Articles | Volume 26, issue 16
https://doi.org/10.5194/acp-26-12067-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/acp-26-12067-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
25 Aug 2026
Research article |
| 25 Aug 2026
| 25 Aug 2026
Evidence of gravity wave contribution to vertical shear and mixing in the lower stratosphere
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Daniel Kunkel
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Annette Miltenberger
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Hans-Christoph Lachnitt
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Thorsten Kaluza
Department of Meteorology, University of Reading, Reading, UK
Cornelis Schwenk
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
Peter Hoor
Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
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We present co-occurrence of gravity waves (GWs) and vertical shear in the North Atlantic lowermost stratosphere using ERA5 reanalysis data. Our results suggest the importance of GWs in the formation and maintenance of tropopause shear layer and ultimately to the potential turbulence occurrence in the extratropical upper troposphere lower stratosphere (UTLS). Overall, small-scale processes, and in particular, GWs can have larger implications for dynamics and composition in the UTLS.
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Atmospheric gravity waves (GWs) significantly enhance vertical shear in the lowermost stratosphere (LMS), influencing turbulence and mixing in the extratropical transition layer. Using idealized baroclinic life cycle experiments with the ICON model, this study demonstrates that moisture and cloud processes amplify GW activity, driving strong shear and turbulence in the LMS. These findings highlight the critical role of GWs in shaping the dynamics in the LMS, particularly for clear air turbulence.
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This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Atmos. Chem. Phys., 26, 7435–7462, https://doi.org/10.5194/acp-26-7435-2026, https://doi.org/10.5194/acp-26-7435-2026, 2026
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Airborne measurements of the aerosol chemical composition were conducted in the 2018 wintertime tropopause region over Germany using a hybrid aerosol mass spectrometer, regarding the atmospheric background and aircraft exhaust plumes. Biomass burning aerosol of North American wildfires contributes to the aerosol population. Soot and engine oil were attributed to aircraft exhaust, and were detected in contrail residuals, implying their impact on chemical processes and properties of contrails.
Chun Hang Chau, Peter Hoor, Katharina Kaiser, and Holger Tost
Atmos. Chem. Phys., 26, 3637–3652, https://doi.org/10.5194/acp-26-3637-2026, https://doi.org/10.5194/acp-26-3637-2026, 2026
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Madhuri Umbarkar, Daniel Kunkel, and Ulrich Achatz
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We present co-occurrence of gravity waves (GWs) and vertical shear in the North Atlantic lowermost stratosphere using ERA5 reanalysis data. Our results suggest the importance of GWs in the formation and maintenance of tropopause shear layer and ultimately to the potential turbulence occurrence in the extratropical upper troposphere lower stratosphere (UTLS). Overall, small-scale processes, and in particular, GWs can have larger implications for dynamics and composition in the UTLS.
Sylvia C. Sullivan, Aiko Voigt, Edgardo Sepúlveda Araya, Silvia Bucci, Annette Miltenberger, Meredith K. Kupinski, Christian Rolf, and Martina Krämer
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We examined how model resolution affects the moisture and cloud content of large weather systems that move warm, moist air into the upper troposphere. By comparing high- and low-resolution simulations, we found that models which can resolve convectively ascending air produce drier air and more outgoing longwave radiation. This shows that model grid-spacing impacts modeled upper-level moisture and Earth's radiative balance.
