Articles | Volume 26, issue 8
https://doi.org/10.5194/acp-26-5355-2026
© 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/acp-26-5355-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
21 Apr 2026
Research article |
| 21 Apr 2026
Multi-decadal ozone air quality and the role of temperature in Switzerland during summertime
Clara M. Nussbaumer
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science (IAC), ETH Zürich, 8092 Zürich, Switzerland
Colette L. Heald
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science (IAC), ETH Zürich, 8092 Zürich, Switzerland
Amanda M. Häne
Institute for Atmospheric and Climate Science (IAC), ETH Zürich, 8092 Zürich, Switzerland
Christoph Hüglin
Swiss Federal Laboratories for Materials Science and Technology (Empa), 8600 Dübendorf, Switzerland
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Natalie M. Mahowald, Longlei Li, Julius Vira, Marje Prank, Douglas S. Hamilton, Hitoshi Matsui, Ron L. Miller, P. Louis Lu, Ezgi Akyuz, Daphne Meidan, Peter Hess, Heikki Lihavainen, Christine Wiedinmyer, Jenny Hand, Maria Grazia Alaimo, Célia Alves, Andres Alastuey, Paulo Artaxo, Africa Barreto, Francisco Barraza, Silvia Becagli, Giulia Calzolai, Shankararaman Chellam, Ying Chen, Patrick Chuang, David D. Cohen, Cristina Colombi, Evangelia Diapouli, Gaetano Dongarra, Konstantinos Eleftheriadis, Johann Engelbrecht, Corinne Galy-Lacaux, Cassandra Gaston, Dario Gomez, Yenny González Ramos, Roy M. Harrison, Chris Heyes, Barak Herut, Philip Hopke, Christoph Hüglin, Maria Kanakidou, Zsofia Kertesz, Zbigniew Klimont, Katriina Kyllönen, Fabrice Lambert, Xiaohong Liu, Remi Losno, Franco Lucarelli, Willy Maenhaut, Beatrice Marticorena, Randall V. Martin, Nikolaos Mihalopoulos, Yasser Morera-Gómez, Adina Paytan, Joseph Prospero, Sergio Rodríguez, Patricia Smichowski, Daniela Varrica, Brenna Walsh, Crystal L. Weagle, and Xi Zhao
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Stuart K. Grange, Pascal Rubli, Andrea Fischer, Dominik Brunner, Christoph Hueglin, and Lukas Emmenegger
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Hector Navarro-Barboza, Jordi Rovira, Vincenzo Obiso, Andrea Pozzer, Marta Via, Andres Alastuey, Xavier Querol, Noemi Perez, Marjan Savadkoohi, Gang Chen, Jesus Yus-Díez, Matic Ivancic, Martin Rigler, Konstantinos Eleftheriadis, Stergios Vratolis, Olga Zografou, Maria Gini, Benjamin Chazeau, Nicolas Marchand, Andre S. H. Prevot, Kaspar Dallenbach, Mikael Ehn, Krista Luoma, Tuukka Petäjä, Anna Tobler, Jaroslaw Necki, Minna Aurela, Hilkka Timonen, Jarkko Niemi, Olivier Favez, Jean-Eudes Petit, Jean-Philippe Putaud, Christoph Hueglin, Nicolas Pascal, Aurélien Chauvigné, Sébastien Conil, Marco Pandolfi, and Oriol Jorba
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Olivia G. Norman, Colette L. Heald, Solomon Bililign, Pedro Campuzano-Jost, Hugh Coe, Marc N. Fiddler, Jaime R. Green, Jose L. Jimenez, Katharina Kaiser, Jin Liao, Ann M. Middlebrook, Benjamin A. Nault, John B. Nowak, Johannes Schneider, and André Welti
