Articles | Volume 3, issue 3
https://doi.org/10.5194/wcd-3-777-2022
© 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-3-777-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
| 
21 Jul 2022
Research article | Highlight paper |
| 21 Jul 2022
| 21 Jul 2022
Trends in the tropospheric general circulation from 1979 to 2022
Adrian J. Simmons
CORRESPONDING AUTHOR
Copernicus Department, European Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading RG2 9AX, UK
Related authors
Peter W. Thorne, John M. Nicklas, John J. Kennedy, Bruce Calvert, Baylor Fox-Kemper, Mark T. Richardson, Adrian Simmons, Ed Hawkins, Robert Rhode, Kathryn Cowtan, Nerilie J. Abram, Axel Andersson, Simon Noone, Phillipe Marbaix, Nathan Lenssen, Dirk Olonscheck, Tristram Walsh, Stephen Outten, Ingo Bethke, Bjorn H. Samset, Chris Smith, Anna Pirani, Jan Fuglestvedt, Lavanya Rajamani, Richard A. Betts, Elizabeth C. Kent, Blair Trewin, Colin Morice, Tim Osborn, Samantha N. Burgess, Oliver Geden, Andrew Parnell, Piers M. Forster, Chris Hewitt, Zeke Hausfather, Valerie Masson-Delmotte, Jochem Marotzke, Nathan Gillett, Sonia I. Seneviratne, Gavin A. Schmidt, Duo Chan, Stefan Brönnimann, Andy Reisinger, Matthew Menne, Maisa Rojas Corradi, Christopher Kadow, Peter Huybers, David B. Stephenson, Emily Wallis, Joeri Rogelj, Andrew Schurer, Karen McKinnon, Panmao Zhai, Fatima Driouech, Wilfran Moufouma Okia, Saeed Vazifehkhah, Sophie Szopa, Christopher J. Merchant, Shoji Hirahara, Masayoshi Ishii, Francois A. Engelbrecht, Qingxiang Li, June-Yi Lee, Alex J. Cannon, Christophe Cassou, Karina von Schuckmann, Amir H. Delju, and Ellie Murtagh
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-825, https://doi.org/10.5194/essd-2025-825, 2026
Preprint under review for ESSD
Short summary
Short summary
We reassess the basis for determining the present level of long-term global warming. Unbiased estimates of both realised warming and anthropogenic warming are possible that approximate a 20-year retrospective mean. Our resulting estimates of 1.40 [1.23–1.58] °C (realised) and 1.34 [1.18–1.50] °C (anthropogenic) as at end of 2024 highlight the urgency of immediate, far-reaching and sustained climate mitigation actions if we are to meet the long term temperature goal of the Paris Agreement.
Peter W. Thorne, John M. Nicklas, John J. Kennedy, Bruce Calvert, Baylor Fox-Kemper, Mark T. Richardson, Adrian Simmons, Ed Hawkins, Robert Rhode, Kathryn Cowtan, Nerilie J. Abram, Axel Andersson, Simon Noone, Phillipe Marbaix, Nathan Lenssen, Dirk Olonscheck, Tristram Walsh, Stephen Outten, Ingo Bethke, Bjorn H. Samset, Chris Smith, Anna Pirani, Jan Fuglestvedt, Lavanya Rajamani, Richard A. Betts, Elizabeth C. Kent, Blair Trewin, Colin Morice, Tim Osborn, Samantha N. Burgess, Oliver Geden, Andrew Parnell, Piers M. Forster, Chris Hewitt, Zeke Hausfather, Valerie Masson-Delmotte, Jochem Marotzke, Nathan Gillett, Sonia I. Seneviratne, Gavin A. Schmidt, Duo Chan, Stefan Brönnimann, Andy Reisinger, Matthew Menne, Maisa Rojas Corradi, Christopher Kadow, Peter Huybers, David B. Stephenson, Emily Wallis, Joeri Rogelj, Andrew Schurer, Karen McKinnon, Panmao Zhai, Fatima Driouech, Wilfran Moufouma Okia, Saeed Vazifehkhah, Sophie Szopa, Christopher J. Merchant, Shoji Hirahara, Masayoshi Ishii, Francois A. Engelbrecht, Qingxiang Li, June-Yi Lee, Alex J. Cannon, Christophe Cassou, Karina von Schuckmann, Amir H. Delju, and Ellie Murtagh
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-825, https://doi.org/10.5194/essd-2025-825, 2026
Preprint under review for ESSD
Short summary
Short summary
We reassess the basis for determining the present level of long-term global warming. Unbiased estimates of both realised warming and anthropogenic warming are possible that approximate a 20-year retrospective mean. Our resulting estimates of 1.40 [1.23–1.58] °C (realised) and 1.34 [1.18–1.50] °C (anthropogenic) as at end of 2024 highlight the urgency of immediate, far-reaching and sustained climate mitigation actions if we are to meet the long term temperature goal of the Paris Agreement.
