, Botoșani, Piatra Neamț and Focșani, the share of days with ITU ≥ 80 was equal to 0). Between 11-13 and 19-21 and only in the months of June-August ITU exceeded 80 units. In Iași, the share of hours with ITU over 80% was 14.6%, in Galati 9.8%, and in Piatra Neamț only 0.23%. Daily cases with ITU values above 66% held 57.5% of the time and were due to anticyclonic billow baric fields.

Conclusions. Through the ITU we demonstrated that in Moldova, on summer days, between 11:00 and 21:00, in a predominantly anticyclonic synoptic context, there is a moderate bio-meteorological risk for the population that goes outside the home during this time.

How to cite: Alina, N., Bogdan, N., Dumitru, M., Petruț-Ionel, B., Lucian, S., and Elena Maria, E.: Bioclimatic characteristics of the county seat cities in the Moldova - Romania region, outlined by ITU, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2638, https://doi.org/10.5194/egusphere-egu23-2638, 2023.

vCL.4
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EGU23-16915
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Siarhei Barodka, Tsimafei Schlender, Piotr Silkov, Aliaksei Borisovets, Aliaksei Sycheuski, Ilya Bruchkouski, and Tatiana Tabalchuk

This study is devoted to analysis of the impact of urban canyons and other features of urban morphology on formation of wind patterns and micrometeorological weather regimes in the urban area of Minsk, Belarus. For that purpose we combine urban morphology analysis with high-resolution mesoscale simulations with the WRF-BEP+BEM modelling system and observational data.

Urban morphology parameters for Minsk are first obtained on basis of OpenStreetMap (OSM) vector data processed with machine learning techniques. We then apply several algorithms of urban street canyon identification to this data to get an overall picture of main urban morphology features of Minsk and their possible role in wind patterns formation. Furthermore, OSM data is processed to form a representation of buildings data and other urban parameters for use in the WRF-BEP+BEM modelling system along with other sources of data for land use/land cover description. Modelling results are then analyzed along with observational data, which includes available satellite data, regular ground-based measurements, crowdsourced data from citizen weather stations and compact sensors, and our own street observations conducted with mobile instruments during several field campaigns in different parts of Minsk (including previously identified urban canyon zones.

How to cite: Barodka, S., Schlender, T., Silkov, P., Borisovets, A., Sycheuski, A., Bruchkouski, I., and Tabalchuk, T.: Impact of urban canyons on atmospheric processes in Minsk, Belarus: observational and modelling study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16915, https://doi.org/10.5194/egusphere-egu23-16915, 2023.

vCL.5
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EGU23-14793
Leif Backman, Esko Karvinen, Olli Nevalainen, Leena Järvi, and Liisa Kulmala

Urban green areas can be used as means for sequestering carbon, but also to manage run-off water and to reduce the urban heat island effect. Urban green spaces are often managed, including irrigation, removal of litter and modification of soil. In addition, urban green areas are often subjected to stress factors such as heat, pollution and drought. Here we study various carbon cycle components of urban trees using the JSBACH ecosystem model, focusing on the impact of drought. The study area is Kumpula, a semi-urban area situated in Helsinki, Southern Finland. In 2020 and 2021, an intensive measurement campaign took place involving a park area with tilia trees (Tilia cordata) and an urban forest dominated by Silver birch (Betula pendula). The observations included soil texture, soil temperature and moisture, and soil respiration. We used remote sensing data (Sentinel-2) for the leaf area index. Photosynthesis was measured using leaf cuvettes, and sap flow was measured for birch and lime trees. In addition, we used net ecosystem exchange from eddy covariance measurements at the Kumpula SMEAR III urban measurement station, operated by the University of Helsinki. The meteorological forcing data, to drive the model, was derived from observations at the Kumpula weather observation station, operated by the Finnish Meteorological Institute, and the SMEAR III station.

How to cite: Backman, L., Karvinen, E., Nevalainen, O., Järvi, L., and Kulmala, L.: Impact of drought on urban trees – a modelling study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14793, https://doi.org/10.5194/egusphere-egu23-14793, 2023.