Articles | Volume 7, issue 3
https://doi.org/10.5194/wcd-7-1385-2026
© Author(s) 2026. 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-7-1385-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
05 Aug 2026
Research article |
| 05 Aug 2026
| 05 Aug 2026
Austral summer MJO forecast skill in S2S models: decadal shifts and their drivers
Securing Antarctica's Environmental Future, Monash University, Clayton, VIC, Australia
School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia
Julie M. Arblaster
Securing Antarctica's Environmental Future, Monash University, Clayton, VIC, Australia
School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia
Matthew C. Wheeler
Securing Antarctica's Environmental Future, Monash University, Clayton, VIC, Australia
Research, Bureau of Meteorology, Melbourne, VIC, Australia
Eun-Pa Lim
Securing Antarctica's Environmental Future, Monash University, Clayton, VIC, Australia
Research, Bureau of Meteorology, Melbourne, VIC, Australia
Jadwiga H. Richter
National Center for Atmospheric Research, Boulder, Colorado, USA
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Prince Xavier, Martin Willett, Tim Graham, Paul Earnshaw, Dan Copsey, Nikesh Narayan, Charline Marzin, Alistair Sellar, Duncan Ackerley, Adam Blaker, Ed Blockley, Alejandro Bodas-Salcedo, Andrew Bushell, Nakbin Choi, Xin Rong Chua, Catherine Guiavarc'h, Muhammad Hassim, Julian Heming, Debra Hudson, Sarah Ineson, Anthony Jones, Colin Jones, Richard Keane, Kiwook Kim, Jiyeong Kim, Till Kuhlbrodt, Myong-In Lee, Richard Levine, Chen Li, Gill Martin, Alex Megann, Anne Mccabe, Aurel Moise, Leighton Regayre, Jeff Ridley, Luke Roberts, Sandeep Sahany, Reinhard K. H. Schiemann, David Storkey, Warren Tennant, Lorenzo Tomassini, Yoko Tsushima, Graham P. Weedon, Alex West, Matthew C. Wheeler, Keith Williams, Xiaobing Zhou, and Hongyan Zhu
EGUsphere, https://doi.org/10.5194/egusphere-2026-4281, https://doi.org/10.5194/egusphere-2026-4281, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
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GC5 is the Met Office's newest climate and weather model, combining an updated atmosphere/land component with an improved ocean and sea-ice component. Compared to its predecessor GC4, it better simulates global temperatures, winds, monsoons over India and SE Asia, and African weather, and forecasts tropical cyclones more accurately. Southern Ocean errors shrank too. Some tropical patterns and regional biases worsened slightly. A lower-resolution version will underpin the UK's Earth System Model.
Aleena M. Jaison, Lesley J. Gray, Scott M. Osprey, James A. Anstey, Martin B. Andrews, Neal Butchart, Zhaoyang Chai, Dong-Chan Hong, Kai Huang, Yoshio Kawatani, Jeff R. Knight, Pu Lin, Francois Lott, Yixiong Lu, Hiroaki Naoe, Jadwiga H. Richter, Nan Rosenbloom, Federico Serva, Anne K. Smith, Seok-Woo Son, Qi Tang, Shingo Watanabe, Jinbo Xie, and Kohei Yoshida
EGUsphere, https://doi.org/10.5194/egusphere-2026-4135, https://doi.org/10.5194/egusphere-2026-4135, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
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The tropical upper stratosphere has winds that switch between westerly and easterly every six months known as the semi-annual oscillation (SAO). Climate models commonly show an easterly bias in the SAO. We analysed data from many models to test if correcting the biases in winds lower in the stratosphere could improve SAO. We find correcting the lower-level wind biases reduces the SAO easterly bias, though further improvements, such as better representation of atmospheric waves, are still needed.
