Articles | Volume 19, issue 2
https://doi.org/10.5194/amt-19-745-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-19-745-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
29 Jan 2026
Research article |
| 29 Jan 2026
| 29 Jan 2026
ACROPOLIS: Munich urban CO2 sensor network
Technical University of Munich (TUM), Munich, Germany
Technical University of Munich (TUM), Munich, Germany
Felix Böhm
Technical University of Munich (TUM), Munich, Germany
Mali Chariot
Laboratoire des Science du Climat et de l'Environnement (LSCE/IPSL), Gif-sur-Yvette, France
Lukas Emmenegger
Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
Lars Frölich
Technical University of Munich (TUM), Munich, Germany
Stuart Grange
Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
University of Bern, Bern, Switzerland
Daniel Kühbacher
Technical University of Munich (TUM), Munich, Germany
Klaus Kürzinger
Technical University of Munich (TUM), Munich, Germany
Olivier Laurent
Laboratoire des Science du Climat et de l'Environnement (LSCE/IPSL), Gif-sur-Yvette, France
Moritz Makowski
Technical University of Munich (TUM), Munich, Germany
Pascal Rubli
Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
Adrian Schmitt
Technical University of Munich (TUM), Munich, Germany
Adrian Wenzel
Technical University of Munich (TUM), Munich, Germany
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Atmos. Meas. Tech., 16, 4391–4407, https://doi.org/10.5194/amt-16-4391-2023, https://doi.org/10.5194/amt-16-4391-2023, 2023
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Foteini Stavropoulou, Katarina Vinković, Bert Kers, Marcel de Vries, Steven van Heuven, Piotr Korbeń, Martina Schmidt, Julia Wietzel, Pawel Jagoda, Jaroslav M. Necki, Jakub Bartyzel, Hossein Maazallahi, Malika Menoud, Carina van der Veen, Sylvia Walter, Béla Tuzson, Jonas Ravelid, Randulph Paulo Morales, Lukas Emmenegger, Dominik Brunner, Michael Steiner, Arjan Hensen, Ilona Velzeboer, Pim van den Bulk, Hugo Denier van der Gon, Antonio Delre, Maklawe Essonanawe Edjabou, Charlotte Scheutz, Marius Corbu, Sebastian Iancu, Denisa Moaca, Alin Scarlat, Alexandru Tudor, Ioana Vizireanu, Andreea Calcan, Magdalena Ardelean, Sorin Ghemulet, Alexandru Pana, Aurel Constantinescu, Lucian Cusa, Alexandru Nica, Calin Baciu, Cristian Pop, Andrei Radovici, Alexandru Mereuta, Horatiu Stefanie, Alexandru Dandocsi, Bas Hermans, Stefan Schwietzke, Daniel Zavala-Araiza, Huilin Chen, and Thomas Röckmann
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In this study, machine learning models are employed to model NO2 and O3 concentrations. We employed a wide range of sources of data, including meteorological and column satellite measurements, to model NO2 and O3 concentrations. The spatial and temporal variability, and their drivers, were investigated. Notably, the machine learning model established the relationship between NOx and O3. Despite the fact that metropolitan regions are NO2 hotspots, rural areas have high O3 concentrations.
Jinghui Lian, Thomas Lauvaux, Hervé Utard, François-Marie Bréon, Grégoire Broquet, Michel Ramonet, Olivier Laurent, Ivonne Albarus, Mali Chariot, Simone Kotthaus, Martial Haeffelin, Olivier Sanchez, Olivier Perrussel, Hugo Anne Denier van der Gon, Stijn Nicolaas Camiel Dellaert, and Philippe Ciais
Atmos. Chem. Phys., 23, 8823–8835, https://doi.org/10.5194/acp-23-8823-2023, https://doi.org/10.5194/acp-23-8823-2023, 2023
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This study quantifies urban CO2 emissions via an atmospheric inversion for the Paris metropolitan area over a 6-year period from 2016 to 2021. Results show a long-term decreasing trend of about 2 % ± 0.6 % per year in the annual CO2 emissions over Paris. We conclude that our current capacity can deliver near-real-time CO2 emission estimates at the city scale in under a month, and the results agree within 10 % with independent estimates from multiple city-scale inventories.
Adil Shah, Olivier Laurent, Luc Lienhardt, Grégoire Broquet, Rodrigo Rivera Martinez, Elisa Allegrini, and Philippe Ciais
Atmos. Meas. Tech., 16, 3391–3419, https://doi.org/10.5194/amt-16-3391-2023, https://doi.org/10.5194/amt-16-3391-2023, 2023
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As methane (CH4) contributes to global warming, more CH4 measurements are required to better characterise source emissions. Hence, we tested a cheap CH4 sensor for 338 d of landfill sampling. We derived an excellent CH4 response model in a stable environment. However, different types of air with the same CH4 level had diverse sensor responses. We characterised temperature and water vapour response but could not replicate field sampling. Thus, other species may cause sensor interactions.
Andreas Forstmaier, Jia Chen, Florian Dietrich, Juan Bettinelli, Hossein Maazallahi, Carsten Schneider, Dominik Winkler, Xinxu Zhao, Taylor Jones, Carina van der Veen, Norman Wildmann, Moritz Makowski, Aydin Uzun, Friedrich Klappenbach, Hugo Denier van der Gon, Stefan Schwietzke, and Thomas Röckmann
Atmos. Chem. Phys., 23, 6897–6922, https://doi.org/10.5194/acp-23-6897-2023, https://doi.org/10.5194/acp-23-6897-2023, 2023
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Large cities emit greenhouse gases which contribute to global warming. In this study, we measured the release of one important green house gas, methane, in Hamburg. Multiple sources that contribute to methane emissions were located and quantified. Methane sources were found to be mainly caused by human activity (e.g., by release from oil and gas refineries). Moreover, potential natural sources have been located, such as the Elbe River and lakes.
