Articles | Volume 21, issue 12
https://doi.org/10.5194/acp-21-9839-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-21-9839-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
01 Jul 2021
Research article |
| 01 Jul 2021
| 01 Jul 2021
Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruption
Min-Jee Kang
Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
Hye-Yeong Chun
CORRESPONDING AUTHOR
Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea
Related authors
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.
Min-Jee Kang, Hye-Yeong Chun, and Rolando R. Garcia
Atmos. Chem. Phys., 20, 14669–14693, https://doi.org/10.5194/acp-20-14669-2020, https://doi.org/10.5194/acp-20-14669-2020, 2020
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In winter 2015/16, the descent of the westerly quasi-biennial oscillation (QBO) jet was interrupted by easterly winds. We find that Rossby–gravity and inertia–gravity waves weaken the jet core in early stages, and small-scale convective gravity waves, as well as horizontal and vertical components of Rossby waves, reverse the wind sign in later stages. The strong negative wave forcing in the tropics results from the enhanced convection, an anomalous wind profile, and barotropic instability.
Quang Thai Trinh, Silvio Kalisch, Peter Preusse, Manfred Ern, Hye-Yeong Chun, Stephen D. Eckermann, Min-Jee Kang, and Martin Riese
Atmos. Chem. Phys., 16, 7335–7356, https://doi.org/10.5194/acp-16-7335-2016, https://doi.org/10.5194/acp-16-7335-2016, 2016
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Convection is an important source of atmospheric gravity waves (GWs). In this work, scales of convective GWs seen by limb sounders were first defined based on observed spectral information. Interactions of these waves with the background were considered. Long-scale convective GWs addressed by this approach showed significant importance in driving the QBO. Zonal mean of GW momentum flux and its vertical gradients are in good agreement with respective observations provided by limb sounders.
Ji-Hee Yoo and Hye-Yeong Chun
EGUsphere, https://doi.org/10.5194/egusphere-2025-748, https://doi.org/10.5194/egusphere-2025-748, 2025
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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This study revisits the Southern Hemisphere’s only major sudden stratospheric warming in September 2002, marked by an unprecedented polar vortex split. In addition to upward-propagating planetary wave 2 (PW2), westward PW2 generated in situ by barotropic–baroclinic instability, contributed to the vortex split. Unstable PW2 growth resulted from nonlinear wave-wave interactions and over-reflection. Vortex destabilization occurred as the anomalously poleward-shifted vortex reversed to easterlies.
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
Short summary
Short summary
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.
Soo-Hyun Kim, Jeonghoe Kim, Jung-Hoon Kim, and Hye-Yeong Chun
Atmos. Meas. Tech., 15, 2277–2298, https://doi.org/10.5194/amt-15-2277-2022, https://doi.org/10.5194/amt-15-2277-2022, 2022
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The cube root of the energy dissipation rate (EDR), as a standard reporting metric of atmospheric turbulence, is estimated using 1 Hz commercial quick access recorder data from Korean-based national air carriers with two different types of aircraft. Various EDRs are estimated using zonal, meridional, and derived vertical wind components and the derived equivalent vertical gust. Characteristics of the observed EDR estimates using 1 Hz flight data are examined to observe strong turbulence cases.
Min-Jee Kang, Hye-Yeong Chun, and Rolando R. Garcia
Atmos. Chem. Phys., 20, 14669–14693, https://doi.org/10.5194/acp-20-14669-2020, https://doi.org/10.5194/acp-20-14669-2020, 2020
Short summary
Short summary
In winter 2015/16, the descent of the westerly quasi-biennial oscillation (QBO) jet was interrupted by easterly winds. We find that Rossby–gravity and inertia–gravity waves weaken the jet core in early stages, and small-scale convective gravity waves, as well as horizontal and vertical components of Rossby waves, reverse the wind sign in later stages. The strong negative wave forcing in the tropics results from the enhanced convection, an anomalous wind profile, and barotropic instability.
In-Sun Song, Changsup Lee, Hye-Yeong Chun, Jeong-Han Kim, Geonhwa Jee, Byeong-Gwon Song, and Julio T. Bacmeister
Atmos. Chem. Phys., 20, 7617–7644, https://doi.org/10.5194/acp-20-7617-2020, https://doi.org/10.5194/acp-20-7617-2020, 2020
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A modeling study on the effects of propagation of atmospheric gravity waves is carried out for the 2009 sudden stratospheric warming (SSW) event. It is found that gravity-wave-induced momentum fluxes are significantly affected by horizontal refraction and the Earth's curvature effects. Gravity wave convergence and effects of ray geometry also have some impact. In the evolution of the SSW, significantly enhanced momentum fluxes are likely to change nonlocally nearby large-scale vortex structures.
