Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Australian hot and dry extremes induced by weakenings of the stratospheric polar vortex

Nature Geoscience volume 12, pages 896–901 (2019)Cite this article

Subjects

Abstract

The occurrence of extreme hot and dry conditions in warm seasons can have large impacts on human health, energy and water supplies, agriculture and wildfires. Australian hot and dry extremes have been known to be associated with the occurrence of El Niño and other variations of tropospheric circulation. Here we identify an additional driver: variability of the stratospheric Antarctic polar vortex. On the basis of statistical analyses using observational data covering the past 40 yr, we show that weakenings and warmings of the stratospheric polar vortex, which episodically occur during austral spring, substantially increase the chances of hot and dry extremes and of associated fire-conducive weather across subtropical eastern Australia from austral spring to early summer. The promotion of these Australian climate extremes results from the downward coupling of the weakened polar vortex to tropospheric levels, where it is linked to the low-index polarity of the Southern Annular Mode, an equatorward shift of the mid-latitude westerly jet stream and subsidence and warming in the subtropics. Because of the long timescale of the polar vortex variations, the enhanced likelihood of early-summertime hot and dry extremes and wildfire risks across eastern Australia may be predictable a season in advance during years of vortex weakenings.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: The S–T coupled mode and its relationship with the SAM.
Fig. 2: Anomalous Australian climate conditions during the nine polar vortex weakening years.
Fig. 3: Changes in the likelihood of extreme high Tmax, low rainfall and high wildfire danger during the nine polar vortex weakening years.
Fig. 4: Monthly standardized SAM index anomalies during the nine polar vortex weakening years.
Fig. 5: Circulation and cloud cover changes over Australia during the nine polar vortex weakening years.

Data availability

The datasets used in this study are available online in the following locations: ERA-Interim reanalysis, https://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/; JRA-55 reanalysis, https://jra.kishou.go.jp/JRA-55/index_en.html; Hurrell et al. merged SST analysis, https://climatedataguide.ucar.edu/climate-data/merged-hadley-noaaoi-sea-surface-temperature-sea-ice-concentration-hurrell-et-al-2008; Reynolds OI v2 SST analysis, https://www.esrl.noaa.gov/psd/data/gridded/data.noaa.oisst.v2.html; AWAP analysis, http://www.bom.gov.au/climate/data-services/maps.shtml; CPC AAO index, https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/aao.shtml. FFDI data are available by contacting the contributing author A.J.D. (andrew.dowdy@bom.gov.au). All the other data used for the analysis in this study are available by contacting the corresponding author.

Code availability

All the codes and scripts used for the analysis in this study are available by contacting the corresponding author.

References

  1. Managing Climate Variability R&D Program. Climate Kelpie http://managingclimate.gov.au/publications/improved-seasonal-forecasts-the-benefits-for-agriculture-other-sectors-and-australias-economy/

  2. Australian Government Department of Agriculture Meat, wool and dairy. Australian Government http://www.agriculture.gov.au/ag-farm-food/meat-wool-dairy (2019).

  3. Bjerknes, J. Atmospheric teleconnections from the equatorial Pacific. Mon. Weather Rev. 97, 163–172 (1959).

    Article  Google Scholar 

  4. Saji, N. H., Goswami, B. N., Vinayachandran, P. N. & Yamagata, T. A dipole mode in the tropical Indian Ocean. Nature 401, 360–363 (1999).

    Google Scholar 

  5. Thompson, D. W. J. & Wallace, J. M. Annular mode in the extratropical circulation. Part I: month-to-month variability. J. Clim. 13, 1000–1016 (2000).

    Article  Google Scholar 

  6. Hendon, H. H., Thompson, D. W. J. & Wheeler, M. C. Australian rainfall and surface temperature variations associated with the Southern Hemisphere annular mode. J. Clim. 20, 2452–2467 (2007).

    Article  Google Scholar 

  7. Min, S.-K., Cai, W. & Whetton, P. Influence of climate variability on seasonal extremes over Australia. J. Geophys. Res. Atmos. 118, 643–654 (2013).

    Article  Google Scholar 

  8. Perkins, S. E., Argüeso, D. & White, C. J. Relationships between climate variability, soil moisture, and Australian heatwaves. J. Geophys. Res. Atmos. 120, 8144–8164 (2015).