Rodrigo Andres Rivera Martinez, Diego Santaren, Olivier Laurent, Gregoire Broquet, Ford Cropley, Cécile Mallet, Michel Ramonet, Adil Shah, Leonard Rivier, Caroline Bouchet, Catherine Juery, Olivier Duclaux, and Philippe Ciais
Atmos. Meas. Tech., 16, 2209–2235, https://doi.org/10.5194/amt-16-2209-2023, https://doi.org/10.5194/amt-16-2209-2023, 2023
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A network of low-cost sensors is a good alternative to improve the detection of fugitive CH4 emissions. We present the results of four tests conducted with two types of Figaro sensors that were assembled on four chambers in a laboratory experiment: a comparison of five models to reconstruct the CH4 signal, a strategy to reduce the training set size, a detection of age effects in the sensors and a test of the capability to transfer a model between chambers for the same type of sensor.
Nadia K. Colombi, Daniel J. Jacob, Laura Hyesung Yang, Shixian Zhai, Viral Shah, Stuart K. Grange, Robert M. Yantosca, Soontae Kim, and Hong Liao
Atmos. Chem. Phys., 23, 4031–4044, https://doi.org/10.5194/acp-23-4031-2023, https://doi.org/10.5194/acp-23-4031-2023, 2023
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Surface ozone, detrimental to human and ecosystem health, is very high and increasing in South Korea. Using a global model of the atmosphere, we found that emissions from South Korea and China contribute equally to the high ozone observed. We found that in the absence of all anthropogenic emissions over East Asia, ozone is still very high, implying that the air quality standard in South Korea is not practically achievable unless this background external to East Asia can be decreased.
Lars Mächler, Daniel Baggenstos, Florian Krauss, Jochen Schmitt, Bernhard Bereiter, Remo Walther, Christoph Reinhard, Béla Tuzson, Lukas Emmenegger, and Hubertus Fischer
Atmos. Meas. Tech., 16, 355–372, https://doi.org/10.5194/amt-16-355-2023, https://doi.org/10.5194/amt-16-355-2023, 2023
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We present a new method to extract the gases from ice cores and measure their greenhouse gas composition. The ice is sublimated continuously with a near-infrared laser, releasing the gases, which are then analyzed on a laser absorption spectrometer. The main advantage over previous efforts is a low effective resolution of 1–2 cm. This capability is crucial for the analysis of highly thinned ice, as expected from ongoing drilling efforts to extend ice core history further back in time.
Maximilian Rißmann, Jia Chen, Gregory Osterman, Xinxu Zhao, Florian Dietrich, Moritz Makowski, Frank Hase, and Matthäus Kiel
Atmos. Meas. Tech., 15, 6605–6623, https://doi.org/10.5194/amt-15-6605-2022, https://doi.org/10.5194/amt-15-6605-2022, 2022
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The Orbiting Carbon Observatory 2 (OCO-2) measures atmospheric concentrations of the most potent greenhouse gas, CO2, globally. By comparing its measurements to a ground-based monitoring network in Munich (MUCCnet), we find that the satellite is able to reliably detect urban CO2 concentrations. Furthermore, spatial CO2 differences captured by OCO-2 and MUCCnet are strongly correlated, which indicates that OCO-2 could be helpful in determining urban CO2 emissions from space.
Benjamin Zanger, Jia Chen, Man Sun, and Florian Dietrich
Geosci. Model Dev., 15, 7533–7556, https://doi.org/10.5194/gmd-15-7533-2022, https://doi.org/10.5194/gmd-15-7533-2022, 2022
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Gaussian priors (GPs) used in least squares inversion do not reflect the true distributions of greenhouse gas emissions well. A method that does not rely on GPs is sparse reconstruction (SR). We show that necessary conditions for SR are satisfied for cities and that the application of a wavelet transform can further enhance sparsity. We apply the theory of compressed sensing to SR. Our results show that SR needs fewer measurements and is superior for assessing unknown emitters compared to GPs.
Simone M. Pieber, Béla Tuzson, Stephan Henne, Ute Karstens, Christoph Gerbig, Frank-Thomas Koch, Dominik Brunner, Martin Steinbacher, and Lukas Emmenegger
Atmos. Chem. Phys., 22, 10721–10749, https://doi.org/10.5194/acp-22-10721-2022, https://doi.org/10.5194/acp-22-10721-2022, 2022
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Understanding regional greenhouse gas emissions into the atmosphere is a prerequisite to mitigate climate change. In this study, we investigated the regional contributions of carbon dioxide (CO2) at the location of the high Alpine observatory Jungfraujoch (JFJ, Switzerland, 3580 m a.s.l.). To this purpose, we combined receptor-oriented atmospheric transport simulations for CO2 concentration in the period 2009–2017 with stable carbon isotope (δ13C–CO2) information.