Kai Huang, Chang-Hyun Park, Seung-Yoon Back, Jorge L. García-Franco, Hera Kim, Pu Lin, Scott Osprey, Jadwiga Richter, Chih-Chieh Chen, Seok-Woo Son, Shigeo Yoden, Yuna Lim, Neal Butchart, James Anstey, Yoshio Kawatani, Martin B. Andrews, Francois Lott, Yixiong Lu, Zhaoyang Chai, Nan Rosenbloom, Qi Tang, Jinbo Xie, Federico Serva, Dong-Chan Hong, Shingo Watanabe, Aleena M. Jaison, Hiroaki Naoe, and Kohei Yoshida
EGUsphere, https://doi.org/10.5194/egusphere-2026-3744, https://doi.org/10.5194/egusphere-2026-3744, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
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The tropical atmosphere has large-scale wind and rainfall patterns shaping weather worldwide. Winds high above the tropics are thought to influence a major tropical rainfall system, but climate models fail to reproduce this link. We tested 12 climate models after constraining their high-altitude winds to match observations. Although the winds then matched, the models failed to capture the tropical response, as they did not realistically simulate it. Improving this is key to better prediction.
Hyun-Kyu Lee, James A. Anstey, Hye-Yeong Chun, Shingo Watanabe, Francois Lott, Zhaoyang Chai, Yixiong Lu, Qi Tang, Jinbo Xie, Dong-Chan Hong, Seok-Woo Son, Federico Serva, Pu Lin, Martin B. Andrews, Neal Butchart, Aleena M. Jaison, Jeff R. Knight, Scott Osprey, Hiroaki Naoe, Kohei Yoshida, Yoshio Kawatani, and Jadwiga H. Richter
EGUsphere, https://doi.org/10.5194/egusphere-2026-2856, https://doi.org/10.5194/egusphere-2026-2856, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
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This study investigates the systematic biases in equatorial wave forcing of the quasi-biennial oscillation (QBO) by comparing internally generated and bias-corrected experiments using a multi-model ensemble. Although nudging effectively mitigates QBO biases, systematic biases in wave forcing are not fully resolved. The equatorial wave forcing in the lower stratosphere remains weaker than that in reanalyses, while an eastward wave forcing bias is observed in the mid-to-upper stratosphere.
James A. Anstey, Neal Butchart, Scott Osprey, Yoshio Kawatani, Kevin Hamilton, Jadwiga H. Richter, Tim Stockdale, Martin B. Andrews, Zhaoyang Chai, Paolo Davini, Dong-Chan Hong, Kai Huang, Aleena M. Jaison, Tobias Kerzenmacher, Jeff R. Knight, Pu Lin, Francois Lott, Yixiong Lu, Hiroaki Naoe, Federico Serva, Isla Simpson, Seok-Woo Son, Qi Tang, Shingo Watanabe, Jinbo Xie, and Kohei Yoshida
EGUsphere, https://doi.org/10.5194/egusphere-2026-1165, https://doi.org/10.5194/egusphere-2026-1165, 2026
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We describe experiments where modelled tropical stratosphere winds are adjusted by "nudging" them toward realistic time-evolving eastward and westward Quasi-Biennial Oscillation (QBO) winds. The effects of this bias correction on other atmospheric processes, such as the stratospheric polar vortex or tropical waves that force the QBO, can then be assessed. We describe details of the experiments, the multi-model ensemble that has performed them, and basic validation of the nudging response.
Elio Campitelli, Ariaan Purich, Julie Arblaster, Eun-Pa Lim, Matthew C. Wheeler, and Phillip Reid
The Cryosphere, 20, 2557–2587, https://doi.org/10.5194/tc-20-2557-2026, https://doi.org/10.5194/tc-20-2557-2026, 2026
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By comparing sea-ice forecasts made by the same model but using different initial conditions, we show that better initial sea-ice initial conditions improve sea-ice forecasts a lot in Summer and Autumn, but not as much in winter. This means that forecasting groups should focus efforts in assimilating observations in Summer and that research on how easy it is to predict sea ice need to analyse all seasons.