    Article  Google Scholar 

  9. Hirota, I., Hirooka, T. & Shiotani, M. Upper stratospheric circulations in the two hemispheres observed by satellites. Q. J. R. Meteorol. Soc. 109, 443–454 (1983).

    Article  Google Scholar 

  10. Kodera, K. & Kuroda, Y. Dynamical response to the solar cycle. J. Geophys. Res. Atmos. 107, 4749 (2002).

    Article  Google Scholar 

  11. Waugh, D. W., Sobel, A. H. & Polvani, L. M. What is the polar vortex and how does it influence weather? Bull. Am. Meteorol. Soc. 98, 37–44 (2017).

    Article  Google Scholar 

  12. McIntyre, M. E. How well do we understand the dynamics of stratospheric warmings? J. Meteorol. Soc. Jpn Ser. II 60, 37–65 (1982).

    Article  Google Scholar 

  13. Randel, W. J. The seasonal evolution of planetary-waves in the Southern Hemisphere stratosphere and troposphere. Q. J. R. Meteorol. Soc. 114, 1385–1409 (1988).

    Article  Google Scholar 

  14. Hio, Y. & Yoden, S. Interannual variations of the seasonal march in the Southern Hemisphere stratosphere for 1979–2002 and characterization of the unprecedented year 2002. J. Atmos. Sci. 62, 567–580 (2005).

    Article  Google Scholar 

  15. Baldwin, M. P. et al. Stratospheric memory and skill of extended-range weather forecasts. Science 301, 636–640 (2003).

    Article  Google Scholar 

  16. Charlton, A. J., O’Neill, A., Stephenson, D. B., Lahoz, W. A. & Baldwin, M. P. Can knowledge of the state of the stratosphere be used to improve statistical forecasts of the troposphere? Q. J. R. Meteorol. Soc. 129, 3205–3224 (2003).

    Article  Google Scholar 

  17. Byrne, N. J. & Shepherd, T. G. Seasonal persistence of circulation anomalies in the Southern Hemisphere stratosphere and its implications for the troposphere. J. Clim. 31, 3467–3483 (2018).

    Article  Google Scholar 

  18. Lim, E.-P., Hendon, H. H. & 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. Atmos. 123, 12002–12016 (2018).

    Article  Google Scholar 

  19. Sigmond, M., Scinocca, J. F., Kharin, V. V. & Shepherd, T. G. Enhanced seasonal forecast skill following stratospheric sudden warmings. Nat. Geosci. 6, 98–102 (2013).

    Article  Google Scholar 

  20. Baldwin, M. P. & Dunkerton, T. J. Propagation of the Arctic Oscillation from the stratosphere to the troposphere. J. Geophys. Res. Atmos. 104, 30937–30946 (1999).

    Article  Google Scholar 

  21. Shiotani, M. & Hirota, I. Planetary wave-mean flow interaction in the stratosphere: a comparison between Northern and Southern hemispheres. Q. J. R. Meteorol. Soc. 111, 309–334 (1985).

    Article  Google Scholar 

  22. Kuroda, Y. & Kodera, K. Interannual variability in the troposphere and stratosphere of the Southern Hemisphere winter. J. Geophys. Res. Atmos. 103, 13787–13799 (1998).

    Article  Google Scholar 

  23. Shiotani, M., Shimoda, N. & Hirota, I. Interannual variability of the stratospheric circulation in the Southern Hemisphere. Q. J. R. Meteorol. Soc. 119, 531–546 (1993).

    Article  Google Scholar 

  24. Seviour, W. J. M. et al. Skillful seasonal prediction of the Southern Annular Mode and Antarctic ozone. J. Clim. 27, 7462–7474 (2014).

    Article  Google Scholar 

  25. Thompson, D. W. J., Baldwin, M. P. & Solomon, S. Stratosphere–troposphere coupling in the Southern Hemisphere. J. Atmos. Sci. 62, 708–715 (2005).

    Article  Google Scholar 

  26. Thompson, D. W. J. & Solomon, S. Interpretation of recent Southern Hemisphere climate change. Science 296, 895–899 (2002).