Soo-Hyun Kim, Hye-Yeong Chun, Jung-Hoon Kim, Robert D. Sharman, and Matt Strahan
Atmos. Meas. Tech., 13, 1373–1385, https://doi.org/10.5194/amt-13-1373-2020, https://doi.org/10.5194/amt-13-1373-2020, 2020
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We retrieve the eddy dissipation rate (EDR) from the derived equivalent vertical gust included in the Aircraft Meteorological Data Relay data for more reliable and consistent observations of aviation turbulence globally with the single preferred EDR metric. We convert the DEVG to the EDR using two methods (lognormal mapping scheme and best-fit curve between EDR and DEVG), and the DEVG-derived EDRs are evaluated against in situ EDR data reported by US-operated carriers.
Neal Butchart, James A. Anstey, Kevin Hamilton, Scott Osprey, Charles McLandress, Andrew C. Bushell, Yoshio Kawatani, Young-Ha Kim, Francois Lott, John Scinocca, Timothy N. Stockdale, Martin Andrews, Omar Bellprat, Peter Braesicke, Chiara Cagnazzo, Chih-Chieh Chen, Hye-Yeong Chun, Mikhail Dobrynin, Rolando R. Garcia, Javier Garcia-Serrano, Lesley J. Gray, Laura Holt, Tobias Kerzenmacher, Hiroaki Naoe, Holger Pohlmann, Jadwiga H. Richter, Adam A. Scaife, Verena Schenzinger, Federico Serva, Stefan Versick, Shingo Watanabe, Kohei Yoshida, and Seiji Yukimoto
Geosci. Model Dev., 11, 1009–1032, https://doi.org/10.5194/gmd-11-1009-2018, https://doi.org/10.5194/gmd-11-1009-2018, 2018
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This paper documents the numerical experiments to be used in phase 1 of the Stratosphere–troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi), which was set up to improve the representation of the QBO and tropical stratospheric variability in global climate models.
Byeong-Gwon Song and Hye-Yeong Chun
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-729, https://doi.org/10.5194/acp-2016-729, 2016
Revised manuscript not accepted
Quang Thai Trinh, Silvio Kalisch, Peter Preusse, Manfred Ern, Hye-Yeong Chun, Stephen D. Eckermann, Min-Jee Kang, and Martin Riese
Atmos. Chem. Phys., 16, 7335–7356, https://doi.org/10.5194/acp-16-7335-2016, https://doi.org/10.5194/acp-16-7335-2016, 2016
Short summary
Short summary
Convection is an important source of atmospheric gravity waves (GWs). In this work, scales of convective GWs seen by limb sounders were first defined based on observed spectral information. Interactions of these waves with the background were considered. Long-scale convective GWs addressed by this approach showed significant importance in driving the QBO. Zonal mean of GW momentum flux and its vertical gradients are in good agreement with respective observations provided by limb sounders.
Young-Ha Kim, Hye-Yeong Chun, Sang-Hun Park, In-Sun Song, and Hyun-Joo Choi
Atmos. Chem. Phys., 16, 4799–4815, https://doi.org/10.5194/acp-16-4799-2016, https://doi.org/10.5194/acp-16-4799-2016, 2016
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We investigated the characteristics of atmospheric gravity waves that are generated in a baroclinic life cycle simulation using a high-resolution global model. We analysed the spatiotemporal scales, vertical-propagation aspects, and sources of the gravity waves as well as their phase-velocity spectrum. The wave characteristics investigated in this study are crucial information for parameterizing gravity waves in large-scale models.
Y.-H. Kim and H.-Y. Chun
Atmos. Chem. Phys., 15, 6577–6587, https://doi.org/10.5194/acp-15-6577-2015, https://doi.org/10.5194/acp-15-6577-2015, 2015
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The momentum forcing of the stratospheric quasi-biennial oscillation (QBO) by equatorial waves is estimated using recent reanalysis data sets. The Kelvin wave produces primary forcing of the QBO in the easterly-to-westerly transition phase below 30hPa, whereas mesoscale gravity waves produce larger forcing than the Kelvin wave above 30hPa. Still, the recent reanalyses underestimate the forcing by the large-scale equatorial waves.
