UP2.1 | Cities and urban areas in the earth-atmosphere system
Cities and urban areas in the earth-atmosphere system
Including Tromp Foundation Travel Award to young scientists (TFTAYS)
Conveners: Maria de Fatima Andrade, Arianna Valmassoi, Pavol Nejedlik | Co-conveners: Ranjeet Sokhi, K. Heinke Schlünzen, Jan-Peter Schulz
Orals Mon1
| Mon, 08 Sep, 09:00–10:30 (CEST)
 
Room E3+E4
Orals Mon2
| Mon, 08 Sep, 11:00–12:30 (CEST)
 
Room E3+E4
Orals Mon3
| Mon, 08 Sep, 14:00–15:30 (CEST)
 
Room E3+E4
Posters P-Tue
| Attendance Tue, 09 Sep, 16:00–17:15 (CEST) | Display Mon, 08 Sep, 08:00–Tue, 09 Sep, 18:00
 
Grand Hall, P54–59
Mon, 09:00
Mon, 11:00
Mon, 14:00
Tue, 16:00
Cities and urban environments are a key aspect of the United Nations (UN) Agenda for Sustainable Development, and include scientific and socio-economic perspectives. As urbanisation processes continue across the world, its representation and understanding needs to be further improved to fully assess its impact on weather, air quality, water quality, energy consumption/production and climate. These aspects are crucial both for advancing current knowledge and creating effective sustainable solutions. Key challenges in accomplishing this task vary according to the level of complexity and multi-scale dimension of diverse urban environments.

This session welcomes modelling and observational studies that aim to investigate different aspects of urbanization (e.g. urban heat island, air quality, vulnerability to extreme events, urban/peri-urban agriculture) and its feedback on weather and climate systems, with a particular focus on application for sustainable adaptation plans. Novel methods that aim to assess urban representation and/or to bridge the different scales of the diversity of topologies are encouraged. The impact of cities on weather, air quality, climate and/or their extremes (e.g. drought, precipitation, air pollution episodes), as well as on climate change and on population and adaptation will also be discussed in this session.

Topics may include:
• New urban parameterizations, methods to derive urban parameters for numerical models.
• Implementation of climate mitigations, adaptation strategies (e.g. blue-green infrastructures) and self-government policies in cities and urban context.
• Impact of the different urban parameterizations on the atmospheric dynamics at different scales.
• Impact of the urbanization including estate and industrial on weather and/or climate extremes.
• Field measurements of urban climate, e.g. precipitation, CO2 concentrations and flux, boundary layer characteristics.
• Population vulnerability to urban climate and climate change.
• Extreme events' (e.g. drought, rainfall events, heat wave) impacts on urban areas.
• Urban emissions of climate forcers, air pollutants and anthropogenic heat.
• Urban air quality and meteorological interactions.
• Meteorology or air pollution modelling of all scales with focus on urban areas.
• Coupling and downscaling of global, regional and urban scale modelling approaches to quantify climate and atmospheric composition impacts and feedbacks.
• Integrated monitoring, modelling and forecast systems for urban hazards.
• Urban transition to cleaner fuels and their meteorological or AQ impacts.
• Crowd sourced data/novel data sources in cities
• Successes, challenges and limits of AI approaches for urban research
• Assimilation of 4D data and machine learning applied for air quality simulation
• Social science analyses of cities

Organised jointly with:
World Meteorological Organization (WMO) Global Atmospheric Watch Project GAW Urban Research in Meteorology and Environment (GURME)
WMO World Weather Research Programme (WWRP)

Orals Mon1: Mon, 8 Sep, 09:00–10:30 | Room E3+E4

Chairpersons: K. Heinke Schlünzen, Pavol Nejedlik, Jan-Peter Schulz
Local and global climate change effects and how urban areas counteract
09:00–09:15
|
EMS2025-273
|
Onsite presentation
Aleksandra Zwolska, Marek Półrolniczak, and Leszek Kolendowicz

The study determined the influence of changes in land use and land cover (LULC) on land surface temperature (LST) over a 33-year period based on a medium-sized European city (Poznań, Poland). The LST was estimated from Landsat 5, 8 and Terra (MOD11A2v6) satellites. The local estimation of climate patterns was based on the Local Climate Zones (LCZ) classification utilised with the methodology proposed by the World Urban Database and Access Portal Tools (WUDAPT). Moreover, the Copernicus’ imperviousness density product (IMD) was used. Between 2006 and 2018 the area with IMD of 41–100% increased by 6.95 km2, 0–20% decreased by 7.03 km2. The contribution of built-up LCZs increased by 7.4% (19.21 km2) between 1988 and 2021 reaching 13% (34 km2) within open mid-rise LCZ. Due to urbanisation and reforestation, low plants LCZ shrunk by 12.7%. For every 10% increase in IMD, LST increases by up to 0.14 °C. Between 1988 and 2021 the LSTm in specific LCZs rose from 1.52 up to 2.97 °C. As per LST models LCZ change from natural to built-up led up to 1.19 °C LST rise. The increase of the LSTm was registered even when the LCZ remained unchanged. The results highlight a clear trend of intensifying urban heat island effects driven by the transformation of natural and semi-natural areas into impervious and built-up surfaces. The spatial distribution of LST patterns strongly correlates with the extent and density of artificial surfaces, as confirmed by both remote sensing data and LCZ classification. Additionally, the study emphasizes the utility of integrating multi-source satellite data with standardised urban classification methods to detect fine-scale thermal responses to urban development. These insights provide valuable input for urban planning and climate adaptation strategies aimed at mitigating future temperature rises in expanding urban areas.

How to cite: Zwolska, A., Półrolniczak, M., and Kolendowicz, L.: Urban growth’s implications on land surface temperature in a medium-sized European city based on LCZ classification, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-273, https://doi.org/10.5194/ems2025-273, 2025.

Show EMS2025-273 recording (10min) recording
09:15–09:30
|
EMS2025-424
|
Onsite presentation
Juan Pedro Montavez, Eloisa Raluy, Alejandro Cordero, Leandro Segado-Moreno, Salvador Gil-Guirado, and Pedro Jiménez-Guerrero

The interactions between urban climate and air pollution are complex and bidirectional. On one hand, urban characteristics, such as the heat island effect and  higher surface roughness, modify local circulations and can enhance the accumulation of pollutants under certain conditions. On the other hand, atmospheric pollutants, such as aerosols or green house gases, can alter radiative and thermodynamic processes, affecting air temperature, cloud formation, and atmospheric stability.  However, the knowledge on these feedbacks is still scarce. In this context, high resolution coupled atmosphere-chemistry models can help to understand better these interactions.  

We present a set of high-resolution (1km)  WRF-Chem simulations over several large and medium-sized European cities to investigate the impact of urban areas on local meteorology and air quality, as well as the interactions between pollutants and urban climate modification. The experiments include idealized configurations removing and including urban areas, and activating and deactivating anthropogenic emissions. The comparison among the experiments permit as to identify the relative role of each factor in the generation of the urban climate.  The results show that the model is capable of reproducing the Urban Heat Island (UHI) effect and capturing its influence on local circulations. When urban emissions are introduced through the atmospheric chemistry module, average impacts on meteorological variables are generally modest. However, under specific weather conditions, typically characterized by weak winds and overcast skies, urban emissions can significantly alter local atmospheric dynamics. On the other hand, the results indicate that a full inclusion of the city morphological features enhances the pollution urban island.

