Articles | Volume 3, issue 2
https://doi.org/10.5194/wcd-3-645-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-3-645-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
15 Jun 2022
Research article |
| 15 Jun 2022
| 15 Jun 2022
Relationship between southern hemispheric jet variability and forced response: the role of the stratosphere
Department of Physics, Imperial College London, London, United Kingdom
Paulo Ceppi
Department of Physics, Imperial College London, London, United Kingdom
Grantham Institute, Imperial College London, London, United Kingdom
Theodore G. Shepherd
Department of Meteorology, University of Reading, Reading, United Kingdom
Related authors
Philipp Breul, Paulo Ceppi, and Peer Nowack
EGUsphere, https://doi.org/10.5194/egusphere-2025-221, https://doi.org/10.5194/egusphere-2025-221, 2025
Short summary
Short summary
We explore how Pacific low-level clouds influence projections of regional climate change by adjusting a climate model to enhance low cloud response to surface temperatures. We find significant changes in projected warming patterns and circulation changes, under increased CO2 conditions. Our findings are supported by similar relationships across state-of-the-art climate models. These results highlight the importance of accurately representing clouds for predicting regional climate change impacts.
Philipp Breul, Paulo Ceppi, and Theodore G. Shepherd
Weather Clim. Dynam., 4, 39–47, https://doi.org/10.5194/wcd-4-39-2023, https://doi.org/10.5194/wcd-4-39-2023, 2023
Short summary
Short summary
Accurately predicting the response of the midlatitude jet stream to climate change is very important, but models show a variety of possible scenarios. Previous work identified a relationship between climatological jet latitude and future jet shift in the southern hemispheric winter. We show that the relationship does not hold in separate sectors and propose that zonal asymmetries are the ultimate cause in the zonal mean. This questions the usefulness of the relationship.
Richard G. Williams, Philip Goodwin, Paulo Ceppi, Chris D. Jones, and Andrew MacDougall
EGUsphere, https://doi.org/10.5194/egusphere-2025-800, https://doi.org/10.5194/egusphere-2025-800, 2025
Short summary
Short summary
How the climate system responds when carbon emissions cease is an open question: some climate models reveal a slight warming, whereas most models reveal a slight cooling. Their climate response is affected by how the planet takes up heat and radiates heat back to space, and how the land and ocean sequester carbon from the atmosphere. A framework is developed to connect the temperature response of the climate models to competing and opposing-signed thermal and carbon contributions.
Philipp Breul, Paulo Ceppi, and Peer Nowack
EGUsphere, https://doi.org/10.5194/egusphere-2025-221, https://doi.org/10.5194/egusphere-2025-221, 2025
Short summary
Short summary
We explore how Pacific low-level clouds influence projections of regional climate change by adjusting a climate model to enhance low cloud response to surface temperatures. We find significant changes in projected warming patterns and circulation changes, under increased CO2 conditions. Our findings are supported by similar relationships across state-of-the-art climate models. These results highlight the importance of accurately representing clouds for predicting regional climate change impacts.
Fiona Raphaela Spuler, Marlene Kretschmer, Magdalena Alonso Balmaseda, Yevgeniya Kovalchuk, and Theodore G. Shepherd
EGUsphere, https://doi.org/10.5194/egusphere-2024-4115, https://doi.org/10.5194/egusphere-2024-4115, 2025
Short summary
Short summary
Large-scale atmospheric dynamics modulate the occurrence of extreme events and can be leveraged to improve their predictability. In this paper, we introduce a generative machine learning method to identify dynamical drivers of a relevant impact variable in the form of targeted circulation regimes. Applying the method to study extreme precipitation over Morocco, we show that these regimes are more predictive of the impact while maintaining their own predictability and physical consistency.
Henrik Auestad, Clemens Spensberger, Andrea Marcheggiani, Paulo Ceppi, Thomas Spengler, and Tim Woollings
Weather Clim. Dynam., 5, 1269–1286, https://doi.org/10.5194/wcd-5-1269-2024, https://doi.org/10.5194/wcd-5-1269-2024, 2024
Short summary
Short summary
Latent heating due to condensation can influence atmospheric circulation by strengthening or weakening horizontal temperature contrasts. Strong temperature contrasts intensify storms and imply the existence of strong upper tropospheric winds called jets. It remains unclear whether latent heating preferentially reinforces or abates the existing jet. We show that this disagreement is attributable to how the jet is defined, confirming that latent heating reinforces the jet.