Cited articles
Bell, B., Hersbach, H., Simmons, A., Berrisford, P., Dahlgren, P., Horányi, A., Muñoz-Sabater, J., Nicolas, J., Radu, R., Schepers, D., Soci, C., Villaume, S., Bidlot, J.-R., Haimberger, L., Woollen, J., Buontempo, C., and Thépaut, J.-N.: The ERA5 global reanalysis:
Preliminary extension to 1950, Q. J. Roy. Meteor. Soc., 147, 4186–4227,
https://doi.org/10.1002/qj.4174, 2021.
Berrisford, P., Dee, D., Poli, P., Brugge, R., Fielding, K., Fuentes, M.,
Kållberg, P., Kobayashi, S., Uppala, S., and Simmons, A.: The
ERA-Interim archive, Version 2.0. ERA Report Series no. 1, 23 pp, https://www.ecmwf.int/en/elibrary/8174-era-interim-archive-version-20 (last access: 15 July 2022), 2011.
Byrne, N. J., Shepherd, T. G., Woollings, T., and Plumb, R. A.:
Nonstationarity in southern hemisphere climate variability associated with
the seasonal breakdown of the stratospheric polar vortex, J. Climate, 30,
7125–7139, https://doi.org/10.1175/JCLI-D-17-0097.1, 2017.
Cheng, L., Foster, G., Hausfather, Z., Trenberth. K. E., and Abraham, J.:
Improved quantification of the rate of ocean warming, J. Climate, 35, 4827–4840, https://doi.org/10.1175/JCLI-D-21-0895.1,
2022.
Chung, E.-S., Timmermann, A., Soden, B. J., Ha, K.-J., Shi, L., and John, V.
O.: Reconciling opposing Walker circulation trends in observations and model
projections, Nat. Clim. Chang., 9, 405–412,
https://doi.org/10.1038/s41558-019-0446-4, 2019.
de Boisséson, E., Balmaseda, M. A., Abdalla, S., Källén, E., and
Janssen, P. A. E. M.: How robust is the recent strengthening of the Tropical
Pacific trade winds?, Geophys. Res. Lett., 41, 4398–4405,
https://doi.org/10.1002/2014GL060257, 2014.
Dee D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P.,
Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P.,
Bechtold, P., Beljaars, A. C. M., van de Berg, L., Bidlot, J., Bormann, N.,
Delsol, C., Dragani, R., Fuentes, M., Geer, A. J., Haimberger, L., Healy, S.
B., Hersbach, H., Hólm, E. V., Isaksen, L., Kållberg, P.,
Köhler, M., Matricardi, M., McNally, A. P., Monge-Sanz, B. M.,
Morcrette, J.-J., Park, B.-K., Peubey, C., de Rosnay, P., Tavolato, C.,
Thépaut, J.-N., and Vitart , F.: The ERA-Interim reanalysis:
configuration and performance of the data assimilation system, Q. J. Roy. Meteor. Soc., 137, 553–597, https://doi.org/10.1002/qj.828, 2011.
Dong, B., Sutton, R. T., Shaffrey, L., and Harvey, B.: Recent decadal
weakening of the summer Eurasian westerly jet attributable to anthropogenic
aerosol emissions, Nat. Commun., 13, 1148,
https://doi.org/10.1038/s41467-022-28816-5, 2022.
Francis, J. A. and Vavrus, S. J.: Evidence linking Arctic amplification to
extreme weather in mid-latitudes, Geophys. Res. Lett., 39, L06801,
https://doi.org/10.1029/2012GL051000, 2012.