Blanca Ayarzagüena, Amy H. Butler, Peter Hitchcock, Chaim I. Garfinkel, Zac D. Lawrence, Wuhan Ning, Philip Rupp, Zheng Wu, Hilla Afargan-Gerstman, Natalia Calvo, Alvaro de la Cámara, Martin Jucker, Gerbrand Koren, Daniel De Maeseneire, Gloria L. Manney, Marisol Osman, Masakazu Taguchi, Cory Barton, Dong-Chan Hong, Yu-Kyung Hyun, Hera Kim, Jeff Knight, Piero Malguzzi, Daniele Mastrangelo, Jiyoung Oh, Inna Polichtchouk, Jadwiga H. Richter, Isla R. Simpson, Seok-Woo Son, Damien Specq, and Tim Stockdale
Weather Clim. Dynam., 7, 411–437, https://doi.org/10.5194/wcd-7-411-2026, https://doi.org/10.5194/wcd-7-411-2026, 2026
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Sudden Stratospheric Warmings (SSWs) are known to follow a sustained wave dissipation in the stratosphere, which depends on both the tropospheric and stratospheric states. However, the relative role of each state is still unclear. Using a new set of subseasonal to seasonal forecasts, we show that the stratospheric state does not drastically affect the precursors of three recent SSWs, but modulates the stratospheric wave activity, with impacts depending on SSW features.
Martin B. Andrews, Neal Butchart, James A. Anstey, Ewa Bednarz, Dillon Elsbury, Jorge L. García-Franco, Vinay Kumar, Froila M. Palmeiro, Natasha E. Trencham, Kohei Yoshida, Zhaoyang Chai, Dong-Chan Hong, Kai Huang, Aleena M. Jaison, Yoshio Kawatani, Jeff R. Knight, Pu Lin, François Lott, Yixiong Lu, Hiroaki Naoe, Scott M. Osprey, Jadwiga H. Richter, Federico Serva, Seok-Woo Son, Qi Tang, Shingo Watanabe, and Jinbo Xie
EGUsphere, https://doi.org/10.5194/egusphere-2026-737, https://doi.org/10.5194/egusphere-2026-737, 2026
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The observed winds in the upper atmosphere over the equator have alternating easterly and westerly regions that descend towards the lower atmosphere before dissipating, with a period of approximately 28 months. This is known as the Quasi-Biennial Oscillation (QBO). The QBO is known to influence remote regions of the atmosphere. This paper details the results of multi-model experiments where the QBO is nudged towards the observed QBO allowing the assessment of these remote connections.
William J. M. Seviour, Justin Finkel, Philip Rupp, Regan Mudhar, Amy H. Butler, Chaim I. Garfinkel, Peter Hitchcock, Blanca Ayarzagüena, Dong-Chan Hong, Yu-Kyung Hyun, Hera Kim, Eun-Pa Lim, Daniel De Maeseneire, Gabriele Messori, Gerbrand Koren, Michael Sigmond, Isla R. Simpson, and Seok-Woo Son
EGUsphere, https://doi.org/10.5194/egusphere-2026-230, https://doi.org/10.5194/egusphere-2026-230, 2026
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Variability of the stratospheric polar vortex is thought to play a role in driving weather extremes, but quantifying this role for a given event has proved challenging. Using a new set of perturbed subseasonal forecast experiments from 7 modelling centres we determine the stratospheric contribution to the risk and severity of three recent extreme weather events. The forecast-based methodology that we develop is applicable to understanding a range of other drivers of weather extremes.
Dillon Elsbury, Federico Serva, Julie M. Caron, Seung-Yoon Back, Clara Orbe, Jadwiga H. Richter, James A. Anstey, Neal Butchart, Chih-Chieh Chen, Javier García-Serrano, Anne Glanville, Yoshio Kawatani, Tobias Kerzenmacher, Francois Lott, Hiroaki Naoe, Scott Osprey, Froila M. Palmeiro, Seok-Woo Son, Masakazu Taguchi, Stefan Versick, Shingo Watanabe, and Kohei Yoshida
Weather Clim. Dynam., 7, 317–339, https://doi.org/10.5194/wcd-7-317-2026, https://doi.org/10.5194/wcd-7-317-2026, 2026
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We used climate models to test how constant El Niño and La Niña ocean conditions shape the Madden-Julian Oscillation during northern winter. El Niño made this weather pattern move faster, while La Niña slowed it down. The Quasi-Biennial Oscillation, a repeating wind pattern high in the atmosphere, had little effect. This shows that long-lasting ocean conditions mainly drive the changes we found.
