Articles | Volume 16, issue 22 
            
                
                    
                    
            
            
            https://doi.org/10.5194/acp-16-14755-2016
                    © Author(s) 2016. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-16-14755-2016
                    © Author(s) 2016. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
Movement, drivers and bimodality of the South Asian High
Matthias Nützel
CORRESPONDING AUTHOR
                                            
                                    
                                            Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
                                        
                                    Martin Dameris
                                            Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
                                        
                                    Hella Garny
                                            Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
                                        
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                                        Matthias Nützel, Sabine Brinkop, Martin Dameris, Hella Garny, Patrick Jöckel, Laura L. Pan, and Mijeong Park
                                    Atmos. Chem. Phys., 22, 15659–15683, https://doi.org/10.5194/acp-22-15659-2022, https://doi.org/10.5194/acp-22-15659-2022, 2022
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                                                Record low ozone values were observed in March 2020. Dynamical and chemical circumstances leading to low ozone values in spring 2020 are discussed and are compared to similar dynamical conditions in the Northern Hemisphere in 1996/1997 and 2010/2011. 2019/2020 showed an unusual persistent polar vortex with low stratospheric temperatures, which were permanently below 195 K at 50 hPa. This enabled enhanced formation of polar stratospheric clouds and a subsequent clear reduction of total ozone.
                                            
                                            
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                                                Numerical models of Earth's climate system have been gaining more and more complexity over the last decades. Therefore, it is important to establish simplified models to improve process understanding. In our study, we present and document the development of a new simplified model setup within the framework of a complex climate model system that uses the same routines to calculate atmospheric dynamics as the complex model but is simplified in the representation of clouds and radiation.
                                            
                                            
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                                    Atmos. Chem. Phys., 19, 13759–13771, https://doi.org/10.5194/acp-19-13759-2019, https://doi.org/10.5194/acp-19-13759-2019, 2019
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                                                A chemistry–climate model (CCM) study is performed, investigating the consequences of a constant CFC-11 surface mixing ratio for stratospheric ozone in the future. The total column ozone is particularly affected in both polar regions in winter and spring. It turns out that the calculated ozone changes, especially in the upper stratosphere, are smaller than expected. In this attitudinal region the additional ozone depletion due to the catalysis by reactive chlorine is partly compensated for.
                                            
                                            
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                                                We investigate the transport pathways of water vapour from the upper troposphere in the Asian monsoon region to the stratosphere. In the employed chemistry-transport model we use a tagging method, such that the impact of different source regions on the stratospheric water vapour budget can be quantified. A key finding is that the Asian monsoon (compared to other source regions) is very efficient in transporting air masses and water vapour to the tropical and extratropical stratosphere.
                                            
                                            
                                        Patrick Jöckel, Holger Tost, Andrea Pozzer, Markus Kunze, Oliver Kirner, Carl A. M. Brenninkmeijer, Sabine Brinkop, Duy S. Cai, Christoph Dyroff, Johannes Eckstein, Franziska Frank, Hella Garny, Klaus-Dirk Gottschaldt, Phoebe Graf, Volker Grewe, Astrid Kerkweg, Bastian Kern, Sigrun Matthes, Mariano Mertens, Stefanie Meul, Marco Neumaier, Matthias Nützel, Sophie Oberländer-Hayn, Roland Ruhnke, Theresa Runde, Rolf Sander, Dieter Scharffe, and Andreas Zahn
                                    Geosci. Model Dev., 9, 1153–1200, https://doi.org/10.5194/gmd-9-1153-2016, https://doi.org/10.5194/gmd-9-1153-2016, 2016
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                                                With an advanced numerical global chemistry climate model (CCM) we performed several detailed
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                                        Laura Stecher, Franziska Winterstein, Patrick Jöckel, Michael Ponater, Mariano Mertens, and Martin Dameris
                                    Atmos. Chem. Phys., 25, 5133–5158, https://doi.org/10.5194/acp-25-5133-2025, https://doi.org/10.5194/acp-25-5133-2025, 2025
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                                        William J. Collins, Fiona M. O'Connor, Connor R. Barker, Rachael E. Byrom, Sebastian D. Eastham, Øivind Hodnebrog, Patrick Jöckel, Eloise A. Marais, Mariano Mertens, Gunnar Myhre, Matthias Nützel, Dirk Olivié, Ragnhild Bieltvedt Skeie, Laura Stecher, Larry W. Horowitz, Vaishali Naik, Gregory Faluvegi, Ulas Im, Lee T. Murray, Drew Shindell, Kostas Tsigaridis, Nathan Luke Abraham, and James Keeble
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                                        Eric A. Ray, Fred L. Moore, Hella Garny, Eric J. Hintsa, Bradley D. Hall, Geoff S. Dutton, David Nance, James W. Elkins, Steven C. Wofsy, Jasna Pittman, Bruce Daube, Bianca C. Baier, Jianghanyang Li, and Colm Sweeney
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                                                In this study we describe new techniques to derive age of air from multiple simultaneous measurements of long-lived trace gases in order to improve the fidelity of the age-of-air estimates and to be able to compare age of air from measurements taken from different instruments, platforms and decades.  This technique also allows new transport information to be obtained from the measurements such as the primary source latitude that can also be compared to models. 
                                            
                                            
                                        Matthias Nützel, Laura Stecher, Patrick Jöckel, Franziska Winterstein, Martin Dameris, Michael Ponater, Phoebe Graf, and Markus Kunze
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                                    Short summary
                                            
                                                We extended the infrastructure of our modelling system to enable the use of an additional radiation scheme. After calibrating the model setups to the old and the new radiation scheme, we find that the simulation with the new scheme shows considerable improvements, e.g. concerning the cold-point temperature and stratospheric water vapour. Furthermore, perturbations of radiative fluxes associated with greenhouse gas changes, e.g. of methane, tend to be improved when the new scheme is employed.
                                            
                                            
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                                                Transport circulation in the stratosphere is important for the distribution of tracers, but its strength is hard to measure. Mean transport times can be inferred from observations of trace gases with certain properties, such as sulfur hexafluoride (SF6). However, this gas has a chemical sink in the high atmosphere, which can lead to substantial biases in inferred transport times. In this paper we present a method to correct mean transport times derived from SF6 for the effects of chemical sinks.
                                            
                                            
                                        Ryan S. Williams, Michaela I. Hegglin, Patrick Jöckel, Hella Garny, and Keith P. Shine
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                                                During winter, a brief but abrupt reversal of the mean stratospheric westerly flow (~30 km high) around the Arctic occurs ~6 times a decade. Using a chemistry–climate model, about half of these events are shown to induce large anomalies in Arctic ozone (>25 %) and water vapour (>±25 %) around ~8–12 km altitude for up to 2–3 months, important for weather forecasting. We also calculate a doubling to trebling of the risk in breaches of mid-latitude surface air quality (ozone) standards (~60 ppbv).
                                            
                                            
                                        Roland Eichinger, Sebastian Rhode, Hella Garny, Peter Preusse, Petr Pisoft, Aleš Kuchař, Patrick Jöckel, Astrid Kerkweg, and Bastian Kern
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                                                The columnar approach of gravity wave (GW) schemes results in dynamical model biases, but parallel decomposition makes horizontal GW propagation computationally unfeasible. In the global model EMAC, we approximate it by GW redistribution at one altitude using tailor-made redistribution maps generated with a ray tracer. More spread-out GW drag helps reconcile the model with observations and close the 60°S GW gap. Polar vortex dynamics are improved, enhancing climate model credibility.
                                            
                                            
                                        Frederik Harzer, Hella Garny, Felix Ploeger, Harald Bönisch, Peter Hoor, and Thomas Birner
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                                                We study the statistical relation between year-by-year fluctuations in winter-mean ozone and the strength of the stratospheric polar vortex. In the latitude–pressure plane, regression analysis shows that anomalously weak polar vortex years are associated with three pronounced local ozone maxima over the polar cap relative to the winter climatology. These response maxima primarily reflect the non-trivial combination of different ozone transport processes with varying relative contributions.
                                            
                                            
                                        Matthias Nützel, Sabine Brinkop, Martin Dameris, Hella Garny, Patrick Jöckel, Laura L. Pan, and Mijeong Park
                                    Atmos. Chem. Phys., 22, 15659–15683, https://doi.org/10.5194/acp-22-15659-2022, https://doi.org/10.5194/acp-22-15659-2022, 2022
                                    Short summary
                                    Short summary
                                            
                                                During the Asian summer monsoon season, a large high-pressure system is present at levels close to the tropopause above Asia. We analyse how air masses are transported from surface levels to this high-pressure system, which shows distinct features from the surrounding air masses. To this end, we employ multiannual data from two complementary models that allow us to analyse the climatology as well as the interannual and intraseasonal variability of these transport pathways.
                                            
                                            
                                        Kostas Eleftheratos, John Kapsomenakis, Ilias Fountoulakis, Christos S. Zerefos, Patrick Jöckel, Martin Dameris, Alkiviadis F. Bais, Germar Bernhard, Dimitra Kouklaki, Kleareti Tourpali, Scott Stierle, J. Ben Liley, Colette Brogniez, Frédérique Auriol, Henri Diémoz, Stana Simic, Irina Petropavlovskikh, Kaisa Lakkala, and Kostas Douvis
                                    Atmos. Chem. Phys., 22, 12827–12855, https://doi.org/10.5194/acp-22-12827-2022, https://doi.org/10.5194/acp-22-12827-2022, 2022
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                                                We present the future evolution of DNA-active ultraviolet (UV) radiation in view of increasing greenhouse gases (GHGs) and decreasing ozone depleting substances (ODSs). It is shown that DNA-active UV radiation might increase after 2050 between 50° N–50° S due to GHG-induced reductions in clouds and ozone, something that is likely not to happen at high latitudes, where DNA-active UV radiation will continue its downward trend mainly due to stratospheric ozone recovery from the reduction in ODSs.
                                            