How to cite: Montavez, J. P., Raluy, E., Cordero, A., Segado-Moreno, L., Gil-Guirado, S., and Jiménez-Guerrero, P.: Urban climate and pollution feedbacks in high resolution WRF-CHEM experiments., EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-424, https://doi.org/10.5194/ems2025-424, 2025.

09:30–09:45
|
EMS2025-54
|
Onsite presentation
Admir Créso Targino, Gabriel Yoshikazu Oukawa, Patricia Krecl, Patrícia Faria, and Ligia Flávia Batista

Rapid urbanisation exacerbates urban heat stress, posing significant risks to human well-being under a warming climate. This research investigates nature-based solutions for urban heat stress mitigation, implemented within a climate service framework and using a mid-sized Brazilian city as a case study. We employed the SOlar and LongWave Environmental Irradiance Geometry (SOLWEIG) model to simulate mean radiant temperature and the Universal Thermal Climate Index (UTCI) for winter and summer at high spatial (2 and 10 m) and temporal (1 hr) resolutions. Our case study sought to: (i) characterise the hourly, seasonal, and weather-dependent variations in urban heat stress; (ii) identify the neighbourhoods and population groups most vulnerable to extreme heat across key Local Climate Zones; and (iii) develop strategies for maximising tree canopy cover to improve thermal comfort. We explored the potential of green infrastructure enhancement through four scenarios (no trees; current tree cover; and two levels of increased tree cover) utilising a developed algorithm that optimises tree cover by replacing smaller trees with larger specimens and strategically planting new, mature trees. Our spatial analysis of UTCI distribution highlighted that the city centre (where a significant fraction of the elderly population resides), along with its adjacent neighbourhoods, experienced the highest percentage of summer hours exceeding strong and very strong heat stress thresholds, which poses significant health risks to the population. Notably, during the summer, the city centre recorded 194 hr above the very strong heat stress threshold (> 38 °C). Doubling the canopy area in the city centre can lead to UTCI reductions of up to 1.2 °C compared to the baseline (current tree cover). Further expanding the canopy to 2.8 times the original area resulted in an additional decrease of 0.9 °C, bringing the total reduction to 2.1 °C. A closer analysis of two blocks in the city centre revealed UTCI reductions of up to 1.0 °C and 3.1 °C when considering two scenarios with a progressive increase in the number of trees, compared to the baseline during the hottest hours of the day (12:00–14:00). This study demonstrates the effectiveness of our framework as a practical, accessible, customisable and cost-efficient tool for cities to assess and implement tree-based heat mitigation strategies.

How to cite: Targino, A. C., Oukawa, G. Y., Krecl, P., Faria, P., and Batista, L. F.: Urban heat stress reduction through optimised tree cover scenarios, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-54, https://doi.org/10.5194/ems2025-54, 2025.

09:45–10:00
|
EMS2025-584
|
Onsite presentation
Sorin Cheval, Vlad Amihaesei, Teodora Cardos, Vasile Craciunescu, Stefan Dinicila, Stefan Gabrian, Vladut Falcescu, Cristian Ioja, Mirabela Marin, Dana Micu, Mihai Razvan Nita, Nicu Constatin Tudose, Cezar Ungurean, and Liliana Velea

Water scarcity is one of the most critical impacts of climate change in many parts of the world. Water scarcity results from a combination of limited or uneven precipitation, excessive consumption, and inefficient management practices driven by various economic activities, and this often occurs in metropolitan areas. This study centres on the Brașov Metropolitan Region (BMR), situated in central Romania, a region undergoing a significant increase in average temperatures while maintaining relatively stable annual precipitation levels. Despite the overall consistency in precipitation amounts, climate projections and historical analyses indicate an intensification in the frequency and severity of extreme hydrometeorological events, notably heavy rainfall episodes and prolonged drought periods, which collectively pose growing challenges for sustainable water management in the area. At the same time, the BMR is defined by population increase, changing consumption patterns, urban expansion, and economic growth (including tourism intensification). All contribute to an increasing pressure on water resources, which become insufficient in some periods of the year. Different indicators were used to assess the water scarcity in the area of interest, such as the Falkenmark Indicator, Green-Blue Water Scarcity, and Water Stress Index, in the present climate and under different climate scenarios and socioeconomic perspectives. The study employs data and information from publicly available sources and data collected from local sources during the project implementation and the outcomes of hectometer scale earth systems modelling focusing on the floods that occurred in the past decade, leveraging available meter scale urban data sets available for the BMR. 

The results support the co-development of viable solutions that consider both the climatic and socioeconomic pressures and are firmly based on the long-term participatory approach involving the quadruple helix, such as policymakers, business, citizens (including vulnerable communities), and academia.

The quadruple helix perspective on water scarcity was given in the Living Lab Brașov, where the 27 stakeholders (including vulnerable groups) confirmed it as a critical challenge. Associated risks, drivers, and measures were identified to understand and address BMR's water scarcity. 

The results are obtained in the project Climate-Resilient Development Pathways in Metropolitan Regions of Europe (CARMINE), funded by the Εuropean Union under the Horizon Europe Programme (Grant agreement 101137851). 

How to cite: Cheval, S., Amihaesei, V., Cardos, T., Craciunescu, V., Dinicila, S., Gabrian, S., Falcescu, V., Ioja, C., Marin, M., Micu, D., Nita, M. R., Tudose, N. C., Ungurean, C., and Velea, L.: Vulnerability to water scarcity in metropolitan areas under climate change and development challenges, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-584, https://doi.org/10.5194/ems2025-584, 2025.

Show EMS2025-584 recording (14min) recording
10:00–10:15
|
EMS2025-651
|
Onsite presentation
Xabier Pedruzo Bagazgoitia, BIrgit Sützl, Emanuel Dutra, Joe McNorton, Christoph Rüdiger, and Aristofanis Tsiringakis

Current research on future urban climate involves several steps from global climate simulation planning (e.g. CMIP), through downscaling and down to impact modelling. This process is often time-consuming and can introduce physical and technical inconsistencies due to the variety of tools and assumptions involved. With the advent of coupled km-scale multi-decadal modelling, pioneered in the nextGEMS project and operationalized by Destination Earth, the workflow can now be accelerated and simplified by directly performing urban climate analysis on the global simulations.

We present what is, to our knowledge, the first analysis of urban climate on global km-scale climate simulations. We exploit the fully coupled IFS-FESOM and IFS-NEMO simulations produced on the nextGEMS project. These span for several years across horizontal resolutions of 28, 9 and 4.4 km, and include a 30-year historical simulation (1990-2020) at 9 km, as well as a 30-uear future scenario (scenario 2020-2050) following the SSP3-7.0  scenario.

We present a robust automated methodology that, based on surface static information, allows to gather and filter simulation information over all kinds of urban areas and their rural references worldwide. We then show the spatiotemporal features of such urban and rural model representations consistently for hundreds of cities worldwide. We further analyze the sensitivity of the nextGEMS present-day multi-annual simulations to spatial resolution, with a particular focus on the thermal aspects of urban climate and its contrast to the rural counterpart in each season. By exploiting km-scale surface temperature remote sensing products by LSA-SAF, we can confirm that the models are able to capture key spatial and temporal features of the typical surface urban heat island diurnal cycle, and that performance improves with increasing spatial resolution.

Finally, we make use of the available multi-decadal simulations by IFS-FESOM to explore the evolution of urban climates for both past and future scenario and group urban areas according to their expected change. We further investigate the possible amplifiers, such as orography or urban density, in an attempt to explain the different trends for cities worldwide found in the simulations.