Yunsong Liu, Jean-Daniel Paris, Mihalis Vrekoussis, Panayiota Antoniou, Christos Constantinides, Maximilien Desservettaz, Christos Keleshis, Olivier Laurent, Andreas Leonidou, Carole Philippon, Panagiotis Vouterakos, Pierre-Yves Quéhé, Philippe Bousquet, and Jean Sciare
Atmos. Meas. Tech., 15, 4431–4442, https://doi.org/10.5194/amt-15-4431-2022, https://doi.org/10.5194/amt-15-4431-2022, 2022
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This paper details laboratory-based and field developments of a cost-effective and compacted UAV CO2 sensor system to address the challenge of measuring CO2 with sufficient precision and acquisition frequency. We assess its performance extensively through laboratory and field tests and provide a case study in an urban area (Nicosia, Cyprus). We therefore expect that this portable system will be widely used for measuring CO2 emission and distribution in natural or urban environments.
Vigneshkumar Balamurugan, Jia Chen, Zhen Qu, Xiao Bi, and Frank N. Keutsch
Atmos. Chem. Phys., 22, 7105–7129, https://doi.org/10.5194/acp-22-7105-2022, https://doi.org/10.5194/acp-22-7105-2022, 2022
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In this study, we investigated the response of secondary pollutants to changes in precursor emissions, focusing on the formation of secondary PM, during the COVID-19 lockdown period. We show that, due to the decrease in primary NOx emissions, atmospheric oxidizing capacity is increased. The nighttime increase in ozone, caused by less NO titration, results in higher NO3 radicals, which contribute significantly to the formation of PM nitrates. O3 should be limited in order to control PM pollution.
Stuart K. Grange, Gaëlle Uzu, Samuël Weber, Jean-Luc Jaffrezo, and Christoph Hueglin
Atmos. Chem. Phys., 22, 7029–7050, https://doi.org/10.5194/acp-22-7029-2022, https://doi.org/10.5194/acp-22-7029-2022, 2022
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Oxidative potential (OP), a biologically relevant metric for particulate matter (PM), was linked to PM10 and PM2.5 sources and constituents across Switzerland between 2018 and 2019. Wood burning and non-exhaust traffic emissions were identified as key processes that led to enhanced OP. Therefore, the make-up of the PM mix was very important for OP. The results highlight the importance of the management of wood burning and non-exhaust emissions to reduce OP, and presumably biological harm.
Adam Brighty, Véronique Jacob, Gaëlle Uzu, Lucille Borlaza, Sébastien Conil, Christoph Hueglin, Stuart K. Grange, Olivier Favez, Cécile Trébuchon, and Jean-Luc Jaffrezo
Atmos. Chem. Phys., 22, 6021–6043, https://doi.org/10.5194/acp-22-6021-2022, https://doi.org/10.5194/acp-22-6021-2022, 2022
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With an revised analytical method and long-term sampling strategy, we have been able to elucidate much more information about atmospheric plant debris, a poorly understood class of particulate matter. We found weaker seasonal patterns at urban locations compared to rural locations and significant interannual variability in concentrations between previous years and 2020, during the COVID-19 pandemic. This suggests a possible man-made influence on plant debris concentration and source strength.
Andreas Luther, Julian Kostinek, Ralph Kleinschek, Sara Defratyka, Mila Stanisavljević, Andreas Forstmaier, Alexandru Dandocsi, Leon Scheidweiler, Darko Dubravica, Norman Wildmann, Frank Hase, Matthias M. Frey, Jia Chen, Florian Dietrich, Jarosław Nȩcki, Justyna Swolkień, Christoph Knote, Sanam N. Vardag, Anke Roiger, and André Butz
Atmos. Chem. Phys., 22, 5859–5876, https://doi.org/10.5194/acp-22-5859-2022, https://doi.org/10.5194/acp-22-5859-2022, 2022
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Coal mining is an extensive source of anthropogenic methane emissions. In order to reduce and mitigate methane emissions, it is important to know how much and where the methane is emitted. We estimated coal mining methane emissions in Poland based on atmospheric methane measurements and particle dispersion modeling. In general, our emission estimates suggest higher emissions than expected by previous annual emission reports.
Carlos Alberti, Frank Hase, Matthias Frey, Darko Dubravica, Thomas Blumenstock, Angelika Dehn, Paolo Castracane, Gregor Surawicz, Roland Harig, Bianca C. Baier, Caroline Bès, Jianrong Bi, Hartmut Boesch, André Butz, Zhaonan Cai, Jia Chen, Sean M. Crowell, Nicholas M. Deutscher, Dragos Ene, Jonathan E. Franklin, Omaira García, David Griffith, Bruno Grouiez, Michel Grutter, Abdelhamid Hamdouni, Sander Houweling, Neil Humpage, Nicole Jacobs, Sujong Jeong, Lilian Joly, Nicholas B. Jones, Denis Jouglet, Rigel Kivi, Ralph Kleinschek, Morgan Lopez, Diogo J. Medeiros, Isamu Morino, Nasrin Mostafavipak, Astrid Müller, Hirofumi Ohyama, Paul I. Palmer, Mahesh Pathakoti, David F. Pollard, Uwe Raffalski, Michel Ramonet, Robbie Ramsay, Mahesh Kumar Sha, Kei Shiomi, William Simpson, Wolfgang Stremme, Youwen Sun, Hiroshi Tanimoto, Yao Té, Gizaw Mengistu Tsidu, Voltaire A. Velazco, Felix Vogel, Masataka Watanabe, Chong Wei, Debra Wunch, Marcia Yamasoe, Lu Zhang, and Johannes Orphal
Atmos. Meas. Tech., 15, 2433–2463, https://doi.org/10.5194/amt-15-2433-2022, https://doi.org/10.5194/amt-15-2433-2022, 2022
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Space-borne greenhouse gas missions require ground-based validation networks capable of providing fiducial reference measurements. Here, considerable refinements of the calibration procedures for the COllaborative Carbon Column Observing Network (COCCON) are presented. Laboratory and solar side-by-side procedures for the characterization of the spectrometers have been refined and extended. Revised calibration factors for XCO2, XCO and XCH4 are provided, incorporating 47 new spectrometers.
