Articles | Volume 20, issue 21
Research article 30 Oct 2020
Research article | 30 Oct 2020
Using the climate feedback response analysis method to quantify climate feedbacks in the middle atmosphere
Maartje Sanne Kuilman et al.
Maartje Sanne Kuilman and Bodil Karlsson
Atmos. Chem. Phys., 18, 4217–4228,Short summary
In this study, we investigate the role of the winter residual circulation in the summer mesopause region using the Whole Atmosphere Community Climate Model. In addition, we study the role of the summer stratosphere in shaping the conditions of the summer polar mesosphere. We strengthen the evidence that the variability in the summer mesopause region is mainly driven by changes in the summer mesosphere rather than in the summer stratosphere.
Zixuan Han, Qiong Zhang, Qiang Li, Ran Feng, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Bette L. Otto-Bliesner, Esther C. Brady, Nan Rosenbloom, Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Kerim H. Nisancioglu, Christian Stepanek, Gerrit Lohmann, Linda E. Sohl, Mark A. Chandler, Ning Tan, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, W. Richard Peltier, Charles J. R. Williams, Daniel J. Lunt, Jianbo Cheng, Qin Wen, and Natalie J. Burls
Clim. Past Discuss.,
Preprint under review for CPShort summary
Understanding the potential processes responsible for large-scale hydrological cycle changes in a warmer climate is of great importance. Our study implies that an imbalance of interhemispheric atmospheric energy during the mid-Pliocene could have led to changes in the dynamic effect, offsetting the thermodynamic effect and hence altering mid-Pliocene hydroclimate cycling. Besides, a robust westward shift in Pacific Walker circulation can moisten the northern Indian Ocean.
Arthur Merlijn Oldeman, Michiel L. J. Baatsen, Anna S. von der Heydt, Henk A. Dijkstra, Julia C. Tindall, Ayako Abe-Ouchi, Alice R. Booth, Esther C. Brady, Wing-Le Chan, Deepak Chandan, Mark A. Chandler, Camille Contoux, Ran Feng, Chuncheng Guo, Alan M. Haywood, Stephen J. Hunter, Youichi Kamae, Qiang Li, Xiangyu Li, Gerrit Lohmann, Daniel J. Lunt, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, W. Richard Peltier, Gabriel M. Pontes, Gilles Ramstein, Linda E. Sohl, Christian Stepanek, Ning Tan, Qiong Zhang, Zhongshi Zhang, Ilana Wainer, and Charles J. R. Williams
Clim. Past Discuss.,
Preprint under review for CPShort summary
In this work, we have studied the behaviour of El Niño events in the mid-Pliocene, a period of around three million years ago, using a collection of seventeen climate models. It is an interesting period to study, as it saw similar atmospheric carbon dioxide levels as the present-day. We find that the El Niño events were less strong in the mid-Pliocene simulations, when compared to pre-industrial climate. Our results could help to interpret El Niño behaviour in future climate projections.
Qiong Zhang, Ellen Berntell, Josefine Axelsson, Jie Chen, Zixuan Han, Wesley de Nooijer, Zhengyao Lu, Qiang Li, Qiang Zhang, Klaus Wyser, and Shuting Yang
Geosci. Model Dev., 14, 1147–1169,Short summary
Paleoclimate modelling has long been regarded as a strong out-of-sample test bed of the climate models that are used for the projection of future climate changes. Here, we document the model experimental setups for the three past warm periods with EC-Earth3-LR and present the results on the large-scale features. The simulations demonstrate good performance of the model in capturing the climate response under different climate forcings.
Ellen Berntell, Qiong Zhang, Qiang Li, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Kerim H. Nisancioglu, Christian Stepanek, Gerrit Lohmann, Linda E. Sohl, Mark A. Chandler, Ning Tan, Camille Contoux, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, William Richard Peltier, Ayako Abe-Ouchi, Wing-Le Chan, Youichi Kamae, Charles J. R. Williams, and Dan Lunt
Clim. Past Discuss.,
Revised manuscript accepted for CPShort summary
The mid-Pliocene Warm Period (~3.2 Ma) is often considered an analogue for near-future climate projections, and model results from the PlioMIP2 ensemble show a robust increase of rainfall over West Africa and the Sahara region compared to pre-industrial conditions. Though previous studies of future projections indicate a west/east drying/wetting contrast over Sahel, these results indicate a uniform rainfall increase over Sahel in warm climates characterized by increased greenhouse gas forcing.
Zhongshi Zhang, Xiangyu Li, Chuncheng Guo, Odd Helge Otterå, Kerim H. Nisancioglu, Ning Tan, Camille Contoux, Gilles Ramstein, Ran Feng, Bette L. Otto-Bliesner, Esther Brady, Deepak Chandan, W. Richard Peltier, Michiel L. J. Baatsen, Anna S. von der Heydt, Julia E. Weiffenbach, Christian Stepanek, Gerrit Lohmann, Qiong Zhang, Qiang Li, Mark A. Chandler, Linda E. Sohl, Alan M. Haywood, Stephen J. Hunter, Julia C. Tindall, Charles Williams, Daniel J. Lunt, Wing-Le Chan, and Ayako Abe-Ouchi
Clim. Past, 17, 529–543,Short summary
The Atlantic Meridional Overturning Circulation (AMOC) is an important topic in the Pliocene Model Intercomparison Project. Previous studies have suggested a much stronger AMOC during the Pliocene than today. However, our current multi-model intercomparison shows large model spreads and model–data discrepancies, which can not support the previous hypothesis. Our study shows good consistency with future projections of the AMOC.