How to cite: Pedruzo Bagazgoitia, X., Sützl, B., Dutra, E., McNorton, J., Rüdiger, C., and Tsiringakis, A.: Global urban climate analysis on multi-decadal km-scale climate simulations, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-651, https://doi.org/10.5194/ems2025-651, 2025.

Show EMS2025-651 recording (13min) recording
10:15–10:30
|
EMS2025-673
|
Onsite presentation
Tomas Halenka, Gaby Langendijk, and Peter Hoffmann

Cities play a fundamental role in climate at local to regional scales through modification of heat and moisture fluxes, as well as affecting local atmospheric chemistry and composition, alongside air-pollution dispersion. Vice versa, regional climate change impacts urban areas and is expected to affect cities and their citizens increasingly in the upcoming decades when the share of the population living in urban areas is growing and is projected to reach about 70 % by 2050. This is especially critical in connection to extreme events, for instance, heat waves with extremely high temperatures exacerbated by the urban heat island effect, in particular during night-time, with significant consequences for human health.

From the perspective of recent regional climate model development with resolution achieving city scales within convection permitting RCMs, parameterization of urban processes plays an important role to understand local/regional climate change. The inclusion of the individual urban processes affecting energy balance and transport (i.e. heat, humidity, momentum fluxes, emissions) via special urban land-surface interaction parameterization of local processes becomes vital to simulate the urban effects properly. This enables improved assessment of climate change impacts in cities and planning adaptation and/or mitigation options, as well as adequate preparation for climate-related risks (e.g. heat waves, smog conditions, etc.).

We introduced this topic to the CORDEX platform, within the framework of flagship pilot studies on challenging issues and gaps in regional climate change knowledge. The main aims and progress of this activity will be presented, especially an analysis of Stage-0 experiments using case studies of heat wave and convection episode within ensemble of nearly 40 simulations for City of Paris with convection permitting RCMs from different groups over the world. Further outlook of long term (10 years – Stage 1 experiment) climate simulation with these models in common strategy to IMPETUS4CHANGE Horizon Europe Project will be presented as well, The development of Global Satellite Cities experiment will be introduced as another part of Stage 1 experiment. Outlooks for further experiments will be explained as well.

How to cite: Halenka, T., Langendijk, G., and Hoffmann, P.: CORDEX Flagship Pilot Study URB-RCC: Urban Environments and Regional Climate Change – Where We Are and Where We Are Going, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-673, https://doi.org/10.5194/ems2025-673, 2025.

Show EMS2025-673 recording (14min) recording

Orals Mon2: Mon, 8 Sep, 11:00–12:30 | Room E3+E4

Chairpersons: Pavol Nejedlik, K. Heinke Schlünzen, Maria de Fatima Andrade
11:00–11:15
|
EMS2025-27
|
solicited
|
Onsite presentation
Alice Guccione, Paolo Bassi, Fabien Desbiolles, Matteo Borgnino, Fabio D'Andrea, and Claudia Pasquero

Extreme rainfall is expected to increase because of global warming, driven by the increase in atmospheric heat which boosts the atmospheric water content, subsequently altering precipitation patterns. The Clausius‐Clapeyron (CC) equation dictates a 7\% increase in atmospheric capacity to hold water for every 1 °C temperature increase, and although many deviations from CC scaling have been observed, there is a consensus in the literature that extreme precipitation is changing. Urban areas are particularly affected by weather extremes, although the impact of urbanization on intense rainfall remains difficult to quantify. This study investigates changes in extreme precipitation events using daily data from 6028 weather stations worldwide, extracted from the Global Historical Climatological Network (GHCN). While previous studies examined similar trends and found the largest frequency increase for the most intense events, this work also incorporates urbanization factors. The analysis focuses on the 60 most intense precipitation events within the 1962-2021 timeframe, evaluating trends in frequency at each station, and considering stationarity assumptions. Two urbanization indices were used to categorize stations, revealing correlations with changes in extreme event frequency, indicating that the occurrence of extreme precipitations is increasing significantly more in densely populated urban areas. In addition to these observations, the study conducted seasonal analyses, revealing that, for both indices, the frequency versus urbanization index trend is primarily attributed to measurements in the autumn and winter seasons. The observed changes offer a valuable insights into the intricate relationships between heavy rainfall and urban areas, highlighting a correlation between the frequency of extreme precipitation events and urbanization at a global scale. Future research should focus on how specific variables contribute to the observed variations in the characteristics of extremes. These deeper investigations can provide insights into the underlying physical mechanisms driving the variations in the characteristics of extreme precipitation found in this work.

How to cite: Guccione, A., Bassi, P., Desbiolles, F., Borgnino, M., D'Andrea, F., and Pasquero, C.: Global Extreme Precipitation Changes in Relation to Urbanization, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-27, https://doi.org/10.5194/ems2025-27, 2025.

Show EMS2025-27 recording (9min) recording
11:15–11:30
|
EMS2025-309
|
Onsite presentation
Maria de Fatima Andrade, Marcia Talita Marques, Jose Agostinho Gonçalves de Medeiros, Marco Aurélio Menezes Franco, and Eduardo Landulfo

Since 2020, the METROCLIMA Network (www.metroclima.iag.usp.br) has been monitoring greenhouse gases (GHGs) across São Paulo, Brazil, with five strategically located stations: Pico do Jaraguá (-23.46, -46.77), IAG-USP (-23.56, -46.73), UNICID (-23.54, -46.56), and ICESP (-23.56, -46.67), measuring CO₂ and CH₄ via CRDS analyzers, and a flux tower at Cientec (-23.65, -46.62) equipped with an IRGASON system. The network aims to assess São Paulo’s role as a major emission source impacting regional air quality and climate. Each monitoring station is equipped with two calibration gas cylinders: one containing a natural air standard (traceable to NOAA/ESRL references) and one containing a target gas mixture for routine instrument calibration. Stable carbon isotope analysis (δ¹³C-CO₂) at IAG-USP has revealed shifts in dominant CO₂ sources during extreme events, such as reduced vehicular emissions during the 2020 COVID-19 lockdown and increased contributions from Amazonian and Pantanal wildfires in the spring period. The data highlight the dual influence of anthropogenic and biogenic sources, with urban vegetation significantly modulating CO₂ concentrations despite strong emissions from transportation.

From 2019–2024, CO₂ concentrations in São Paulo increased at rates of 3.64 ppm/year (UNICID), 3.69 ppm/year (IAG-USP), and 1.73 ppm/year (Pico do Jaraguá) — significantly higher than the 2.4 ppm/year global average (WMO, 2023). Similarly, CH levels rose by 42 ppb/year in the urban station. These discrepancies highlight São Paulo’s strong anthropogenic influence, with traffic and waste emissions as likely drivers. Isotopic data revealed shifts in CO₂ sources, such as reduced fossil fuel combustion during the 2020 lockdown and increased biomass burning influence from Amazonian wildfires.

Methane variability was particularly pronounced in densely populated areas, suggesting contributions from vehicular emissions, landfills, and natural gas leaks. In São Paulo, the main source of methane is the landfills, responsible for 98.7% of emissions, including those with biogas production. While urban emissions dominate, vegetation partially offsets CO₂ levels at greener sites, demonstrating the complex interplay between urbanization and local biogenic processes. These findings underscore the need for expanded GHG monitoring in cities, where localized trends often surpass global averages, and stress the importance of international collaboration to refine emission inventories and mitigation strategies.