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Natalie M. Mahowald, Longlei Li, Julius Vira, Marje Prank, Douglas S. Hamilton, Hitoshi Matsui, Ron L. Miller, Louis Lu, Ezgi Akyuz, Daphne Meidan, Peter Hess, Heikki Lihavainen, Christine Wiedinmyer, Jenny Hand, Maria Grazia Alaimo, Célia Alves, Andres Alastuey, Paulo Artaxo, Africa Barreto, Francisco Barraza, Silvia Becagli, Giulia Calzolai, Shankarararman Chellam, Ying Chen, Patrick Chuang, David D. Cohen, Cristina Colombi, Evangelia Diapouli, Gaetano Dongarra, Konstantinos Eleftheriadis, Corinne Galy-Lacaux, Cassandra Gaston, Dario Gomez, Yenny González Ramos, Hannele Hakola, Roy M. Harrison, Chris Heyes, Barak Herut, Philip Hopke, Christoph Hüglin, Maria Kanakidou, Zsofia Kertesz, Zbiginiw Klimont, Katriina Kyllönen, Fabrice Lambert, Xiaohong Liu, Remi Losno, Franco Lucarelli, Willy Maenhaut, Beatrice Marticorena, Randall V. Martin, Nikolaos Mihalopoulos, Yasser Morera-Gomez, Adina Paytan, Joseph Prospero, Sergio Rodríguez, Patricia Smichowski, Daniela Varrica, Brenna Walsh, Crystal Weagle, and Xi Zhao
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2024-1, https://doi.org/10.5194/essd-2024-1, 2024
Preprint withdrawn
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Aerosol particles can interact with incoming solar radiation and outgoing long wave radiation, change cloud properties, affect photochemistry, impact surface air quality, and when deposited impact surface albedo of snow and ice, and modulate carbon dioxide uptake by the land and ocean. Here we present a new compilation of aerosol observations including composition, a methodology for comparing the datasets to model output, and show the implications of these results using one model.
Clara M. Nussbaumer, Bryan K. Place, Qindan Zhu, Eva Y. Pfannerstill, Paul Wooldridge, Benjamin C. Schulze, Caleb Arata, Ryan Ward, Anthony Bucholtz, John H. Seinfeld, Allen H. Goldstein, and Ronald C. Cohen
Atmos. Chem. Phys., 23, 13015–13028, https://doi.org/10.5194/acp-23-13015-2023, https://doi.org/10.5194/acp-23-13015-2023, 2023
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NOx is a precursor to hazardous tropospheric ozone and can be emitted from various anthropogenic sources. It is important to quantify NOx emissions in urban environments to improve the local air quality, which still remains a challenge, as sources are heterogeneous in space and time. In this study, we calculate NOx emissions over Los Angeles, based on aircraft measurements in June 2021, and compare them to a local emission inventory, which we find mostly overpredicts the measured values.
Clara M. Nussbaumer, Horst Fischer, Jos Lelieveld, and Andrea Pozzer
Atmos. Chem. Phys., 23, 12651–12669, https://doi.org/10.5194/acp-23-12651-2023, https://doi.org/10.5194/acp-23-12651-2023, 2023
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Ozone is a greenhouse gas and contributes to the earth’s radiative energy budget and therefore to global warming. This effect is the largest in the upper troposphere. In this study, we investigate the processes controlling ozone formation and the sensitivity to its precursors in the upper tropical troposphere based on model simulations by the ECHAM5/MESSy2 Atmospheric Chemistry (EMAC) model. We find that NO? emissions from lightning most importantly affect ozone chemistry at these altitudes.