Randulph Morales, Jonas Ravelid, Katarina Vinkovic, Piotr Korbeń, Béla Tuzson, Lukas Emmenegger, Huilin Chen, Martina Schmidt, Sebastian Humbel, and Dominik Brunner
Atmos. Meas. Tech., 15, 2177–2198, https://doi.org/10.5194/amt-15-2177-2022, https://doi.org/10.5194/amt-15-2177-2022, 2022
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Mapping trace gas emission plumes using in situ measurements from unmanned aerial vehicles (UAVs) is an emerging and attractive possibility to quantify emissions from localized sources. We performed an extensive controlled-release experiment to develop an optimal quantification method and to determine the related uncertainties under various environmental and sampling conditions. Our approach was successful in quantifying local methane sources from drone-based measurements.
Johannes Gensheimer, Alexander J. Turner, Philipp Köhler, Christian Frankenberg, and Jia Chen
Biogeosciences, 19, 1777–1793, https://doi.org/10.5194/bg-19-1777-2022, https://doi.org/10.5194/bg-19-1777-2022, 2022
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We develop a convolutional neural network, named SIFnet, that increases the spatial resolution of SIF from TROPOMI by a factor of 10 to a spatial resolution of 0.005°. SIFnet utilizes coarse SIF observations, together with a broad range of high-resolution auxiliary data. The insights gained from interpretable machine learning techniques allow us to make quantitative claims about the relationships between SIF and other common parameters related to photosynthesis.
Gerrit Kuhlmann, Ka Lok Chan, Sebastian Donner, Ying Zhu, Marc Schwaerzel, Steffen Dörner, Jia Chen, Andreas Hueni, Duc Hai Nguyen, Alexander Damm, Annette Schütt, Florian Dietrich, Dominik Brunner, Cheng Liu, Brigitte Buchmann, Thomas Wagner, and Mark Wenig
Atmos. Meas. Tech., 15, 1609–1629, https://doi.org/10.5194/amt-15-1609-2022, https://doi.org/10.5194/amt-15-1609-2022, 2022
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Nitrogen dioxide (NO2) is an air pollutant whose concentration often exceeds air quality guideline values, especially in urban areas. To map the spatial distribution of NO2 in Munich, we conducted the Munich NO2 Imaging Campaign (MuNIC), where NO2 was measured with stationary, mobile, and airborne in situ and remote sensing instruments. The campaign provides a unique dataset that has been used to compare the different instruments and to study the spatial variability of NO2 and its sources.
Dominique Rust, Ioannis Katharopoulos, Martin K. Vollmer, Stephan Henne, Simon O'Doherty, Daniel Say, Lukas Emmenegger, Renato Zenobi, and Stefan Reimann
Atmos. Chem. Phys., 22, 2447–2466, https://doi.org/10.5194/acp-22-2447-2022, https://doi.org/10.5194/acp-22-2447-2022, 2022
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Artificial halocarbons contribute to ozone layer depletion and to global warming. We measured the atmospheric concentrations of halocarbons at the Beromünster tower, modelled the Swiss emissions, and compared the results to the internationally reported Swiss emissions inventory. For most of the halocarbons, we found good agreement, whereas one refrigerant might be overestimated in the inventory. In addition, we present first emission estimates of the newest types of halocarbons.
Pramod Kumar, Grégoire Broquet, Camille Yver-Kwok, Olivier Laurent, Susan Gichuki, Christopher Caldow, Ford Cropley, Thomas Lauvaux, Michel Ramonet, Guillaume Berthe, Frédéric Martin, Olivier Duclaux, Catherine Juery, Caroline Bouchet, and Philippe Ciais
Atmos. Meas. Tech., 14, 5987–6003, https://doi.org/10.5194/amt-14-5987-2021, https://doi.org/10.5194/amt-14-5987-2021, 2021
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This study presents a simple atmospheric inversion modeling framework for the localization and quantification of unknown CH4 and CO2 emissions from point sources based on near-surface mobile concentration measurements and a Gaussian plume dispersion model. It is applied for the estimate of a series of brief controlled releases of CH4 and CO2 with a wide range of rates during the TOTAL TADI-2018 experiment. Results indicate a ~10 %–40 % average error on the estimate of the release rates.
Taylor S. Jones, Jonathan E. Franklin, Jia Chen, Florian Dietrich, Kristian D. Hajny, Johannes C. Paetzold, Adrian Wenzel, Conor Gately, Elaine Gottlieb, Harrison Parker, Manvendra Dubey, Frank Hase, Paul B. Shepson, Levi H. Mielke, and Steven C. Wofsy
Atmos. Chem. Phys., 21, 13131–13147, https://doi.org/10.5194/acp-21-13131-2021, https://doi.org/10.5194/acp-21-13131-2021, 2021
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Methane emissions from leaks in natural gas pipes are often a large source in urban areas, but they are difficult to measure on a city-wide scale. Here we use an array of innovative methane sensors distributed around the city of Indianapolis and a new method of combining their data with an atmospheric model to accurately determine the magnitude of these emissions, which are about 70 % larger than predicted. This method can serve as a framework for cities trying to account for their emissions.