Ralf Döscher, Mario Acosta, Andrea Alessandri, Peter Anthoni, Almut Arneth, Thomas Arsouze, Tommi Bergmann, Raffaele Bernadello, Souhail Bousetta, Louis-Philippe Caron, Glenn Carver, Miguel Castrillo, Franco Catalano, Ivana Cvijanovic, Paolo Davini, Evelien Dekker, Francisco J. Doblas-Reyes, David Docquier, Pablo Echevarria, Uwe Fladrich, Ramon Fuentes-Franco, Matthias Gröger, Jost v. Hardenberg, Jenny Hieronymus, M. Pasha Karami, Jukka-Pekka Keskinen, Torben Koenigk, Risto Makkonen, Francois Massonnet, Martin Ménégoz, Paul A. Miller, Eduardo Moreno-Chamarro, Lars Nieradzik, Twan van Noije, Paul Nolan, Declan O’Donnell, Pirkka Ollinaho, Gijs van den Oord, Pablo Ortega, Oriol Tintó Prims, Arthur Ramos, Thomas Reerink, Clement Rousset, Yohan Ruprich-Robert, Philippe Le Sager, Torben Schmith, Roland Schrödner, Federico Serva, Valentina Sicardi, Marianne Sloth Madsen, Benjamin Smith, Tian Tian, Etienne Tourigny, Petteri Uotila, Martin Vancoppenolle, Shiyu Wang, David Wårlind, Ulrika Willén, Klaus Wyser, Shuting Yang, Xavier Yepes-Arbós, and Qiong Zhang
Geosci. Model Dev. Discuss.,
Revised manuscript under review for GMDShort summary
The Earth System Model EC-Earth3 is documented here. Key performance metrics show physical behaviour and biases well within the frame known from recent models. With improved physical and dynamic features, new ESM components, community tools, and largely improved physical performance compared to the CMIP5 version, EC-Earth3 represents a clear step forward for the only European community ESM. We demonstrate here that EC-Earth3 is suited for a range of tasks in CMIP6 and beyond.
Bette L. Otto-Bliesner, Esther C. Brady, Anni Zhao, Chris M. Brierley, Yarrow Axford, Emilie Capron, Aline Govin, Jeremy S. Hoffman, Elizabeth Isaacs, Masa Kageyama, Paolo Scussolini, Polychronis C. Tzedakis, Charles J. R. Williams, Eric Wolff, Ayako Abe-Ouchi, Pascale Braconnot, Silvana Ramos Buarque, Jian Cao, Anne de Vernal, Maria Vittoria Guarino, Chuncheng Guo, Allegra N. LeGrande, Gerrit Lohmann, Katrin J. Meissner, Laurie Menviel, Polina A. Morozova, Kerim H. Nisancioglu, Ryouta O'ishi, David Salas y Mélia, Xiaoxu Shi, Marie Sicard, Louise Sime, Christian Stepanek, Robert Tomas, Evgeny Volodin, Nicholas K. H. Yeung, Qiong Zhang, Zhongshi Zhang, and Weipeng Zheng
Clim. Past, 17, 63–94,Short summary
The CMIP6–PMIP4 Tier 1 lig127k experiment was designed to address the climate responses to strong orbital forcing. We present a multi-model ensemble of 17 climate models, most of which have also completed the CMIP6 DECK experiments and are thus important for assessing future projections. The lig127ksimulations show strong summer warming over the NH continents. More than half of the models simulate a retreat of the Arctic minimum summer ice edge similar to the average for 2000–2018.
Masa Kageyama, Louise C. Sime, Marie Sicard, Maria-Vittoria Guarino, Anne de Vernal, Ruediger Stein, David Schroeder, Irene Malmierca-Vallet, Ayako Abe-Ouchi, Cecilia Bitz, Pascale Braconnot, Esther C. Brady, Jian Cao, Matthew A. Chamberlain, Danny Feltham, Chuncheng Guo, Allegra N. LeGrande, Gerrit Lohmann, Katrin J. Meissner, Laurie Menviel, Polina Morozova, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, Ryouta O'ishi, Silvana Ramos Buarque, David Salas y Melia, Sam Sherriff-Tadano, Julienne Stroeve, Xiaoxu Shi, Bo Sun, Robert A. Tomas, Evgeny Volodin, Nicholas K. H. Yeung, Qiong Zhang, Zhongshi Zhang, Weipeng Zheng, and Tilo Ziehn
Clim. Past, 17, 37–62,Short summary
The Last interglacial (ca. 127 000 years ago) is a period with increased summer insolation at high northern latitudes, resulting in a strong reduction in Arctic sea ice. The latest PMIP4-CMIP6 models all simulate this decrease, consistent with reconstructions. However, neither the models nor the reconstructions agree on the possibility of a seasonally ice-free Arctic. Work to clarify the reasons for this model divergence and the conflicting interpretations of the records will thus be needed.
Wesley de Nooijer, Qiong Zhang, Qiang Li, Qiang Zhang, Xiangyu Li, Zhongshi Zhang, Chuncheng Guo, Kerim H. Nisancioglu, Alan M. Haywood, Julia C. Tindall, Stephen J. Hunter, Harry J. Dowsett, Christian Stepanek, Gerrit Lohmann, Bette L. Otto-Bliesner, Ran Feng, Linda E. Sohl, Mark A. Chandler, Ning Tan, Camille Contoux, Gilles Ramstein, Michiel L. J. Baatsen, Anna S. von der Heydt, Deepak Chandan, W. Richard Peltier, Ayako Abe-Ouchi, Wing-Le Chan, Youichi Kamae, and Chris M. Brierley
Clim. Past, 16, 2325–2341,Short summary
The simulations for the past climate can inform us about the performance of climate models in different climate scenarios. Here, we analyse Arctic warming in an ensemble of 16 simulations of the mid-Pliocene Warm Period (mPWP), when the CO2 level was comparable to today. The results highlight the importance of slow feedbacks in the model simulations and imply that we must be careful when using simulations of the mPWP as an analogue for future climate change.
Alan M. Haywood, Julia C. Tindall, Harry J. Dowsett, Aisling M. Dolan, Kevin M. Foley, Stephen J. Hunter, Daniel J. Hill, Wing-Le Chan, Ayako Abe-Ouchi, Christian Stepanek, Gerrit Lohmann, Deepak Chandan, W. Richard Peltier, Ning Tan, Camille Contoux, Gilles Ramstein, Xiangyu Li, Zhongshi Zhang, Chuncheng Guo, Kerim H. Nisancioglu, Qiong Zhang, Qiang Li, Youichi Kamae, Mark A. Chandler, Linda E. Sohl, Bette L. Otto-Bliesner, Ran Feng, Esther C. Brady, Anna S. von der Heydt, Michiel L. J. Baatsen, and Daniel J. Lunt
Clim. Past, 16, 2095–2123,Short summary
The large-scale features of middle Pliocene climate from the 16 models of PlioMIP Phase 2 are presented. The PlioMIP2 ensemble average was ~ 3.2 °C warmer and experienced ~ 7 % more precipitation than the pre-industrial era, although there are large regional variations. PlioMIP2 broadly agrees with a new proxy dataset of Pliocene sea surface temperatures. Combining PlioMIP2 and proxy data suggests that a doubling of atmospheric CO2 would increase globally averaged temperature by 2.6–4.8 °C.