Anna Breuninger, Philipp Joppe, Jonas Wilsch, Cornelis Schwenk, Heiko Bozem, Nicolas Emig, Laurin Merkel, Rainer Rossberg, Timo Keber, Arthur Kutschka, Philipp Waleska, Stefan Hofmann, Sarah Richter, Florian Ungeheuer, Konstantin Dörholt, Thorsten Hoffmann, Annette Miltenberger, Johannes Schneider, Peter Hoor, and Alexander L. Vogel
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Heiko Bozem, Philipp Joppe, Yun Li, Nicolas Emig, Armin Afchine, Anna Breuninger, Joachim Curtius, Stefan Hofmann, Sadath Ismayil, Konrad Kandler, Daniel Kunkel, Arthur Kutschka, Hans-Christoph Lachnitt, Andreas Petzold, Sarah Richter, Timo Röschenthaler, Christian Rolf, Lisa Schneider, Johannes Schneider, Alexander Vogel, and Peter Hoor
Atmos. Meas. Tech., 18, 6545–6568, https://doi.org/10.5194/amt-18-6545-2025, https://doi.org/10.5194/amt-18-6545-2025, 2025
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Philipp Joppe, Johannes Schneider, Jonas Wilsch, Heiko Bozem, Anna Breuninger, Joachim Curtius, Martin Ebert, Nicolas Emig, Peter Hoor, Sadath Ismayil, Konrad Kandler, Daniel Kunkel, Isabel Kurth, Hans-Christoph Lachnitt, Yun Li, Annette Miltenberger, Sarah Richter, Christian Rolf, Lisa Schneider, Cornelis Schwenk, Nicole Spelten, Alexander L. Vogel, Yafang Cheng, and Stephan Borrmann
Atmos. Chem. Phys., 25, 15077–15103, https://doi.org/10.5194/acp-25-15077-2025, https://doi.org/10.5194/acp-25-15077-2025, 2025
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Linda Ort, Andrea Pozzer, Peter Hoor, Florian Obersteiner, Andreas Zahn, Thomas B. Ryerson, Chelsea R. Thompson, Jeff Peischl, Róisín Commane, Bruce Daube, Ilann Bourgeois, Jos Lelieveld, and Horst Fischer
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Sophie Bauchinger, Andreas Engel, Markus Jesswein, Timo Keber, Harald Bönisch, Florian Obersteiner, Andreas Zahn, Nicolas Emig, Peter Hoor, Hans-Christoph Lachnitt, Franziska Weyland, Linda Ort, and Tanja J. Schuck
Atmos. Chem. Phys., 25, 14167–14186, https://doi.org/10.5194/acp-25-14167-2025, https://doi.org/10.5194/acp-25-14167-2025, 2025
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We compared different ways to define the upper barrier of the troposphere in the extra-tropics, the “tropopause”. By analysing ozone distributions sorted by different definitions, we found that the traditional temperature-based tropopause works less well than dynamic or tracer-based definitions. We saw a sharper transition of ozone across the tropopause using a higher value of potential vorticity than often used and recommend this value for future studies of exchange processes in this region.
Nicolas Emig, Annette K. Miltenberger, Peter M. Hoor, and Andreas Petzold
Atmos. Chem. Phys., 25, 13077–13101, https://doi.org/10.5194/acp-25-13077-2025, https://doi.org/10.5194/acp-25-13077-2025, 2025
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This study presents in situ observations of cirrus occurrence from aircraft measurements in the extratropical transition layer (ExTL) using simultaneous measurements from two platforms. Lagrangian diagnostics based on high-resolution ICON simulations show long residence times of the cirrus in stratospheric air, allowing us to separate different diabatic processes during transit. The findings suggest that radiative diabatic cloud processes significantly impact the tropopause thermodynamic structure.
Chun Hang Chau, Peter Hoor, and Holger Tost
Atmos. Chem. Phys., 25, 13123–13140, https://doi.org/10.5194/acp-25-13123-2025, https://doi.org/10.5194/acp-25-13123-2025, 2025
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This study examines how the turbulence in the upper troposphere/lower stratosphere (UTLS) could modify the tracer distribution under different situations. Using a multi-scale chemistry model with a novel diagnostic, we found that both the pre-existing tracer gradient and the dynamical and thermodynamical forcing play a role in modifying the tracer distribution. These results allow further research on the UTLS turbulent mixing and its implications for the climate system.
Johannes Schneider, Christiane Schulz, Florian Rubach, Anna Ludwig, Jonas Wilsch, Philipp Joppe, Christian Gurk, Sergej Molleker, Laurent Poulain, Florian Obersteiner, Torsten Gehrlein, Harald Bönisch, Andreas Zahn, Peter Hoor, Nicolas Emig, Heiko Bozem, Stephan Borrmann, and Markus Hermann
Atmos. Meas. Tech., 18, 5103–5128, https://doi.org/10.5194/amt-18-5103-2025, https://doi.org/10.5194/amt-18-5103-2025, 2025
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An instrumented container laboratory is operated on regular commercial passenger flights to obtain a long-term representative dataset on the composition of the upper troposphere and lower stratosphere. Here we report on the development of a fully automated aerosol mass spectrometer for this project. We present technical specifications, necessary modifications for the automation, instrument calibration and comparisons, detection limits, and the first in-flight data.
Cornelis Schwenk, Annette Miltenberger, and Annika Oertel
Atmos. Chem. Phys., 25, 11333–11361, https://doi.org/10.5194/acp-25-11333-2025, https://doi.org/10.5194/acp-25-11333-2025, 2025
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We studied how different parameter choices concerning cloud processes affect the simulated transport of water and ice into the upper atmosphere (which affects the greenhouse effect) during a weather system called a warm conveyor belt. Using a set of model experiments, we found that some parameters have a strong effect on humidity and ice, especially during fast ascents. These findings could help improve weather and climate models and may also be relevant for future climate engineering studies.