How to cite: Andrade, M. D. F., Marques, M. T., Gonçalves de Medeiros, J. A., Menezes Franco, M. A., and Landulfo, E.: Characterizing Urban GHG Emissions: Results from São Paulo's Atmospheric Observing Network, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-309, https://doi.org/10.5194/ems2025-309, 2025.

Air quality in urban areas
11:30–11:45
|
EMS2025-65
|
Onsite presentation
Yu Zou, Xianghong Guan, Rosa Flores, Xiaolu Yan, Xiuji Liang, Liya Fan, Tao Deng, Xuejiao Deng, Daiqi Ye, and Paul Doskey

Oxygenated volatile organic compounds (OVOCs) are important precursors and intermediate products of atmospheric photochemical reactions, which can promote the formation of secondary pollutants such as ozone (O3) and secondary organic aerosol (SOA). The photochemical age parameterization model is widely used to analyze primary and secondary sources of OVOCs. However, a key challenge lies in selecting appropriate tracers, chemicals used to estimate contributions from different emission sources. Accurate tracer selection is crucial for improving source apportionment accuracy, yet it is often constrained by local emission inventories and may not fully capture rapid atmospheric chemical transformations, introducing uncertainty in OVOC apportionment. This study presents a novel approach integrating eight different machine learning methods to identify optimal tracers for OVOCs during extreme summer temperatures (experimental group) and average spring temperatures (control group). Our results demonstrated notable differences in tracer effectiveness between these two groups. In the spring, toluene and carbon monoxide (CO) were identified as the most effective tracers for OVOCs with high and low reactivity, respectively. In the summer, acetylene or CO were better suited for moderate and low reactivity OVOCs. By incorporating machine learning for tracer selection, we significantly improved the accuracy of the photochemical age parameterization model. The machine learning outputs correlated well with the model’s performance, particularly in terms of fitting accuracy of OVOCs. However, extremely high temperatures during summer disrupted the usual patterns of OVOC production and removal, which led to inconsistencies in matching high reactivity OVOCs with their tracers. Future research involves collecting more data on OVOC behavior under high-temperature conditions and applying Fourier transformation techniques. This will help in identifying characteristic patterns and improving the dynamic accuracy of our model.

How to cite: Zou, Y., Guan, X., Flores, R., Yan, X., Liang, X., Fan, L., Deng, T., Deng, X., Ye, D., and Doskey, P.: Optimizing OVOCs Source Apportionment with Machine Learning-Enhanced Photochemical Age-based Parameterization Model, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-65, https://doi.org/10.5194/ems2025-65, 2025.

Show EMS2025-65 recording (14min) recording
11:45–12:00
|
EMS2025-98
|
Onsite presentation
|
Petra Dolšak Lavrič, Damijan Bec, Marko Rus, Don Ciglenečki, Andreja Kukec, and Matej Ogrin

Air pollution, particular aerosols and their precursors, has a substantial impacts on local weather and climate by increasing cloud condensation nuclei and altering how much solar energy is absorbed or reflected by the atmosphere. To accurately model these impacts, emissions inventories, dispersion models, and receptor models perform best when using high-resolution inputs. Currently, Europe has adopted regulations aimed at improving air quality and encouraging detailed studies of emission sources. While emission records over time indicate an overall decline, the transport sector has grown in recent decades, mostly because an annual increase in vehicle numbers. Although advancements in vehicle technology aim to reduce emissions, concerns remain that the increasing number of vehicles on the road may hinder this progress. Additionally, a critical knowledge gap has been identified in the bottom-up approach used to estimate emissions from transit vehicles and tourism activities.

Our study identifies and evaluates the issue of vehicle congestion on the roads during the summer, primarily driven by transit demands and tourism activities.

The methodology to capture an understanding of traffic-related emissions from the summer vehicle peak was developed. Summer traffic peak was estimated by comparing the summer vehicle numbers with those of other parts of the year. Vehicle numbers were recognized by vehicle counters located on a Slovenian highway junction in the year 2021. Moreover, the study also revealed the emissions from the summer traffic peak, calculated by the COPERT emission model.

We observed that, on an average summer day, there are up to 11,520 additional vehicles on Slovenian roads. Our study found that in the year 2021, on average, there were increases of 85%, 19%, 34%, and 17%, with up to 88%, 33%, 63%, and 32% increases in motorcycles, buses, passenger cars, and light duty vehicles. Meanwhile, it is recognized that the decrease in heavy duty vehicles is, on average, −14%. Those results help to understand contributions to estimation of urban source of emissions, which lead to improve the inputs data for the dispersion and additional atmosphere models. The methodology could also be copied in other places.

How to cite: Dolšak Lavrič, P., Bec, D., Rus, M., Ciglenečki, D., Kukec, A., and Ogrin, M.: Contribution of Tourist and Transit Vehicle Emissions to Air Pollution on Slovenian Roads during Summer, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-98, https://doi.org/10.5194/ems2025-98, 2025.

Show EMS2025-98 recording (13min) recording
12:00–12:15
|
EMS2025-430
|
Onsite presentation
Ágoston Vilmos Tordai and Róbert Mészáros

Urban air quality exhibits significant spatial variability at street level due to the complex interactions between traffic patterns, building structures, vegetation, and local microclimate. Traditional fixed monitoring stations provide valuable long-term data but cannot capture these fine-scale variations that directly affect human exposure to pollutants. Since 2022, we have implemented an extensive bicycle-based mobile measurement campaign in Budapest, Hungary, to characterize these patterns and develop methodologies for high-resolution urban air quality assessment.

Our approach utilizes bicycle-mounted instruments to collect spatially dense data on PM2.5 and PM10 concentrations across diverse urban environments. The measurement setup includes calibrated TSI DustTrak II Aerosol Monitor (8532) instruments equipped with impactors, along with temperature and humidity sensors with appropriate shielding. GPS data provides precise location information for each measurement point. The sampling routes were carefully designed to represent various urban settings, including high-traffic corridors, residential areas, street canyons, open boulevards, and green spaces. Over 200 measurement runs have been conducted to date, creating a robust dataset for analysis. A sophisticated data processing workflow was developed, including outlier removal, noise reduction, and spatial gridding techniques.

Analysis of this comprehensive dataset has revealed distinct patterns in the spatial distribution of particulate matter across the urban landscape. We identified characteristic "local air quality zones" associated with specific urban features and configurations. The dataset allows for the investigation of both spatial patterns and temporal variations in urban air quality, providing insights not available from fixed-site monitoring. The PM2.5/PM10 ratio variations across urban fabric have offered additional insights into the likely sources and characteristics of particulate pollution in different urban environments.

Our findings demonstrate that urban morphology creates distinct microclimatic and air quality zones at scales too fine to be captured by traditional monitoring networks. The methodology developed provides a robust framework for high-resolution urban air quality assessment applicable to other urban environments. These insights can inform targeted interventions in urban planning and traffic management to reduce exposure to air pollution at the street level. The approach also establishes a foundation for the validation and calibration of low-cost sensor networks and computational fluid dynamics models for urban applications. Ongoing work is focused on quantifying the relationships between urban features and air quality outcomes, as well as exploring seasonal and diurnal patterns in these relationships.

This work has been implemented by the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014) project within the framework of Hungary's National Recovery and Resilience Plan supported by the Recovery and Resilience Facility of the European Union.