Stuart K. Grange, James D. Lee, Will S. Drysdale, Alastair C. Lewis, Christoph Hueglin, Lukas Emmenegger, and David C. Carslaw
Atmos. Chem. Phys., 21, 4169–4185, https://doi.org/10.5194/acp-21-4169-2021, https://doi.org/10.5194/acp-21-4169-2021, 2021
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The changes in mobility across Europe due to the COVID-19 lockdowns had consequences for air quality. We compare what was experienced to estimates of "what would have been" without the lockdowns. Nitrogen dioxide (NO2), an important vehicle-sourced pollutant, decreased by a third. However, ozone (O3) increased in response to lower NO2. Because NO2 is decreasing over time, increases in O3 can be expected in European urban areas and will require management to avoid future negative outcomes.
Alkuin Maximilian Koenig, Olivier Magand, Paolo Laj, Marcos Andrade, Isabel Moreno, Fernando Velarde, Grover Salvatierra, René Gutierrez, Luis Blacutt, Diego Aliaga, Thomas Reichler, Karine Sellegri, Olivier Laurent, Michel Ramonet, and Aurélien Dommergue
Atmos. Chem. Phys., 21, 3447–3472, https://doi.org/10.5194/acp-21-3447-2021, https://doi.org/10.5194/acp-21-3447-2021, 2021
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The environmental cycling of atmospheric mercury, a harmful global contaminant, is still not sufficiently constrained, partly due to missing data in remote regions. Here, we address this issue by presenting 20 months of atmospheric mercury measurements, sampled in the Bolivian Andes. We observe a significant seasonal pattern, whose key features we explore. Moreover, we deduce ratios to constrain South American biomass burning mercury emissions and the mercury uptake by the Amazon rainforest.
Manuel Graf, Philipp Scheidegger, André Kupferschmid, Herbert Looser, Thomas Peter, Ruud Dirksen, Lukas Emmenegger, and Béla Tuzson
Atmos. Meas. Tech., 14, 1365–1378, https://doi.org/10.5194/amt-14-1365-2021, https://doi.org/10.5194/amt-14-1365-2021, 2021
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Water vapor is the most important natural greenhouse gas. The accurate and frequent measurement of its abundance, especially in the upper troposphere and lower stratosphere (UTLS), is technically challenging. We developed and characterized a mid-IR absorption spectrometer for highly accurate water vapor measurements in the UTLS. The instrument is sufficiently small and lightweight (3.9 kg) to be carried by meteorological balloons, which enables frequent and cost-effective soundings.
Florian Dietrich, Jia Chen, Benno Voggenreiter, Patrick Aigner, Nico Nachtigall, and Björn Reger
Atmos. Meas. Tech., 14, 1111–1126, https://doi.org/10.5194/amt-14-1111-2021, https://doi.org/10.5194/amt-14-1111-2021, 2021
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Climate change is one of the defining issues of our time. However, most of the current emission estimates are based on calculations, not on actual measurements as it is difficult to quantify the emissions of large sources such as cities. This study shows how to use the relatively new approach of column measurements to quantify urban greenhouse gas emissions in an exact way using only a few compact measurement systems. The approach can be used to evaluate the effectiveness of mitigation policies.
Cited articles
Aigner, P. and Chen, J.: ACROPOLIS-data-processing, Zenodo [code], https://doi.org/10.5281/zenodo.15977933, 2025a. a, b
Aigner, P. and Chen, J.: ThingsBoard-Downloader, Zenodo [code], https://doi.org/10.5281/zenodo.15847934, 2025b. a, b
Aigner, P., Chen, J., and Kürzinger, K.: ICOS Cities 2024-12 release mid-cost CO2 data from the Munich network ACROPOLIS, ICOS ERIC – Carbon Porta [data set], https://doi.org/10.18160/B09J-YS2G, 2024. a
Aigner, P., Frölich, L., and Chen, J.: ACROPOLIS-edge, Version 0.0.95, Zenodo [code], https://doi.org/10.5281/zenodo.15849217, 2025. a, b, c
Aigner, P., Chen, J., and Kürzinger, K.: ICOS Cities 2025-12 release mid-cost CO2 data from the Munich network ACROPOLIS, ICOS ERIC – Carbon Portal [data set], https://doi.org/10.18160/HWNB-7CD8, 2026. a
Arzoumanian, E., Vogel, F. R., Bastos, A., Gaynullin, B., Laurent, O., Ramonet, M., and Ciais, P.: Characterization of a commercial lower-cost medium-precision non-dispersive infrared sensor for atmospheric CO2 monitoring in urban areas, Atmos. Meas. Tech., 12, 2665–2677, https://doi.org/10.5194/amt-12-2665-2019, 2019. a, b