Tim Lüttmer, Annette Miltenberger, and Peter Spichtinger
Atmos. Chem. Phys., 25, 10245–10265, https://doi.org/10.5194/acp-25-10245-2025, https://doi.org/10.5194/acp-25-10245-2025, 2025
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We investigate ice formation pathways in a warm conveyor belt case study. We employ a multi-phase microphysics scheme that distinguishes between ice from different nucleation processes. Ice crystals in the cirrus outflow mostly stem from in situ formation. Hence, they were formed directly from the vapor phase. Sedimentational redistribution modulates cirrus properties and leads to disagreement between cirrus origin classifications based on thermodynamic history and nucleation processes.
Madhuri Umbarkar and Daniel Kunkel
Atmos. Chem. Phys., 25, 10159–10182, https://doi.org/10.5194/acp-25-10159-2025, https://doi.org/10.5194/acp-25-10159-2025, 2025
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Atmospheric gravity waves (GWs) significantly enhance vertical shear in the lowermost stratosphere (LMS), influencing turbulence and mixing in the extratropical transition layer. Using idealized baroclinic life cycle experiments with the ICON model, this study demonstrates that moisture and cloud processes amplify GW activity, driving strong shear and turbulence in the LMS. These findings highlight the critical role of GWs in shaping the dynamics in the LMS, particularly for clear air turbulence.
Rodrigo J. Seguel, Charlie Opazo, Yann Cohen, Owen R. Cooper, Laura Gallardo, Björn-Martin Sinnhuber, Florian Obersteiner, Andreas Zahn, Peter Hoor, Susanne Rohs, and Andreas Marsing
Atmos. Chem. Phys., 25, 8553–8573, https://doi.org/10.5194/acp-25-8553-2025, https://doi.org/10.5194/acp-25-8553-2025, 2025
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We explored ozone differences between the Northern Hemisphere and Southern Hemispheres in the upper troposphere–lower stratosphere. We found lower ozone (with stratospheric origin) in the Southern Hemisphere, especially during years of severe ozone depletion. Sudden stratospheric warming events increased the ozone in each hemisphere, highlighting the relationship between stratospheric processes and ozone in the upper troposphere, where ozone is an important greenhouse gas.
Markus Jesswein, Valentin Lauther, Nicolas Emig, Peter Hoor, Timo Keber, Hans-Christoph Lachnitt, Linda Ort, Tanja Schuck, Johannes Strobel, Ronja Van Luijt, C. Michael Volk, Franziska Weyland, and Andreas Engel
Atmos. Chem. Phys., 25, 8107–8126, https://doi.org/10.5194/acp-25-8107-2025, https://doi.org/10.5194/acp-25-8107-2025, 2025
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The study investigates transport within the Asian Summer Monsoon, focusing on how CH2Cl2 reaches the subarctic tropopause region. Using data from the PHILEAS campaign in 2023, events with increased mixing ratios were detected. Their origin, the transport paths to the tropopause region, and the potential entry into the stratosphere were analyzed. The East Asian Summer Monsoon was identified as the main transport pathway, with only a small contribution to the stratosphere in the following days.
Franziska Weyland, Peter Hoor, Daniel Kunkel, Thomas Birner, Felix Plöger, and Katharina Turhal
Atmos. Chem. Phys., 25, 1227–1252, https://doi.org/10.5194/acp-25-1227-2025, https://doi.org/10.5194/acp-25-1227-2025, 2025
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The lowermost stratosphere (LMS) plays an important role in the Earth's climate, containing strong gradients of ozone and water vapor. Our results indicate that the thermodynamic structure of the LMS was changing between 1979–2019 in response to anthropogenic climate change and the recovery of stratospheric ozone, also indicating large-scale circulation changes. We find that both the upper and the lower LMS boundaries show an (upward) trend, which has implications for the LMS mass.
Cornelis Schwenk and Annette Miltenberger
Atmos. Chem. Phys., 24, 14073–14099, https://doi.org/10.5194/acp-24-14073-2024, https://doi.org/10.5194/acp-24-14073-2024, 2024
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Warm conveyor belts (WCBs) transport moisture into the upper atmosphere, where it acts as a greenhouse gas. This transport is not well understood, and the role of rapidly rising air is unclear. We simulate a WCB and look at fast- and slow-rising air to see how moisture is (differently) transported. We find that for fast-ascending air more ice particles reach higher into the atmosphere and that frozen cloud particles are removed differently than during slow ascent, which has more water vapour.