Hiroaki Naoe, Jorge L. García-Franco, Chang-Hyun Park, Mario Rodrigo, Froila M. Palmeiro, Federico Serva, Masakazu Taguchi, Kohei Yoshida, James A. Anstey, Javier García-Serrano, Seok-Woo Son, Yoshio Kawatani, Neal Butchart, Kevin Hamilton, Chih-Chieh Chen, Anne Glanville, Tobias Kerzenmacher, François Lott, Clara Orbe, Scott Osprey, Mijeong Park, Jadwiga H. Richter, Stefan Versick, and Shingo Watanabe
Weather Clim. Dynam., 6, 1419–1442, https://doi.org/10.5194/wcd-6-1419-2025, https://doi.org/10.5194/wcd-6-1419-2025, 2025
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Links between the stratospheric Quasi-Biennial Oscillation (QBO) and atmospheric circulations in the tropics, subtropics, and polar regions, as well as their modulation by the El Nino–Southern Oscillation, are examined through model experiments. The QBO–polar vortex connection is reproduced by a multi-model ensemble at about half the observed amplitude. Weak performance of QBO signals in these regions is likely due to unrealistically weak QBO amplitudes in the lower stratosphere.
Yoshio Kawatani, Kevin Hamilton, Shingo Watanabe, Masakazu Taguchi, Federico Serva, James A. Anstey, Jadwiga H. Richter, Neal Butchart, Clara Orbe, Scott M. Osprey, Hiroaki Naoe, Dillon Elsbury, Chih-Chieh Chen, Javier García-Serrano, Anne Glanville, Tobias Kerzenmacher, François Lott, Froila M. Palmeiro, Mijeong Park, Stefan Versick, and Kohei Yoshida
Weather Clim. Dynam., 6, 1045–1073, https://doi.org/10.5194/wcd-6-1045-2025, https://doi.org/10.5194/wcd-6-1045-2025, 2025
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The Quasi-Biennial Oscillation (QBO) of the tropical stratospheric mean winds has been relatively steady over the 7 decades it has been observed, but there are always cycle-to-cycle variations. This study used several global atmospheric models to investigate systematic modulation of the QBO by the El Niño/La Niña cycle. All models simulated shorter periods during El Niño, in agreement with observations. By contrast, the models disagreed even on the sign of the El Niño effect on QBO amplitude.
John P. Dunne, Helene T. Hewitt, Julie M. Arblaster, Frédéric Bonou, Olivier Boucher, Tereza Cavazos, Beth Dingley, Paul J. Durack, Birgit Hassler, Martin Juckes, Tomoki Miyakawa, Matt Mizielinski, Vaishali Naik, Zebedee Nicholls, Eleanor O'Rourke, Robert Pincus, Benjamin M. Sanderson, Isla R. Simpson, and Karl E. Taylor
Geosci. Model Dev., 18, 6671–6700, https://doi.org/10.5194/gmd-18-6671-2025, https://doi.org/10.5194/gmd-18-6671-2025, 2025
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The seventh phase of the Coupled Model Intercomparison Project (CMIP7) coordinates efforts to answer key and timely climate science questions and facilitate delivery of relevant multi-model simulations for prediction and projection; characterization, attribution, and process understanding; and vulnerability, impact, and adaptation analysis. Key to the CMIP7 design are the mandatory Diagnostic, Evaluation and Characterization of Klima and optional Assessment Fast Track experiments.
Jinbo Xie, Qi Tang, Michael Prather, Jadwiga Richter, and Shixuan Zhang
Atmos. Chem. Phys., 25, 9315–9333, https://doi.org/10.5194/acp-25-9315-2025, https://doi.org/10.5194/acp-25-9315-2025, 2025
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Analysis of the interaction between the climate and ozone in the stratosphere is complicated by the inability of climate models to simulate the quasi-biennial oscillation (QBO) – an important climate mode in the stratosphere. We use a set of model simulations that realistically simulate QBO and a novel ozone diagnostic tool to separate temperature- and circulation-driven QBO impacts. These are important for diagnosing model–model differences in QBO–ozone responses for climate projections.