Sebastian Sippel, Clair Barnes, Camille Cadiou, Erich Fischer, Sarah Kew, Marlene Kretschmer, Sjoukje Philip, Theodore G. Shepherd, Jitendra Singh, Robert Vautard, and Pascal Yiou
Weather Clim. Dynam., 5, 943–957, https://doi.org/10.5194/wcd-5-943-2024, https://doi.org/10.5194/wcd-5-943-2024, 2024
Short summary
Short summary
Winter temperatures in central Europe have increased. But cold winters can still cause problems for energy systems, infrastructure, or human health. Here we tested whether a record-cold winter, such as the one observed in 1963 over central Europe, could still occur despite climate change. The answer is yes: it is possible, but it is very unlikely. Our results rely on climate model simulations and statistical rare event analysis. In conclusion, society must be prepared for such cold winters.
Sarah Wilson Kemsley, Paulo Ceppi, Hendrik Andersen, Jan Cermak, Philip Stier, and Peer Nowack
Atmos. Chem. Phys., 24, 8295–8316, https://doi.org/10.5194/acp-24-8295-2024, https://doi.org/10.5194/acp-24-8295-2024, 2024
Short summary
Short summary
Aiming to inform parameter selection for future observational constraint analyses, we incorporate five candidate meteorological drivers specifically targeting high clouds into a cloud controlling factor framework within a range of spatial domain sizes. We find a discrepancy between optimal domain size for predicting locally and globally aggregated cloud radiative anomalies and identify upper-tropospheric static stability as an important high-cloud controlling factor.
Wilson C. H. Chan, Nigel W. Arnell, Geoff Darch, Katie Facer-Childs, Theodore G. Shepherd, and Maliko Tanguy
Nat. Hazards Earth Syst. Sci., 24, 1065–1078, https://doi.org/10.5194/nhess-24-1065-2024, https://doi.org/10.5194/nhess-24-1065-2024, 2024
Short summary
Short summary
The most recent drought in the UK was declared in summer 2022. We pooled a large sample of plausible winters from seasonal hindcasts and grouped them into four clusters based on their atmospheric circulation configurations. Drought storylines representative of what the drought could have looked like if winter 2022/23 resembled each winter circulation storyline were created to explore counterfactuals of how bad the 2022 drought could have been over winter 2022/23 and beyond.
Philip Goodwin, Richard Williams, Paulo Ceppi, and B. B. Cael
EGUsphere, https://doi.org/10.5194/egusphere-2023-2307, https://doi.org/10.5194/egusphere-2023-2307, 2023
Preprint archived
Short summary
Short summary
Climate feedbacks are normally evaluated by considering the change over time for Earth's energy balance and surface temperatures in the climate system. However, we only have around 1 degree Celsius of temperature change to utilise. Here, climate feedbacks are instead evaluated from the change in latitude of Earth's energy balance and surface temperatures, where we have around 70 degrees Celsius of temperature change to utilise.
Philipp Breul, Paulo Ceppi, and Theodore G. Shepherd
Weather Clim. Dynam., 4, 39–47, https://doi.org/10.5194/wcd-4-39-2023, https://doi.org/10.5194/wcd-4-39-2023, 2023
Short summary
Short summary
Accurately predicting the response of the midlatitude jet stream to climate change is very important, but models show a variety of possible scenarios. Previous work identified a relationship between climatological jet latitude and future jet shift in the southern hemispheric winter. We show that the relationship does not hold in separate sectors and propose that zonal asymmetries are the ultimate cause in the zonal mean. This questions the usefulness of the relationship.
Wilson C. H. Chan, Theodore G. Shepherd, Katie Facer-Childs, Geoff Darch, and Nigel W. Arnell
Hydrol. Earth Syst. Sci., 26, 1755–1777, https://doi.org/10.5194/hess-26-1755-2022, https://doi.org/10.5194/hess-26-1755-2022, 2022
Short summary
Short summary
We select the 2010–2012 UK drought and investigate an alternative unfolding of the drought from changes to its attributes. We created storylines of drier preconditions, alternative seasonal contributions, a third dry winter, and climate change. Storylines of the 2010–2012 drought show alternative situations that could have resulted in worse conditions than observed. Event-based storylines exploring plausible situations are used that may lead to high impacts and help stress test existing systems.