Chris M. Brierley, Anni Zhao, Sandy P. Harrison, Pascale Braconnot, Charles J. R. Williams, David J. R. Thornalley, Xiaoxu Shi, Jean-Yves Peterschmitt, Rumi Ohgaito, Darrell S. Kaufman, Masa Kageyama, Julia C. Hargreaves, Michael P. Erb, Julien Emile-Geay, Roberta D'Agostino, Deepak Chandan, Matthieu Carré, Partrick J. Bartlein, Weipeng Zheng, Zhongshi Zhang, Qiong Zhang, Hu Yang, Evgeny M. Volodin, Robert A. Tomas, Cody Routson, W. Richard Peltier, Bette Otto-Bliesner, Polina A. Morozova, Nicholas P. McKay, Gerrit Lohmann, Allegra N. Legrande, Chuncheng Guo, Jian Cao, Esther Brady, James D. Annan, and Ayako Abe-Ouchi
Clim. Past, 16, 1847–1872,Short summary
This paper provides an initial exploration and comparison to climate reconstructions of the new climate model simulations of the mid-Holocene (6000 years ago). These use state-of-the-art models developed for CMIP6 and apply the same experimental set-up. The models capture several key aspects of the climate, but some persistent issues remain.
Josephine R. Brown, Chris M. Brierley, Soon-Il An, Maria-Vittoria Guarino, Samantha Stevenson, Charles J. R. Williams, Qiong Zhang, Anni Zhao, Ayako Abe-Ouchi, Pascale Braconnot, Esther C. Brady, Deepak Chandan, Roberta D'Agostino, Chuncheng Guo, Allegra N. LeGrande, Gerrit Lohmann, Polina A. Morozova, Rumi Ohgaito, Ryouta O'ishi, Bette L. Otto-Bliesner, W. Richard Peltier, Xiaoxu Shi, Louise Sime, Evgeny M. Volodin, Zhongshi Zhang, and Weipeng Zheng
Clim. Past, 16, 1777–1805,Short summary
El Niño–Southern Oscillation (ENSO) is the largest source of year-to-year variability in the current climate, but the response of ENSO to past or future changes in climate is uncertain. This study compares the strength and spatial pattern of ENSO in a set of climate model simulations in order to explore how ENSO changes in different climates, including past cold glacial climates and past climates with different seasonal cycles, as well as gradual and abrupt future warming cases.
Martin Renoult, James Douglas Annan, Julia Catherine Hargreaves, Navjit Sagoo, Clare Flynn, Marie-Luise Kapsch, Qiang Li, Gerrit Lohmann, Uwe Mikolajewicz, Rumi Ohgaito, Xiaoxu Shi, Qiong Zhang, and Thorsten Mauritsen
Clim. Past, 16, 1715–1735,Short summary
Interest in past climates as sources of information for the climate system has grown in recent years. In particular, studies of the warm mid-Pliocene and cold Last Glacial Maximum showed relationships between the tropical surface temperature of the Earth and its sensitivity to an abrupt doubling of atmospheric CO2. In this study, we develop a new and promising statistical method and obtain similar results as previously observed, wherein the sensitivity does not seem to exceed extreme values.
Charlotta Högberg, Stefan Lossow, Farahnaz Khosrawi, Ralf Bauer, Kaley A. Walker, Patrick Eriksson, Donal P. Murtagh, Gabriele P. Stiller, Jörg Steinwagner, and Qiong Zhang
Atmos. Chem. Phys., 19, 2497–2526,Short summary
Five δD (H2O) data sets obtained from satellite observations have been evaluated using profile-to-profile and climatological comparisons. The focus is on stratospheric altitudes, but results from the upper troposphere to the lower mesosphere are also provided. There are clear quantitative differences in the δD ratio in key areas of scientific interest, resulting in difficulties drawing robust conclusions on atmospheric processes affecting the water vapour budget and distribution.
Jianqiu Zheng, Qiong Zhang, Qiang Li, Qiang Zhang, and Ming Cai
Clim. Past, 15, 291–305,Short summary
This paper addresses two important issues with the EC-Earth Pliocene simulation, including the following: (1) quantification of albedo and insulation effects of Arctic sea ice on interface heat exchange and (2) an explanation as to why Arctic amplification in surface air temperature (SST) peaks in winter while there is maximum SST warming in summer. These issues provide potential implications for researching Arctic amplification and climate change.
Maartje Sanne Kuilman and Bodil Karlsson
Atmos. Chem. Phys., 18, 4217–4228,Short summary
In this study, we investigate the role of the winter residual circulation in the summer mesopause region using the Whole Atmosphere Community Climate Model. In addition, we study the role of the summer stratosphere in shaping the conditions of the summer polar mesosphere. We strengthen the evidence that the variability in the summer mesopause region is mainly driven by changes in the summer mesosphere rather than in the summer stratosphere.
Masa Kageyama, Pascale Braconnot, Sandy P. Harrison, Alan M. Haywood, Johann H. Jungclaus, Bette L. Otto-Bliesner, Jean-Yves Peterschmitt, Ayako Abe-Ouchi, Samuel Albani, Patrick J. Bartlein, Chris Brierley, Michel Crucifix, Aisling Dolan, Laura Fernandez-Donado, Hubertus Fischer, Peter O. Hopcroft, Ruza F. Ivanovic, Fabrice Lambert, Daniel J. Lunt, Natalie M. Mahowald, W. Richard Peltier, Steven J. Phipps, Didier M. Roche, Gavin A. Schmidt, Lev Tarasov, Paul J. Valdes, Qiong Zhang, and Tianjun Zhou
Geosci. Model Dev., 11, 1033–1057,Short summary
The Paleoclimate Modelling Intercomparison Project (PMIP) takes advantage of the existence of past climate states radically different from the recent past to test climate models used for climate projections and to better understand these climates. This paper describes the PMIP contribution to CMIP6 (Coupled Model Intercomparison Project, 6th phase) and possible analyses based on PMIP results, as well as on other CMIP6 projects.