Mari R. Tye, Ming Ge, Jadwiga H. Richter, Ethan D. Gutmann, Allyson Rugg, Cindy L. Bruyère, Sue Ellen Haupt, Flavio Lehner, Rachel McCrary, Andrew J. Newman, and Andy Wood
Hydrol. Earth Syst. Sci., 29, 1117–1133, https://doi.org/10.5194/hess-29-1117-2025, https://doi.org/10.5194/hess-29-1117-2025, 2025
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There is a perceived mismatch between the spatial scales on which global climate models can produce data and those needed for water management decisions. However, poor communication of specific metrics relevant to local decisions is also a problem. We assessed the credibility of a set of water management decision metrics in the Community Earth System Model v2 (CESM2). CESM2 shows potentially greater use of its output in long-range water management decisions.
Chaim I. Garfinkel, Zachary D. Lawrence, Amy H. Butler, Etienne Dunn-Sigouin, Irene Erner, Alexey Y. Karpechko, Gerbrand Koren, Marta Abalos, Blanca Ayarzagüena, David Barriopedro, Natalia Calvo, Alvaro de la Cámara, Andrew Charlton-Perez, Judah Cohen, Daniela I. V. Domeisen, Javier García-Serrano, Neil P. Hindley, Martin Jucker, Hera Kim, Robert W. Lee, Simon H. Lee, Marisol Osman, Froila M. Palmeiro, Inna Polichtchouk, Jian Rao, Jadwiga H. Richter, Chen Schwartz, Seok-Woo Son, Masakazu Taguchi, Nicholas L. Tyrrell, Corwin J. Wright, and Rachel W.-Y. Wu
Weather Clim. Dynam., 6, 171–195, https://doi.org/10.5194/wcd-6-171-2025, https://doi.org/10.5194/wcd-6-171-2025, 2025
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Variability in the extratropical stratosphere and troposphere is coupled, and because of the longer timescales characteristic of the stratosphere, this allows for a window of opportunity for surface prediction. This paper assesses whether models used for operational prediction capture these coupling processes accurately. We find that most processes are too weak; however downward coupling from the lower stratosphere to the near surface is too strong.
Khalil Karami, Rolando Garcia, Christoph Jacobi, Jadwiga H. Richter, and Simone Tilmes
Atmos. Chem. Phys., 23, 3799–3818, https://doi.org/10.5194/acp-23-3799-2023, https://doi.org/10.5194/acp-23-3799-2023, 2023
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Alongside mitigation and adaptation efforts, stratospheric aerosol intervention (SAI) is increasingly considered a third pillar to combat dangerous climate change. We investigate the teleconnection between the quasi-biennial oscillation in the equatorial stratosphere and the Arctic stratospheric polar vortex under a warmer climate and an SAI scenario. We show that the Holton–Tan relationship weakens under both scenarios and discuss the physical mechanisms responsible for such changes.
Ewa M. Bednarz, Daniele Visioni, Ben Kravitz, Andy Jones, James M. Haywood, Jadwiga Richter, Douglas G. MacMartin, and Peter Braesicke
Atmos. Chem. Phys., 23, 687–709, https://doi.org/10.5194/acp-23-687-2023, https://doi.org/10.5194/acp-23-687-2023, 2023
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Building on Part 1 of this two-part study, we demonstrate the role of biases in climatological circulation and specific aspects of model microphysics in driving the differences in simulated sulfate distributions amongst three Earth system models. We then characterize the simulated changes in stratospheric and free-tropospheric temperatures, ozone, water vapor, and large-scale circulation, elucidating the role of the above aspects in the surface responses discussed in Part 1.
John T. Fasullo and Jadwiga H. Richter
Atmos. Chem. Phys., 23, 163–182, https://doi.org/10.5194/acp-23-163-2023, https://doi.org/10.5194/acp-23-163-2023, 2023
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The continued high levels of anthropogenic greenhouse gas emissions increase the likelihood that key climate warming thresholds will be exceeded in the coming decades. Here we examine a recently proposed geoengineering approach using two recently produced climate model experiments. We find the associated latitudinal distribution of aerosol mass to exhibit substantial uncertainty, suggesting the need for significant flexibility in the location and amount of aerosol delivery, if implemented.