Beatriz M. Monge-Sanz, Alessio Bozzo, Nicholas Byrne, Martyn P. Chipperfield, Michail Diamantakis, Johannes Flemming, Lesley J. Gray, Robin J. Hogan, Luke Jones, Linus Magnusson, Inna Polichtchouk, Theodore G. Shepherd, Nils Wedi, and Antje Weisheimer
Atmos. Chem. Phys., 22, 4277–4302, https://doi.org/10.5194/acp-22-4277-2022, https://doi.org/10.5194/acp-22-4277-2022, 2022
Short summary
Short summary
The stratosphere is emerging as one of the keys to improve tropospheric weather and climate predictions. This study provides evidence of the role the stratospheric ozone layer plays in improving weather predictions at different timescales. Using a new ozone modelling approach suitable for high-resolution global models that provide operational forecasts from days to seasons, we find significant improvements in stratospheric meteorological fields and stratosphere–troposphere coupling.
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
Short summary
Short summary
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.
Linda van Garderen, Frauke Feser, and Theodore G. Shepherd
Nat. Hazards Earth Syst. Sci., 21, 171–186, https://doi.org/10.5194/nhess-21-171-2021, https://doi.org/10.5194/nhess-21-171-2021, 2021
Short summary
Short summary
The storyline method is used to quantify the effect of climate change on a particular extreme weather event using a global atmospheric model by simulating the event with and without climate change. We present the method and its successful application for the climate change signals of the European 2003 and the Russian 2010 heatwaves.
Marlene Kretschmer, Giuseppe Zappa, and Theodore G. Shepherd
Weather Clim. Dynam., 1, 715–730, https://doi.org/10.5194/wcd-1-715-2020, https://doi.org/10.5194/wcd-1-715-2020, 2020
Short summary
Short summary
The winds in the polar stratosphere affect the weather in the mid-latitudes, making it important to understand potential changes in response to global warming. However, climate model projections disagree on how this so-called polar vortex will change in the future. Here we show that sea ice loss in the Barents and Kara (BK) seas plays a central role in this. The time when the BK seas become ice-free differs between models, which explains some of the disagreement regarding vortex projections.
Cited articles
Barnes, E. A. and Hartmann, D. L.: Testing a Theory for the Effect of Latitude on the Persistence of Eddy-Driven Jets Using CMIP3 Simulations, Geophys. Res. Lett., 37, L15801, https://doi.org/10.1029/2010GL044144, 2010. a, b, c
Barnes, E. A. and Polvani, L.: Response of the Midlatitude Jets, and of
Their Variability, to Increased Greenhouse Gases in the CMIP5
Models, J. Climate, 26, 7117–7135, https://doi.org/10.1175/JCLI-D-12-00536.1, 2013. a
Barnes, E. A. and Thompson, D. W. J.: Comparing the Roles of Barotropic versus Baroclinic Feedbacks in the Atmosphere's Response to Mechanical Forcing, J. Atmos. Sci., 71, 177–194,
https://doi.org/10.1175/JAS-D-13-070.1, 2014. a, b, c
Barsugli, J. J. and Battisti, D. S.: The Basic Effects of Atmosphere – Ocean Thermal Coupling on Midlatitude Variability, J. Atmos. Sci., 55, 477–493, https://doi.org/10.1175/1520-0469(1998)055<0477:TBEOAO>2.0.CO;2, 1998. a
Breul, P.: WCD_2021-78_Code, figshare [code], https://doi.org/10.6084/m9.figshare.20051258.v1, 2022a. a
Breul, P.: Data, figshare [data set], https://doi.org/10.6084/m9.figshare.20055467.v1, 2022b. a