                                            
                                        Felix Ploeger and Hella Garny
                                    Atmos. Chem. Phys., 22, 5559–5576, https://doi.org/10.5194/acp-22-5559-2022, https://doi.org/10.5194/acp-22-5559-2022, 2022
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                                                We investigate hemispheric asymmetries in stratospheric circulation changes in the last 2 decades in model simulations and atmospheric observations. We find that observed trace gas changes can be explained by a structural circulation change related to a deepening circulation in the Northern Hemisphere relative to the Southern Hemisphere. As this asymmetric signal is small compared to internal variability observed circulation trends over the recent past are not in contradiction to climate models.
                                            
                                            
                                        Sheena Loeffel, Roland Eichinger, Hella Garny, Thomas Reddmann, Frauke Fritsch, Stefan Versick, Gabriele Stiller, and Florian Haenel
                                    Atmos. Chem. Phys., 22, 1175–1193, https://doi.org/10.5194/acp-22-1175-2022, https://doi.org/10.5194/acp-22-1175-2022, 2022
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                                                SF6-derived trends of stratospheric AoA from observations and model simulations disagree in sign. SF6 experiences chemical degradation, which we explicitly integrate in a global climate model. In our simulations, the AoA trend changes sign when SF6 sinks are considered; thus, the process has the potential to reconcile simulated with observed AoA trends. We show that the positive AoA trend is due to the SF6 sinks themselves and provide a first approach for a correction to account for SF6 loss.
                                            
                                            
                                        Marta Abalos, Natalia Calvo, Samuel Benito-Barca, Hella Garny, Steven C. Hardiman, Pu Lin, Martin B. Andrews, Neal Butchart, Rolando Garcia, Clara Orbe, David Saint-Martin, Shingo Watanabe, and Kohei Yoshida
                                    Atmos. Chem. Phys., 21, 13571–13591, https://doi.org/10.5194/acp-21-13571-2021, https://doi.org/10.5194/acp-21-13571-2021, 2021
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                                                The stratospheric Brewer–Dobson circulation (BDC), responsible for transporting mass, tracers and heat globally in the stratosphere, is evaluated in a set of state-of-the-art climate models. The acceleration of the BDC in response to increasing greenhouse gases is most robust in the lower stratosphere. At higher levels, the well-known inconsistency between model and observational BDC trends can be partly reconciled by accounting for limited sampling and large uncertainties in the observations.
                                            
                                            
                                        Simone Dietmüller, Hella Garny, Roland Eichinger, and William T. Ball
                                    Atmos. Chem. Phys., 21, 6811–6837, https://doi.org/10.5194/acp-21-6811-2021, https://doi.org/10.5194/acp-21-6811-2021, 2021
                            Laura Stecher, Franziska Winterstein, Martin Dameris, Patrick Jöckel, Michael Ponater, and Markus Kunze
                                    Atmos. Chem. Phys., 21, 731–754, https://doi.org/10.5194/acp-21-731-2021, https://doi.org/10.5194/acp-21-731-2021, 2021
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                                                This study investigates the impact of strongly increased atmospheric methane mixing ratios on the Earth's climate. An interactive model system including atmospheric dynamics, chemistry, and a mixed-layer ocean model is used to analyse the effect of doubled and quintupled methane mixing ratios. We assess feedbacks on atmospheric chemistry and changes in the stratospheric circulation, focusing on the impact of tropospheric warming, and their relevance for the model's climate sensitivity.
                                            
                                            
                                        Martin Dameris, Diego G. Loyola, Matthias Nützel, Melanie Coldewey-Egbers, Christophe Lerot, Fabian Romahn, and Michel van Roozendael
                                    Atmos. Chem. Phys., 21, 617–633, https://doi.org/10.5194/acp-21-617-2021, https://doi.org/10.5194/acp-21-617-2021, 2021
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                                                Record low ozone values were observed in March 2020. Dynamical and chemical circumstances leading to low ozone values in spring 2020 are discussed and are compared to similar dynamical conditions in the Northern Hemisphere in 1996/1997 and 2010/2011. 2019/2020 showed an unusual persistent polar vortex with low stratospheric temperatures, which were permanently below 195 K at 50 hPa. This enabled enhanced formation of polar stratospheric clouds and a subsequent clear reduction of total ozone.
                                            
                                            
                                        Hella Garny, Roland Walz, Matthias Nützel, and Thomas Birner
                                    Geosci. Model Dev., 13, 5229–5257, https://doi.org/10.5194/gmd-13-5229-2020, https://doi.org/10.5194/gmd-13-5229-2020, 2020
                                    Short summary
                                    Short summary
                                            
                                                Numerical models of Earth's climate system have been gaining more and more complexity over the last decades. Therefore, it is important to establish simplified models to improve process understanding. In our study, we present and document the development of a new simplified model setup within the framework of a complex climate model system that uses the same routines to calculate atmospheric dynamics as the complex model but is simplified in the representation of clouds and radiation.
                                            
                                            
                                        Frauke Fritsch, Hella Garny, Andreas Engel, Harald Bönisch, and Roland Eichinger
                                    Atmos. Chem. Phys., 20, 8709–8725, https://doi.org/10.5194/acp-20-8709-2020, https://doi.org/10.5194/acp-20-8709-2020, 2020
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                                                We test two methods to derive age of air as a diagnostic of the Brewer–Dobson circulation from non-linear increasing trace gases such as SF6 using a chemistry-climate model and observations. Both the model and the observations show systematic variation of the age of air trend dependent on the chosen assumptions that are required when deriving age of air from measurements. This provides insight into the differences in age of air trends of observations and models.
                                            
                                            
                                        Marta Abalos, Clara Orbe, Douglas E. Kinnison, David Plummer, Luke D. Oman, Patrick Jöckel, Olaf Morgenstern, Rolando R. Garcia, Guang Zeng, Kane A. Stone, and Martin Dameris
                                    Atmos. Chem. Phys., 20, 6883–6901, https://doi.org/10.5194/acp-20-6883-2020, https://doi.org/10.5194/acp-20-6883-2020, 2020
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                                                A set of state-of-the art chemistry–climate models is used to examine future changes in downward transport from the stratosphere, a key contributor to tropospheric ozone. The acceleration of the stratospheric circulation results in increased stratosphere-to-troposphere transport. In the subtropics, downward advection into the troposphere is enhanced due to climate change. At higher latitudes, the ozone reservoir above the tropopause is enlarged due to the stronger circulation and ozone recovery.
                                            
                                            
                                        Martin Dameris, Patrick Jöckel, and Matthias Nützel
                                    Atmos. Chem. Phys., 19, 13759–13771, https://doi.org/10.5194/acp-19-13759-2019, https://doi.org/10.5194/acp-19-13759-2019, 2019
                                    Short summary
                                    Short summary
                                            
                                                A chemistry–climate model (CCM) study is performed, investigating the consequences of a constant CFC-11 surface mixing ratio for stratospheric ozone in the future. The total column ozone is particularly affected in both polar regions in winter and spring. It turns out that the calculated ozone changes, especially in the upper stratosphere, are smaller than expected. In this attitudinal region the additional ozone depletion due to the catalysis by reactive chlorine is partly compensated for.
                                            
                                            
                                        Andreas Chrysanthou, Amanda C. Maycock, Martyn P. Chipperfield, Sandip Dhomse, Hella Garny, Douglas Kinnison, Hideharu Akiyoshi, Makoto Deushi, Rolando R. Garcia, Patrick Jöckel, Oliver Kirner, Giovanni Pitari, David A. Plummer, Laura Revell, Eugene Rozanov, Andrea Stenke, Taichu Y. Tanaka, Daniele Visioni, and Yousuke Yamashita
                                    Atmos. Chem. Phys., 19, 11559–11586, https://doi.org/10.5194/acp-19-11559-2019, https://doi.org/10.5194/acp-19-11559-2019, 2019
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                                                We perform the first multi-model comparison of the impact of nudged meteorology on the stratospheric residual circulation (RC) in chemistry–climate models. Nudging meteorology does not constrain the mean strength of RC compared to free-running simulations, and despite the lack of agreement in the mean circulation, nudging tightly constrains the inter-annual variability in the tropical upward mass flux in the lower stratosphere. In summary, nudging strongly affects the representation of RC.
                                            
                                            
                                        Matthias Nützel, Aurélien Podglajen, Hella Garny, and Felix Ploeger
                                    Atmos. Chem. Phys., 19, 8947–8966, https://doi.org/10.5194/acp-19-8947-2019, https://doi.org/10.5194/acp-19-8947-2019, 2019
                                    Short summary
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                                                We investigate the transport pathways of water vapour from the upper troposphere in the Asian monsoon region to the stratosphere. In the employed chemistry-transport model we use a tagging method, such that the impact of different source regions on the stratospheric water vapour budget can be quantified. A key finding is that the Asian monsoon (compared to other source regions) is very efficient in transporting air masses and water vapour to the tropical and extratropical stratosphere.
                                            