Johann H. Jungclaus, Edouard Bard, Mélanie Baroni, Pascale Braconnot, Jian Cao, Louise P. Chini, Tania Egorova, Michael Evans, J. Fidel González-Rouco, Hugues Goosse, George C. Hurtt, Fortunat Joos, Jed O. Kaplan, Myriam Khodri, Kees Klein Goldewijk, Natalie Krivova, Allegra N. LeGrande, Stephan J. Lorenz, Jürg Luterbacher, Wenmin Man, Amanda C. Maycock, Malte Meinshausen, Anders Moberg, Raimund Muscheler, Christoph Nehrbass-Ahles, Bette I. Otto-Bliesner, Steven J. Phipps, Julia Pongratz, Eugene Rozanov, Gavin A. Schmidt, Hauke Schmidt, Werner Schmutz, Andrew Schurer, Alexander I. Shapiro, Michael Sigl, Jason E. Smerdon, Sami K. Solanki, Claudia Timmreck, Matthew Toohey, Ilya G. Usoskin, Sebastian Wagner, Chi-Ju Wu, Kok Leng Yeo, Davide Zanchettin, Qiong Zhang, and Eduardo Zorita
Geosci. Model Dev., 10, 4005–4033,Short summary
Climate model simulations covering the last millennium provide context for the evolution of the modern climate and for the expected changes during the coming centuries. They can help identify plausible mechanisms underlying palaeoclimatic reconstructions. Here, we describe the forcing boundary conditions and the experimental protocol for simulations covering the pre-industrial millennium. We describe the PMIP4 past1000 simulations as contributions to CMIP6 and additional sensitivity experiments.
Bette L. Otto-Bliesner, Pascale Braconnot, Sandy P. Harrison, Daniel J. Lunt, Ayako Abe-Ouchi, Samuel Albani, Patrick J. Bartlein, Emilie Capron, Anders E. Carlson, Andrea Dutton, Hubertus Fischer, Heiko Goelzer, Aline Govin, Alan Haywood, Fortunat Joos, Allegra N. LeGrande, William H. Lipscomb, Gerrit Lohmann, Natalie Mahowald, Christoph Nehrbass-Ahles, Francesco S. R. Pausata, Jean-Yves Peterschmitt, Steven J. Phipps, Hans Renssen, and Qiong Zhang
Geosci. Model Dev., 10, 3979–4003,Short summary
The PMIP4 and CMIP6 mid-Holocene and Last Interglacial simulations provide an opportunity to examine the impact of two different changes in insolation forcing on climate at times when other forcings were relatively similar to present. This will allow exploration of the role of feedbacks relevant to future projections. Evaluating these simulations using paleoenvironmental data will provide direct out-of-sample tests of the reliability of state-of-the-art models to simulate climate changes.
Masa Kageyama, Samuel Albani, Pascale Braconnot, Sandy P. Harrison, Peter O. Hopcroft, Ruza F. Ivanovic, Fabrice Lambert, Olivier Marti, W. Richard Peltier, Jean-Yves Peterschmitt, Didier M. Roche, Lev Tarasov, Xu Zhang, Esther C. Brady, Alan M. Haywood, Allegra N. LeGrande, Daniel J. Lunt, Natalie M. Mahowald, Uwe Mikolajewicz, Kerim H. Nisancioglu, Bette L. Otto-Bliesner, Hans Renssen, Robert A. Tomas, Qiong Zhang, Ayako Abe-Ouchi, Patrick J. Bartlein, Jian Cao, Qiang Li, Gerrit Lohmann, Rumi Ohgaito, Xiaoxu Shi, Evgeny Volodin, Kohei Yoshida, Xiao Zhang, and Weipeng Zheng
Geosci. Model Dev., 10, 4035–4055,Short summary
The Last Glacial Maximum (LGM, 21000 years ago) is an interval when global ice volume was at a maximum, eustatic sea level close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. This paper describes the implementation of the LGM numerical experiment for the PMIP4-CMIP6 modelling intercomparison projects and the associated sensitivity experiments.
Michiel M. Helsen, Roderik S. W. van de Wal, Thomas J. Reerink, Richard Bintanja, Marianne S. Madsen, Shuting Yang, Qiang Li, and Qiong Zhang
The Cryosphere, 11, 1949–1965,Short summary
Ice sheets reflect most incoming solar radiation back into space due to their high reflectivity (albedo). The albedo of ice sheets changes as a function of, for example, liquid water content and ageing of snow. In this study we have improved the description of albedo over the Greenland ice sheet in a global climate model. This is an important step, which also improves estimates of the annual ice mass gain or loss over the ice sheet using this global climate model.
M. Ballarotta, F. Roquet, S. Falahat, Q. Zhang, and G. Madec
Clim. Past Discuss.,
Revised manuscript not acceptedShort summary
We investigate the impact of the ocean geothermal heating (OGH) on a glacial ocean state using numerical simulations. We found that the OGH is a significant forcing of the abyssal ocean and thermohaline circulation. Applying the OGH warms the Antarctic Bottom Water by ~0.4°C and strengthens the deep circulation by 15% to 30%. The geothermally heated waters are advected from the Indo-Pacific to the North Atlantic basin, indirectly favouring the deep convection in the North Atlantic.