Gelaro, R., McCarty, W., Suárez, M. J., Todling, R., Molod, A., Takacs,
L., Randles, C. A., Darmenov, A., Bosilovich, M. G., Reichle, R., Wargan,
K., Coy, L., Cullather, R., Draper, C., Akella, S., Buchard, V., Conaty, A.,
da Silva, A. M., Gu, W., Kim, G., Koster, R., Lucchesi, R., Merkova, D.,
Nielsen, J. E., Partyka, G., Pawson, S., Putman, W., Rienecker, M.,
Schubert, S. D., Sienkiewicz, M., and Zhao, B.: The Modern-Era Retrospective
Analysis for Research and Applications, Version 2 (MERRA-2), J. Climate, 30,
5419–5454, https://doi.org/10.1175/JCLI-D-16-0758.1, 2017.
Gulev, S. K., Thorne, P. W., Ahn, J., Dentener, F. J., Domingues, C. M.,
Gerland, S., Gong, D., Kaufman, D. S., Nnamchi, H. C., Quaas, J., Rivera, J.
A., Sathyendranath, S., Smith, S. L., Trewin, B., von Shuckmann, K., and Vose, R. S.: Changing State of the Climate System, in: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth
Assessment Report of the Intergovernmental Panel on Climate Change, edited
by: Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Péan, C.,
Berger, S., Caud, N., Chen, Y., Goldfarb, L., Gomis, M. I., Huang, M.,
Leitzell, K., Lonnoy, E., Matthews, J. B. R., Maycock, T. K., Waterfield,
T., Yelekçi, O., Yu, R., and Zhou, B., Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA, 287–422,
https://www.ipcc.ch/report/ar6/wg1/ (last access: 15 July 2022), 2021.
Haimberger, L.: Homogenization of radiosonde temperature time series using
innovation statistics, J. Climate, 20, 1377–1403,
https://doi.org/10.1175/JCLI4050.1, 2007.
Haimberger, L., Tavolato, C., and Sperka, S.: Toward elimination of the warm
bias in historic radiosonde temperature records: Some new results from a
comprehensive intercomparison of upper-air data, J. Climate, 21, 4587–4606,
https://doi.org/10.1175/2008JCLI1929.1, 2008.
Haimberger, L., Tavolato, C., and Sperka, S.: Homogenization of the global
radiosonde temperature dataset through combined comparison with reanalysis
background series and neighboring stations, J. Climate, 25, 8108–8131,
https://doi.org/10.1175/JCLI-D-11-00668.1, 2012.
Harrington, L. J.: Temperature emergence at decision-relevant scales,
Environ. Res. Lett., 16, 094018, https://doi.org/10.1088/1748-9326/ac19dc, 2021.
Hawkins, E., Frame, D., Harrington, L. J., Joshi, M., King, A., Rojas, M.,
and Sutton, R.: Observed emergence of the climate change signal: from the
familiar to the unknown, Geophys. Res. Lett., 47, e2019GL086259,
https://doi.org/10.1029/2019GL086259, 2020.
Hersbach H., Peubey, C., Simmons, A., Berrisford, P., Poli, P., and Dee, D.:
ERA-20CM: a twentieth-century atmospheric model ensemble, Q. J. Roy. Meteor. Soc., 141, 2350–2375, https://doi.org/10.1002/qj.2528, 2015.
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., De Chiara, G., Dahlgren, P., Dee, D.,
Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer,
A., Haimberger, L., Healy, S., Hogan, R., Hólm, E., Janisková, M.,
Keeley, S., Laloyaux, P., Lopez, P., 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.
Hoskins, B. J. and Hodges, K. I.: The annual cycle of northern hemisphere
storm tracks, Part I: Seasons. J. Climate, 32, 1743–1760,
https://doi.org/10.1175/JCLI-D-17-0870.1, 2019a.
Hoskins, B. J. and Hodges, K. I.: The annual cycle of northern hemisphere
storm tracks, Part II: Regional detail, J. Climate, 32, 1761–1775,
https://doi.org/10.1175/JCLI-D-17-0871.1, 2019b.
Hoskins, B. J. and Woollings, T.: Persistent extratropical regimes and
climate extremes, Curr. Clim. Change Rep., 1, 115–124, https://doi.org/10.1007/s40641-015-0020-8, 2015.
Huang, S., Wang, B., and Wen, Z.: Dramatic weakening of the tropical
easterly jet projected by CMIP6 Models, J. Climate, 33, 8439–8455,
https://doi.org/10.1175/jcli-d-19-1002.1, 2020.