Byrne, N. J., Shepherd, T. G., and Polichtchouk, I.: Subseasonal-to-Seasonal Predictability of the Southern Hemisphere Eddy-Driven Jet During Austral Spring and Early Summer, J. Geophys. Res.-Atmos., 124, 6841–6855, https://doi.org/10.1029/2018JD030173, 2019. a
Ceppi, P. and Shepherd, T. G.: The Role of the Stratospheric Polar Vortex for the Austral Jet Response to Greenhouse Gas Forcing, Geophys. Res. Lett., 46, 6972–6979, https://doi.org/10.1029/2019GL082883, 2019. a, b, c
Ceppi, P., Zelinka, M. D., and Hartmann, D. L.: The Response of the Southern Hemispheric Eddy-Driven Jet to Future Changes in Shortwave Radiation in CMIP5, Geophys. Res. Lett., 41, 3244–3250,
https://doi.org/10.1002/2014GL060043, 2014. a
Cooper, F. C. and Haynes, P. H.: Climate Sensitivity via a Nonparametric
Fluctuation–Dissipation Theorem, J. Atmos. Sci., 68, 937–953, https://doi.org/10.1175/2010JAS3633.1, 2011. a, b
Cooper, F. C., Esler, J. G., and Haynes, P. H.: Estimation of the local response to a forcing in a high dimensional system using the fluctuation-dissipation theorem, Nonlin. Processes Geophys., 20, 239–248, https://doi.org/10.5194/npg-20-239-2013, 2013. a
Curtis, P. E., Ceppi, P., and Zappa, G.: Role of the Mean State for the Southern Hemispheric Jet Stream Response to CO2 Forcing in CMIP6 Models, Environ. Res. Lett., 15, 064011, https://doi.org/10.1088/1748-9326/ab8331, 2020. a
Fuchs, D., Sherwood, S., and Hernandez, D.: An Exploration of Multivariate Fluctuation Dissipation Operators and Their Response to Sea Surface Temperature Perturbations, J. Atmos. Sci., 72, 472–486, https://doi.org/10.1175/JAS-D-14-0077.1, 2015. a, b, c
Gerber, E. P., Polvani, L. M., and Ancukiewicz, D.: Annular Mode Time Scales in the Intergovernmental Panel on Climate Change Fourth Assessment Report Models, Geophys. Res. Lett., 35, L22707, https://doi.org/10.1029/2008GL035712, 2008a. a, b
Gerber, E. P., Voronin, S., and Polvani, L. M.: Testing the Annular Mode Autocorrelation Time Scale in Simple Atmospheric General Circulation Models, Mon. Weather Rev., 136, 1523–1536, https://doi.org/10.1175/2007MWR2211.1, 2008b. a
Gerber, E. P., Baldwin, M. P., Akiyoshi, H., Austin, J., Bekki, S., Braesicke, P., Butchart, N., Chipperfield, M., Dameris, M., Dhomse, S., Frith, S. M., Garcia, R. R., Garny, H., Gettelman, A., Hardiman, S. C., Karpechko, A., Marchand, M., Morgenstern, O., Nielsen, J. E., Pawson, S., Peter, T., Plummer, D. A., Pyle, J. A., Rozanov, E., Scinocca, J. F., Shepherd, T. G., and Smale, D.: Stratosphere-Troposphere Coupling and Annular Mode Variability in Chemistry-Climate Models, J. Geophys. Res.-Atmos., 115, D00M06, https://doi.org/10.1029/2009JD013770, 2010. a, b
Gritsun, A. and Branstator, G.: Numerical aspects of applying the fluctuation dissipation theorem to study climate system sensitivity to external forcings, Russ. J. Numer. Anal. M., 31, 339–354, https://doi.org/10.1515/rnam-2016-0032, 2016. a, b
Harvey, B. J., Shaffrey, L. C., and Woollings, T. J.: Equator-to-Pole
Temperature Differences and the Extra-Tropical Storm Track Responses of the
CMIP5 Climate Models, Clim. Dynam., 43, 1171–1182,
https://doi.org/10.1007/s00382-013-1883-9, 2014. a
Hassanzadeh, P. and Kuang, Z.: The Linear Response Function of an Idealized Atmosphere. Part II: Implications for the Practical Use of the Fluctuation–Dissipation Theorem and the Role of Operator’s Nonnormality, J. Atmos. Sci., 73, 3441–3452, https://doi.org/10.1175/JAS-D-16-0099.1, 2016. a, b, c, d