Katharina Turhal, Felix Plöger, Jan Clemens, Thomas Birner, Franziska Weyland, Paul Konopka, and Peter Hoor
Atmos. Chem. Phys., 24, 13653–13679, https://doi.org/10.5194/acp-24-13653-2024, https://doi.org/10.5194/acp-24-13653-2024, 2024
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The tropopause separates the troposphere, where many greenhouse gases originate, from the stratosphere. This study examines a tropopause defined by potential vorticity – an analogue for angular momentum that changes sharply in the subtropics, creating a transport barrier. Between 1980 and 2017, this tropopause shifted poleward at lower altitudes and equatorward above, suggesting height-dependent changes in atmospheric circulation that may affect greenhouse gas distribution and global warming.
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.
Niklas Karbach, Lisa Höhler, Peter Hoor, Heiko Bozem, Nicole Bobrowski, and Thorsten Hoffmann
Atmos. Meas. Tech., 17, 4081–4086, https://doi.org/10.5194/amt-17-4081-2024, https://doi.org/10.5194/amt-17-4081-2024, 2024
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The system presented here can accurately generate and reproduce a stable flow of gas mixtures of known concentrations over several days using ambient air as a dilution medium. In combination with the small size and low weight of the system, this enables the calibration of hydrogen sensors in the field, reducing the influence of matrix effects on the accuracy of the sensor. The system is inexpensive to assemble and easy to maintain, which is the key to reliable measurement results.
Philipp Joppe, Johannes Schneider, Katharina Kaiser, Horst Fischer, Peter Hoor, Daniel Kunkel, Hans-Christoph Lachnitt, Andreas Marsing, Lenard Röder, Hans Schlager, Laura Tomsche, Christiane Voigt, Andreas Zahn, and Stephan Borrmann
Atmos. Chem. Phys., 24, 7499–7522, https://doi.org/10.5194/acp-24-7499-2024, https://doi.org/10.5194/acp-24-7499-2024, 2024
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From aircraft measurements in the upper troposphere/lower stratosphere, we find a correlation between the ozone and particulate sulfate in the lower stratosphere. The correlation exhibits some variability over the measurement period exceeding the background sulfate-to-ozone correlation. From our analysis, we conclude that gas-to-particle conversion of volcanic sulfur dioxide leads to observed enhanced sulfate aerosol mixing ratios.
Edward Groot, Patrick Kuntze, Annette Miltenberger, and Holger Tost
Weather Clim. Dynam., 5, 779–803, https://doi.org/10.5194/wcd-5-779-2024, https://doi.org/10.5194/wcd-5-779-2024, 2024
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Deep convective clouds (thunderstorms), which may cause severe weather, tend to coherently organise into structured cloud systems. Accurate representation of these systems in models is difficult due to their complex dynamics and, in numerical simulations, the dependence of their dynamics on resolution. Here, the effect of convective organisation and geometry on their outflow winds (altitudes of 7–14 km) is investigated. Representation of their dynamics and outflows improves at higher resolution.
Tanja J. Schuck, Johannes Degen, Eric Hintsa, Peter Hoor, Markus Jesswein, Timo Keber, Daniel Kunkel, Fred Moore, Florian Obersteiner, Matt Rigby, Thomas Wagenhäuser, Luke M. Western, Andreas Zahn, and Andreas Engel
Atmos. Chem. Phys., 24, 689–705, https://doi.org/10.5194/acp-24-689-2024, https://doi.org/10.5194/acp-24-689-2024, 2024
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We study the interhemispheric gradient of sulfur hexafluoride (SF6), a strong long-lived greenhouse gas. Its emissions are stronger in the Northern Hemisphere; therefore, mixing ratios in the Southern Hemisphere lag behind. Comparing the observations to a box model, the model predicts air in the Southern Hemisphere to be older. For a better agreement, the emissions used as model input need to be increased (and their spatial pattern changed), and we need to modify north–south transport.
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.