IPCC: Climate Change 2021: The Physical Science Basis. Contribution of
Working Group I to the Sixth Assessment Report of the Intergovernmental
Panel on Climate Change, edited by: Masson-Delmotte, V., Zhai, P., Pirani,
A., Connors, S. L., Péan, C., Berger, S., Caud, N., Chen, Y., Goldfarb,
L., Gomis, M. I., Huang, M., Leitzell, K., Lonnoy, E., Matthews, J. B. R.,
Maycock, T. K., Waterfield, T., Yelekçi, O., Yu, R., and Zhou, B.,
Cambridge University Press, https://www.ipcc.ch/report/ar6/wg1/ (last access: 15 July 2022), in press, 2022.
Keil, P., Mauritsen, T., Jungclaus, J., Hedemann, C., Olonscheck, D., and
Ghosh, R.: Multiple drivers of the North Atlantic warming hole, Nat. Clim.
Chang., 10, 667–671, https://doi.org/10.1038/s41558-020-0819-8, 2020.
Kobayashi, S., Ota, Y., Harada, Y., Ebita, A., Moriya, M., Onoda, H., Onogi,
K., Kamahori, H., Kobayashi, C., Endo, H. Miyaoka, K., and Takahashi, K.: The
JRA-55 Reanalysis: General Specifications and Basic Characteristics, J.
Meteorol. Soc. Jpn., 93, 5–48, https://doi.org/10.2151/jmsj.2015-001, 2015.
Lenssen, N., Schmidt, G., Hansen, J., Menne, M., Persin, A., Ruedy, R., and
Zyss, D.: Improvements in the GISTEMP uncertainty model, J. Geophys. Res.-Atmos., 124, 6307–6326, https://doi.org/10.1029/2018JD029522, 2019.
Lewis, J. M.: Ooishi's observation. Viewed in the context of jet stream
discovery, B. Am. Meteorol. Soc., 84, 357–370, https://doi.org/10.1175/BAMS-84-3-357, 2003.
Lim, E.-P., Hendon, H. H., and Thompson, D. W. J.: Seasonal evolution of
stratosphere-troposphere coupling in the southern hemisphere and
implications for the predictability of surface climate, J. Geophys. Res.,
123, 12002–12016, https://doi.org/10.1029/2018JD029321, 2018.
Lorenz, E. N.: Available potential energy and the maintenance of the general
circulation, Tellus, 7, 157–167, https://doi.org/10.1111/j.2153-3490.1955.tb01148.x, 1955.
Lorenz, E. N.: The nature and theory of the general circulation of the
atmosphere, World Meteorological Organization, No. 218, TP. 115, 161 pp., https://library.wmo.int/index.php?lvl=notice_display&id=5571#.YtEtPYTMJro
(last access: 15 July 2022), 1967.
Ma, Q., Lembo, V., and Franzke, C. L. E.: The Lorenz energy cycle: trends
and the impact of modes of climate variability, Tellus, 73, 1–15,
https://doi.org/10.1080/16000870.2021.1900033, 2021.
Ma, S. and Zhou, T.: Robust strengthening and westward shift of the tropical
Pacific Walker Circulation during 1979–2012: A comparison of 7 sets of
reanalysis data and 26 CMIP5 models, J. Climate, 29, 3097–3116,
https://doi.org/10.1175/JCLI-D-15-0398.1, 2016.
Manney, G. L. and Hegglin, M. I.: Seasonal and regional variations of
long-term changes in upper-tropospheric jets from reanalyses, J. Climate,
34, 9181–9200, https://doi.org/10.1175/JCLI-D-17-0303.1, 2018.
Manney, G. L., Hegglin, M. I., and Lawrence, Z. D.: Seasonal and regional
signatures of ENSO in upper tropospheric jet characteristics from
reanalyses, J. Climate, 31, 423–448, https://doi.org/10.1175/JCLI-D-20-0947.1, 2021.
Morice, C. P., Kennedy, J. J., Rayner, N. A., Winn, J. P., Hogan, E.,
Killick, R. E., Dunn, R. J. H., Osborn, T. J., Jones, P. D., and Simpson, I.
R.: An updated assessment of near-surface temperature change from 1850: the
HadCRUT5 dataset, J. Geophys. Res.-Atmos., 126, e2019JD032361,
https://doi.org/10.1029/2019JD032361, 2020.