J. Seguinot, C. Khroulev, I. Rogozhina, A. P. Stroeven, and Q. Zhang
The Cryosphere, 8, 1087–1103,
Related subject area
Subject: Dynamics | Research Activity: Atmospheric Modelling | Altitude Range: Stratosphere | Science Focus: Physics (physical properties and processes)Contributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruptionDifferences in the quasi-biennial oscillation response to stratospheric aerosol modification depending on injection strategy and speciesThe advective Brewer–Dobson circulation in the ERA5 reanalysis: climatology, variability, and trendsIs our dynamical understanding of the circulation changes associated with the Antarctic ozone hole sensitive to the choice of reanalysis dataset?The impact of increasing stratospheric radiative damping on the quasi-biennial oscillation periodAnalysis of recent lower-stratospheric ozone trends in chemistry climate modelsAsymmetry and pathways of inter-hemispheric transport in the upper troposphere and lower stratosphereEffects of prescribed CMIP6 ozone on simulating the Southern Hemisphere atmospheric circulation response to ozone depletionReanalysis intercomparison of potential vorticity and potential-vorticity-based diagnosticsClimate impact of volcanic eruptions: the sensitivity to eruption season and latitude in MPI-ESM ensemble experimentsInfluence of the El Niño–Southern Oscillation on entry stratospheric water vapor in coupled chemistry–ocean CCMI and CMIP6 modelsReappraising the appropriate calculation of a common meteorological quantity: potential temperatureImpact of Lagrangian transport on lower-stratospheric transport timescales in a climate modelRole of equatorial waves and convective gravity waves in the 2015/16 quasi-biennial oscillation disruptionSensitivity of the Southern Hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistryCharacterizing quasi-biweekly variability of the Asian monsoon anticyclone using potential vorticity and large-scale geopotential height fieldClimatological impact of the Brewer–Dobson circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalysesPolar stratospheric clouds initiated by mountain waves in a global chemistry–climate model: a missing piece in fully modelling polar stratospheric ozone depletionDeep-convective influence on the upper troposphere–lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign resultsThe effect of interactive ozone chemistry on weak and strong stratospheric polar vortex eventsLagrangian gravity wave spectra in the lower stratosphere of current (re)analysesRepresentation of the equatorial stratopause semiannual oscillation in global atmospheric reanalysesA convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphereSensitivity of age of air trends to the derivation method for non-linear increasing inert SF6Adding value to extended-range forecasts in northern Europe by statistical post-processing using stratospheric observationsPropagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming eventFuture trends in stratosphere-to-troposphere transport in CCMI modelsSimulating age of air and the distribution of SF6 in the stratosphere with the SILAM modelA tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortexTemperature and tropopause characteristics from reanalyses data in the tropical tropopause layerThe efficiency of transport into the stratosphere via the Asian and North American summer monsoon circulationsEvidence of small-scale quasi-isentropic mixing in ridges of extratropical baroclinic wavesThe effect of atmospheric nudging on the stratospheric residual circulation in chemistry–climate modelsOn the representation of major stratospheric warmings in reanalysesInfluence of Arctic stratospheric ozone on surface climate in CCMI modelsQuantification of water vapour transport from the Asian monsoon to the stratosphereExtratropical age of air trends and causative factors in climate projection simulationsComposite analysis of the tropopause inversion layer in extratropical baroclinic wavesLagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipeDeriving stratospheric age of air spectra using an idealized set of chemically active trace gasesThe global diabatic circulation of the stratosphere as a metric for the Brewer–Dobson circulationThe importance of interactive chemistry for stratosphere–troposphere couplingFrom ERA-Interim to ERA5: the considerable impact of ECMWF's next-generation reanalysis on Lagrangian transport simulationsOn the value of reanalyses prior to 1979 for dynamical studies of stratosphere–troposphere couplingThe influence of mixing on the stratospheric age of air changes in the 21st centuryStructural changes in the shallow and transition branch of the Brewer–Dobson circulation induced by El NiñoQuantifying the variability of the annular modes: reanalysis uncertainty vs. sampling uncertaintyResponse of Arctic ozone to sudden stratospheric warmingsLong-range transport of volcanic aerosol from the 2010 Merapi tropical eruption to AntarcticaComparison of mean age of air in five reanalyses using the BASCOE transport model
Min-Jee Kang and Hye-Yeong Chun
Atmos. Chem. Phys., 21, 9839–9857,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.
Henning Franke, Ulrike Niemeier, and Daniele Visioni
Atmos. Chem. Phys., 21, 8615–8635,Short summary
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,Short summary
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.
Andrew Orr, Hua Lu, Patrick Martineau, Edwin P. Gerber, Gareth J. Marshall, and Thomas J. Bracegirdle
Atmos. Chem. Phys., 21, 7451–7472,Short summary
Reanalysis datasets combine observations and weather forecast simulations to create our best estimate of the state of the atmosphere and are important for climate monitoring. Differences in the technical details of these products mean that they may give different results. This study therefore examined how changes associated with the so-called Antarctic ozone hole are represented, which is one of the most important climate changes in recent decades, and showed that they were broadly consistent.
Tiehan Zhou, Kevin DallaSanta, Larissa Nazarenko, Gavin A. Schmidt, and Zhonghai Jin
Atmos. Chem. Phys., 21, 7395–7407,Short summary
Stratospheric radiative damping increases with rising CO2. Sensitivity experiments using the one-dimensional mechanistic models of the quasi-biennial oscillation (QBO) indicate a shortening of the simulated QBO period due to the enhancing of the radiative damping. This result suggests that increasing radiative damping may play a role in determining the QBO period in a warming climate along with wave momentum flux entering the stratosphere and tropical vertical residual velocity.
Simone Dietmüller, Hella Garny, Roland Eichinger, and William T. Ball
Atmos. Chem. Phys., 21, 6811–6837,
Xiaolu Yan, Paul Konopka, Marius Hauck, Aurélien Podglajen, and Felix Ploeger
Atmos. Chem. Phys., 21, 6627–6645,Short summary
Inter-hemispheric transport is important for understanding atmospheric tracers because of the asymmetry in emissions between the Southern Hemisphere (SH) and Northern Hemisphere (NH). This study finds that the air masses from the NH extratropics to the atmosphere are about 5 times larger than those from the SH extratropics. The interplay between the Asian summer monsoon and westerly ducts triggers the cross-Equator transport from the NH to the SH in boreal summer and fall.
Ioana Ivanciu, Katja Matthes, Sebastian Wahl, Jan Harlaß, and Arne Biastoch
Atmos. Chem. Phys., 21, 5777–5806,Short summary
The Antarctic ozone hole has driven substantial dynamical changes in the Southern Hemisphere atmosphere over the past decades. This study separates the historical impacts of ozone depletion from those of rising levels of greenhouse gases and investigates how these impacts are captured in two types of climate models: one using interactive atmospheric chemistry and one prescribing the CMIP6 ozone field. The effects of ozone depletion are more pronounced in the model with interactive chemistry.
Luis F. Millán, Gloria L. Manney, and Zachary D. Lawrence
Atmos. Chem. Phys., 21, 5355–5376,Short summary
We assess how consistently reanalyses represent potential vorticity (PV) among each other. PV helps describe dynamical processes in the stratosphere because it acts approximately as a tracer of the movement of air parcels; it is extensively used to identify the location of the tropopause and to identify and characterize the stratospheric polar vortex. Overall, PV from all reanalyses agrees well with the reanalysis ensemble mean.
Zhihong Zhuo, Ingo Kirchner, Stephan Pfahl, and Ulrich Cubasch
Atmos. Chem. Phys. Discuss.,
Preprint under review for ACPShort summary
The impact of volcanic eruptions varies with eruption season and latitude. This study simulated eruptions at different latitude 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.
Chaim I. Garfinkel, Ohad Harari, Shlomi Ziskin Ziv, Jian Rao, Olaf Morgenstern, Guang Zeng, Simone Tilmes, Douglas Kinnison, Fiona M. O'Connor, Neal Butchart, Makoto Deushi, Patrick Jöckel, Andrea Pozzer, and Sean Davis
Atmos. Chem. Phys., 21, 3725–3740,Short summary
Water vapor is the dominant greenhouse gas in the atmosphere, and El Niño is the dominant mode of variability in the ocean–atmosphere system. The connection between El Niño and water vapor above ~ 17 km is unclear, with single-model studies reaching a range of conclusions. This study examines this connection in 12 different models. While there are substantial differences among the models, all models appear to capture the fundamental physical processes correctly.