                                            
                                        Petr Šácha, Roland Eichinger, Hella Garny, Petr Pišoft, Simone Dietmüller, Laura de la Torre, David A. Plummer, Patrick Jöckel, Olaf Morgenstern, Guang Zeng, Neal Butchart, and Juan A. Añel
                                    Atmos. Chem. Phys., 19, 7627–7647, https://doi.org/10.5194/acp-19-7627-2019, https://doi.org/10.5194/acp-19-7627-2019, 2019
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                                                Climate models robustly project a Brewer–Dobson circulation (BDC) acceleration in the course of climate change. Analyzing mean age of stratospheric air (AoA) from a subset of climate projection simulations, we find a remarkable agreement in simulating the largest AoA trends in the extratropical stratosphere. This is shown to be related with the upward shift of the circulation, resulting in a so-called stratospheric shrinkage, which could be one of the so-far-omitted BDC acceleration drivers.
                                            
                                            
                                        Franziska Winterstein, Fabian Tanalski, Patrick Jöckel, Martin Dameris, and Michael Ponater
                                    Atmos. Chem. Phys., 19, 7151–7163, https://doi.org/10.5194/acp-19-7151-2019, https://doi.org/10.5194/acp-19-7151-2019, 2019
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                                                The atmospheric concentrations of the anthropogenic greenhouse gas methane are predicted to rise in the future. In this paper we investigate how very strong methane concentrations will impact the atmosphere. We analyse two experiments, one with doubled and one with quintupled methane concentrations and focus on the rapid atmospheric changes before the ocean adjusts to the induced
forcing. In particular these are changes in temperature, ozone, the hydroxyl radical and stratospheric water vapour.
                                            
                                            
                                        Marius Hauck, Frauke Fritsch, Hella Garny, and Andreas Engel
                                    Atmos. Chem. Phys., 19, 5269–5291, https://doi.org/10.5194/acp-19-5269-2019, https://doi.org/10.5194/acp-19-5269-2019, 2019
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                                                The paper presents a modified method to invert mixing ratios of chemically active tracers into stratospheric age spectra. It features an imposed seasonal cycle to include transport seasonality into the spectra. An idealized set of tracers from a model is used as proof of concept and results are in good agreement with the model reference, except for the lowermost stratosphere. Applicability is studied with focus on number of tracers and error tolerance, providing a starting point for future work.
                                            
                                            
                                        Roland Eichinger, Simone Dietmüller, Hella Garny, Petr Šácha, Thomas Birner, Harald Bönisch, Giovanni Pitari, Daniele Visioni, Andrea Stenke, Eugene Rozanov, Laura Revell, David A. Plummer, Patrick Jöckel, Luke Oman, Makoto Deushi, Douglas E. Kinnison, Rolando Garcia, Olaf Morgenstern, Guang Zeng, Kane Adam Stone, and Robyn Schofield
                                    Atmos. Chem. Phys., 19, 921–940, https://doi.org/10.5194/acp-19-921-2019, https://doi.org/10.5194/acp-19-921-2019, 2019
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                                                To shed more light upon the changes in stratospheric circulation in the 21st century, climate projection simulations of 10 state-of-the-art global climate models, spanning from 1960 to 2100, are analyzed. The study shows that in addition to changes in transport, mixing also plays an important role in stratospheric circulation and that the properties of mixing vary over time. Furthermore, the influence of mixing is quantified and a dynamical framework is provided to understand the changes.
                                            
                                            
                                        Birgit Hassler, Stefanie Kremser, Greg E. Bodeker, Jared Lewis, Kage Nesbit, Sean M. Davis, Martyn P. Chipperfield, Sandip S. Dhomse, and Martin Dameris
                                    Earth Syst. Sci. Data, 10, 1473–1490, https://doi.org/10.5194/essd-10-1473-2018, https://doi.org/10.5194/essd-10-1473-2018, 2018
                            Blanca Ayarzagüena, Lorenzo M. Polvani, Ulrike Langematz, Hideharu Akiyoshi, Slimane Bekki, Neal Butchart, Martin Dameris, Makoto Deushi, Steven C. Hardiman, Patrick Jöckel, Andrew Klekociuk, Marion Marchand, Martine Michou, Olaf Morgenstern, Fiona M. O'Connor, Luke D. Oman, David A. Plummer, Laura Revell, Eugene Rozanov, David Saint-Martin, John Scinocca, Andrea Stenke, Kane Stone, Yousuke Yamashita, Kohei Yoshida, and Guang Zeng
                                    Atmos. Chem. Phys., 18, 11277–11287, https://doi.org/10.5194/acp-18-11277-2018, https://doi.org/10.5194/acp-18-11277-2018, 2018
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                                                Stratospheric sudden warmings (SSWs) are natural major disruptions of the polar stratospheric circulation that also affect surface weather. In the literature there are conflicting claims as to whether SSWs will change in the future. The confusion comes from studies using different models and methods. Here we settle the question by analysing 12 models with a consistent methodology, to show that no robust changes in frequency and other features are expected over the 21st century.
                                            
                                            
                                        Franziska Frank, Patrick Jöckel, Sergey Gromov, and Martin Dameris
                                    Atmos. Chem. Phys., 18, 9955–9973, https://doi.org/10.5194/acp-18-9955-2018, https://doi.org/10.5194/acp-18-9955-2018, 2018
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                                                It is frequently assumed that one methane molecule produces two water molecules. Applying various modeling concepts, we find that the yield of water from methane is vertically not constantly 2. In the upper stratosphere and lower mesosphere, transport of intermediate H2 molecules even led to a yield greater  than 2. We conclude that for a realistic chemical source of stratospheric water vapor, one must also take other sources (H2), intermediates and the chemical removal of water into account.
                                            
                                            
                                        Sandip S. Dhomse, Douglas Kinnison, Martyn P. Chipperfield, Ross J. Salawitch, Irene Cionni, Michaela I. Hegglin, N. Luke Abraham, Hideharu Akiyoshi, Alex T. Archibald, Ewa M. Bednarz, Slimane Bekki, Peter Braesicke, Neal Butchart, Martin Dameris, Makoto Deushi, Stacey Frith, Steven C. Hardiman, Birgit Hassler, Larry W. Horowitz, Rong-Ming Hu, Patrick Jöckel, Beatrice Josse, Oliver Kirner, Stefanie Kremser, Ulrike Langematz, Jared Lewis, Marion Marchand, Meiyun Lin, Eva Mancini, Virginie Marécal, Martine Michou, Olaf Morgenstern, Fiona M. O'Connor, Luke Oman, Giovanni Pitari, David A. Plummer, John A. Pyle, Laura E. Revell, Eugene Rozanov, Robyn Schofield, Andrea Stenke, Kane Stone, Kengo Sudo, Simone Tilmes, Daniele Visioni, Yousuke Yamashita, and Guang Zeng
                                    Atmos. Chem. Phys., 18, 8409–8438, https://doi.org/10.5194/acp-18-8409-2018, https://doi.org/10.5194/acp-18-8409-2018, 2018
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                                                We analyse simulations from the Chemistry-Climate Model Initiative (CCMI) to estimate the return dates of the stratospheric ozone layer from depletion by anthropogenic chlorine and bromine. The simulations from 20 models project that global column ozone will return to 1980 values in 2047 (uncertainty range 2042–2052). Return dates in other regions vary depending on factors related to climate change and importance of chlorine and bromine. Column ozone in the tropics may continue to decline.
                                            
                                            
                                        Stefan Lossow, Dale F. Hurst, Karen H. Rosenlof, Gabriele P. Stiller, Thomas von Clarmann, Sabine Brinkop, Martin Dameris, Patrick Jöckel, Doug E. Kinnison, Johannes Plieninger, David A. Plummer, Felix Ploeger, William G. Read, Ellis E. Remsberg, James M. Russell, and Mengchu Tao
                                    Atmos. Chem. Phys., 18, 8331–8351, https://doi.org/10.5194/acp-18-8331-2018, https://doi.org/10.5194/acp-18-8331-2018, 2018
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                                                Trend estimates of lower stratospheric H2O derived from the FPH observations at Boulder and a merged zonal mean satellite data set clearly differ for the time period from the late 1980s to 2010. We investigate if a sampling bias between Boulder and the zonal mean around the Boulder latitude can explain these trend discrepancies. Typically they are small and not sufficient to explain the trend discrepancies in the observational database.
                                            
                                            
                                        Simone Dietmüller, Roland Eichinger, Hella Garny, Thomas Birner, Harald Boenisch, Giovanni Pitari, Eva Mancini, Daniele Visioni, Andrea Stenke, Laura Revell, Eugene Rozanov, David A. Plummer, John Scinocca, Patrick Jöckel, Luke Oman, Makoto Deushi, Shibata Kiyotaka, Douglas E. Kinnison, Rolando Garcia, Olaf Morgenstern, Guang Zeng, Kane Adam Stone, and Robyn Schofield
                                    Atmos. Chem. Phys., 18, 6699–6720, https://doi.org/10.5194/acp-18-6699-2018, https://doi.org/10.5194/acp-18-6699-2018, 2018
                            Stefan Lossow, Hella Garny, and Patrick Jöckel
                                    Atmos. Chem. Phys., 17, 11521–11539, https://doi.org/10.5194/acp-17-11521-2017, https://doi.org/10.5194/acp-17-11521-2017, 2017
                            Simone Dietmüller, Hella Garny, Felix Plöger, Patrick Jöckel, and Duy Cai
                                    Atmos. Chem. Phys., 17, 7703–7719, https://doi.org/10.5194/acp-17-7703-2017, https://doi.org/10.5194/acp-17-7703-2017, 2017
                            Duy Cai, Martin Dameris, Hella Garny, Felix Bunzel, Patrick Jöckel, and Phoebe Graf
                                        Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-870, https://doi.org/10.5194/acp-2016-870, 2016
                                    Revised manuscript not accepted 
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                                                Reliable information on weather and climate are of increasing interest for economy, politics and society.
In particular decadal timescales become more and more important. This study focuses on stratospheric processes relevant for the dynamical variability on intra decadal timescale. We apply a so called power spectra analysis. With this method and further analyses we could determine a minimum vertical resolution for numerical models, which is required to capture these processes.
                                            