Jean-Philippe Putaud, Enrico Pisoni, Alexander Mangold, Christoph Hueglin, Jean Sciare, Michael Pikridas, Chrysanthos Savvides, Jakub Ondracek, Saliou Mbengue, Alfred Wiedensohler, Kay Weinhold, Maik Merkel, Laurent Poulain, Dominik van Pinxteren, Hartmut Herrmann, Andreas Massling, Claus Nordstroem, Andrés Alastuey, Cristina Reche, Noemí Pérez, Sonia Castillo, Mar Sorribas, Jose Antonio Adame, Tuukka Petaja, Katrianne Lehtipalo, Jarkko Niemi, Véronique Riffault, Joel F. de Brito, Augustin Colette, Olivier Favez, Jean-Eudes Petit, Valérie Gros, Maria I. Gini, Stergios Vratolis, Konstantinos Eleftheriadis, Evangelia Diapouli, Hugo Denier van der Gon, Karl Espen Yttri, and Wenche Aas
Atmos. Chem. Phys., 23, 10145–10161, https://doi.org/10.5194/acp-23-10145-2023, https://doi.org/10.5194/acp-23-10145-2023, 2023
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Many European people are still exposed to levels of air pollution that can affect their health. COVID-19 lockdowns in 2020 were used to assess the impact of the reduction in human mobility on air pollution across Europe by comparing measurement data with values that would be expected if no lockdown had occurred. We show that lockdown measures did not lead to consistent decreases in the concentrations of fine particulate matter suspended in the air, and we investigate why.
Qindan Zhu, Bryan Place, Eva Y. Pfannerstill, Sha Tong, Huanxin Zhang, Jun Wang, Clara M. Nussbaumer, Paul Wooldridge, Benjamin C. Schulze, Caleb Arata, Anthony Bucholtz, John H. Seinfeld, Allen H. Goldstein, and Ronald C. Cohen
Atmos. Chem. Phys., 23, 9669–9683, https://doi.org/10.5194/acp-23-9669-2023, https://doi.org/10.5194/acp-23-9669-2023, 2023
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Nitrogen oxide (NOx) is a hazardous air pollutant, and it is the precursor of short-lived climate forcers like tropospheric ozone and aerosol particles. While NOx emissions from transportation has been strictly regulated, soil NOx emissions are overlooked. We use the airborne flux measurements to observe NOx emissions from highways and urban and cultivated soil land cover types. We show non-negligible soil NOx emissions, which are significantly underestimated in current model simulations.
Kevin J. Nihill, Matthew M. Coggon, Christopher Y. Lim, Abigail R. Koss, Bin Yuan, Jordan E. Krechmer, Kanako Sekimoto, Jose L. Jimenez, Joost de Gouw, Christopher D. Cappa, Colette L. Heald, Carsten Warneke, and Jesse H. Kroll
Atmos. Chem. Phys., 23, 7887–7899, https://doi.org/10.5194/acp-23-7887-2023, https://doi.org/10.5194/acp-23-7887-2023, 2023
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In this work, we collect emissions from controlled burns of biomass fuels that can be found in the western United States into an environmental chamber in order to simulate their oxidation as they pass through the atmosphere. These findings provide a detailed characterization of the composition of the atmosphere downwind of wildfires. In turn, this will help to explore the effects of these changing emissions on downwind populations and will also directly inform atmospheric and climate models.
Lenard L. Röder, Patrick Dewald, Clara M. Nussbaumer, Jan Schuladen, John N. Crowley, Jos Lelieveld, and Horst Fischer
Atmos. Meas. Tech., 16, 1167–1178, https://doi.org/10.5194/amt-16-1167-2023, https://doi.org/10.5194/amt-16-1167-2023, 2023
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Field experiments in atmospheric chemistry provide insights into chemical interactions of our atmosphere. However, high data coverage and accuracy are needed to enable further analysis. In this study, we explore a statistical method that combines knowledge about the chemical reactions with information from measurements to increase the quality of field experiment datasets. We test the algorithm for several applications and discuss limitations that depend on the specific variable and the dynamics.