    Article  Google Scholar 

  27. Gillett, N. P., Kell, T. D. & Jones, P. D. Regional climate impacts of the Southern Annular Mode. Geophys. Res. Lett. 33, L23704 (2006).

    Article  Google Scholar 

  28. Bandoro, J., Solomon, S., Donohoe, A., Thompson, D. W. J. & Santer, B. D. Influences of the Antarctic ozone hole on southern hemispheric summer climate change. J. Clim. 27, 6245–6264 (2014).

    Article  Google Scholar 

  29. Kang, S. M., Polvani, L. M., Fyfe, J. C. & Sigmond, M. Impact of polar ozone depletion on subtropical precipitation. Science 332, 951–954 (2011).

    Article  Google Scholar 

  30. Hendon, H. H., Lim, E.-P. & Nguyen, H. Seasonal variations of subtropical precipitation associated with the Southern Annular Mode. J. Clim. 27, 3446–3460 (2014).

    Article  Google Scholar 

  31. Lim, E. P. & Hendon, H. H. Understanding the contrast of Australian springtime rainfall of 1997 and 2002 in the frame of two flavors of El Niño. J. Clim. 28, 2804–2822 (2015).

    Article  Google Scholar 

  32. Dowdy, A. J. Climatological variability of fire weather in Australia. J. Appl. Meteorol. Climatol. 57, 221–234 (2018).

    Article  Google Scholar 

  33. Wilks, D. S. Statistical Methods in the Atmospheric Sciences (Academic Press, 2006).

  34. Ceppi, P. & Hartmann, D. L. On the speed of the eddy-driven jet and the width of the Hadley cell in the Southern Hemisphere. J. Clim. 26, 3450–3465 (2013).

    Article  Google Scholar 

  35. Quinting, J. F., Parker, T. J. & Reeder, M. J. Two synoptic routes to subtropical heat waves as illustrated in the Brisbane region of Australia. Geophys. Res. Lett. 45, 10700–10708 (2018).

    Article  Google Scholar 

  36. L’Heureux, M. L. & Thompson, D. W. J. Observed relationships between the El Niño–Southern Oscillation and the extratropical zonal-mean circulation. J. Clim. 19, 276–287 (2006).

    Article  Google Scholar 

  37. Zhou, T. J. & Yu, R. C. Sea-surface temperature induced variability of the Southern Annular Mode in an atmospheric general circulation model. Geophys. Res. Lett. 31, L24206 (2004).

    Article  Google Scholar 

  38. Lim, E.-P., Hendon, H. H. & Rashid, H. Seasonal predictability of the Southern Annular Mode due to its association with ENSO. J. Clim. 26, 8037–8054 (2013).

    Article  Google Scholar 

  39. Wang, G. et al. Compounding tropical and stratospheric forcing of the record low Antarctic sea-ice in 2016. Nat. Commun. 10, 13 (2019).

    Article  Google Scholar 

  40. Hudson, D. A. et al. ACCESS-S1: the new Bureau of Meteorology multi-week to seasonal prediction system. J. South. Hemisph. Earth Syst. Sci. 67, 132–159 (2017).

    Google Scholar 

  41. Shaw, T. A., Perlwitz, J., Harnik, N., Newman, P. A. & Pawson, S. The impact of stratospheric ozone changes on downward wave coupling in the Southern Hemisphere. J. Clim. 24, 4210–4229 (2011).

    Article  Google Scholar 

  42. Gillett, Z. E. et al. Evaluating the relationship between interannual variations in the Antarctic ozone hole and Southern Hemisphere surface climate in chemistry–climate models. J. Clim. 32, 3131–3151 (2019).

    Article  Google Scholar 

  43. Solomon, S. et al. Emergence of healing in the Antarctic ozone layer. Science 353, 269–274 (2016).

    Article  Google Scholar 

  44. Dee, D. et al. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).

    Article  Google Scholar 

  45. Jones, D., Wang, W. & Fawcett, R. High-quality spatial climate datasets for Australia. Aust. Meteorol. Oceanogr. J. 58, 233–248 (2009).

    Article  Google Scholar 

  46. Kobayashi, S. et al. The JRA-55 reanalysis: general specifications and basic characteristics. J. Meteorol. Soc. Jpn Ser. II 93, 5–48 (2015).