Bares, R., Mitchell, L., Fasoli, B., Bowling, D. R., Catharine, D., Garcia, M., Eng, B., Ehleringer, J., and Lin, J. C.: The Utah urban carbon dioxide (UUCON) and Uintah Basin greenhouse gas networks: instrumentation, data, and measurement uncertainty, Earth Syst. Sci. Data, 11, 1291–1308, https://doi.org/10.5194/essd-11-1291-2019, 2019. a
Böhm, F., Makowski, M., Aigner, P., and Chen, J.: Tenta: Remote and Real-Time Sensor Network Management, Journal of Open Source Software, 10, 7311, https://doi.org/10.21105/joss.07311, 2025. a
Bréon, F. M., Broquet, G., Puygrenier, V., Chevallier, F., Xueref-Remy, I., Ramonet, M., Dieudonné, E., Lopez, M., Schmidt, M., Perrussel, O., and Ciais, P.: An attempt at estimating Paris area CO2 emissions from atmospheric concentration measurements, Atmos. Chem. Phys., 15, 1707–1724, https://doi.org/10.5194/acp-15-1707-2015, 2015. a
Brunner, D., Suter, I., Bernet, L., Constantin, L., Grange, S. K., Rubli, P., Li, J., Chen, J., Bigi, A., and Emmenegger, L.: Building-resolving simulations of anthropogenic and biospheric CO2 in the city of Zurich with GRAMM/GRAL, Atmos. Chem. Phys., 25, 14387–14410, https://doi.org/10.5194/acp-25-14387-2025, 2025. a
Cai, Q., Han, P., Pan, G., Xu, C., Yang, X., Xu, H., Ruan, D., and Zeng, N.: Evaluation of Low-Cost CO2 Sensors Using Reference Instruments and Standard Gases for Indoor Use, Sensors, 24, https://doi.org/10.3390/s24092680, 2024. a
Davis, K. J., Deng, A., Lauvaux, T., Miles, N. L., Richardson, S. J., Sarmiento, D. P., Gurney, K. R., Hardesty, R. M., Bonin, T. A., Brewer, W. A., Lamb, B. K., Shepson, P. B., Harvey, R. M., Cambaliza, M. O., Sweeney, C., Turnbull, J. C., Whetstone, J., and Karion, A.: The Indianapolis Flux Experiment (INFLUX): A test-bed for developing urban greenhouse gas emission measurements, Elementa: Science of the Anthropocene, 5, https://doi.org/10.1525/elementa.188, 2017. a
Delaria, E. R., Kim, J., Fitzmaurice, H. L., Newman, C., Wooldridge, P. J., Worthington, K., and Cohen, R. C.: The Berkeley Environmental Air-quality and CO2 Network: field calibrations of sensor temperature dependence and assessment of network scale CO2 accuracy, Atmos. Meas. Tech., 14, 5487–5500, https://doi.org/10.5194/amt-14-5487-2021, 2021. a, b, c
Dhakal, S., Minx, J., Toth, F., Abdel-Aziz, A., Figueroa Meza, M., Hubacek, K., Jonckheere, I., Kim, Y.-G., Nemet, G., Pachauri, S., Tan, X., and Wiedmann, T.: Emissions Trends and Drivers, in: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Shukla, P., Skea, J., Slade, R., Khourdajie, A. A., van Diemen, R., McCollum, D., Pathak, M., Some, S., Vyas, P., Fradera, R., Belkacemi, M., Hasija, A., Lisboa, G., Luz, S., and Malley, J., book section 2, Cambridge University Press, Cambridge, UK and New York, NY, USA, https://doi.org/10.1017/9781009157926.004, 2022. a
Dodman, D., Hayward, B., Pelling, M., Castan Broto, V., Chow, W., Chu, E., Dawson, R., Khirfan, L., McPhearson, T., Prakash, A., Zheng, Y., and Ziervogel, G.: Cities, Settlements and Key Infrastructure, in: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Pörtner, H. O., Roberts, D. C., Tignor, M., Poloczanska, E. S., Mintenbeck, K., Alegría, A., Craig, M., Langsdorf, S., Löschke, S., Möller, V., Okem, A., and Rama, B., book section 6, Cambridge University Press, Cambridge, UK and New York, NY, USA, https://doi.org/10.1017/9781009325844.008, 2022. a
El Yazidi, A., Ramonet, M., Ciais, P., Broquet, G., Pison, I., Abbaris, A., Brunner, D., Conil, S., Delmotte, M., Gheusi, F., Guerin, F., Hazan, L., Kachroudi, N., Kouvarakis, G., Mihalopoulos, N., Rivier, L., and Serça, D.: Identification of spikes associated with local sources in continuous time series of atmospheric CO, CO2 and CH4, Atmos. Meas. Tech., 11, 1599–1614, https://doi.org/10.5194/amt-11-1599-2018, 2018. a, b
Hall, B. D., Crotwell, A. M., Kitzis, D. R., Mefford, T., Miller, B. R., Schibig, M. F., and Tans, P. P.: Revision of the World Meteorological Organization Global Atmosphere Watch (WMO/GAW) CO2 calibration scale, Atmos. Meas. Tech., 14, 3015–3032, https://doi.org/10.5194/amt-14-3015-2021, 2021. a
Hermes-contributors: Hermes, Version 1.0.1, Zenodo [code], https://doi.org/10.5281/zenodo.16747031, 2025. a
Hoornweg, D., Sugar, L., and Gómez, C. L. T.: Cities and greenhouse gas emissions: moving forward, Environ. Urban., 23, 207–227, https://doi.org/10.1177/0956247810392270, 2011. a, b