Qing Ye, Matthew B. Goss, Jordan E. Krechmer, Francesca Majluf, Alexander Zaytsev, Yaowei Li, Joseph R. Roscioli, Manjula Canagaratna, Frank N. Keutsch, Colette L. Heald, and Jesse H. Kroll
Atmos. Chem. Phys., 22, 16003–16015, https://doi.org/10.5194/acp-22-16003-2022, https://doi.org/10.5194/acp-22-16003-2022, 2022
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The atmospheric oxidation of dimethyl sulfide (DMS) is a major natural source of sulfate particles in the atmosphere. However, its mechanism is poorly constrained. In our work, laboratory measurements and mechanistic modeling were conducted to comprehensively investigate DMS oxidation products and key reaction rates. We find that the peroxy radical (RO2) has a controlling effect on product distribution and aerosol yield, with the isomerization of RO2 leading to the suppression of aerosol yield.
Therese S. Carter, Colette L. Heald, Jesse H. Kroll, Eric C. Apel, Donald Blake, Matthew Coggon, Achim Edtbauer, Georgios Gkatzelis, Rebecca S. Hornbrook, Jeff Peischl, Eva Y. Pfannerstill, Felix Piel, Nina G. Reijrink, Akima Ringsdorf, Carsten Warneke, Jonathan Williams, Armin Wisthaler, and Lu Xu
Atmos. Chem. Phys., 22, 12093–12111, https://doi.org/10.5194/acp-22-12093-2022, https://doi.org/10.5194/acp-22-12093-2022, 2022
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Fires emit many gases which can contribute to smog and air pollution. However, the amount and properties of these chemicals are not well understood, so this work updates and expands their representation in a global atmospheric model, including by adding new chemicals. We confirm that this updated representation generally matches measurements taken in several fire regions. We then show that fires provide ~15 % of atmospheric reactivity globally and more than 75 % over fire source regions.
Patrick Dewald, Clara M. Nussbaumer, Jan Schuladen, Akima Ringsdorf, Achim Edtbauer, Horst Fischer, Jonathan Williams, Jos Lelieveld, and John N. Crowley
Atmos. Chem. Phys., 22, 7051–7069, https://doi.org/10.5194/acp-22-7051-2022, https://doi.org/10.5194/acp-22-7051-2022, 2022
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We measured the gas-phase reactivity of the NO3 radical on the summit (825 m a.s.l.) of a semi-rural mountain in southwestern Germany in July 2021. The impact of VOC-induced NO3 losses (mostly monoterpenes) competing with a loss by reaction with NO and photolysis throughout the diel cycle was estimated. Besides chemistry, boundary layer dynamics and plant-physiological processes presumably have a great impact on our observations, which were compared to previous NO3 measurements at the same site.
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.
Horim Kim, Michael Müller, Stephan Henne, and Christoph Hüglin
Atmos. Meas. Tech., 15, 2979–2992, https://doi.org/10.5194/amt-15-2979-2022, https://doi.org/10.5194/amt-15-2979-2022, 2022
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In this study, the performance of electrochemical sensors for NO and NO2 for measuring air quality was determined over a longer operating period. The performance of NO sensors remained reliable for more than 18 months. However, the NO2 sensors showed decreasing performance over time. During deployment, we found that the NO2 sensors can distinguish general pollution levels, but they proved unsuitable for accurate measurements due to significant biases.
Clara M. Nussbaumer, Andrea Pozzer, Ivan Tadic, Lenard Röder, Florian Obersteiner, Hartwig Harder, Jos Lelieveld, and Horst Fischer
Atmos. Chem. Phys., 22, 6151–6165, https://doi.org/10.5194/acp-22-6151-2022, https://doi.org/10.5194/acp-22-6151-2022, 2022
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The European COVID-19 lockdowns have significantly reduced the emission of primary pollutants such as NOx, which impacts the tropospheric photochemical processes and the abundance of O3. In this study, we present how the lockdowns have affected tropospheric trace gases and ozone production based on in situ observations and modeling simulations. We additionally show that the chemical regime shifted from a transition point to a NOx limitation in the upper troposphere.
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.