Q. T. Trinh, S. Kalisch, P. Preusse, H.-Y. Chun, S. D. Eckermann, M. Ern, and M. Riese
Atmos. Meas. Tech., 8, 1491–1517, https://doi.org/10.5194/amt-8-1491-2015, https://doi.org/10.5194/amt-8-1491-2015, 2015
J. Y. Jia, P. Preusse, M. Ern, H.-Y. Chun, J. C. Gille, S. D. Eckermann, and M. Riese
Ann. Geophys., 32, 1373–1394, https://doi.org/10.5194/angeo-32-1373-2014, https://doi.org/10.5194/angeo-32-1373-2014, 2014
S. H. Kim, H.-Y. Chun, and W. Jang
Atmos. Chem. Phys., 14, 3175–3182, https://doi.org/10.5194/acp-14-3175-2014, https://doi.org/10.5194/acp-14-3175-2014, 2014
Related subject area
Subject: Dynamics | Research Activity: Atmospheric Modelling and Data Analysis | Altitude Range: Stratosphere | Science Focus: Physics (physical properties and processes)
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
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
Stratospheric Aerosol Intervention Experiment for the Chemistry-Climate Model Intercomparison Project
Age of air from in situ trace gas measurements: insights from a new technique
Tropospheric links to uncertainty in stratospheric subseasonal predictions
Explaining the period fluctuation of the quasi-biennial oscillation
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
Lagrangian Coherent Structures to Examine Mixing in the Stratosphere
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
Climate impact of volcanic eruptions: the sensitivity to eruption season and latitude in MPI-ESM ensemble experiments
Differences in the quasi-biennial oscillation response to stratospheric aerosol modification depending on injection strategy and species
The advective Brewer–Dobson circulation in the ERA5 reanalysis: climatology, variability, and trends
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.
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.
Simone Tilmes, Ewa M. Bednarz, Andrin Jörimann, Daniele Visioni, Douglas E. Kinnison, Gabriel Chiodo, and David Plummer
EGUsphere, https://doi.org/10.5194/egusphere-2024-3586, https://doi.org/10.5194/egusphere-2024-3586, 2024
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This paper describes the details of a new multi-model intercomparison experiment to assess the effects of Stratospheric Aerosol Injections on stratospheric chemistry and dynamics and, therefore, ozone. In this experiment, all models will use the same prescribed stratospheric aerosol distribution and fixed sea-surface temperatures and sea ice. We discuss the advantages and differences of this more constrained experiment compared to previous more interactive model experiments.
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.
Young-Ha Kim
EGUsphere, https://doi.org/10.5194/egusphere-2024-3195, https://doi.org/10.5194/egusphere-2024-3195, 2024
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The paper addresses a fundamental but unresolved question about the 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.
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.
Jezabel Curbelo and Marianna Linz
EGUsphere, https://doi.org/10.5194/egusphere-2024-1348, https://doi.org/10.5194/egusphere-2024-1348, 2024
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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.
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.
Zhihong Zhuo, Ingo Kirchner, Stephan Pfahl, and Ulrich Cubasch
Atmos. Chem. Phys., 21, 13425–13442, https://doi.org/10.5194/acp-21-13425-2021, https://doi.org/10.5194/acp-21-13425-2021, 2021
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The impact of volcanic eruptions varies with eruption season and latitude. This study simulated eruptions at different latitudes and in different seasons with a fully coupled climate model. The climate impacts of northern and southern hemispheric eruptions are reversed but are insensitive to eruption season. Results suggest that the regional climate impacts are due to the dynamical response of the climate system to radiative effects of volcanic aerosols and the subsequent regional feedbacks.
Henning Franke, Ulrike Niemeier, and Daniele Visioni
Atmos. Chem. Phys., 21, 8615–8635, https://doi.org/10.5194/acp-21-8615-2021, https://doi.org/10.5194/acp-21-8615-2021, 2021
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Stratospheric aerosol modification (SAM) can alter the quasi-biennial oscillation (QBO). Our simulations with two different models show that the characteristics of the QBO response are primarily determined by the meridional structure of the aerosol-induced heating. Therefore, the QBO response to SAM depends primarily on the location of injection, while injection type and rate act to scale the specific response. Our results have important implications for evaluating adverse side effects of SAM.
Mohamadou Diallo, Manfred Ern, and Felix Ploeger
Atmos. Chem. Phys., 21, 7515–7544, https://doi.org/10.5194/acp-21-7515-2021, https://doi.org/10.5194/acp-21-7515-2021, 2021
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Despite good agreement in the spatial structure, there are substantial differences in the strength of the Brewer–Dobson circulation (BDC) and its modulations in the UTLS and upper stratosphere. The tropical upwelling is generally weaker in ERA5 than in ERAI due to weaker planetary and gravity wave breaking in the UTLS. Analysis of the BDC trend shows an acceleration of the BDC of about 1.5 % decade-1 due to the long-term intensification in wave breaking, consistent with climate predictions.
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Short summary
In winter 2019/20, the westerly quasi-biennial oscillation (QBO) phase was disrupted again by easterly winds. It is found that strong Rossby waves from the Southern Hemisphere weaken the jet core in early stages, and strong mixed Rossby–gravity waves reverse the wind in later stages. Inertia–gravity waves and small-scale convective gravity waves also provide negative forcing. These strong waves are attributed to an anomalous wind profile, barotropic instability, and slightly strong convection.
In winter 2019/20, the westerly quasi-biennial oscillation (QBO) phase was disrupted again by...
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