                                            
                                        Sabine Brinkop, Martin Dameris, Patrick Jöckel, Hella Garny, Stefan Lossow, and Gabriele Stiller
                                    Atmos. Chem. Phys., 16, 8125–8140, https://doi.org/10.5194/acp-16-8125-2016, https://doi.org/10.5194/acp-16-8125-2016, 2016
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                                                This study investigates the water vapour decline in the stratosphere beginning in the year 2000 and other similarly strong stratospheric water vapour reductions. The driving forces are tropical sea surface temperature (SST) changes due to coincidence with a preceding ENSO event and supported by the west to east change of the QBO. 
There are indications that both SSTs and the specific dynamical state of the atmosphere contribute to the long period of low water vapour values from 2001 to 2006.
                                            
                                            
                                        Patrick Jöckel, Holger Tost, Andrea Pozzer, Markus Kunze, Oliver Kirner, Carl A. M. Brenninkmeijer, Sabine Brinkop, Duy S. Cai, Christoph Dyroff, Johannes Eckstein, Franziska Frank, Hella Garny, Klaus-Dirk Gottschaldt, Phoebe Graf, Volker Grewe, Astrid Kerkweg, Bastian Kern, Sigrun Matthes, Mariano Mertens, Stefanie Meul, Marco Neumaier, Matthias Nützel, Sophie Oberländer-Hayn, Roland Ruhnke, Theresa Runde, Rolf Sander, Dieter Scharffe, and Andreas Zahn
                                    Geosci. Model Dev., 9, 1153–1200, https://doi.org/10.5194/gmd-9-1153-2016, https://doi.org/10.5194/gmd-9-1153-2016, 2016
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                                                With an advanced numerical global chemistry climate model (CCM) we performed several detailed
combined hind-cast  and projection simulations of the period 1950 to 2100 to assess the
past, present, and potential future dynamical and chemical state of the Earth atmosphere.
The manuscript documents the model and the various applied model set-ups and provides
a first evaluation of the simulation results from a global perspective as a quality check of the data.
                                            
                                            
                                        Hella Garny and William J. Randel
                                    Atmos. Chem. Phys., 16, 2703–2718, https://doi.org/10.5194/acp-16-2703-2016, https://doi.org/10.5194/acp-16-2703-2016, 2016
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                                                We investigate the fate of air that originates in the monsoon region in the upper troposphere, where it was transported to by convection. We find that almost half of the air parcels released in the monsoon region in the upper troposphere reach the stratosphere within 60 days, and most ascend to the tropical lower stratosphere. This suggests that trace gases, including pollutants, that are transported into the stratosphere via the Asian monsoon are in a position to enter the deep stratosphere.
                                            
                                            
                                        L. E. Revell, F. Tummon, A. Stenke, T. Sukhodolov, A. Coulon, E. Rozanov, H. Garny, V. Grewe, and T. Peter
                                    Atmos. Chem. Phys., 15, 5887–5902, https://doi.org/10.5194/acp-15-5887-2015, https://doi.org/10.5194/acp-15-5887-2015, 2015
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                                                We have examined the effects of ozone precursor emissions and climate change on the tropospheric ozone budget. Under RCP 6.0, ozone in the future is governed primarily by changes in nitrogen oxides (NOx). Methane is also important, and induces an increase in tropospheric ozone that is approximately one-third of that caused by NOx. This study highlights the critical role that emission policies globally have to play in determining tropospheric ozone evolution through the 21st century.
                                            
                                            
                                        P. Valks, N. Hao, S. Gimeno Garcia, D. Loyola, M. Dameris, P. Jöckel, and A. Delcloo
                                    Atmos. Meas. Tech., 7, 2513–2530, https://doi.org/10.5194/amt-7-2513-2014, https://doi.org/10.5194/amt-7-2513-2014, 2014
                            S. Meul, U. Langematz, S. Oberländer, H. Garny, and P. Jöckel
                                    Atmos. Chem. Phys., 14, 2959–2971, https://doi.org/10.5194/acp-14-2959-2014, https://doi.org/10.5194/acp-14-2959-2014, 2014
                            V. Grewe, C. Frömming, S. Matthes, S. Brinkop, M. Ponater, S. Dietmüller, P. Jöckel, H. Garny, E. Tsati, K. Dahlmann, O. A. Søvde, J. Fuglestvedt, T. K. Berntsen, K. P. Shine, E. A. Irvine, T. Champougny, and P. Hullah
                                    Geosci. Model Dev., 7, 175–201, https://doi.org/10.5194/gmd-7-175-2014, https://doi.org/10.5194/gmd-7-175-2014, 2014
                            H. Garny, G. E. Bodeker, D. Smale, M. Dameris, and V. Grewe
                                    Atmos. Chem. Phys., 13, 7279–7300, https://doi.org/10.5194/acp-13-7279-2013, https://doi.org/10.5194/acp-13-7279-2013, 2013
                            Related subject area
            Subject: Dynamics | Research Activity: Atmospheric Modelling and Data Analysis | Altitude Range: Stratosphere | Science Focus: Physics (physical properties and processes)
            
                    
                        
                            
                            
                                     
                                Lagrangian coherent structures to examine mixing in the stratosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Stratospheric Aerosol Intervention experiment for the Chemistry–Climate Model Initiative
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Explaining the period fluctuation of the quasi-biennial oscillation
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                On the estimation of stratospheric age of air from correlations of multiple trace gases
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The joint effect of mid-latitude winds and the westerly quasi-biennial oscillation phase on the Antarctic stratospheric polar vortex and ozone
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Covariability of dynamics and composition in the Asian monsoon tropopause layer from satellite observations and reanalysis products
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Gravity waves as a mechanism of troposphere–stratosphere–mesosphere coupling during sudden stratospheric warming
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Hemispheric asymmetry in recent stratospheric age of air changes
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Transport into the polar stratosphere from the Asian monsoon region
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                A dynamical separation of deep and shallow branches in the stratospheric circulation
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Age of air from in situ trace gas measurements: insights from a new technique
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Tropospheric links to uncertainty in stratospheric subseasonal predictions
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                            
                                     
                                Effects of Ozone-Climate Interactions on the Temperature Variation in the Arctic Stratosphere
                                
                                        
                                            
                                    
                            
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The impact of El Niño–Southern Oscillation on the total column ozone over the Tibetan Plateau
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Exploring ozone variability in the upper troposphere and lower stratosphere using dynamical coordinates
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Climatology of the terms and variables of transformed Eulerian-mean (TEM) equations from multiple reanalyses: MERRA-2, JRA-55, ERA-Interim, and CFSR
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Quasi-biennial oscillation modulation of stratospheric water vapour in the Asian monsoon
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Crucial role of obliquely propagating gravity waves in the quasi-biennial oscillation dynamics
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Technical note: Multi-year changes in the Brewer–Dobson circulation from Halogen Occultation Experiment (HALOE) methane
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Exploring the ENSO modulation of the QBO periods with GISS E2.2 models
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The impact of ENSO and NAO initial conditions and anomalies on the modeled response to Pinatubo-sized volcanic forcing
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Stratospherically induced circulation changes under the extreme conditions of the no-Montreal-Protocol scenario
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Vortex preconditioning of the 2021 sudden stratospheric warming: barotropic–baroclinic instability associated with the double westerly jets
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                On the pattern of interannual polar vortex–ozone co-variability during northern hemispheric winter
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                A mountain ridge model for quantifying oblique mountain wave propagation and distribution
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Weakening of the tropical tropopause layer cold trap with global warming
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                On the magnitude and sensitivity of the quasi-biennial oscillation response to a tropical volcanic eruption
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The response of the North Pacific jet and stratosphere-to-troposphere transport of ozone over western North America to RCP8.5 climate forcing
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The Holton–Tan mechanism under stratospheric aerosol intervention
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Very-long-period oscillations in the atmosphere (0–110 km) – Part 2: Latitude– longitude comparisons and trends
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Driving mechanisms for the El Niño–Southern Oscillation impact on stratospheric ozone
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Exploring the link between austral stratospheric polar vortex anomalies and surface climate in chemistry-climate models
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The impact of improved spatial and temporal resolution of reanalysis data on Lagrangian studies of the tropical tropopause layer
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Dynamics of ENSO-driven stratosphere-to-troposphere transport of ozone over North America
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Ozone–gravity wave interaction in the upper stratosphere/lower mesosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                How can Brewer–Dobson circulation trends be estimated from changes in stratospheric water vapour and methane?
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The semi-annual oscillation (SAO) in the upper troposphere and lower stratosphere (UTLS)
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Interactions between the stratospheric polar vortex and Atlantic circulation on seasonal to multi-decadal timescales
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Impacts of three types of solar geoengineering on the Atlantic Meridional Overturning Circulation
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Enhanced upward motion through the troposphere over the tropical western Pacific and its implications for the transport of trace gases from the troposphere to the stratosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Evolution of the intensity and duration of the Southern Hemisphere stratospheric polar vortex edge for the period 1979–2020
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Characterization of transport from the Asian summer monsoon anticyclone into the UTLS via shedding of low potential vorticity cutoffs
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Long-range prediction and the stratosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Weakening of Antarctic stratospheric planetary wave activities in early austral spring since the early 2000s: a response to sea surface temperature trends
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The impact of sulfur hexafluoride (SF6) sinks on age of air climatologies and trends
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Specified dynamics scheme impacts on wave-mean flow dynamics, convection, and tracer transport in CESM2 (WACCM6)
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Propagation paths and source distributions of resolved gravity waves in ECMWF-IFS analysis fields around the southern polar night jet
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Observation and modeling of high-7Be concentration events at the surface in northern Europe associated with the instability of the Arctic polar vortex in early 2003
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                Eastward-propagating planetary waves in the polar middle atmosphere
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
                        