Annika Oertel, Annette K. Miltenberger, Christian M. Grams, and Corinna Hoose
Atmos. Chem. Phys., 23, 8553–8581, https://doi.org/10.5194/acp-23-8553-2023, https://doi.org/10.5194/acp-23-8553-2023, 2023
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Warm conveyor belts (WCBs) are cloud- and precipitation-producing airstreams in extratropical cyclones that are important for the large-scale flow and cloud radiative forcing. We analyze cloud formation processes during WCB ascent in a two-moment microphysics scheme. Quantification of individual diabatic heating rates shows the importance of condensation, vapor deposition, rain evaporation, melting, and cloud-top radiative cooling for total heating and WCB-related potential vorticity structure.
Luis F. Millán, Gloria L. Manney, Harald Boenisch, Michaela I. Hegglin, Peter Hoor, Daniel Kunkel, Thierry Leblanc, Irina Petropavlovskikh, Kaley Walker, Krzysztof Wargan, and Andreas Zahn
Atmos. Meas. Tech., 16, 2957–2988, https://doi.org/10.5194/amt-16-2957-2023, https://doi.org/10.5194/amt-16-2957-2023, 2023
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The determination of atmospheric composition trends in the upper troposphere and lower stratosphere (UTLS) is still highly uncertain. We present the creation of dynamical diagnostics to map several ozone datasets (ozonesondes, lidars, aircraft, and satellite measurements) in geophysically based coordinate systems. The diagnostics can also be used to analyze other greenhouse gases relevant to surface climate and UTLS chemistry.
Hans-Christoph Lachnitt, Peter Hoor, Daniel Kunkel, Martina Bramberger, Andreas Dörnbrack, Stefan Müller, Philipp Reutter, Andreas Giez, Thorsten Kaluza, and Markus Rapp
Atmos. Chem. Phys., 23, 355–373, https://doi.org/10.5194/acp-23-355-2023, https://doi.org/10.5194/acp-23-355-2023, 2023
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We present an analysis of high-resolution airborne measurements during a flight of the DEEPWAVE 2014 campaign in New Zealand. The focus of this flight was to study the effects of enhanced mountain wave activity over the Southern Alps. We discuss changes in the upstream and downstream distributions of N2O and CO and show that these changes are related to turbulence-induced trace gas fluxes which have persistent effects on the trace gas composition in the lower stratosphere.
Paul Konopka, Mengchu Tao, Marc von Hobe, Lars Hoffmann, Corinna Kloss, Fabrizio Ravegnani, C. Michael Volk, Valentin Lauther, Andreas Zahn, Peter Hoor, and Felix Ploeger
Geosci. Model Dev., 15, 7471–7487, https://doi.org/10.5194/gmd-15-7471-2022, https://doi.org/10.5194/gmd-15-7471-2022, 2022
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Pure trajectory-based transport models driven by meteorology derived from reanalysis products (ERA5) take into account only the resolved, advective part of transport. That means neither mixing processes nor unresolved subgrid-scale advective processes like convection are included. The Chemical Lagrangian Model of the Stratosphere (CLaMS) includes these processes. We show that isentropic mixing dominates unresolved transport. The second most important transport process is unresolved convection.
Linda Smoydzin and Peter Hoor
Atmos. Chem. Phys., 22, 7193–7206, https://doi.org/10.5194/acp-22-7193-2022, https://doi.org/10.5194/acp-22-7193-2022, 2022
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Our study presents a detailed analysis of the spatial and temporal distribution of elevated CO level in the upper troposphere over the Pacific using 20 years of MOPITT data. We create a climatology of severe pollution episodes and use trajectory calculations to link each particular pollution event detected in MOPITT satellite data with a distinct source region. Additionally, we analyse uplift mechanisms such as WCB-related upward transport.
Helmut Ziereis, Peter Hoor, Jens-Uwe Grooß, Andreas Zahn, Greta Stratmann, Paul Stock, Michael Lichtenstern, Jens Krause, Vera Bense, Armin Afchine, Christian Rolf, Wolfgang Woiwode, Marleen Braun, Jörn Ungermann, Andreas Marsing, Christiane Voigt, Andreas Engel, Björn-Martin Sinnhuber, and Hermann Oelhaf
Atmos. Chem. Phys., 22, 3631–3654, https://doi.org/10.5194/acp-22-3631-2022, https://doi.org/10.5194/acp-22-3631-2022, 2022
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Airborne observations were conducted in the lowermost Arctic stratosphere during the winter of 2015/2016. The observed distribution of reactive nitrogen shows clear indications of nitrification in mid-winter and denitrification in late winter. This was caused by the formation of polar stratospheric cloud particles, which were observed during several flights. The sedimentation and evaporation of these particles and the descent of air masses cause a redistribution of reactive nitrogen.