Oudar, T., Cattiaux, J., and Douville, H.: Drivers of the northern
extratropical eddy-driven jet change in CMIP5 and CMIP6 models, Geophys.
Res. Lett., 47, e2019GL086695, https://doi.org/10.1029/2019GL086695, 2020.
Pena-Ortiz, C., Gallego, D., Ribera, P., Ordonez, P., and Alvarez-Castro, M.
D. C.: Observed trends in the global jet stream characteristics during the
second half of the 20th century, J. Geophys. Res.-Atmos., 118, 2702–2713,
https://doi.org/10.1002/jgrd.50305, 2013.
Pikovnik, M., Zaplotnik, Ž., Boljka, L., and Žagar, N.: Metrics of the Hadley circulation strength and associated circulation trends, Weather Clim. Dynam., 3, 625–644, https://doi.org/10.5194/wcd-3-625-2022, 2022.
Santer, B. D., Thorne, P. W., Haimberger, L., Taylor, K. E., Wigley, T. M.
L., Lanzante, J. R., Solomon, S., Free, M., Gleckler, P. J., Jones, P. D.,
Karl, T. R., Klein, S. A., Mears, C., Nychka, D., Schmidt, G. A., Sherwood,
S. C., and Wentz, F. J.: Consistency of modelled and observed temperature
trends in the tropical troposphere, Int. J. Climatol., 28, 1703–1722,
https://doi.org/10.1002/joc.1756, 2008.
Screen, J. A., Bracegirdle, T. J., and Simmonds, I.: Polar climate change as
manifest in atmospheric circulation, Curr. Clim. Change Rep., 4, 383–395,
https://doi.org/10.1007/s40641-018-0111-4, 2018.
Serreze, M. and Barry, R.: Processes and impacts of Arctic amplification: A
research synthesis, Global Planet. Change, 77, 85–96,
https://doi.org/10.1016/j.gloplacha.2011.03.004, 2011.
Shepherd, T. G.: Bringing physical reasoning into statistical practice in
climate-change science, Climatic Change, 169, 2, https://doi.org/10.1007/s10584-021-03226-6, 2021.
Simmonds, I. and Li, M.: Trends and variability in polar sea ice, global
atmospheric circulations, and baroclinicity, Ann. NY Acad. Sci., 1504,
167–186, https://doi.org/10.1111/nyas.14673, 2021.
Simmons, A. J. and Hoskins, B. J.: The life cycles of some nonlinear
baroclinic waves, J. Atmos. Sci., 35, 414–432, https://doi.org/10.1175/1520-0469(1978)035<0414:TLCOSN>2.0.CO;2, 1978.
Simmons, A. J., Jones, P. D., da Costa Bechtold, V., Beljaars, A. C. M.,
Kållberg, P. W., Saarinen, S., Uppala, S. M., Viterbo, P., and Wedi, N.:
Comparison of trends and low-frequency variability in CRU, ERA-40 and
NCEP/NCAR analyses of surface air temperature, J. Geophys. Res., 109,
D24115, https://doi.org/10.1029/2004JD005306, 2004.
Simmons, A. J., Berrisford, P., Dee, D. P., Hersbach, H., Hirahara, S., and
Thépaut, J.-N.: A reassessment of temperature variations and trends from
global reanalyses and monthly surface climatological datasets, Q. J.
Roy. Meteor. Soc., 143, 101–119, https://doi.org/10.1002/qj.2949, 2017.
Simmons, A. J., Soci, C., Nicolas, J., Bell, W., Berrisford, P., Dragani,
R., Flemming, J., Haimberger, L., Healy, S., Hersbach, H., Horányi, A.,
Inness, A., Muñoz-Sabater, J. Radu, R., and Schepers, D.: Global
stratospheric temperature bias and other stratospheric aspects of ERA5 and
ERA5.1, ECMWF Tech Memo no. 859, 38 pp., https://doi.org/10.21957/rcxqfmg0, 2020.
Simmons, A. J., Hersbach, H., Muñoz-Sabater, J., Nicolas, J., Vamborg,
F., Berrisford, P., de Rosnay, P., Willett, K., and Woollen, J.: Low
frequency variability and trends in surface air temperature and humidity
from ERA5 and other datasets, ECMWF Tech Memo no. 881, 97 pp.,
https://doi.org/10.21957/ly5vbtbfd, 2021.