How to cite: Tordai, Á. V. and Mészáros, R.: Street-Level Urban Air Quality Patterns: Insights from a Comprehensive Mobile Measurement Campaign in Budapest, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-430, https://doi.org/10.5194/ems2025-430, 2025.

12:15–12:30
|
EMS2025-327
|
Onsite presentation
Clemens Drüe and Kristin Jonas

The air quality in ancient Roman cities is still unclear, but historical sources suggest that there was noticeable air pollution, at least in terms of odour. As a pilot study for a smaller settlement, we simulated the combined pollution from heating, cooking and industrial activities. The Roman vicus modelled is located in the modern town of Eisenberg (Pfalz), in the Pfalz region, near Kaiserslautern. Utilising archaeological data on pottery locations and historical buildings, the simulation was conducted to estimate air pollution levels around the vicus.

The simulation utilised the German regulatory pollution dispersion model AUSTAL, driven by weather data from the Copernicus European reanalysis (CERRA) and the SRTM topographic dataset. The Roman vicus consisted of almost twenty buildings, most of which have been archaeologically excavated and are well documented. The vicus is known to have housed potteries, but in most cases the actual use of the excavated houses is unknown. Therefore, we had to assume the location of the pottery workshops in the eastern part. The industrial sources were modelled after measurements taken during experimental pottery production by LEIZA, Mainz, in a reconstructed kiln. The residential sources were modelled after hourly recordings of firewood usage in Nepal, where traditional rural buildings are remarkably similar to those of the Roman period in Central Europe.

The simulation showed clearly the benefits of considering daily cycles rather than averages in the modelling of the air quality. The results obtained demonstrated that, in general, the pollution levels were found to be low when compared to today's limits. However, it turns out that the levels of pollutants are similar to those found in contemporary villages where houses are mainly heated with wood and briquettes.

How to cite: Drüe, C. and Jonas, K.: An experimental reconstruction of the air quality in the Roman vicus Eisenberg, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-327, https://doi.org/10.5194/ems2025-327, 2025.

Show EMS2025-327 recording (14min) recording
Development and assessment of urban models

Orals Mon3: Mon, 8 Sep, 14:00–15:30 | Room E3+E4

Chairpersons: Maria de Fatima Andrade, Pavol Nejedlik, K. Heinke Schlünzen
14:00–14:15
|
EMS2025-367
|
Onsite presentation
Andreas Hoy, Adrian Glodeanu, Igone Garcia, and Ansel Cheng-Wei Yu

The Regions4Climate project, funded under Horizon Europe, supports transformative adaptation by co-developing and testing tailored climate resilience solutions in 12 European regions. One of these is Pärnu, Estonia’s coastal “summer capital,” which—by Nordic standards—is particularly vulnerable to heat due to its unique geographic and climatic setting. The case study focuses on mitigating urban heat-related risks.

Urban heat island (UHI) conditions in Pärnu had not been systematically studied before. To fill this gap, we applied a threefold methodological and approach: (1) deploying a dense real-time weather sensor network, (2) analysing satellite-derived land surface temperatures, and (3) simulating thermal comfort under various climate and land use scenarios using microscale modelling. Together, these methods allow us to observe and understand heat dynamics from regional to street level.

Since June 2023, SEI Tallinn and partners have operated 50 sensors measuring temperature and relative humidity every 10 minutes across a 10×15 km area. Sensor density is highest around the city centre with its diverse microclimatic conditions—residential areas, parks, commercial districts, and beaches—and decreases towards rural surroundings. Locations were selected following the Local Climate Zone framework, considering critical social infrastructures. Results reveal strong daytime UHI heterogeneity, with cooler temperatures in parks and coastal areas and warmer conditions in (often close-by) built-up zones. At night, a more spatially extensive UHI develops, peaking around the city centre. Real-time data are publicly accessible via a dedicated visualization tool.

To complement these measurements, 15 clear-sky warm days between 2013 and 2024 were processed using Landsat 8 data to generate 100 m resolution land surface temperature maps for midday conditions. These maps identify heat hotspots as well as the cooling influence of green and blue infrastructure, guiding hotspot selection for microscale modelling.

Four representative sites—plus a planned new train station area—were selected for ENVI-met simulations at 1 m resolution. Using the Physiological Equivalent Temperature index, we assessed current and future thermal comfort conditions and detected resilience opportunity areas in the city. Simulations quantify heat exposure and mitigation potential of increased vegetation, shade, and urban form changes under climate change.

By integrating data across scales, our approach offers specific, place-based recommendations for heat-resilient urban planning in Pärnu. It underscores the value of existing green and blue spaces, supports their expansion, advocates for heat-conscious building standards, and promotes strategies to reduce daytime heat uptake—particularly in central areas—to protect vulnerable groups and strengthen the climate resilience of Estonia’s “summer capital.”

How to cite: Hoy, A., Glodeanu, A., Garcia, I., and Cheng-Wei Yu, A.: Towards a Heat-Resilient Pärnu: Integrating Sensor Networks, Satellite Data and Microscale Modelling, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-367, https://doi.org/10.5194/ems2025-367, 2025.

Show EMS2025-367 recording (15min) recording
14:15–14:30
|
EMS2025-604
|
Onsite presentation
K. Heinke Schlünzen

Urban climate analyses have a wide range of different targets, including average values of different meteorological variables, percentiles and number of exceedances of certain threshold values. At least 30 years of data are required for this type of analysis. For large scale analysis model results of several ten kilometres resolution are either available for 30 years and more, or they may be calculated with a coarse resolution model in some foreseeable time. However, the urban effects may not present in these type of data. In any case, the coarse resolution data do not provide any inner-urban differences. These can only be found in model results of a resolution of well below 1 km. When aiming at differences in street canyons or next to buildings, the resolution should be very high and not exceed several meters. The high-resolution models that may be used to produce these type of data in a dynamic simulation are very resources consuming and the waiting time is enormous. A dynamic simulation of 30 years is much too time consuming. Therefore, only a few selected meteorological situations are dynamically calculated. These must be selected correctly in order to support the objective of the urban climate analysis. Average temperatures can then be derived by selecting several meteorological situations and using a statistical-dynamical downscaling approach. If, for example, extremes in meteorological variables are to be determined in the urban area (e.g. temperature or wind speed or humidity or radiation) the relevant meteorological situation can be determined from statistics of coarse resolution data. This is, however, not easy with a target such as the extreme intensity of the urban heat island, which depends on temperature, wind speed, humidity and radiation together. Here the combination of the variables that determines the extreme intensity must be taken into account.

For different temperature related variables and for determining the situation that leads to an extreme intensity of the urban heat island, the presentation will show ways for a targeted selection of the meteorological situations that are to be simulated with high-resolution models.  

How to cite: Schlünzen, K. H.: Targeted data selection for different urban climate analyses, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-604, https://doi.org/10.5194/ems2025-604, 2025.