Jadwiga H. Richter, Daniele Visioni, Douglas G. MacMartin, David A. Bailey, Nan Rosenbloom, Brian Dobbins, Walker R. Lee, Mari Tye, and Jean-Francois Lamarque
Geosci. Model Dev., 15, 8221–8243, https://doi.org/10.5194/gmd-15-8221-2022, https://doi.org/10.5194/gmd-15-8221-2022, 2022
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Solar climate intervention using stratospheric aerosol injection is a proposed method of reducing global mean temperatures to reduce the worst consequences of climate change. We present a new modeling protocol aimed at simulating a plausible deployment of stratospheric aerosol injection and reproducibility of simulations using other Earth system models: Assessing Responses and Impacts of Solar climate intervention on the Earth system with stratospheric aerosol injection (ARISE-SAI).
Stephen G. Yeager, Nan Rosenbloom, Anne A. Glanville, Xian Wu, Isla Simpson, Hui Li, Maria J. Molina, Kristen Krumhardt, Samuel Mogen, Keith Lindsay, Danica Lombardozzi, Will Wieder, Who M. Kim, Jadwiga H. Richter, Matthew Long, Gokhan Danabasoglu, David Bailey, Marika Holland, Nicole Lovenduski, Warren G. Strand, and Teagan King
Geosci. Model Dev., 15, 6451–6493, https://doi.org/10.5194/gmd-15-6451-2022, https://doi.org/10.5194/gmd-15-6451-2022, 2022
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The Earth system changes over a range of time and space scales, and some of these changes are predictable in advance. Short-term weather forecasts are most familiar, but recent work has shown that it is possible to generate useful predictions several seasons or even a decade in advance. This study focuses on predictions over intermediate timescales (up to 24 months in advance) and shows that there is promising potential to forecast a variety of changes in the natural environment.
Mari R. Tye, Katherine Dagon, Maria J. Molina, Jadwiga H. Richter, Daniele Visioni, Ben Kravitz, and Simone Tilmes
Earth Syst. Dynam., 13, 1233–1257, https://doi.org/10.5194/esd-13-1233-2022, https://doi.org/10.5194/esd-13-1233-2022, 2022
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We examined the potential effect of stratospheric aerosol injection (SAI) on extreme temperature and precipitation. SAI may cause daytime temperatures to cool but nighttime to warm. Daytime cooling may occur in all seasons across the globe, with the largest decreases in summer. In contrast, nighttime warming may be greatest at high latitudes in winter. SAI may reduce the frequency and intensity of extreme rainfall. The combined changes may exacerbate drying over parts of the global south.
Zachary D. Lawrence, Marta Abalos, Blanca Ayarzagüena, David Barriopedro, Amy H. Butler, Natalia Calvo, Alvaro de la Cámara, Andrew Charlton-Perez, Daniela I. V. Domeisen, Etienne Dunn-Sigouin, Javier García-Serrano, Chaim I. Garfinkel, Neil P. Hindley, Liwei Jia, Martin Jucker, Alexey Y. Karpechko, Hera Kim, Andrea L. Lang, Simon H. Lee, Pu Lin, Marisol Osman, Froila M. Palmeiro, Judith Perlwitz, Inna Polichtchouk, Jadwiga H. Richter, Chen Schwartz, Seok-Woo Son, Irene Erner, Masakazu Taguchi, Nicholas L. Tyrrell, Corwin J. Wright, and Rachel W.-Y. Wu
Weather Clim. Dynam., 3, 977–1001, https://doi.org/10.5194/wcd-3-977-2022, https://doi.org/10.5194/wcd-3-977-2022, 2022
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Forecast models that are used to predict weather often struggle to represent the Earth’s stratosphere. This may impact their ability to predict surface weather weeks in advance, on subseasonal-to-seasonal (S2S) timescales. We use data from many S2S forecast systems to characterize and compare the stratospheric biases present in such forecast models. These models have many similar stratospheric biases, but they tend to be worse in systems with low model tops located within the stratosphere.