                            
                            
                                     
                                The Brewer–Dobson circulation in CMIP6
                                
                                        
                                            
                                    
                            
                            
                        
                    
                    
            
        
        Jezabel Curbelo and Marianna Linz
                                    Atmos. Chem. Phys., 25, 7941–7957, https://doi.org/10.5194/acp-25-7941-2025, https://doi.org/10.5194/acp-25-7941-2025, 2025
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                                                Studying stratospheric mixing is crucial for understanding atmospheric dynamics and chemical transport. We propose a new Lagrangian metric based on the density of transport barriers, attracting/repelling coherent structures, to analyze mixing in the Whole Atmosphere Community Climate Model. Our metric is a promising tool for stratospheric analysis, consistent with commonly used metrics to quantify mixing while also providing the advantage of reflecting Lagrangian transport in physical latitude.
                                            
                                            
                                        Simone Tilmes, Ewa M. Bednarz, Andrin Jörimann, Daniele Visioni, Douglas E. Kinnison, Gabriel Chiodo, and David Plummer
                                    Atmos. Chem. Phys., 25, 6001–6023, https://doi.org/10.5194/acp-25-6001-2025, https://doi.org/10.5194/acp-25-6001-2025, 2025
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                                                In this paper, we describe the details of a new multi-model intercomparison experiment to assess the effects of Stratospheric Aerosol Intervention (SAI) on stratospheric chemistry and dynamics and, therefore, ozone. Second, we discuss the advantages and differences of the more constrained experiment compared to fully interactive model experiments. This way, we advance the process-level understanding of the drivers of SAI-induced atmospheric responses.
                                            
                                            
                                        Young-Ha Kim
                                    Atmos. Chem. Phys., 25, 5647–5664, https://doi.org/10.5194/acp-25-5647-2025, https://doi.org/10.5194/acp-25-5647-2025, 2025
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                                                The paper addresses a fundamental but unresolved question about the tropical stratospheric wind oscillation: why does the period of the oscillation fluctuate irregularly? We use global reanalysis data to provide evidence that the oscillation period is primarily modulated by seasonal variations in small-scale atmospheric wave activity. The findings have implications for seasonal and climate predictions.
                                            
                                            
                                        Florian Voet, Felix Ploeger, Johannes Laube, Peter Preusse, Paul Konopka, Jens-Uwe Grooß, Jörn Ungermann, Björn-Martin Sinnhuber, Michael Höpfner, Bernd Funke, Gerald Wetzel, Sören Johansson, Gabriele Stiller, Eric Ray, and Michaela I. Hegglin
                                    Atmos. Chem. Phys., 25, 3541–3565, https://doi.org/10.5194/acp-25-3541-2025, https://doi.org/10.5194/acp-25-3541-2025, 2025
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                                                This study refines estimates of the stratospheric “age of air”, a measure of how long air circulates in the stratosphere. By analyzing correlations between trace gases measurable by satellites, the research introduces a method that reduces uncertainties and detects small-scale atmospheric features. This improved understanding of stratospheric circulation is crucial for better climate models and predictions, enhancing our ability to assess the impacts of climate change on the atmosphere.
                                            
                                            
                                        Zhe Wang, Jiankai Zhang, Siyi Zhao, and Douwang Li
                                    Atmos. Chem. Phys., 25, 3465–3480, https://doi.org/10.5194/acp-25-3465-2025, https://doi.org/10.5194/acp-25-3465-2025, 2025
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                                                Mid-latitude wind in the upper stratosphere is indispensable in establishing quasi-biennial oscillation (QBO)–vortex coupling in the Southern Hemisphere. During the westerly QBO, positive zonal wind anomalies at 20−40° S in the upper stratosphere in July, named the positive extratropical mode, lead to a stronger polar vortex in November, with a correlation of 0.75, suggesting that the Antarctic stratospheric polar vortex and ozone concentration in spring can be predicted up to 5 months in advance.
                                            
                                            
                                        Shenglong Zhang, Jiao Chen, Jonathon S. Wright, Sean M. Davis, Jie Gao, Paul Konopka, Ninghui Li, Mengqian Lu, Susann Tegtmeier, Xiaolu Yan, Guang J. Zhang, and Nuanliang Zhu
                                        EGUsphere, https://doi.org/10.5194/egusphere-2025-543, https://doi.org/10.5194/egusphere-2025-543, 2025
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                                                This study examines water vapor changes in the upper atmosphere above the Asian summer monsoon using satellite data and climate models. Three key patterns of variability were identified: year-to-year changes, and two shifting distributions driven by weather and monsoon dynamics. Despite uncertainties, modern models are improving in capturing these processes. This enhances understanding of water vapor’s role in the upper atmosphere.
                                            
                                            
                                        Gordana Jovanovic
                                    Atmos. Chem. Phys., 25, 2979–2988, https://doi.org/10.5194/acp-25-2979-2025, https://doi.org/10.5194/acp-25-2979-2025, 2025
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                                                Sudden stratospheric warming (SSW) is a phenomenon that occurs when the temperature in the stratosphere rises by several tens of degrees in just a few days. SSWs are caused by the breaking of atmospheric waves that propagate from the troposphere via the stratosphere to the mesosphere. SSWs impact the tropospheric circulation and the climate and can lead to a dramatic decrease in temperature. During SSW events, the filtration of gravity waves has a major impact on mesospheric cooling.
                                            
                                            
                                        Kimberlee Dubé, Susann Tegtmeier, Felix Ploeger, and Kaley A. Walker
                                    Atmos. Chem. Phys., 25, 1433–1447, https://doi.org/10.5194/acp-25-1433-2025, https://doi.org/10.5194/acp-25-1433-2025, 2025
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                                                The transport rate of air in the stratosphere has changed in response to human emissions of greenhouse gases and ozone-depleting substances. This transport rate can be approximated using measurements of long-lived trace gases. We use observations and model results to derive anomalies and trends in the mean rate of stratospheric air transport. We find that air in the Northern Hemisphere aged by up to 0.3 years per decade relative to air in the Southern Hemisphere over 2004–2017.
                                            
                                            
                                        Xiaolu Yan, Paul Konopka, Felix Ploeger, and Aurélien Podglajen
                                    Atmos. Chem. Phys., 25, 1289–1305, https://doi.org/10.5194/acp-25-1289-2025, https://doi.org/10.5194/acp-25-1289-2025, 2025
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                                                Our study finds that the air mass fractions (AMFs) from the Asian boundary layer (ABL) to the polar regions are about 1.5 times larger than those from the same latitude band in the Southern Hemisphere. The transport of AMFs from the ABL to the polar vortex primarily occurs above 20 km and over timescales exceeding 2 years. Our analysis reveals a strong correlation between the polar pollutants and the AMFs from the ABL. About 20 % of SF6 in the polar stratosphere originates from the ABL.
                                            
                                            
                                        Rasul Baikhadzhaev, Felix Ploeger, Peter Preusse, Manfred Ern, and Thomas Birner
                                        EGUsphere, https://doi.org/10.5194/egusphere-2024-4088, https://doi.org/10.5194/egusphere-2024-4088, 2025
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                                                Across four reanalyses, shallow branch of the stratospheric overturning circulation was found to be driven by the largest waves with wavenumbers 1 to 3, and deep branch of the circulation was found to be driven by smaller-scale waves. Yet, the height of the level separating the branches is depended on the reanalysis considered. Thus using the appropriate separation levels in model inter-comparisons could reduce the spread between models regarding climatology and trends in the circulation.
                                            
                                            
                                        Eric A. Ray, Fred L. Moore, Hella Garny, Eric J. Hintsa, Bradley D. Hall, Geoff S. Dutton, David Nance, James W. Elkins, Steven C. Wofsy, Jasna Pittman, Bruce Daube, Bianca C. Baier, Jianghanyang Li, and Colm Sweeney
                                    Atmos. Chem. Phys., 24, 12425–12445, https://doi.org/10.5194/acp-24-12425-2024, https://doi.org/10.5194/acp-24-12425-2024, 2024
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                                                In this study we describe new techniques to derive age of air from multiple simultaneous measurements of long-lived trace gases in order to improve the fidelity of the age-of-air estimates and to be able to compare age of air from measurements taken from different instruments, platforms and decades.  This technique also allows new transport information to be obtained from the measurements such as the primary source latitude that can also be compared to models. 
                                            
                                            
                                        Rachel W.-Y. Wu, Gabriel Chiodo, Inna Polichtchouk, and Daniela I. V. Domeisen
                                    Atmos. Chem. Phys., 24, 12259–12275, https://doi.org/10.5194/acp-24-12259-2024, https://doi.org/10.5194/acp-24-12259-2024, 2024
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                                                Strong variations in the strength of the stratospheric polar vortex can profoundly affect surface weather extremes; therefore, accurately predicting the stratosphere can improve surface weather forecasts. The research reveals how uncertainty in the stratosphere is linked to the troposphere. The findings suggest that refining models to better represent the identified sources and impact regions in the troposphere is likely to improve the prediction of the stratosphere and its surface impacts.
                                            