Show EMS2025-604 recording (15min) recording
14:30–14:45
|
EMS2025-460
|
Onsite presentation
Branislava Lalic, Ana Firanj Sremac, Stevan Savić, Tania Sharmin, Simon Lannon, Kyriaki Psistaki, and Anastasia Paschalidou

Seasons and their transitions play a critical role in shaping ecosystems and human activities, yet their traditional classifications—meteorological and astronomical—fail to capture the complexities of biosphere-atmosphere interactions. Conventional definitions often overlook the interplay between climate variables, biosphere processes (including human activities), and the actual anticipation of seasons, particularly in the context of global climate change, which has disrupted traditional seasonal patterns. As the climate becomes increasingly variable, the need to redefine how we observe and interpret seasonal change becomes more urgent—not only for ecological and scientific understanding but also for societal adaptation. Urban environments are increasingly recognized as dynamic interfaces where climatic variability, human activity, and biosphere responses converge—often in ways that diverge from traditional seasonal classifications. This study explores seasonal transitions through continuous micrometeorological measurements in three contrasting European cities: Novi Sad (Serbia), Thessaloniki (Greece), and Cardiff (UK), using data from the FAIRNESS micrometeorological platform (FMP2.0). Utilizing the normalized daily temperature range—a biologically grounded seasonality index previously validated in agricultural zones (Lalić et al., 2022; Lalić and Firanj Sremac, 2025)—we identify and characterize the onset, duration, and transition phases of seasons within urban microclimates. Our results reveal distinct spatial and temporal patterns, with clear seasonal offsets and variable transition durations across the cities, reflecting both geographic and anthropogenic influences. These findings not only challenge conventional meteorological and astronomical definitions but also highlight the urban-specific reshaping of seasonal cycles under climate change. The methodology provides scalable and perceptually aligned metrics for urban seasonality, with implications for urban planning, public health, market behaviour, and policy design. As climate variability intensifies, rethinking seasonality through the lens of city-based micrometeorological data becomes crucial for adaptive decision-making across diverse sectors.

Acknowledgements: This research is supported by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Grants No. ‪451-03-137/2025-03/ 200125 & 451-03-136/2025-03/ 200125) and COST Action CA20108 FAIR Network of micrometeorological measurements (FAIRNESS).

How to cite: Lalic, B., Firanj Sremac, A., Savić, S., Sharmin, T., Lannon, S., Psistaki, K., and Paschalidou, A.: Framing Seasonal Changes at the Urban Microscale using FMP2.0 data, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-460, https://doi.org/10.5194/ems2025-460, 2025.

Show EMS2025-460 recording (16min) recording
14:45–15:00
|
EMS2025-43
|
Onsite presentation
Nemo Malhomme, Filippo Biondi, Pietro Tavazzi, Nadim Rooholamin, Georgi Spasov, and Giovanni Stabile

Cities contain a significant proportion of the global population. As they are subjected to unique vulnerabilities to climate-related phenomena, such as the Urban heat Island effect, it is crucial for ensuring the durable safety of city residents to understand urban microclimate. However, global and regional climate models operate at scales too coarse to capture the intricacies of these microclimates. Accurately modeling them requires resolving fine-scale details, including the shape and arrangement of buildings. Unfortunately, such high-resolution simulations come with a substantial computational cost, which limits their applicability, making real-time prediction and design optimization problems mainly inaccessible. Therefore, there is a need for computationally efficient models of urban microclimate.

The DANTE project aims to address this challenge by applying Model Order Reduction (MOR) techniques to lower the computational costs associated with high-resolution urban-scale simulations. MOR involves replacing full-order models - here, detailed Computational Fluid Dynamics (CFD) simulations - with reduced-order models of lower complexity. These models can be derived either by projection of the full-order model onto lower-dimensional manifolds, or through machine learning methodologies.

Regardless of the approach, these models must undergo a rigorous validation process before any application is possible to ensure that they accurately reproduce relevant physical properties. Furthermore, evaluating their performance and quantifying their uncertainties is essential to determine the reliability of their output for real world applications. This validation process requires urban-scale ground truth data, which is not directly available. Instead, lower-resolution data must be downscaled to urban scale. As a result, downscaling is a critical part of developing reliable urban microclimate models.

Traditional statistical downscaling methods rely on large datasets to establish mappings from low-resolution to high-resolution data, but in this context, data is scarce. One solution to this problem is Physics-Informed Neural Networks (PINN), which incorporate physical constraints into the learning process, thereby alleviating data requirements. By enforcing, through a choice of loss function, a set of physical partial differential equations, PINNs are able to more efficiently extract relevant information from the data. They can be used for prediction, but also as continuous function approximators for downscaling data. In this work, we propose a downscaling framework that leverages PINNs to assimilate both regional model data and weather station measurements, generating urban-scale data suitable for evaluating reduced-order models.

How to cite: Malhomme, N., Biondi, F., Tavazzi, P., Rooholamin, N., Spasov, G., and Stabile, G.: Downscaling using physics informed neural networks for model evaluation at urban scale, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-43, https://doi.org/10.5194/ems2025-43, 2025.

Show EMS2025-43 recording (12min) recording
15:00–15:15
|
EMS2025-468
|
Online presentation
Adam Jaczewski, Andrzej Wyszogrodzki, and Witold Interewicz

The impacts of global climate change make cities increasingly vulnerable to environmental challenges, leading to the need for accurate weather forecasts to support various societal functions and ensure public safety. Regional weather and climate models have often employed simplified representations of urban environments, which can lead to inaccuracies in forecasting key meteorological variables such as temperature, humidity, wind, and precipitation within these complex regions. The increasing spatial resolution of the models demands more sophisticated and detailed descriptions of urban surfaces and microphysical processes to capture the unique interactions between the built environment and the atmosphere. This work examines recent advancements in urban parameterisation within the Consortium for Small-scale Modeling (COSMO), specifically focusing on incorporating Local Climate Zones (LCZs) using ECOCLIMAP-SG land use data for the TERRA-URB urban scheme.
In the frame of this study, the methodology for elaborating the new lookup tables will be presented as necessary for implementing ECOCLIMAP-SG and integrating LCZ-specific parameters during the preprocessing steps. The set of the COSMO model simulations at the sub-kilometre scale for Warsaw agglomeration is carried out to justify the added value of using the urban scheme and ECOCLIMAP-SG dataset. The simulation results are compared with meteorological measurements from the surface stations at an hourly resolution. The investigated period covers a heat wave case at the end of June and the beginning of July 2022. The evaluation is performed considering the dependence of the model performance on lead time 48 hours ahead, separately for urban and rural stations. Additionally, spatial verification is conducted to study the model's ability to capture urban effects.

How to cite: Jaczewski, A., Wyszogrodzki, A., and Interewicz, W.: Evaluation of COSMO simulations with TERRA-URB scheme and ECOCLIMAP-SG land use dataset over Warsaw agglomeration, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-468, https://doi.org/10.5194/ems2025-468, 2025.