Franz Conen, Annika Einbock, Claudia Mignani, and Christoph Hüglin
Atmos. Chem. Phys., 22, 3433–3444, https://doi.org/10.5194/acp-22-3433-2022, https://doi.org/10.5194/acp-22-3433-2022, 2022
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Above western Europe, ice typically starts to form in clouds a few kilometres above the ground if suitable aerosol particles are present. In air masses typical for that altitude, we found that such particles most likely originate from bacteria and fungi living on plants. Occasional Saharan dust intrusions seem to contribute little to the number concentration of particles able to freeze cloud droplets between 0°C and −15°C.
Ka Ming Fung, Colette L. Heald, Jesse H. Kroll, Siyuan Wang, Duseong S. Jo, Andrew Gettelman, Zheng Lu, Xiaohong Liu, Rahul A. Zaveri, Eric C. Apel, Donald R. Blake, Jose-Luis Jimenez, Pedro Campuzano-Jost, Patrick R. Veres, Timothy S. Bates, John E. Shilling, and Maria Zawadowicz
Atmos. Chem. Phys., 22, 1549–1573, https://doi.org/10.5194/acp-22-1549-2022, https://doi.org/10.5194/acp-22-1549-2022, 2022
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Understanding the natural aerosol burden in the preindustrial era is crucial for us to assess how atmospheric aerosols affect the Earth's radiative budgets. Our study explores how a detailed description of dimethyl sulfide (DMS) oxidation (implemented in the Community Atmospheric Model version 6 with chemistry, CAM6-chem) could help us better estimate the present-day and preindustrial concentrations of sulfate and other relevant chemicals, as well as the resulting aerosol radiative impacts.
Clara M. Nussbaumer, John N. Crowley, Jan Schuladen, Jonathan Williams, Sascha Hafermann, Andreas Reiffs, Raoul Axinte, Hartwig Harder, Cheryl Ernest, Anna Novelli, Katrin Sala, Monica Martinez, Chinmay Mallik, Laura Tomsche, Christian Plass-Dülmer, Birger Bohn, Jos Lelieveld, and Horst Fischer
Atmos. Chem. Phys., 21, 18413–18432, https://doi.org/10.5194/acp-21-18413-2021, https://doi.org/10.5194/acp-21-18413-2021, 2021
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HCHO is an important atmospheric trace gas influencing the photochemical processes in the Earth’s atmosphere, including the budget of HOx and the abundance of tropospheric O3. This research presents the photochemical calculations of HCHO and O3 based on three field campaigns across Europe. We show that HCHO production via the oxidation of only four volatile organic compound precursors, i.e., CH4, CH3CHO, C5H8 and CH3OH, can balance the observed loss at all sites well.
Clara M. Nussbaumer, Uwe Parchatka, Ivan Tadic, Birger Bohn, Daniel Marno, Monica Martinez, Roland Rohloff, Hartwig Harder, Flora Kluge, Klaus Pfeilsticker, Florian Obersteiner, Martin Zöger, Raphael Doerich, John N. Crowley, Jos Lelieveld, and Horst Fischer
Atmos. Meas. Tech., 14, 6759–6776, https://doi.org/10.5194/amt-14-6759-2021, https://doi.org/10.5194/amt-14-6759-2021, 2021
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NO2 plays a central role in atmospheric photochemical processes and requires accurate measurements. This research presents NO2 data obtained via chemiluminescence using a photolytic converter from airborne studies around Cabo Verde and laboratory investigations. We show the limits and error-proneness of a conventional blue light converter in aircraft measurements affected by humidity and NO levels and suggest the use of an alternative quartz converter for more reliable results.