                                            
                                        Siyi Zhao, Jiankai Zhang, Chongyang Zhang, and Zhe Wang
                                        EGUsphere, https://doi.org/10.5194/egusphere-2024-2740, https://doi.org/10.5194/egusphere-2024-2740, 2024
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                                                By isolating the ozone-cycle coupling process, the study discusses how ozone-climate interaction affects the long-term change of the Arctic stratospheric temperature (AST). From 1980 to 1999, ozone-climate interactions increased AST by promoting upwave propagation and Brewer-Dobson circulation in early winter and reduced AST by reducing ozone shortwave heating in late winter and spring. Our results highlight the effect of ozone-climate interactions on intra-seasonal reversals of AST trends.
                                            
                                            
                                        Yang Li, Wuhu Feng, Xin Zhou, Yajuan Li, and Martyn P. Chipperfield
                                    Atmos. Chem. Phys., 24, 8277–8293, https://doi.org/10.5194/acp-24-8277-2024, https://doi.org/10.5194/acp-24-8277-2024, 2024
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                                                The Tibetan Plateau (TP), the highest and largest plateau, experiences strong surface solar UV radiation, whose excess can cause harmful influences on local biota. Hence, it is critical to study TP ozone. We find ENSO, the strongest interannual phenomenon, tends to induce tropospheric temperature change and thus modulate tropopause variability, which in turn favours ozone change over the TP. Our results have implications for a better understanding of the interannual variability of TP ozone.
                                            
                                            
                                        Luis F. Millán, Peter Hoor, Michaela I. Hegglin, Gloria L. Manney, Harald Boenisch, Paul Jeffery, Daniel Kunkel, Irina Petropavlovskikh, Hao Ye, Thierry Leblanc, and Kaley Walker
                                    Atmos. Chem. Phys., 24, 7927–7959, https://doi.org/10.5194/acp-24-7927-2024, https://doi.org/10.5194/acp-24-7927-2024, 2024
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                                                In the Observed Composition Trends And Variability in the UTLS (OCTAV-UTLS) Stratosphere-troposphere Processes And their Role in Climate (SPARC) activity, we have mapped multiplatform ozone datasets into coordinate systems to systematically evaluate the influence of these coordinates on binned climatological variability. This effort unifies the work of studies that focused on individual coordinate system variability. Our goal was to create the most comprehensive assessment of this topic.
                                            
                                            
                                        Masatomo Fujiwara, Patrick Martineau, Jonathon S. Wright, Marta Abalos, Petr Šácha, Yoshio Kawatani, Sean M. Davis, Thomas Birner, and Beatriz M. Monge-Sanz
                                    Atmos. Chem. Phys., 24, 7873–7898, https://doi.org/10.5194/acp-24-7873-2024, https://doi.org/10.5194/acp-24-7873-2024, 2024
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                                                A climatology of the major variables and terms of the transformed Eulerian-mean (TEM) momentum and thermodynamic equations from four global atmospheric reanalyses is evaluated. The spread among reanalysis TEM momentum balance terms is around 10 % in Northern Hemisphere winter and up to 50 % in Southern Hemisphere winter. The largest uncertainties in the thermodynamic equation (about 50 %) are in the vertical advection, which does not show a structure consistent with the differences in heating.
                                            
                                            
                                        Cristina Peña-Ortiz, Nuria Pilar Plaza, David Gallego, and Felix Ploeger
                                    Atmos. Chem. Phys., 24, 5457–5478, https://doi.org/10.5194/acp-24-5457-2024, https://doi.org/10.5194/acp-24-5457-2024, 2024
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                                                Although water vapour (H2O) in the lower stratosphere is only a few molecules among 1 million air molecules, atmospheric radiative forcing and surface temperature are sensitive to changes in its concentration. Monsoon regions play a key role in H2O transport and its concentration in the lower stratosphere. We show how the quasi-biennial oscillation (QBO) has a major impact on H2O over the Asian monsoon during August through changes in temperature caused by QBO modulation of tropical clouds.
                                            
                                            
                                        Young-Ha Kim, Georg Sebastian Voelker, Gergely Bölöni, Günther Zängl, and Ulrich Achatz
                                    Atmos. Chem. Phys., 24, 3297–3308, https://doi.org/10.5194/acp-24-3297-2024, https://doi.org/10.5194/acp-24-3297-2024, 2024
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                                                The quasi-biennial oscillation, which governs the tropical stratospheric circulation, is driven primarily by small-scale wave processes. We employ a novel method to realistically represent these wave processes in a global model, thereby revealing an aspect of the oscillation that has not been identified before. We find that the oblique propagation of waves, a process neglected by existing climate models, plays a pivotal role in the stratospheric circulation and its oscillation.
                                            
                                            
                                        Ellis Remsberg
                                    Atmos. Chem. Phys., 24, 1691–1697, https://doi.org/10.5194/acp-24-1691-2024, https://doi.org/10.5194/acp-24-1691-2024, 2024
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                                                CH4 data from the Halogen Occultation Experiment show clear changes in the deep and shallow branches of the Brewer–Dobson circulation (BDC) from 1992 to 2005. CH4 decreased in the upper stratosphere in the early 1990s following the Pinatubo eruption. There was also meridional transport of CH4 from the tropics to mid-latitudes in both hemispheres in the late 1990s. CH4 trends in the shallow branch agree with the tropospheric CH4 trends from 1996 to 2005.
                                            
                                            
                                        Tiehan Zhou, Kevin J. DallaSanta, Clara Orbe, David H. Rind, Jeffrey A. Jonas, Larissa Nazarenko, Gavin A. Schmidt, and Gary Russell
                                    Atmos. Chem. Phys., 24, 509–532, https://doi.org/10.5194/acp-24-509-2024, https://doi.org/10.5194/acp-24-509-2024, 2024
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                                                The El Niño–Southern Oscillation (ENSO) tends to speed up and slow down the phase speed of the Quasi-Biennial Oscillation (QBO) during El Niño and La Niña, respectively. The ENSO modulation of the QBO does not show up in the climate models with parameterized but temporally constant gravity wave sources. We show that the GISS E2.2 models can capture the observed ENSO modulation of the QBO period with a horizontal resolution of 2° by 2.5° and its gravity wave sources parameterized interactively.
                                            
                                            
                                        Helen Weierbach, Allegra N. LeGrande, and Kostas Tsigaridis
                                    Atmos. Chem. Phys., 23, 15491–15505, https://doi.org/10.5194/acp-23-15491-2023, https://doi.org/10.5194/acp-23-15491-2023, 2023
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                                                Volcanic aerosols impact global and regional climate conditions but can vary depending on pre-existing initial climate conditions. We ran an ensemble of volcanic aerosol simulations under varying ENSO and NAO initial conditions to understand how initial climate states impact the modeled response to volcanic forcing. Overall we found that initial NAO conditions can impact the strength of the first winter post-eruptive response but are also affected by the choice of anomaly and sampling routine.
                                            
                                            
                                        Franziska Zilker, Timofei Sukhodolov, Gabriel Chiodo, Marina Friedel, Tatiana Egorova, Eugene Rozanov, Jan Sedlacek, Svenja Seeber, and Thomas Peter
                                    Atmos. Chem. Phys., 23, 13387–13411, https://doi.org/10.5194/acp-23-13387-2023, https://doi.org/10.5194/acp-23-13387-2023, 2023
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                                                The Montreal Protocol (MP) has successfully reduced the Antarctic ozone hole by banning chlorofluorocarbons (CFCs) that destroy the ozone layer. Moreover, CFCs are strong greenhouse gases (GHGs) that would have strengthened global warming. In this study, we investigate the surface weather and climate in a world without the MP at the end of the 21st century, disentangling ozone-mediated and GHG impacts of CFCs. Overall, we avoided 1.7 K global surface warming and a poleward shift in storm tracks.
                                            
                                            
                                        Ji-Hee Yoo, Hye-Yeong Chun, and Min-Jee Kang
                                    Atmos. Chem. Phys., 23, 10869–10881, https://doi.org/10.5194/acp-23-10869-2023, https://doi.org/10.5194/acp-23-10869-2023, 2023
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                                                The January 2021 sudden stratospheric warming was preceded by unusual double westerly jets with polar stratospheric and subtropical mesospheric cores. This wind structure promotes anomalous dissipation of tropospheric planetary waves between the two maxima, leading to unusually strong shear instability. Shear instability generates the westward-propagating planetary waves with zonal wavenumber 2 in situ, thereby splitting the polar vortex just before the onset.
                                            
                                            
                                        Frederik Harzer, Hella Garny, Felix Ploeger, Harald Bönisch, Peter Hoor, and Thomas Birner
                                    Atmos. Chem. Phys., 23, 10661–10675, https://doi.org/10.5194/acp-23-10661-2023, https://doi.org/10.5194/acp-23-10661-2023, 2023
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                                                We study the statistical relation between year-by-year fluctuations in winter-mean ozone and the strength of the stratospheric polar vortex. In the latitude–pressure plane, regression analysis shows that anomalously weak polar vortex years are associated with three pronounced local ozone maxima over the polar cap relative to the winter climatology. These response maxima primarily reflect the non-trivial combination of different ozone transport processes with varying relative contributions.
                                            
                                            
                                        Sebastian Rhode, Peter Preusse, Manfred Ern, Jörn Ungermann, Lukas Krasauskas, Julio Bacmeister, and Martin Riese
                                    Atmos. Chem. Phys., 23, 7901–7934, https://doi.org/10.5194/acp-23-7901-2023, https://doi.org/10.5194/acp-23-7901-2023, 2023
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                                                Gravity waves (GWs) transport energy vertically and horizontally within the atmosphere and thereby affect wind speeds far from their sources. Here, we present a model that identifies orographic GW sources and predicts the pathways of the excited GWs through the atmosphere for a better understanding of horizontal GW propagation. We use this model to explain physical patterns in satellite observations (e.g., low GW activity above the Himalaya) and predict seasonal patterns of GW propagation.
                                            