15:15–15:30

Posters: Tue, 9 Sep, 16:00–17:15 | Grand Hall

Display time: Mon, 8 Sep, 08:00–Tue, 9 Sep, 18:00
Chairpersons: Pavol Nejedlik, K. Heinke Schlünzen
Local and global climate change effects and how urban areas counteract
P54
|
EMS2025-81
|
Tromp Foundation Travel Award to young scientists (TFTAYS)
xenia lorenz, Laura Sandra Leo, Nils Eingrüber, Luigi Brogno, Simona Rinaldi, Silvana Di Sabatino, and Dr.in Susanne Crewell

Urban high-density areas are particularly affected by climate change effects. Reduced ventilation, evapotranspiration, albedo as well as increased surface sealing and traffic emissions significantly influence urban microclimates. The ongoing densification of cities results in pollutant trapping and higher heat loads. Magnitudes of the Urban Heat Island (UHI) and the Urban Pollution Island (UPI) effects are expected to intensify in many cities worldwide according to future climate projections. Thermal discomfort, health consequences and higher mortality rates caused by heat stress and air pollution will become an increasing risk for inhabitants. Urban Green Infrastructures (UGI) are widely recognized to mitigate UHI and UPI effects. However, their effectiveness is highly dependent on local conditions, while non-strategical implementations can even cause adverse effects at local level. Therefore, sound-scientific analyses are required to achieve best possible cooling and air quality improvement. Microclimatological modelling is an efficient tool to evaluate the performance of climate change adaptation strategies in urban environments. This study aims to investigate the impact of palisades and UGI on air temperature as well as Carbon Monoxide (CO) concentrations at pedestrian level. The physically-based 3D-gridded ENVI-met model was used to simulate the microclimate of a street canyon (Via Guglielmo Marconi) in a densely-developed residential study area  (Bologna, Italy). To enhance model outputs, ENVI-met database parametrization was adjusted using cadastral datasets and field measurements. The simulations are driven and validated based on local meteorological measurements within the study area. Different scenarios were designed implementing technical- and nature-based solutions (NBSs) in the street canyon including trees, hedges, green walls and palisades. Model outputs were compared to the reference run to statistically evaluate the heat and air pollution mitigation potential. The results show that palisades have a non-significant impact on CO concentrations and even cause warming for pedestrians. Street trees and hedges moderately reduce air temperature by up to -0.45 K, but significantly increase CO concentrations by up to +9.37 %. In contrast, for green walls, a maximum cooling effect of 0.76 K but a non-significant increase in CO concentrations was found. The study concludes that while UGI can effectively reduce local temperatures, careful design and placement are crucial to minimize negative effects on air quality. These findings can have important implications for decision-making in urban planning. Further research could analyze the effects on bio-meteorological thermal comfort indices in the context of climate change adaptation, or compare the results with study areas with different ventilation or pollution conditions.

How to cite: lorenz, X., Leo, L. S., Eingrüber, N., Brogno, L., Rinaldi, S., Di Sabatino, S., and Crewell, Dr. I. S.: Evaluation of heat and air pollution mitigation effects of urban green infrastructures and palisades in a Mediterranean urban high-density area - Scenario analyses based on microclimatological modelling, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-81, https://doi.org/10.5194/ems2025-81, 2025.

Air quality in urban areas
P55
|
EMS2025-318
Leslie Morales-Espinoza, Marcia Talita Amorin Marques, Agostinho Gonçalves de Medeiros, Eduardo Landulfo, Carlos Eduardo Souto-Oliveira, and Maria de Fatima Andrade

The stable isotopic composition of carbon, such as δ¹³C-CO₂, is a valuable tool for tracing the sources of atmospheric CO₂. Within this framework, the METROCLIMA project (www.metroclima.iag.usp.br) aims to develop and evaluate methodologies for quantifying urban greenhouse gas emissions and distinguishing between biogenic and anthropogenic sources. We analyzed data from a METROCLIMA station equipped with a cavity ring-down spectroscopy instrument (Picarro), which continuously measures δ¹³C-CO₂ and CO₂ in real time. The station is located in a partially vegetated urban area at the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG), University of São Paulo (USP) (-23.559478, -46.733533). This study focuses on characterizing total urban CO₂ and identifying potential CO₂ sources during the wildfire seasons (August and September) across four years (2020–2023). Additionally, we analyzed PM₁₀, PM₂.₅, O₃, and NOₓ data from the CETESB monitoring station in Pinheiros (São Paulo’s Environmental Protection Agency).

The isotopic signatures observed during the spring seasons indicate a predominant influence of biomass burning (δ¹³C-CO₂ = −22‰ to -25‰) and fossil fuel combustion (δ¹³C-CO₂ = −30‰ to -37‰), as revealed by Keeling plot analyses (based on intercepts from δ¹³C-CO₂ versus 1/CO₂). HYSPLIT backward trajectory analyses suggest that some of the air masses were likely influenced by plumes originating from the Pantanal and the Atlantic Forest (Mata Atlântica) regions. Other identified source was local wood burning, contributing to a lesser extent each year. Moreover, the temporal behavior of isotopic signals was consistent with CO₂ concentrations and CETESB pollutant data, indicating a strong influence of wildfire plumes on CO₂ levels and air pollutants such as PM₁₀, PM₂.₅, O₃, and CO. Notably, the 2022 wildfire season presented the highest CO₂ concentrations and pollutant levels among the years analyzed.

Here, we provide an initial assessment of CO₂ sources during biomass burning seasons in São Paulo, offering valuable insights that could support future greenhouse gas mitigation strategies.

How to cite: Morales-Espinoza, L., Amorin Marques, M. T., Gonçalves de Medeiros, A., Landulfo, E., Souto-Oliveira, C. E., and Andrade, M. D. F.: Tracing CO₂ sources during biomass burning seasons (2020-2023) using δ¹³C-CO₂ and air pollutants in São Paulo, Brazil, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-318, https://doi.org/10.5194/ems2025-318, 2025.

P56
|
EMS2025-587
Caroline Fernanda Hei Wikuats, Thiago Nogueira, and Maria de Fatima Andrade

The regional and long-range transport of biomass burning plumes can significantly influence air pollutant concentrations in urban environments. In Brazil, recurring fires in the central and northern regions, as well as within the state of São Paulo, contribute to elevated PM2.5 levels across the southern and southeastern areas. During the sampling period of this study (May 2021–August 2022), a large forest fire in the Metropolitan Area of São Paulo (MASP) significantly impacted PM2.5 concentrations at the sampling site near downtown São Paulo, a region already heavily affected by vehicular emissions. PM2.5 was collected using a Partisol 2025i Sequential Air Sampler. Elemental composition was determined via energy-dispersive X-ray fluorescence (EDXRF) and the Lab Organic Carbon-Elemental Carbon (OC-EC) Aerosol Analyzer. Emission sources were identified using Positive Matrix Factorization (PMF), and oxidative potential was assessed through electron spin resonance (OPESR) and dithiothreitol (OPDTT) assays. On August 22, 2021, a major fire occurred at Juquery State Park in Franco da Rocha, burning approximately 1,175 hectares (more than half the park's vegetation) and causing severe damage to local flora and fauna. Soot from the fire was deposited across the city of São Paulo. The highest 24-hour PM2.5 concentrations of the entire campaign were recorded during this episode. Between August 22 and 25, average peak concentrations of PM2.5, OC, and biomass burning-related black carbon (BCBB) reached 43.3, 23.5, and 2.2 µg m-3, respectively. Trajectory analyses using NOAA’s HYSPLIT model indicated that winds from the northwest, north, and northeast transported the smoke plume from the park to the sampling site. The highest PM2.5 and BC concentrations were traced back to the park region, confirming the fire’s impact. After it was controlled, pollutant levels declined, helped by 27.3 mm of rainfall on August 28, following 10 days without precipitation. Atmospheric stability likely also contributed to the four-day duration of the fire. During the event, volume-based OPESR (OPESRv) values decreased while OPDTTv remained elevated, following the trends of PM2.5, OC, and BCBB. Multiple linear regression (MLR) analysis showed significant associations between OPESRv and BCBB, fossil fuel-related BC (BCFF), EC, and several elements, including S, K, Mg, Cu, Br, Ni, Si, Al, Pb, and Cr. OPDTTv showed similar associations, although EC, S, Cu, Na, and Zn were not statistically significant. OC was not significantly associated with OPDTTv, possibly due to a lower redox activity or a stronger influence of metal components. Source-based MLR indicated vehicle emissions and secondary aerosols as the major contributors to OPESRv, while OPDTTv was primarily driven by biomass burning, vehicular emissions, and marine aerosols. Therefore, these results highlight the combined influence of local, regional, and long-range sources, as well as meteorological conditions, on urban air quality.

