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Why Australia was not wet during spring 2020 despite La Niña
The austral spring climate of 2020 was characterised by the occurrence of La Niña, which is the most predictable climate driver of Australian springtime rainfall. Consistent with this La Niña, the Bureau of Meteorology’s dynamical sub-seasonal to seasonal forecast system, ACCESS-S1, made highly conf...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8445951/ https://www.ncbi.nlm.nih.gov/pubmed/34531448 http://dx.doi.org/10.1038/s41598-021-97690-w |
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author | Lim, Eun-Pa Hudson, Debra Wheeler, Matthew C. Marshall, Andrew G. King, Andrew Zhu, Hongyan Hendon, Harry H. de Burgh-Day, Catherine Trewin, Blair Griffiths, Morwenna Ramchurn, Avijeet Young, Griffith |
author_facet | Lim, Eun-Pa Hudson, Debra Wheeler, Matthew C. Marshall, Andrew G. King, Andrew Zhu, Hongyan Hendon, Harry H. de Burgh-Day, Catherine Trewin, Blair Griffiths, Morwenna Ramchurn, Avijeet Young, Griffith |
author_sort | Lim, Eun-Pa |
collection | PubMed |
description | The austral spring climate of 2020 was characterised by the occurrence of La Niña, which is the most predictable climate driver of Australian springtime rainfall. Consistent with this La Niña, the Bureau of Meteorology’s dynamical sub-seasonal to seasonal forecast system, ACCESS-S1, made highly confident predictions of wetter-than-normal conditions over central and eastern Australia for spring when initialised in July 2020 and thereafter. However, many areas of Australia received near average to severely below average rainfall, particularly during November. Possible causes of the deviation of rainfall from its historical response to La Niña and causes of the forecast error are explored with observational and reanalysis data for the period 1979–2020 and real-time forecasts of ACCESS-S1 initialised in July to November 2020. Several compounding factors were identified as key contributors to the drier-than-anticipated spring conditions. Although the ocean surface to the north of Australia was warmer than normal, which would have acted to promote rainfall over northern Australia, it was not as warm as expected from its historical relationship with La Niña and its long-term warming trend. Moreover, a negative phase of the Indian Ocean Dipole mode, which typically acts to increase spring rainfall in southern Australia, decayed earlier than normal in October. Finally, the Madden–Julian Oscillation activity over the equatorial Indian Ocean acted to suppress rainfall across northern and eastern Australia during November. While ACCESS-S1 accurately predicted the strength of La Niña over the Niño3.4 region, it over-predicted the ocean warming to the north of Australia and under-predicted the strength of the November MJO event, leading to an over-prediction of the Australian spring rainfall and especially the November-mean rainfall. |
format | Online Article Text |
id | pubmed-8445951 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-84459512021-09-20 Why Australia was not wet during spring 2020 despite La Niña Lim, Eun-Pa Hudson, Debra Wheeler, Matthew C. Marshall, Andrew G. King, Andrew Zhu, Hongyan Hendon, Harry H. de Burgh-Day, Catherine Trewin, Blair Griffiths, Morwenna Ramchurn, Avijeet Young, Griffith Sci Rep Article The austral spring climate of 2020 was characterised by the occurrence of La Niña, which is the most predictable climate driver of Australian springtime rainfall. Consistent with this La Niña, the Bureau of Meteorology’s dynamical sub-seasonal to seasonal forecast system, ACCESS-S1, made highly confident predictions of wetter-than-normal conditions over central and eastern Australia for spring when initialised in July 2020 and thereafter. However, many areas of Australia received near average to severely below average rainfall, particularly during November. Possible causes of the deviation of rainfall from its historical response to La Niña and causes of the forecast error are explored with observational and reanalysis data for the period 1979–2020 and real-time forecasts of ACCESS-S1 initialised in July to November 2020. Several compounding factors were identified as key contributors to the drier-than-anticipated spring conditions. Although the ocean surface to the north of Australia was warmer than normal, which would have acted to promote rainfall over northern Australia, it was not as warm as expected from its historical relationship with La Niña and its long-term warming trend. Moreover, a negative phase of the Indian Ocean Dipole mode, which typically acts to increase spring rainfall in southern Australia, decayed earlier than normal in October. Finally, the Madden–Julian Oscillation activity over the equatorial Indian Ocean acted to suppress rainfall across northern and eastern Australia during November. While ACCESS-S1 accurately predicted the strength of La Niña over the Niño3.4 region, it over-predicted the ocean warming to the north of Australia and under-predicted the strength of the November MJO event, leading to an over-prediction of the Australian spring rainfall and especially the November-mean rainfall. Nature Publishing Group UK 2021-09-16 /pmc/articles/PMC8445951/ /pubmed/34531448 http://dx.doi.org/10.1038/s41598-021-97690-w Text en © Crown 2021 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Article Lim, Eun-Pa Hudson, Debra Wheeler, Matthew C. Marshall, Andrew G. King, Andrew Zhu, Hongyan Hendon, Harry H. de Burgh-Day, Catherine Trewin, Blair Griffiths, Morwenna Ramchurn, Avijeet Young, Griffith Why Australia was not wet during spring 2020 despite La Niña |
title | Why Australia was not wet during spring 2020 despite La Niña |
title_full | Why Australia was not wet during spring 2020 despite La Niña |
title_fullStr | Why Australia was not wet during spring 2020 despite La Niña |
title_full_unstemmed | Why Australia was not wet during spring 2020 despite La Niña |
title_short | Why Australia was not wet during spring 2020 despite La Niña |
title_sort | why australia was not wet during spring 2020 despite la niña |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8445951/ https://www.ncbi.nlm.nih.gov/pubmed/34531448 http://dx.doi.org/10.1038/s41598-021-97690-w |
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