                                            
                                        Stephen Bourguet and Marianna Linz
                                    Atmos. Chem. Phys., 23, 7447–7460, https://doi.org/10.5194/acp-23-7447-2023, https://doi.org/10.5194/acp-23-7447-2023, 2023
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                                                Here, we show how projected changes to tropical circulation will impact the water vapor concentration in the lower stratosphere, which has implications for surface climate and stratospheric chemistry. In our transport scenarios with slower east–west winds, air parcels ascending into the stratosphere do not experience the same cold temperatures that they would today. This effect could act in concert with previously modeled changes to stratospheric water vapor to amplify surface warming.
                                            
                                            
                                        Flossie Brown, Lauren Marshall, Peter H. Haynes, Rolando R. Garcia, Thomas Birner, and Anja Schmidt
                                    Atmos. Chem. Phys., 23, 5335–5353, https://doi.org/10.5194/acp-23-5335-2023, https://doi.org/10.5194/acp-23-5335-2023, 2023
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                                                Large-magnitude volcanic eruptions have the potential to alter large-scale circulation patterns, such as the quasi-biennial oscillation (QBO). The QBO is an oscillation of the tropical stratospheric zonal winds between easterly and westerly directions. Using a climate model, we show that large-magnitude eruptions can delay the progression of the QBO, with a much longer delay when the shear is easterly than when it is westerly. Such delays may affect weather and transport of atmospheric gases.
                                            
                                            
                                        Dillon Elsbury, Amy H. Butler, John R. Albers, Melissa L. Breeden, and Andrew O'Neil Langford
                                    Atmos. Chem. Phys., 23, 5101–5117, https://doi.org/10.5194/acp-23-5101-2023, https://doi.org/10.5194/acp-23-5101-2023, 2023
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                                                One of the global hotspots where stratosphere-to-troposphere transport (STT) of ozone takes place is over Pacific North America (PNA). However, we do not know how or if STT over PNA will change in response to climate change. Using climate model experiments forced with 
                                            
                                        worst-casescenario Representative Concentration Pathway 8.5 climate change, we find that changes in net chemical production and transport of ozone in the lower stratosphere increase STT of ozone over PNA in the future.
Khalil Karami, Rolando Garcia, Christoph Jacobi, Jadwiga H. Richter, and Simone Tilmes
                                    Atmos. Chem. Phys., 23, 3799–3818, https://doi.org/10.5194/acp-23-3799-2023, https://doi.org/10.5194/acp-23-3799-2023, 2023
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                                                Alongside mitigation and adaptation efforts, stratospheric aerosol intervention (SAI) is increasingly considered a third pillar to combat dangerous climate change. We investigate the teleconnection between the quasi-biennial oscillation in the equatorial stratosphere and the Arctic stratospheric polar vortex under a warmer climate and an SAI scenario. We show that the Holton–Tan relationship weakens under both scenarios and discuss the physical mechanisms responsible for such changes.
                                            
                                            
                                        Dirk Offermann, Christoph Kalicinsky, Ralf Koppmann, and Johannes Wintel
                                    Atmos. Chem. Phys., 23, 3267–3278, https://doi.org/10.5194/acp-23-3267-2023, https://doi.org/10.5194/acp-23-3267-2023, 2023
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                                                Atmospheric oscillations with periods between 5 and more than 200 years are believed to be self-excited (internal) in the atmosphere, i.e. non-anthropogenic. They are found at all altitudes up to 110 km and at four very different geographical locations (75° N, 70° E; 75° N, 280° E; 50° N, 7° E; 50° S, 7° E). Therefore, they hint at a global-oscillation mode. Their amplitudes are on the order of present-day climate trends, and it is therefore difficult to disentangle them.
                                            
                                            
                                        Samuel Benito-Barca, Natalia Calvo, and Marta Abalos
                                    Atmos. Chem. Phys., 22, 15729–15745, https://doi.org/10.5194/acp-22-15729-2022, https://doi.org/10.5194/acp-22-15729-2022, 2022
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                                                The impact of different El Niño flavors (eastern (EP) and central (CP) Pacific El Niño) and La Niña on the stratospheric ozone is studied in a state-of-the-art chemistry–climate model. Ozone reduces in the tropics and increases in the extratropics when an EP El Niño event occurs, the opposite of La Niña. However, CP El Niño has no impact on extratropical ozone. These ozone variations are driven by changes in the stratospheric transport circulation, with an important contribution of mixing.
                                            
                                            
                                        Nora Bergner, Marina Friedel, Daniela I. V. Domeisen, Darryn Waugh, and Gabriel Chiodo
                                    Atmos. Chem. Phys., 22, 13915–13934, https://doi.org/10.5194/acp-22-13915-2022, https://doi.org/10.5194/acp-22-13915-2022, 2022
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                                                Polar vortex extremes, particularly situations with an unusually weak cyclonic circulation in the stratosphere, can influence the surface climate in the spring–summer time in the Southern Hemisphere. Using chemistry-climate models and observations, we evaluate the robustness of the surface impacts. While models capture the general surface response, they do not show the observed climate patterns in midlatitude regions, which we trace back to biases in the models' circulations.
                                            
                                            
                                        Stephen Bourguet and Marianna Linz
                                    Atmos. Chem. Phys., 22, 13325–13339, https://doi.org/10.5194/acp-22-13325-2022, https://doi.org/10.5194/acp-22-13325-2022, 2022
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                                                Here, we tested the impact of spatial and temporal resolution on Lagrangian trajectory studies in a key region of interest for climate feedbacks and stratospheric chemistry. Our analysis shows that new higher-resolution input data provide an opportunity for a better understanding of physical processes that control how air moves from the troposphere to the stratosphere. Future studies of how these processes will change in a warming climate will benefit from these results.
                                            
                                            
                                        John R. Albers, Amy H. Butler, Andrew O. Langford, Dillon Elsbury, and Melissa L. Breeden
                                    Atmos. Chem. Phys., 22, 13035–13048, https://doi.org/10.5194/acp-22-13035-2022, https://doi.org/10.5194/acp-22-13035-2022, 2022
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                                                Ozone transported from the stratosphere contributes to background ozone concentrations in the free troposphere and to surface ozone exceedance events that affect human health. The physical processes whereby the El Niño–Southern Oscillation (ENSO) modulates North American stratosphere-to-troposphere ozone transport during spring are documented, and the usefulness of ENSO for predicting ozone events that may cause exceedances in surface air quality standards are assessed.
                                            
                                            
                                        Axel Gabriel
                                    Atmos. Chem. Phys., 22, 10425–10441, https://doi.org/10.5194/acp-22-10425-2022, https://doi.org/10.5194/acp-22-10425-2022, 2022
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                                                Recent measurements show some evidence that the amplitudes of atmospheric gravity waves (horizontal wavelengths of 100–2000 km), which propagate from the troposphere (0–10 km) to the stratosphere and mesosphere (10–100 km), increase more strongly with height during daytime than during nighttime. This study shows that ozone–temperature coupling in the upper stratosphere can principally produce such an amplification. The results will help to improve atmospheric circulation models.
                                            
                                            
                                        Liubov Poshyvailo-Strube, Rolf Müller, Stephan Fueglistaler, Michaela I. Hegglin, Johannes C. Laube, C. Michael Volk, and Felix Ploeger
                                    Atmos. Chem. Phys., 22, 9895–9914, https://doi.org/10.5194/acp-22-9895-2022, https://doi.org/10.5194/acp-22-9895-2022, 2022
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                                                Brewer–Dobson circulation (BDC) controls the composition of the stratosphere, which in turn affects radiation and climate. As the BDC cannot be measured directly, it is necessary to infer its strength and trends indirectly. In this study, we test in the 
                                            
                                        model worlddifferent methods for estimating the mean age of air trends based on a combination of stratospheric water vapour and methane data. We also provide simple practical advice of a more reliable estimation of the mean age of air trends.
Ming Shangguan and Wuke Wang
                                    Atmos. Chem. Phys., 22, 9499–9511, https://doi.org/10.5194/acp-22-9499-2022, https://doi.org/10.5194/acp-22-9499-2022, 2022
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                                                Skilful predictions of weather and climate on subseasonal to seasonal scales are valuable for decision makers. Here we show the global spatiotemporal variation of the temperature SAO in the UTLS with GNSS RO and reanalysis data. The formation of the SAO is explained by an energy budget analysis. The results show that the SAO in the UTLS is partly modified by the SSTs according to model simulations. The results may provide an important source for seasonal predictions of the surface weather.
                                            
                                            
                                        Oscar Dimdore-Miles, Lesley Gray, Scott Osprey, Jon Robson, Rowan Sutton, and Bablu Sinha
                                    Atmos. Chem. Phys., 22, 4867–4893, https://doi.org/10.5194/acp-22-4867-2022, https://doi.org/10.5194/acp-22-4867-2022, 2022
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                                                This study examines interactions between variations in the strength of polar stratospheric winds and circulation in the North Atlantic in a climate model simulation. It finds that the Atlantic Meridional Overturning Circulation (AMOC) responds with oscillations to sets of consecutive Northern Hemisphere winters, which show all strong or all weak polar vortex conditions. The study also shows that a set of strong vortex winters in the 1990s contributed to the recent slowdown in the observed AMOC.
                                            