How to cite: Hei Wikuats, C. F., Nogueira, T., and Andrade, M. D. F.: Impact of regional biomass burning and meteorological conditions on ambient PM2.5 and oxidative potential in São Paulo, Brazil, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-587, https://doi.org/10.5194/ems2025-587, 2025.

P57
|
EMS2025-254
Victória Peli, Cathy Li, Mario Calderón, Gabriel Perez, Thomas Martin, Amanda Lucena, Edson Barbosa, Matthias Schindler, Felix Laimer, Thomas Gstir, Maria de Fátima Andrade, Edmilson Freitas, Andrea Orfanoz, and Guy Brasseur

The German-Brazilian Project “QUALARIA: Artificial Intelligence based system for sub-urban scale air quality prediction” aims to create an operational artificial intelligence-based system to monitor, simulate and predict air quality in the Metropolitan Area of São Paulo (MASP), with high spatial resolution (https://meteoia.com/qualaria/). Advanced global and regional chemical-meteorological models, such as CAMS global composition forecast, and WRF-Chem simulations are applied to derive the climatological state of air composition, mainly the average levels of air pollutant based on existing local emission inventories. Measurements of PM10, PM2.5 NO2, and O3 concentrations from the São Paulo State Environmental Agency (CETESB) Air Quality Network are used to train the downscaling to capture the pollutant concentration sub-grid spatial variations. The spatial and temporal disaggregated local vehicular emission inventory and the building height from the Global Human Settlement Layer dataset are also used as input. Preliminary results produced air pollution concentration maps at 100 m and showed an increase in Pearson correlation and a reduction in the mean absolute error compared to CAMS forecast. Other high spatial resolution datasets and measurement from other states air quality networks are being explored to increase the input datasets. In the following steps of the project, low-cost sensors are going to be deployed to increase the spatial coverage of MASP and its surroundings, complementing the CETESB stations. Then, from their predicted downscaled pollutant concentration fields, the system will provide an online dashboard to display relevant air quality indicators, and to inform the impacts of air pollution on human health. To improve the dashboard design, stakeholders from the public and private sector are being engaged and consulted for the development of its user interface and features.

How to cite: Peli, V., Li, C., Calderón, M., Perez, G., Martin, T., Lucena, A., Barbosa, E., Schindler, M., Laimer, F., Gstir, T., Andrade, M. D. F., Freitas, E., Orfanoz, A., and Brasseur, G.: QUALARIA Project: An AI System to Monitor and Predict Metropolitan Area of São Paulo Street-Level Air Quality, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-254, https://doi.org/10.5194/ems2025-254, 2025.

P58
|
EMS2025-120
|
Alejandro Herman Delgado Peralta and Maria de Fatima Andrade

Introduction: Besides simulating the secondary formation of air pollutants, anthropogenic emissions classified by sectors are essential to represent sources and their primary contributions to air contamination. The urban megacity, depicted by the metropolitan area of São Paulo (MASP), has faced unsafe fine inhalable particles of 2.5 µm or less in diameter (PM2.5) and ground-level ozone concentrations. Previous source apportionment studies have confirmed that the road transport sector's contribution is more significant than other activities, such as industry and residential emissions.

Methodology: A bottom-up approach was used to enhance the emission inventory by applying emission factors from tunnel experiments and information from vehicles in São Paulo. Source apportionment studies conducted in the MASP were valuable for adjusting global emissions inventories from the EDGAR-HTAPv3 for road transport, industry, energy, residential, waste, agricultural, and aviation for the region. According to the receptor model study, PM2.5 emissions from industry and other sectors in São Paulo account for 10% and 25%, respectively. Results from the receptor model suggest that the road transport sector could contribute approximately 65% of fine particulate matter emissions, with about 40% originating from exhaust and around 25% from resuspension. Moreover, these emission inventories were validated using a photochemical grid model (CMAQ), which accounts for secondary aerosol formation. This model is essential to be applied because a local study conducted in São Paulo demonstrated that secondary processes contribute approximately 56% of the concentration of particles smaller than 1 µm. 

Results: The model performance evaluation for PM2.5 demonstrated promising simulation results compared with stations located within and outside the MASP.

Conclusion: Consequently, simulation results for PM2.5 improved in representing not only observed air mass concentrations but also direct emission contributions by sectors consistent with source apportionment studies, which is very useful for policymakers’ decisions regarding public health.

How to cite: Delgado Peralta, A. H. and Andrade, M. D. F.: Improving Air Quality Modeling in São Paulo, Brazil, Through an Enhanced Emissions Methodology, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-120, https://doi.org/10.5194/ems2025-120, 2025.

Development and assessment of urban models
P59
|
EMS2025-630
Peter Kalverla, Gert-Jan Steeneveld, Alexander Hadjiivanov, Claire Donnelly, Wim Timmermans, Srinidhi Gadde, Dragan Milosevic, and Bianca Sandvik

The accuracy of urban weather and climate simulations is constrained by the availability of localized and detailed urban morphology data. In this evolving field, street view imagery is emerging as a complementary data source, as it becomes openly available through municipal data portals and through crowdsourced platforms like Kartaview and Mapillary. While advanced image analysis techniques exist and are widely used in adjacent fields, their application in weather and climate models remains limited. A key question is whether features extracted from these images can reach sufficient quality for use in urban modelling studies.

Within the Urban-M4 project, we are developing software to interactively explore street view imagery with a focus on use in microscale simulations with WRF and PALM. Our current interest is in estimating radiative properties of urban surfaces, in particular albedo and emissivity of roofs, roads, and facades.

So far, we are able to segment images and extract individual instances of buildings, roads, and other relevant features such as windows and doors. This is done using a combination of prompt-based object detection and labelling with the GroundingDINO model and instance segmentation with the Segment Anything Model (SAM). For the extracted instances, we estimate albedo by aggregating the brightness values of the annotated pixels. As a next step, we aim to add a material classification layer, which would allow for indirect estimation of both albedo and emissivity based on known radiation properties of different materials.

All functionality is bundled in a Python package called streetscapes. It includes tools for retrieving and storing collections of street view images from various sources in a structured way. Images and their derived data (e.g. segmentations, masks, statistics) follow a consistent naming convention, so that processed outputs can be automatically linked to their source. In addition, a metadata system is maintained that keeps track of image properties such as location, file identifiers, and any extracted statistics. This setup allows users to query and filter the dataset for specific use cases. The package also includes functionality to apply image segmentation and other analysis methods, and to prepare outputs (e.g. raster files) suitable for use in urban climate models. The code leaves room for possible extensions such as linking images to individual buildings or applying photogrammetry for advanced texture mapping.

The code is openly available at: https://github.com/Urban-M4/streetscapes.

How to cite: Kalverla, P., Steeneveld, G.-J., Hadjiivanov, A., Donnelly, C., Timmermans, W., Gadde, S., Milosevic, D., and Sandvik, B.: Developing software for mapping urban radiative properties through analysis of street view imagery, EMS Annual Meeting 2025, Ljubljana, Slovenia, 7–12 Sep 2025, EMS2025-630, https://doi.org/10.5194/ems2025-630, 2025.