Jones, C. and Kammen, D. M.: Spatial distribution of U. S. household carbon footprints reveals suburbanization undermines greenhouse gas benefits of urban population density, Environ. Sci. Technol., 48, 895–902, https://doi.org/10.1021/es4034364, 2014. a
Karion, A., Callahan, W., Stock, M., Prinzivalli, S., Verhulst, K. R., Kim, J., Salameh, P. K., Lopez-Coto, I., and Whetstone, J.: Greenhouse gas observations from the Northeast Corridor tower network, Earth Syst. Sci. Data, 12, 699–717, https://doi.org/10.5194/essd-12-699-2020, 2020. a
Karunasingha, D. S. K.: Root mean square error or mean absolute error? Use their ratio as well, Inform. Sciences, 585, 609–629, https://doi.org/10.1016/j.ins.2021.11.036, 2022. a
Keeling, C. D., Bacastow, R. B., Bainbridge, A. E., Ekdahl Jr., C. A., Guenther, P. R., Waterman, L. S., and Chin, J. F.: Atmospheric carbon dioxide variations at Mauna Loa observatory, Hawaii, Tellus, 28, 538–551, 1976. a
Kennedy, C., Steinberger, J., Gasson, B., Hansen, Y., Hillman, T., Havránek, M., Pataki, D., Phdungsilp, A., Ramaswami, A., and Mendez, G. V.: Greenhouse Gas Emissions from Global Cities, Environ. Sci. Technol., 43, 7297–7302, https://doi.org/10.1021/es900213p, 2009. a
Kunz, A.-K., Borchardt, L., Christen, A., Della Coletta, J., Eritt, M., Gutiérrez, X., Hashemi, J., Hilland, R., Jordan, A., Kneißl, R., Legendre, V., Levin, I., Preunkert, S., Rubli, P., Stagakis, S., and Hammer, S.: A relaxed eddy accumulation flask sampling system for 14C-based partitioning of fossil and non-fossil CO2 fluxes, Atmos. Meas. Tech., 18, 5349–5373, https://doi.org/10.5194/amt-18-5349-2025, 2025. a
Lauvaux, T., Gurney, K. R., Miles, N. L., Davis, K. J., Richardson, S. J., Deng, A., Nathan, B. J., Oda, T., Wang, J. A., Hutyra, L., and Turnbull, J.: Policy-Relevant Assessment of Urban CO2 Emissions, Environ. Sci. Technol., 54, 10237–10245, https://doi.org/10.1021/acs.est.0c00343, 2020. a
Lian, J., Laurent, O., Chariot, M., Lienhardt, L., Ramonet, M., Utard, H., Lauvaux, T., Bréon, F.-M., Broquet, G., Cucchi, K., Millair, L., and Ciais, P.: Development and deployment of a mid-cost CO2 sensor monitoring network to support atmospheric inverse modeling for quantifying urban CO2 emissions in Paris, Atmos. Meas. Tech., 17, 5821–5839, https://doi.org/10.5194/amt-17-5821-2024, 2024. a, b, c
Martin, C. R., Zeng, N., Karion, A., Dickerson, R. R., Ren, X., Turpie, B. N., and Weber, K. J.: Evaluation and environmental correction of ambient CO2 measurements from a low-cost NDIR sensor, Atmos. Meas. Tech., 10, 2383–2395, https://doi.org/10.5194/amt-10-2383-2017, 2017. a
Mitchell, L. E., Lin, J. C., Bowling, D. R., Pataki, D. E., Strong, C., Schauer, A. J., Bares, R., Bush, S. E., Stephens, B. B., Mendoza, D., Mallia, D., Holland, L., Gurney, K. R., and Ehleringer, J. R.: Long-term urban carbon dioxide observations reveal spatial and temporal dynamics related to urban characteristics and growth, P. Natl. Acad. Sci. USA, 115, 2912–2917, https://doi.org/10.1073/pnas.1702393115, 2018. a
Mueller, K., Yadav, V., Lopez-Coto, I., Karion, A., Gourdji, S., Martin, C., and Whetstone, J.: Siting Background Towers to Characterize Incoming Air for Urban Greenhouse Gas Estimation: A Case Study in the Washington, DC/Baltimore Area, J. Geophys. Res.-Atmos., 123, 2910–2926, https://doi.org/10.1002/2017JD027364, 2018. a
Müller, M., Graf, P., Meyer, J., Pentina, A., Brunner, D., Perez-Cruz, F., Hüglin, C., and Emmenegger, L.: Integration and calibration of non-dispersive infrared (NDIR) CO2 low-cost sensors and their operation in a sensor network covering Switzerland, Atmos. Meas. Tech., 13, 3815–3834, https://doi.org/10.5194/amt-13-3815-2020, 2020. a
Nalini, K., Lauvaux, T., Abdallah, C., Lian, J., Ciais, P., Utard, H., Laurent, O., and Ramonet, M.: High-Resolution Lagrangian Inverse Modeling of CO2 Emissions Over the Paris Region During the First 2020 Lockdown Period, J. Geophys. Res.-Atmos., 127, https://doi.org/10.1029/2021JD036032, 2022. a
Park, C., Jeong, S., Park, H., Woo, J.-H., Sim, S., Kim, J., Son, J., Park, H., Shin, Y., ho Shin, J., Kwon, S.-M., and young Lee, W.: Challenges in Monitoring Atmospheric CO2 Concentrations in Seoul Using Low-Cost Sensors, Asia-Pac. J. Atmos. Sci., 57, 547–553, https://doi.org/10.1007/s13143-020-00213-2, 2021. a
Park, C., Jeong, S., Park, H., Sim, S., Hong, J., and Oh, E.: Comprehensive assessment of vertical variations in urban atmospheric CO2 concentrations by using tall tower measurement and an atmospheric transport model, Urban Climate, 45, 101283, https://doi.org/10.1016/j.uclim.2022.101283, 2022. a