Manuel Baumgartner, Ralf Weigel, Allan H. Harvey, Felix Plöger, Ulrich Achatz, and Peter Spichtinger
Atmos. Chem. Phys., 20, 15585–15616,Short summary
The potential temperature is routinely used in atmospheric science. We review its derivation and suggest a new potential temperature, based on a temperature-dependent parameterization of the dry air's specific heat capacity. Moreover, we compare the new potential temperature to the common one and discuss the differences which become more important at higher altitudes. Finally, we indicate some consequences of using the new potential temperature in typical applications.
Edward J. Charlesworth, Ann-Kristin Dugstad, Frauke Fritsch, Patrick Jöckel, and Felix Plöger
Atmos. Chem. Phys., 20, 15227–15245,Short summary
Modeling the stratosphere requires models with good representations of chemical transport. To do this, nearly all models divide the atmosphere into boxes. This creates some unwanted problems. However, the only other option is to divide the atmosphere into balloons, and this method is very complicated. Here, we use a model which uses this balloon-like method to estimate the impacts of this method on chemical transport. We find significant differences in sensitive regions of the stratosphere.
Min-Jee Kang, Hye-Yeong Chun, and Rolando R. Garcia
Atmos. Chem. Phys., 20, 14669–14693,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.
Sabine Haase, Jaika Fricke, Tim Kruschke, Sebastian Wahl, and Katja Matthes
Atmos. Chem. Phys., 20, 14043–14061,Short summary
Ozone depletion over Antarctica was shown to influence the tropospheric jet in the Southern Hemisphere. We investigate the atmospheric response to ozone depletion comparing climate model ensembles with interactive and prescribed ozone fields. We show that allowing feedbacks between ozone chemistry and model physics as well as including asymmetries in ozone leads to a strengthened ozone depletion signature in the stratosphere but does not significantly affect the tropospheric jet position.
Arata Amemiya and Kaoru Sato
Atmos. Chem. Phys., 20, 13857–13876,Short summary
The spatial pattern of subseasonal variability of the Asian monsoon anticyclone (AMA) is analyzed using long-term reanalysis data, integrating two different views using potential vorticity and the geopotential height anomaly. This study provides a link between two existing description of the Asian monsoon anticyclone, which is important for the understanding of the whole life cycle of its characteristic subseasonal variability pattern.
Daniele Minganti, Simon Chabrillat, Yves Christophe, Quentin Errera, Marta Abalos, Maxime Prignon, Douglas E. Kinnison, and Emmanuel Mahieu
Atmos. Chem. Phys., 20, 12609–12631,Short summary
The climatology of the N2O transport budget in the stratosphere is studied in the transformed Eulerian mean framework across a variety of datasets: a chemistry climate model, a chemistry transport model driven by four reanalyses and a chemical reanalysis. The impact of vertical advection on N2O agrees well in the datasets, but horizontal mixing presents large differences above the Antarctic and in the whole Northern Hemisphere.
Andrew Orr, J. Scott Hosking, Aymeric Delon, Lars Hoffmann, Reinhold Spang, Tracy Moffat-Griffin, James Keeble, Nathan Luke Abraham, and Peter Braesicke
Atmos. Chem. Phys., 20, 12483–12497,Short summary
Polar stratospheric clouds (PSCs) are clouds found in the Antarctic winter stratosphere and are implicated in the formation of the ozone hole. These clouds can sometimes be formed or enhanced by mountain waves, formed as air passes over hills or mountains. However, this important mechanism is missing in coarse-resolution climate models, limiting our ability to simulate ozone. This study examines an attempt to include the effects of mountain waves and their impact on PSCs and ozone.
Silvia Bucci, Bernard Legras, Pasquale Sellitto, Francesco D'Amato, Silvia Viciani, Alessio Montori, Antonio Chiarugi, Fabrizio Ravegnani, Alexey Ulanovsky, Francesco Cairo, and Fred Stroh
Atmos. Chem. Phys., 20, 12193–12210,Short summary
The paper presents and evaluates a transport analysis method to study the convective injection of air in the upper troposphere–lower stratosphere of the Asian monsoon anticyclone region. The approach is thereby used to analyse the trace gas data collected during the StratoClim aircraft campaign. The results showed that fresh convective air can be injected fast at a high level of the atmosphere (above 17 km), with potential impacts on the stratospheric chemistry of the Northern Hemisphere.
Jessica Oehrlein, Gabriel Chiodo, and Lorenzo M. Polvani
Atmos. Chem. Phys., 20, 10531–10544,Short summary
Winter winds in the stratosphere 10–50 km above the surface impact climate at the surface. Prior studies suggest that this interaction between the stratosphere and the surface is affected by ozone. We compare two ways of including ozone in computer simulations of climate. One method is more realistic but more expensive. We find that the method of including ozone in simulations affects the surface climate when the stratospheric winds are unusually weak but not when they are unusually strong.
Aurélien Podglajen, Albert Hertzog, Riwal Plougonven, and Bernard Legras
Atmos. Chem. Phys., 20, 9331–9350,Short summary
Thanks to the increase in resolution, numerical weather prediction models resolve a growing fraction of the gravity wave (GW) spectrum. Here, we assess the representation of Lagrangian GW fluctuations by comparing trajectories in the models to long-duration balloon observations. Most characteristics of the observed GW spectrum, such as near-inertial oscillations, are qualitatively present. However, the variability remains underestimated, emphasizing the continuous need for GW parameterizations.
Yoshio Kawatani, Toshihiko Hirooka, Kevin Hamilton, Anne K. Smith, and Masatomo Fujiwara
Atmos. Chem. Phys., 20, 9115–9133,Short summary
This paper reports on a project to compare the representation of the semiannual oscillation (SAO) among six major global atmospheric reanalyses and with recent satellite observations. The differences among the zonal mean zonal wind as represented by the various reanalyses display a prominent equatorial maximum that increases with height. It is shown that assimilation of satellite temperature measurements is crucial for the realistic representation of the tropical upper stratospheric circulation.