Smith, D. M., Eade, R., Andrews, M. B., Ayres, H., Clark, A., Chripko, S.,
Deser, C., Dunstone, N. J., García-Serrano, J., Gastineau, G., Graff,
L. S., Hardiman, S. C., He, B., Hermanson, L., Jung, T., Knight, J., Levine,
X., Magnusdottir, G., Manzini, E., Matei, D., Mori, M., Msadek, R., Ortega,
P., Peings, Y., Scaife, A. A., Screen, J. A., Seabrook, M., Semmler, T.,
Sigmond, M., Streffing, J., Sun, L., and Walsh, A.: Robust but weak winter
atmospheric circulation response to future Arctic sea ice loss, Nat. Commun.,
13, 727, https://doi.org/10.1038/s41467-022-28283-y, 2022.
Thompson, C. F. and Schultz, D. M.: The release of inertial instability
near an idealized zonal jet. Geophys. Res. Lett., 48, e2021GL092649,
https://doi.org/10.1029/2021GL092649, 2021.
Thorncroft, C. D., Hoskins, B. J., and McIntyre, M. E.: Two paradigms of
baroclinic-wave life-cycle behaviour, Q. J. Roy. Meteor. Soc., 119,
17–55, https://doi.org/10.1002/qj.49711950903, 1993.
Trewin, B.: A daily homogenized temperature data set for Australia, Int.
Climatol., 33, 1510–1529, https://doi.org/10.1002/joc.3530, 2013.
Wentz, F. J.: A well-calibrated ocean algorithm for SSM/I, J. Geophys. Res.,
102, 8703–8718, https://doi.org/10.1029/96JC01751, 1997.
Wentz, F. J. and Francis, E. A.: Nimbus-7 SMMR Ocean Products, 1979–1984,
Remote Sensing Systems Technical Report 033192, Remote Sensing Systems, Santa Rosa, CA 95404, 36 pp., https://www.remss.com (last access: 16 July 2022), 1992.
Wilks, D. S.: “The stippling shows statistically significant grid points”:
How research results are routinely overstated and overinterpreted, and what
to do about it, B. Am. Meteorol. Soc., 97, 2263–2273,
https://doi.org/10.1175/BAMS-D-15-00267.1, 2016.
Wu, M., Zhou, T., Li, C., Li, H., Chen, X., Wu, B., Zhang, W., and Zhang,
L.: A very likely weakening of Pacific Walker Circulation in constrained
near-future projections, Nat. Commun., 12, 6502,
https://doi.org/10.1038/s41467-021-26693-y, 2021.
Žagar, N., Zaplotnik, Ž., and Karami, K.: Atmospheric subseasonal
variability and circulation regimes: spectra, trends, and uncertainties, J.
Climate, 33, 9375–9390, https://doi.org/10.1175/JCLI-D-20-0225.1, 2020.
Zappa, G. and Shepherd, T. G.: Storylines of atmospheric circulation change
for European regional climate impact assessment, J. Climate, 30, 6561–6577,
https://doi.org/10.1175/JCLI-D-16-0807.1, 2017.
Editorial statement
Analysing and understanding potential trends in the atmospheric circulation over the last decades is an important aspect of atmospheric dynamics. In this article, Adrian Simmons performed a very thorough global trend analysis, with a focus on near-tropopause winds, based on ERA5 reanalyses. The paper provides an excellent overview and emphasises important regional and seasonal differences. It is shown that despite Arctic amplification, the upper-level westerlies mainly strengthened at northern middle latitudes. Focusing on jet-stream wind maxima, it is found that they increased over the North Atlantic. These results and the detailed global trend overview will be useful for the community to further investigate the underlying physical processes that led to these trends in the last decades.
Analysing and understanding potential trends in the atmospheric circulation over the last...
Short summary
This study of changes in temperature and wind since 1979 met its twin aims of (i) increasing confidence in some findings of the latest IPCC assessment and (ii) identifying changes that had received little or no previous attention. It reports a small overall intensification and shift in position of the North Atlantic jet stream and associated storms, and a strengthening of tropical upper-level easterlies. Increases in low-level winds over tropical and southern hemispheric oceans are confirmed.
This study of changes in temperature and wind since 1979 met its twin aims of (i) increasing...