Pearson, R. K., Neuvo, Y., Astola, J., and Gabbouj, M.: Generalized Hampel Filters, EURASIP J. Adv. Sig. Pr., 2016, 87, https://doi.org/10.1186/s13634-016-0383-6, 2016. a, b
Ponomarev, N., Steiner, M., Koene, E., Rubli, P., Grange, S., Constantin, L., Ramonet, M., David, L., Hamzehloo, A., Emmenegger, L., and Brunner, D.: Estimation of CO2 fluxes in the cities of Zurich and Paris using the ICON-ART CTDAS inverse modelling framework, Atmos. Chem. Phys., 26, 547–570, https://doi.org/10.5194/acp-26-547-2026, 2025. a
Portal, I. C. D.: ICOS Cities Data Portal, https://citydata.icos-cp.eu/portal/ (last access: 26 January 2026), 2025. a
Roubeyrie, L. and Celles, S.: Windrose: A Python Matplotlib, Numpy library to manage wind and pollution data, draw windrose, Journal of Open Source Software, 3, 268, https://doi.org/10.21105/joss.00268, 2018. a
Shusterman, A. A., Teige, V. E., Turner, A. J., Newman, C., Kim, J., and Cohen, R. C.: The BErkeley Atmospheric CO2 Observation Network: initial evaluation, Atmos. Chem. Phys., 16, 13449–13463, https://doi.org/10.5194/acp-16-13449-2016, 2016. a, b, c
Szopa, S., Naik, V., Adhikary, B., Artaxo, P., Berntsen, T., Collins, W., Fuzzi, S., Gallardo, L., Kiendler-Scharr, A., Klimont, Z., Liao, H., Unger, N., and Zanis, P.: Short-Lived Climate Forcers, in: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M. I., Huang, M., Leitzell, K., Lonnoy, E., Matthews, J. B. R., Maycock, T. K., Waterfield, T., Yelekçi, O., Yu, R., and Zhou, B., book section 6, Cambridge University Press, Cambridge, UK and New York, NY, USA, 817–921, https://doi.org/10.1017/9781009157896.008, 2021. a
ThingsBoard-contributors: ThingsBoard (version 3.7.0) – Open-source IoT platform [code], https://github.com/thingsboard/thingsboard (last access: 26 January 2026), 2024. a
Turnbull, J. C., Sweeney, C., Karion, A., Newberger, T., Lehman, S. J., Tans, P. P., Davis, K. J., Lauvaux, T., Miles, N. L., Richardson, S. J., Cambaliza, M. O., Shepson, P. B., Gurney, K., Patarasuk, R., and Razlivanov, I.: Toward quantification and source sector identification of fossil fuel CO2 emissions from an urban area: Results from the INFLUX experiment, Journal of Geophysical Research: Atmospheres, 120, 292–312, https://doi.org/10.1002/2014JD022555, 2015. a
Turner, A. J., Shusterman, A. A., McDonald, B. C., Teige, V., Harley, R. A., and Cohen, R. C.: Network design for quantifying urban CO2 emissions: assessing trade-offs between precision and network density, Atmos. Chem. Phys., 16, 13465–13475, https://doi.org/10.5194/acp-16-13465-2016, 2016. a, b
Verhulst, K. R., Karion, A., Kim, J., Salameh, P. K., Keeling, R. F., Newman, S., Miller, J., Sloop, C., Pongetti, T., Rao, P., Wong, C., Hopkins, F. M., Yadav, V., Weiss, R. F., Duren, R. M., and Miller, C. E.: Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project – Part 1: calibration, urban enhancements, and uncertainty estimates, Atmos. Chem. Phys., 17, 8313–8341, https://doi.org/10.5194/acp-17-8313-2017, 2017. a
Wagner, W. and Pruß, A.: The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use, Journal of Physical and Chemical Reference Data, 31, 387–535, https://doi.org/10.1063/1.1461829, 2002. a
Wu, L., Broquet, G., Ciais, P., Bellassen, V., Vogel, F., Chevallier, F., Xueref-Remy, I., and Wang, Y.: What would dense atmospheric observation networks bring to the quantification of city CO2 emissions?, Atmos. Chem. Phys., 16, 7743–7771, https://doi.org/10.5194/acp-16-7743-2016, 2016. a
Xueref-Remy, I., Dieudonné, E., Vuillemin, C., Lopez, M., Lac, C., Schmidt, M., Delmotte, M., Chevallier, F., Ravetta, F., Perrussel, O., Ciais, P., Bréon, F.-M., Broquet, G., Ramonet, M., Spain, T. G., and Ampe, C.: Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area, Atmos. Chem. Phys., 18, 3335–3362, https://doi.org/10.5194/acp-18-3335-2018, 2018. a, b
Short summary
Dense urban CO2 monitoring is challenging due to cost and operational constraints. We developed a mid-cost sensor network for Munich, deployed on 17 rooftops. Temperature-stabilized enclosures and automated 2-point calibration ensured reliable performance, assessed by side-by-side comparison with a Picarro reference. In 1.5 years, the network collected 90 million measurements and resolved urban-rural gradients and seasonal diurnal patterns, capturing spatial CO2 variability at city scale.
Dense urban CO2 monitoring is challenging due to cost and operational constraints. We developed...