Marius Hauck, Harald Bönisch, Peter Hoor, Timo Keber, Felix Ploeger, Tanja J. Schuck, and Andreas Engel
Atmos. Chem. Phys., 20, 8763–8785,Short summary
This study features an extended inversion method that includes transport across the extratropical tropopause to derive age spectra in the lowermost stratosphere from in situ trace gas measurements. The refined method is validated in a model setup and applied to data gained with the HALO research aircraft. Results are congruent with the findings of previous studies so that the method provides a promising toolset for the analysis of stratospheric dynamics based on observations in the future.
Frauke Fritsch, Hella Garny, Andreas Engel, Harald Bönisch, and Roland Eichinger
Atmos. Chem. Phys., 20, 8709–8725,Short summary
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.
Natalia Korhonen, Otto Hyvärinen, Matti Kämäräinen, David S. Richardson, Heikki Järvinen, and Hilppa Gregow
Atmos. Chem. Phys., 20, 8441–8451,Short summary
Reanalysis data of the strength of the polar vortex is applied in the post-processing of the European Centre for Medium-Range Weather Forecasts (ECMWF) winter surface temperature forecasts for weeks 3–4 and 5–6 over northern Europe. In this way, the skill scores of these forecasts are slightly improved. It is also found that, in cases where the polar vortex was weak at the start of the forecast, the mean skill scores of these forecasts were higher than average.
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,Short summary
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.
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,Short summary
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.
Rostislav Kouznetsov, Mikhail Sofiev, Julius Vira, and Gabriele Stiller
Atmos. Chem. Phys., 20, 5837–5859,Short summary
Estimates of the age of stratospheric air (AoA), its distribution, and trends, obtained by different experimental methods, differ among each other. AoA derived form MIPAS satellite observations, the richest observational dataset on sulfur hexafluoride (SF6) in the stratosphere, are a clear outlier. With multi-decade simulations of AoA and SF6 in the stratosphere, we show that the origin of the discrepancy is in a methodology of deriving AoA from observations rather than in observational data.
Koji Yamazaki, Tetsu Nakamura, Jinro Ukita, and Kazuhira Hoshi
Atmos. Chem. Phys., 20, 5111–5127,Short summary
It has been well known that the stratospheric quasi-biennial oscillation (QBO) affects the winter Arctic polar vortex. This relation has been explained through stratospheric processes. We show that a tropospheric process also plays a role, especially in early winter, based on data analysis and numerical simulations. The QBO modifies tropical convection, which affects planetary waves in the midlatitude troposphere, then modulating vertical propagation and the polar vortex.
Susann Tegtmeier, James Anstey, Sean Davis, Rossana Dragani, Yayoi Harada, Ioana Ivanciu, Robin Pilch Kedzierski, Kirstin Krüger, Bernard Legras, Craig Long, James S. Wang, Krzysztof Wargan, and Jonathon S. Wright
Atmos. Chem. Phys., 20, 753–770,Short summary
The tropical tropopause layer is an important atmospheric region right in between the troposphere and the stratosphere. We evaluate the representation of this layer in reanalyses data sets, which create a complete picture of the state of Earth's atmosphere using atmospheric modeling and available observations. The recent reanalyses show realistic temperatures in the tropical tropopause layer. However, where the temperature is lowest, the so-called cold point, the reanalyses are too cold.
Xiaolu Yan, Paul Konopka, Felix Ploeger, Aurélien Podglajen, Jonathon S. Wright, Rolf Müller, and Martin Riese
Atmos. Chem. Phys., 19, 15629–15649,Short summary
The Asian and North American summer monsoons (ASM and NASM) have considerable influence on stratospheric chemistry and physics. More air mass is transported from the monsoon regions to the tropical stratosphere when the tracers are released clearly below the tropopause than when they are released close to the tropopause. Results for different altitudes of air origin reveal two transport pathways (monsoon and tropical) from the upper troposphere over the monsoon regions to the tropical pipe.
Daniel Kunkel, Peter Hoor, Thorsten Kaluza, Jörn Ungermann, Björn Kluschat, Andreas Giez, Hans-Christoph Lachnitt, Martin Kaufmann, and Martin Riese
Atmos. Chem. Phys., 19, 12607–12630,Short summary
In this study we present a mixing process around the tropopause in extratropical baroclinic waves. We analyze airborne data from a flight during the WISE campaign in autumn 2017 over the North Atlantic. We use idealized experiments to study the mixing process. Although the process occurs on a small geographical scale, it might be of importance due to its relation to a frequent feature of the extratropical UTLS. The process is relevant for STE but is not fully included in climatologies.
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,Short summary
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.
Blanca Ayarzagüena, Froila M. Palmeiro, David Barriopedro, Natalia Calvo, Ulrike Langematz, and Kiyotaka Shibata
Atmos. Chem. Phys., 19, 9469–9484,Short summary
Sudden stratospheric warmings (SSWs) are abrupt rises in the wintertime polar stratosphere that also affect the troposphere. Their study is hampered by the limited observations in the stratosphere and mostly relies on reanalyses, i.e., models that include observations. Here we compare the representation of SSWs by the most used reanalyses. SSW results are consistent across reanalyses but some differences are found, in particular before the satellite era.
Ohad Harari, Chaim I. Garfinkel, Shlomi Ziskin Ziv, Olaf Morgenstern, Guang Zeng, Simone Tilmes, Douglas Kinnison, Makoto Deushi, Patrick Jöckel, Andrea Pozzer, Fiona M. O'Connor, and Sean Davis
Atmos. Chem. Phys., 19, 9253–9268,Short summary
Ozone depletion in the Antarctic has been shown to influence surface conditions, but the effects of ozone depletion in the Arctic on surface climate are unclear. We show that Arctic ozone does influence surface climate in both polar regions and tropical regions, though the proximate cause of these surface impacts is not yet clear.
Matthias Nützel, Aurélien Podglajen, Hella Garny, and Felix Ploeger
Atmos. Chem. Phys., 19, 8947–8966,Short summary
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,Short summary
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.
Thorsten Kaluza, Daniel Kunkel, and Peter Hoor
Atmos. Chem. Phys., 19, 6621–6636,Short summary
We present a comprehensive mean evolution of the tropopause inversion layer in mid-latitudes, an atmospheric feature that is located in the region that separates the well-mixed troposphere and the stably stratified stratosphere. We counter-intuitively find this region, which is expected to stabilise atmospheric flow, to exhibit favourable conditions for turbulent exchange between troposphere and stratosphere. This is an important result concerning the overall assessment of exchange processes.