Gang Chen, Yulia Sosedova, Francesco Canonaco, Roman Fröhlich, Anna Tobler, Athanasia Vlachou, Kaspar R. Daellenbach, Carlo Bozzetti, Christoph Hueglin, Peter Graf, Urs Baltensperger, Jay G. Slowik, Imad El Haddad, and André S. H. Prévôt
Atmos. Chem. Phys., 21, 15081–15101, https://doi.org/10.5194/acp-21-15081-2021, https://doi.org/10.5194/acp-21-15081-2021, 2021
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A novel, advanced source apportionment technique was applied to a dataset measured in Magadino. Rolling positive matrix factorisation (PMF) allows for retrieving more realistic, time-dependent, and detailed information on organic aerosol sources. The strength of the rolling PMF mechanism is highlighted by comparing it with results derived from conventional seasonal PMF. Overall, this comprehensive interpretation of aerosol chemical speciation monitor data could be a role model for similar work.
Ivan Tadic, Clara M. Nussbaumer, Birger Bohn, Hartwig Harder, Daniel Marno, Monica Martinez, Florian Obersteiner, Uwe Parchatka, Andrea Pozzer, Roland Rohloff, Martin Zöger, Jos Lelieveld, and Horst Fischer
Atmos. Chem. Phys., 21, 8195–8211, https://doi.org/10.5194/acp-21-8195-2021, https://doi.org/10.5194/acp-21-8195-2021, 2021
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Although mechanisms of tropospheric ozone (O3) formation are well understood, studies reporting on ozone formation derived from field measurements are challenging and remain sparse in number. We use airborne measurements to quantify nitric oxide (NO) and O3 distributions in the upper troposphere over the Atlantic Ocean and western Africa and compare our measurements to model simulations. Our results show that NO and ozone formation are greatest over the tropical areas of western Africa.
Clara M. Nussbaumer, Ivan Tadic, Dirk Dienhart, Nijing Wang, Achim Edtbauer, Lisa Ernle, Jonathan Williams, Florian Obersteiner, Isidoro Gutiérrez-Álvarez, Hartwig Harder, Jos Lelieveld, and Horst Fischer
Atmos. Chem. Phys., 21, 7933–7945, https://doi.org/10.5194/acp-21-7933-2021, https://doi.org/10.5194/acp-21-7933-2021, 2021
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Lightning over continental and coastal areas is frequent and accompanied by deep convection, while lightning over marine areas and particularly in tropical cyclones is rare. This research presents in situ observations of the tropical storm Florence 2018 near Cabo Verde. We show the absence of lightning in the tropical storm despite the occurrence of deep convective processes by atmospheric trace gas measurements of O3, NO, CO, H2O2, DMS and CH2I.
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Massagué, J., Torre-Pascual, E., Carnerero, C., Escudero, M., Alastuey, A., Pandolfi, M., Querol, X., and Gangoiti, G.: Extreme ozone episodes in a major Mediterranean urban area, Atmos. Chem. Phys., 24, 4827–4850, https://doi.org/10.5194/acp-24-4827-2024, 2024. a
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McDonald, B. C., de Gouw, J. A., Gilman, J. B., Jathar, S. H., Akherati, A., Cappa, C. D., Jimenez, J. L., Lee-Taylor, J., Hayes, P. L., McKeen, S. A., Cui, Y. Y., Kim, S., Gentner, D. R., Isaacman-VanWertz, G., Goldstein, A. H., Harley, R. A., Frost, G. J., Roberts, J. M., Ryerson, T. B., and Trainer, M.: Volatile chemical products emerging as largest petrochemical source of urban organic emissions, Science, 359, 760–764, https://doi.org/10.1126/science.aaq0524, 2018. a
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Short summary
Ground-level ozone is harmful to human health. While precursors to ozone were strongly reduced over the past decades, unhealthy levels of ozone are still frequently reported in Switzerland. In this study, we investigate changes in ozone and its relationship with temperature over time. We find that precursor reductions have positively affected ozone in remote locations, while ozone is increasing close to busy roads. High ozone is often associated with hot summer days.
Ground-level ozone is harmful to human health. While precursors to ozone were strongly reduced...
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