Peter Hitchcock, Amy Butler, Andrew Charlton-Perez, Chaim I. Garfinkel, Tim Stockdale, James Anstey, Dann Mitchell, Daniela I. V. Domeisen, Tongwen Wu, Yixiong Lu, Daniele Mastrangelo, Piero Malguzzi, Hai Lin, Ryan Muncaster, Bill Merryfield, Michael Sigmond, Baoqiang Xiang, Liwei Jia, Yu-Kyung Hyun, Jiyoung Oh, Damien Specq, Isla R. Simpson, Jadwiga H. Richter, Cory Barton, Jeff Knight, Eun-Pa Lim, and Harry Hendon
Geosci. Model Dev., 15, 5073–5092, https://doi.org/10.5194/gmd-15-5073-2022, https://doi.org/10.5194/gmd-15-5073-2022, 2022
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This paper describes an experimental protocol focused on sudden stratospheric warmings to be carried out by subseasonal forecast modeling centers. These will allow for inter-model comparisons of these major disruptions to the stratospheric polar vortex and their impacts on the near-surface flow. The protocol will lead to new insights into the contribution of the stratosphere to subseasonal forecast skill and new approaches to the dynamical attribution of extreme events.
Roseanna C. McKay, Julie M. Arblaster, and Pandora Hope
Weather Clim. Dynam., 3, 413–428, https://doi.org/10.5194/wcd-3-413-2022, https://doi.org/10.5194/wcd-3-413-2022, 2022
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Understanding what makes it hot in Australia in spring helps us better prepare for harmful impacts. We look at how the higher latitudes and tropics change the atmospheric circulation from early to late spring and how that changes maximum temperatures in Australia. We find that the relationship between maximum temperatures and the tropics is stronger in late spring than early spring. These findings could help improve forecasts of hot months in Australia in spring.
Adam A. Scaife, Mark P. Baldwin, Amy H. Butler, Andrew J. Charlton-Perez, Daniela I. V. Domeisen, Chaim I. Garfinkel, Steven C. Hardiman, Peter Haynes, Alexey Yu Karpechko, Eun-Pa Lim, Shunsuke Noguchi, Judith Perlwitz, Lorenzo Polvani, Jadwiga H. Richter, John Scinocca, Michael Sigmond, Theodore G. Shepherd, Seok-Woo Son, and David W. J. Thompson
Atmos. Chem. Phys., 22, 2601–2623, https://doi.org/10.5194/acp-22-2601-2022, https://doi.org/10.5194/acp-22-2601-2022, 2022
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Great progress has been made in computer modelling and simulation of the whole climate system, including the stratosphere. Since the late 20th century we also gained a much clearer understanding of how the stratosphere interacts with the lower atmosphere. The latest generation of numerical prediction systems now explicitly represents the stratosphere and its interaction with surface climate, and here we review its role in long-range predictions and projections from weeks to decades ahead.
Daniele Visioni, Simone Tilmes, Charles Bardeen, Michael Mills, Douglas G. MacMartin, Ben Kravitz, and Jadwiga H. Richter
Atmos. Chem. Phys., 22, 1739–1756, https://doi.org/10.5194/acp-22-1739-2022, https://doi.org/10.5194/acp-22-1739-2022, 2022
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Aerosols are simulated in a simplified way in climate models: in the model analyzed here, they are represented in every grid as described by three simple logarithmic distributions, mixing all different species together. The size can evolve when new particles are formed, particles merge together to create a larger one or particles are deposited to the surface. This approximation normally works fairly well. Here we show however that when large amounts of sulfate are simulated, there are problems.
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Short summary
A key pattern of tropical weather, the Madden-Julian Oscillation, has become significantly harder to predict since the late 1990s. We discovered this by comparing forecasts from major models across two time periods. The decrease in forecast skill is linked to changes in large-scale climate patterns, not just model errors. This means to improve long-range weather forecasts, models must better simulate how these large-scale patterns interact with tropical weather.
A key pattern of tropical weather, the Madden-Julian Oscillation, has become significantly...