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., Chiara, G. D., Dahlgren, P., Dee, D., Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer, A., Haimberger, L., Healy, S., Hogan, R. J., Hólm, E., Janisková, M., Keeley, S., Laloyaux, P., Lopez, P., Lupu, C., Radnoti, G., de Rosnay, P., Rozum, I., Vamborg, F., Villaume, S., and Thépaut, J.-N.: The ERA5 Global Reanalysis, Q. J. Roy. Meteor. Soc., 146, 1999–2049, https://doi.org/10.1002/qj.3803, 2020. a
Kretschmer, M., Adams, S. V., Arribas, A., Prudden, R., Robinson, N., Saggioro, E., and Shepherd, T. G.: Quantifying Causal Pathways of
Teleconnections, B. Am. Meteorol. Soc., 102,
E2247–E2263, https://doi.org/10.1175/BAMS-D-20-0117.1, 2021. a
Leith, C. E.: Climate Response and Fluctuation Dissipation, J. Atmos. Sci., 32, 2022–2026, https://doi.org/10.1175/1520-0469(1975)032<2022:CRAFD>2.0.CO;2, 1975. a, b
Lutsko, N. J., Held, I. M., and Zurita-Gotor, P.: Applying the Fluctuation–Dissipation Theorem to a Two-Layer Model of Quasigeostrophic Turbulence, J. Atmos. Sci., 72, 3161–3177, https://doi.org/10.1175/JAS-D-14-0356.1, 2015. a
Majda, A. J., Gershgorin, B., and Yuan, Y.: Low-Frequency Climate Response and Fluctuation–Dissipation Theorems: Theory and Practice, J. Atmos. Sci., 67, 1186–1201, https://doi.org/10.1175/2009JAS3264.1, 2010. a, b, c
Ring, M. J. and Plumb, R. A.: The Response of a Simplified GCM to Axisymmetric Forcings: Applicability of the Fluctuation–Dissipation Theorem, J. Atmos. Sci., 65, 3880–3898, https://doi.org/10.1175/2008JAS2773.1, 2008. a, b, c, d
Shepherd, T. G.: Atmospheric Circulation as a Source of Uncertainty in Climate Change Projections, Nat. Geosci., 7, 703–708, https://doi.org/10.1038/ngeo2253, 2014. a
Sheshadri, A., Plumb, R. A., Lindgren, E. A., and Domeisen, D. I. V.: The Vertical Structure of Annular Modes, J. Atmos. Sci., 75, 3507–3519, https://doi.org/10.1175/JAS-D-17-0399.1, 2018. a
Simpson, I. R. and Polvani, L. M.: Revisiting the Relationship between Jet Position, Forced Response, and Annular Mode Variability in the Southern Midlatitudes: SH Jet Latitudes, Jet Shifts and the SAM, Geophys. Res. Lett., 43, 2896–2903, https://doi.org/10.1002/2016GL067989, 2016. a, b, c, d, e, f, g, h
Simpson, I. R., Shepherd, T. G., Hitchcock, P., and Scinocca, J. F.: Southern Annular Mode Dynamics in Observations and Models. Part II: Eddy Feedbacks, J. Climate, 26, 5220–5241, https://doi.org/10.1175/JCLI-D-12-00495.1, 2013. a
Vallis, G. K., Gerber, E. P., Kushner, P. J., and Cash, B. A.: A Mechanism and Simple Dynamical Model of the North Atlantic Oscillation and Annular Modes, J. Atmos. Sci., 61, 264–280,
https://doi.org/10.1175/1520-0469(2004)061<0264:AMASDM>2.0.CO;2, 2004. a
Wilcox, L. J. and Charlton-Perez, A. J.: Final Warming of the Southern Hemisphere Polar Vortex in High- and Low-Top CMIP5 Models, J. Geophys. Res.-Atmos., 118, 2535–2546, https://doi.org/10.1002/jgrd.50254, 2013. a
Short summary
Understanding how the mid-latitude jet stream will respond to a changing climate is highly important. Unfortunately, climate models predict a wide variety of possible responses. Theoretical frameworks can link an internal jet variability timescale to its response. However, we show that stratospheric influence approximately doubles the internal timescale, inflating predicted responses. We demonstrate an approach to account for the stratospheric influence and recover correct response predictions.
Understanding how the mid-latitude jet stream will respond to a changing climate is highly...