Bärbel Vogel, Rolf Müller, Gebhard Günther, Reinhold Spang, Sreeharsha Hanumanthu, Dan Li, Martin Riese, and Gabriele P. Stiller
Atmos. Chem. Phys., 19, 6007–6034,Short summary
We identified the transport pathways of air masses from the region of the Asian monsoon (e.g. pollution and greenhouse gases caused by increasing population and growing industries in Asia) into the lower stratosphere. Even small changes of the chemical composition of the lower stratosphere have an impact on surface climate (e.g. surface temperatures). Therefore, it is important to identify transport pathways to the stratosphere to allow potential environmental risks to be assessed.
Marius Hauck, Frauke Fritsch, Hella Garny, and Andreas Engel
Atmos. Chem. Phys., 19, 5269–5291,Short summary
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.
Marianna Linz, Marta Abalos, Anne Sasha Glanville, Douglas E. Kinnison, Alison Ming, and Jessica L. Neu
Atmos. Chem. Phys., 19, 5069–5090,Short summary
The stratospheric circulation is important for transporting ozone and water vapor, and models of the stratosphere differ. The metrics used to compare models are inconsistent between studies and cannot be calculated from observational data. In this paper, we explore a metric for the circulation that can be calculated from observations and examine how it relates to the more commonly used metrics. We find substantial differences in the upper and lower stratosphere depending on the choice of metric.
Sabine Haase and Katja Matthes
Atmos. Chem. Phys., 19, 3417–3432,Short summary
The Antarctic ozone hole influences surface climate in the Southern Hemisphere. Recent studies have shown that stratospheric ozone depletion in the Arctic can also affect the surface. We evaluate the importance of the direct and indirect representation of ozone variability in a climate model for this surface response. We show that allowing feedbacks between ozone chemistry, radiation, and dynamics enhances and prolongs the surface response to Northern Hemisphere spring ozone depletion.
Lars Hoffmann, Gebhard Günther, Dan Li, Olaf Stein, Xue Wu, Sabine Griessbach, Yi Heng, Paul Konopka, Rolf Müller, Bärbel Vogel, and Jonathon S. Wright
Atmos. Chem. Phys., 19, 3097–3124,Short summary
ECMWF's new ERA5 reanalysis provides higher spatiotemporal resolution, yielding an improved representation of meso- and synoptic-scale features of the atmosphere. We assessed the impact of this challenging new data set on Lagrangian trajectory calculations for the free troposphere and stratosphere. Key findings are considerable transport deviations between the ERA5 and ERA-Interim simulations as well as significantly improved conservation of potential temperature in the stratosphere for ERA5.
Atmos. Chem. Phys., 19, 2749–2764,Short summary
Studies of the dynamics of stratosphere–troposphere coupling benefit from long observational records in order to distinguish common dynamical features from unrelated atmospheric variability. On the basis of a comparison between a range of reanalysis products, this study argues that the period from 1958 to 1979 is of significant value in the Northern Hemisphere for this purpose, despite the lack of global satellite records.
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,Short summary
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.
Mohamadou Diallo, Paul Konopka, Michelle L. Santee, Rolf Müller, Mengchu Tao, Kaley A. Walker, Bernard Legras, Martin Riese, Manfred Ern, and Felix Ploeger
Atmos. Chem. Phys., 19, 425–446,Short summary
This paper assesses the structural changes in the shallow and transition branches of the BDC induced by El Nino using the Lagrangian model simulations driven by ERAi and JRA-55 combined with MLS observations. We found a clear evidence of a weakening of the transition branch due to an upward shift in the dissipation height of the planetary and gravity waves and a strengthening of the shallow branch due to enhanced GW breaking in the tropics–subtropics and PW breaking at high latitudes.
Edwin P. Gerber and Patrick Martineau
Atmos. Chem. Phys., 18, 17099–17117,Short summary
The annular modes characterize the variability of the extratropical circulation. We show that they are extremely consistent across all reanalyses during the satellite era (1979 onward). Consequently, uncertainty in the annual cycle of variability of the tropospheric jet streams and their coupling with the stratospheric polar vortices is dominated by sampling uncertainty. Pre-satellite reanalysis of the Northern Hemisphere appears to be of high quality and can help reduce this uncertainty.
Alvaro de la Cámara, Marta Abalos, Peter Hitchcock, Natalia Calvo, and Rolando R. Garcia
Atmos. Chem. Phys., 18, 16499–16513,Short summary
Long chemistry–climate runs are used to investigate the changes that sudden stratospheric warmings (extreme and fast disruptions of the wintertime stratospheric polar vortex) induce on Arctic ozone. Ozone increases rapidly during the onset of the events, driven by deep changes in the stratospheric transport circulation. These anomalies decay slowly, particularly in the lower stratosphere where they can last up to 2 months. Irreversible mixing makes an important contribution to this behavior.
Xue Wu, Sabine Griessbach, and Lars Hoffmann
Atmos. Chem. Phys., 18, 15859–15877,Short summary
Volcanic aerosol is an important source of sulfur for Antarctica, where local sources of sulfur are rare. Midlatitude and high-latitude volcanism can directly influence the aerosol budget of the polar stratosphere, but tropical volcanic eruptions can also enhance polar aerosols by transport. Our study investigates pathway and transport processes of volcanic aerosol from the tropics to the lower stratosphere over Antarctica by combining Lagrangian transport simulation and satellite observations.
Simon Chabrillat, Corinne Vigouroux, Yves Christophe, Andreas Engel, Quentin Errera, Daniele Minganti, Beatriz M. Monge-Sanz, Arjo Segers, and Emmanuel Mahieu
Atmos. Chem. Phys., 18, 14715–14735,Short summary
Mean age of stratospheric air is computed for the period 1989–2015 with a kinematic transport model which uses surface pressure and wind fields from five reanalyses: ERA-I, MERRA-2, MERRA, CFSR, JRA-55. The spread between the resulting datasets is as large as in climate model intercomparisons; the age trends have large disagreement and depend strongly on the considered period. We highlight the need for similar studies using diabatic transport models which also use temperature and heating rates.
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In this study, we quantify the temperature changes in the middle atmosphere due to different feedback processes using the climate feedback response analysis method. We have found that the change due to the increase in CO2 alone cools the middle atmosphere. The combined effect of the different feedbacks causes the atmosphere to cool less. The ozone feedback is the most important feedback process, while the cloud, water vapour and albedo feedback play only a minor role.
In this study, we quantify the temperature changes in the middle atmosphere due to different...