Valentin Lauther, Bärbel Vogel, Johannes Wintel, Andrea Rau, Peter Hoor, Vera Bense, Rolf Müller, and C. Michael Volk
Atmos. Chem. Phys., 22, 2049–2077, https://doi.org/10.5194/acp-22-2049-2022, https://doi.org/10.5194/acp-22-2049-2022, 2022
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We show airborne in situ measurements of the very short-lived ozone-depleting substances CH2Cl2 and CHCl3, revealing particularly high concentrations of both species in the lower stratosphere. Back-trajectory calculations and 3D model simulations show that the air masses with high concentrations originated in the Asian boundary layer and were transported via the Asian summer monsoon. We also identify a fast transport pathway into the stratosphere via the North American monsoon and by hurricanes.
Stefan Niebler, Annette Miltenberger, Bertil Schmidt, and Peter Spichtinger
Weather Clim. Dynam., 3, 113–137, https://doi.org/10.5194/wcd-3-113-2022, https://doi.org/10.5194/wcd-3-113-2022, 2022
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We use machine learning to create a network that detects and classifies four types of synoptic-scale weather fronts from ERA5 atmospheric reanalysis data. We present an application of our method, showing its use case in a scientific context. Additionally, our results show that multiple sources of training data are necessary to perform well on different regions, implying differences within those regions. Qualitative evaluation shows that the results are physically plausible.
Rachel E. Hawker, Annette K. Miltenberger, Jill S. Johnson, Jonathan M. Wilkinson, Adrian A. Hill, Ben J. Shipway, Paul R. Field, Benjamin J. Murray, and Ken S. Carslaw
Atmos. Chem. Phys., 21, 17315–17343, https://doi.org/10.5194/acp-21-17315-2021, https://doi.org/10.5194/acp-21-17315-2021, 2021
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We find that ice-nucleating particles (INPs), aerosols that can initiate the freezing of cloud droplets, cause substantial changes to the properties of radiatively important convectively generated anvil cirrus. The number concentration of INPs had a large effect on ice crystal number concentration while the INP temperature dependence controlled ice crystal size and cloud fraction. The results indicate information on INP number and source is necessary for the representation of cloud glaciation.
Markus Jesswein, Heiko Bozem, Hans-Christoph Lachnitt, Peter Hoor, Thomas Wagenhäuser, Timo Keber, Tanja Schuck, and Andreas Engel
Atmos. Chem. Phys., 21, 17225–17241, https://doi.org/10.5194/acp-21-17225-2021, https://doi.org/10.5194/acp-21-17225-2021, 2021
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This study presents and compares inorganic chlorine (Cly) derived from observations with the HALO research aircraft in the Antarctic late winter–early fall 2019 and the Arctic winter 2015–2016. Trend-corrected correlations from the Northern Hemisphere show excellent agreement with those from the Southern Hemisphere. After observation allocation inside and outside the vortex based on N2O measurements, results of the two campaigns reveal substantial differences in Cly within the respective vortex.
Meike K. Rotermund, Vera Bense, Martyn P. Chipperfield, Andreas Engel, Jens-Uwe Grooß, Peter Hoor, Tilman Hüneke, Timo Keber, Flora Kluge, Benjamin Schreiner, Tanja Schuck, Bärbel Vogel, Andreas Zahn, and Klaus Pfeilsticker
Atmos. Chem. Phys., 21, 15375–15407, https://doi.org/10.5194/acp-21-15375-2021, https://doi.org/10.5194/acp-21-15375-2021, 2021
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Airborne total bromine (Brtot) and tracer measurements suggest Brtot-rich air masses persistently protruded into the lower stratosphere (LS), creating a high Brtot region over the North Atlantic in fall 2017. The main source is via isentropic transport by the Asian monsoon and to a lesser extent transport across the extratropical tropopause as quantified by a Lagrange model. The transport of Brtot via Central American hurricanes is also observed. Lastly, the impact of Brtot on LS O3 is assessed.
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Short summary
We present an extratropical cyclone case study over the North Atlantic focusing on the role of atmospheric gravity waves (GW) in the generation of strong vertical shear and (clear-air) turbulence (CAT), as well as their impact on tracer distribution in the lowermost stratosphere. Our findings suggest that GW related processes should be considered as a key for upper troposphere lower stratosphere (UTLS) transport and mixing, and as an important candidate for the interpretation of CAT in the UTLS.
We present an extratropical cyclone case study over the North Atlantic focusing on the role of...
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