                                            
                                        Mengdie Xie, John C. Moore, Liyun Zhao, Michael Wolovick, and Helene Muri
                                    Atmos. Chem. Phys., 22, 4581–4597, https://doi.org/10.5194/acp-22-4581-2022, https://doi.org/10.5194/acp-22-4581-2022, 2022
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                                                We use data from six Earth system models to estimate Atlantic meridional overturning circulation (AMOC) changes and its drivers under four different solar geoengineering methods. Solar dimming seems relatively more effective than marine cloud brightening or stratospheric aerosol injection at reversing greenhouse-gas-driven declines in AMOC. Geoengineering-induced AMOC amelioration is due to better maintenance of air–sea temperature differences and reduced loss of Arctic summer sea ice.
                                            
                                            
                                        Kai Qie, Wuke Wang, Wenshou Tian, Rui Huang, Mian Xu, Tao Wang, and Yifeng Peng
                                    Atmos. Chem. Phys., 22, 4393–4411, https://doi.org/10.5194/acp-22-4393-2022, https://doi.org/10.5194/acp-22-4393-2022, 2022
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                                                We identify a significantly intensified upward motion over the tropical western Pacific (TWP) and an enhanced tropical upwelling in boreal winter during 1958–2017 due to the warming of global sea surface temperatures (SSTs). Our results suggest that more tropospheric trace gases over the TWP could be elevated to the lower stratosphere, which implies that the emission from the maritime continent plays a more important role in the stratospheric processes and the global climate.
                                            
                                            
                                        Audrey Lecouffe, Sophie Godin-Beekmann, Andrea Pazmiño, and Alain Hauchecorne
                                    Atmos. Chem. Phys., 22, 4187–4200, https://doi.org/10.5194/acp-22-4187-2022, https://doi.org/10.5194/acp-22-4187-2022, 2022
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                                                This study uses a model developped at LATMOS (France) to analyze the behavior of the Antarctic polar vortex from 1979 to 2020 at 675 K, 550 K, and 475 K isentropic levels. We found that the vortex edge intensity is stronger during the September–October–November period, while its edge position is less extended during this period. The polar vortex is stronger and lasts longer during solar minimum years. Breakup dates of the polar vortex are linked to the ozone hole and maximum wind speed.
                                            
                                            
                                        Jan Clemens, Felix Ploeger, Paul Konopka, Raphael Portmann, Michael Sprenger, and Heini Wernli
                                    Atmos. Chem. Phys., 22, 3841–3860, https://doi.org/10.5194/acp-22-3841-2022, https://doi.org/10.5194/acp-22-3841-2022, 2022
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                                                Highly polluted air flows from the surface to higher levels of the atmosphere during the Asian summer monsoon. At high levels, the air is trapped within eddies. Here, we study how air masses can leave the eddy within its cutoff, how they distribute, and how their chemical composition changes. We found evidence for transport from the eddy to higher latitudes over the North Pacific and even Alaska. During transport, trace gas concentrations within cutoffs changed gradually, showing steady mixing.
                                            
                                            
                                        Adam A. Scaife, Mark P. Baldwin, Amy H. Butler, Andrew J. Charlton-Perez, Daniela I. V. Domeisen, Chaim I. Garfinkel, Steven C. Hardiman, Peter Haynes, Alexey Yu Karpechko, Eun-Pa Lim, Shunsuke Noguchi, Judith Perlwitz, Lorenzo Polvani, Jadwiga H. Richter, John Scinocca, Michael Sigmond, Theodore G. Shepherd, Seok-Woo Son, and David W. J. Thompson
                                    Atmos. Chem. Phys., 22, 2601–2623, https://doi.org/10.5194/acp-22-2601-2022, https://doi.org/10.5194/acp-22-2601-2022, 2022
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                                                Great progress has been made in computer modelling and simulation of the whole climate system, including the stratosphere. Since the late 20th century we also gained a much clearer understanding of how the stratosphere interacts with the lower atmosphere. The latest generation of numerical prediction systems now explicitly represents the stratosphere and its interaction with surface climate, and here we review its role in long-range predictions and projections from weeks to decades ahead.
                                            
                                            
                                        Yihang Hu, Wenshou Tian, Jiankai Zhang, Tao Wang, and Mian Xu
                                    Atmos. Chem. Phys., 22, 1575–1600, https://doi.org/10.5194/acp-22-1575-2022, https://doi.org/10.5194/acp-22-1575-2022, 2022
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                                                Antarctic stratospheric wave activities in September have been weakening significantly since the 2000s. Further analysis supports the finding that sea surface temperature (SST) trends over 20° N–70° S lead to the weakening of stratospheric wave activities, while the response of stratospheric wave activities to ozone recovery is weak. Thus, the SST trend should be taken into consideration when exploring the mechanism for the climate transition in the southern hemispheric stratosphere around 2000.
                                            
                                            
                                        Sheena Loeffel, Roland Eichinger, Hella Garny, Thomas Reddmann, Frauke Fritsch, Stefan Versick, Gabriele Stiller, and Florian Haenel
                                    Atmos. Chem. Phys., 22, 1175–1193, https://doi.org/10.5194/acp-22-1175-2022, https://doi.org/10.5194/acp-22-1175-2022, 2022
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                                                SF6-derived trends of stratospheric AoA from observations and model simulations disagree in sign. SF6 experiences chemical degradation, which we explicitly integrate in a global climate model. In our simulations, the AoA trend changes sign when SF6 sinks are considered; thus, the process has the potential to reconcile simulated with observed AoA trends. We show that the positive AoA trend is due to the SF6 sinks themselves and provide a first approach for a correction to account for SF6 loss.
                                            
                                            
                                        Nicholas A. Davis, Patrick Callaghan, Isla R. Simpson, and Simone Tilmes
                                    Atmos. Chem. Phys., 22, 197–214, https://doi.org/10.5194/acp-22-197-2022, https://doi.org/10.5194/acp-22-197-2022, 2022
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                                                Specified dynamics schemes attempt to constrain the atmospheric circulation in a climate model to isolate the role of transport in chemical variability, evaluate model physics, and interpret field campaign observations. We show that the specified dynamics scheme in CESM2 erroneously suppresses convection and induces circulation errors that project onto errors in tracers, even using the most optimal settings. Development of a more sophisticated scheme is necessary for future progress.
                                            
                                            
                                        Cornelia Strube, Peter Preusse, Manfred Ern, and Martin Riese
                                    Atmos. Chem. Phys., 21, 18641–18668, https://doi.org/10.5194/acp-21-18641-2021, https://doi.org/10.5194/acp-21-18641-2021, 2021
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                                                High gravity wave (GW) momentum fluxes in the lower stratospheric southern polar vortex around 60° S are still poorly understood. Few GW sources are found at these latitudes. We present a ray tracing case study on waves resolved in high-resolution global model temperatures southeast of New Zealand. We show that lateral propagation of more than 1000 km takes place below 20 km altitude, and a variety of orographic and non-orographic sources located north of 50° S generate the wave field.
                                            
                                            
                                        Erika Brattich, Hongyu Liu, Bo Zhang, Miguel Ángel Hernández-Ceballos, Jussi Paatero, Darko Sarvan, Vladimir Djurdjevic, Laura Tositti, and Jelena Ajtić
                                    Atmos. Chem. Phys., 21, 17927–17951, https://doi.org/10.5194/acp-21-17927-2021, https://doi.org/10.5194/acp-21-17927-2021, 2021
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                                                In this study we analyse the output of a chemistry and transport model together with observations of different meteorological and compositional variables to demonstrate the link between sudden stratospheric warming and transport of stratospheric air to the surface in the subpolar regions of Europe during the cold season. Our findings have particular implications for atmospheric composition since climate projections indicate more frequent sudden stratospheric warming under a warmer climate.
                                            
                                            
                                        Liang Tang, Sheng-Yang Gu, and Xian-Kang Dou
                                    Atmos. Chem. Phys., 21, 17495–17512, https://doi.org/10.5194/acp-21-17495-2021, https://doi.org/10.5194/acp-21-17495-2021, 2021
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                                                Our study explores the variation in the occurrence date, peak amplitude and wave period for eastward waves and the role of instability, background wind structure and the critical layer in eastward wave propagation and amplification.
                                            
                                            
                                        Marta Abalos, Natalia Calvo, Samuel Benito-Barca, Hella Garny, Steven C. Hardiman, Pu Lin, Martin B. Andrews, Neal Butchart, Rolando Garcia, Clara Orbe, David Saint-Martin, Shingo Watanabe, and Kohei Yoshida
                                    Atmos. Chem. Phys., 21, 13571–13591, https://doi.org/10.5194/acp-21-13571-2021, https://doi.org/10.5194/acp-21-13571-2021, 2021
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                                                The stratospheric Brewer–Dobson circulation (BDC), responsible for transporting mass, tracers and heat globally in the stratosphere, is evaluated in a set of state-of-the-art climate models. The acceleration of the BDC in response to increasing greenhouse gases is most robust in the lower stratosphere. At higher levels, the well-known inconsistency between model and observational BDC trends can be partly reconciled by accounting for limited sampling and large uncertainties in the observations.
                                            
                                            
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                Short summary
                    Using seven reanalyses, we study the movement and drivers of the upper tropospheric–lower stratospheric anticyclone (AC) that forms during the Asian summer monsoon and is debated to be an important pathway for air masses to the stratosphere. We find that the distribution of the AC's centre position, and especially the so-called bimodality, largely depends on the reanalysis. Furthermore, we can connect shifts of the AC to precipitation and convection anomalies over India and the western Pacific.
                    Using seven reanalyses, we study the movement and drivers of the upper tropospheric–lower...
                    
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