    Article  Google Scholar 

  47. Kalnay, E. et al. The NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc. 77, 437–471 (1996).

    Article  Google Scholar 

  48. Jones, D. A. & Trewin, B. C. On the relationships between the El Niño–Southern Oscillation and Australian land surface temperature. Int. J. Climatol. 20, 697–719 (2000).

    Article  Google Scholar 

  49. Ashok, K., Behera, S. K., Rao, S. A., Weng, H. & Yamagata, T. El Niño Modoki and its possible teleconnection. J. Geophys. Res. Oceans 112, C11007 (2007).

    Article  Google Scholar 

  50. Lim, E.-P. et al. Dynamical forecast of inter–El Niño variations of tropical SST and Australian spring rainfall. Mon. Weather Rev. 137, 3796–3810 (2009).

    Article  Google Scholar 

  51. Hurrell, J. W., Hack, J. J., Shea, D., Caron, J. M. & Rosinski, J. A new sea surface temperature and sea ice boundary dataset for the community atmosphere model. J. Clim. 21, 5145–5153 (2008).

    Article  Google Scholar 

  52. Reynolds, R. W., Rayner, N. A., Smith, T. M., Stokes, D. C. & Wang, W. An improved in situ and satellite SST analysis for climate. J. Clim. 15, 1609–1625 (2002).

    Article  Google Scholar 

Download references

Acknowledgements

This study is part of the Forewarned is Forearmed project, which is supported by funding from the Australian Government Department of Agriculture as part of its Rural R&D for Profit programme. G.B. and J.M.A. were supported by the Australian Research Council Centre of Excellence for Climate Extremes (grant CE170100023). J.M.A. was also supported by the Regional and Global Model Analysis component of the Earth and Environmental System Modeling Program of the US Department of Energy’s Office of Biological & Environmental Research via National Science Foundation IA 1947282. A.J.D. was supported by funding from the Australian Government’s National Environmental Science Program. D.W.J.T. was supported by the NSF Climate and Large-Scale Dynamics Program. We thank T. Cowan and B. Trewin at the Bureau of Meteorology for their constructive feedback on the manuscript. We also thank M. Griffiths at the Bureau of Meteorology for processing AWAP data for the analysis of the study. This research was undertaken at the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government. The NCAR Command Language (NCL; http://www.ncl.ucar.edu) version 6.4.0 was used for data analysis and visualization of the results. We also acknowledge NCAR/UCAR, NOAA, ECMWF and the Japanese Met Agent for producing and providing the Hurrell et al. (2008) SST analysis, the Reynolds OI v2 SST analysis, the ERA-Interim reanalysis and the JRA-55 reanalysis, respectively.

Author information

Authors and Affiliations

  1. Bureau of Meteorology, Melbourne, Victoria, Australia

    Eun-Pa Lim, Harry H. Hendon, Debra Hudson & Andrew J. Dowdy

  2. ARC Centre of Excellence for Climate Extremes, Monash University, Clayton, Victoria, Australia

    Ghyslaine Boschat & Julie M. Arblaster

  3. School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia

    Ghyslaine Boschat & Julie M. Arblaster

  4. Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA

    David W. J. Thompson

  5. National Center for Atmospheric Research, Boulder, CO, USA

    Julie M. Arblaster

Authors
  1. Eun-Pa Lim
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Harry H. Hendon
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Ghyslaine Boschat
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Debra Hudson
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. David W. J. Thompson
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Andrew J. Dowdy
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Julie M. Arblaster
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

E.-P.L. and H.H.H. conceived ideas for the study, E.-P.L. and G.B. conducted data analysis, H.H.H. wrote the first version of the manuscript and all authors contributed to the interpretation of the results and the writing of the manuscript.

Corresponding author

Correspondence to Eun-Pa Lim.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary Handling Editor(s): Heike Langenberg.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary figures.

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Lim, EP., Hendon, H.H., Boschat, G. et al. Australian hot and dry extremes induced by weakenings of the stratospheric polar vortex. Nat. Geosci. 12, 896–901 (2019). https://doi.org/10.1038/s41561-019-0456-x

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41561-019-0456-x

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing