Interdecadal cycles in Australian annual rainfall

Selkirk, Tobias F.; Western, Andrew W.; Webb, J. Angus

doi:https://doi.org/10.5194/hess-29-2167-2025

Articles | Volume 29, issue 9

https://doi.org/10.5194/hess-29-2167-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-29-2167-2025

© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 29, issue 9

Research article

|

08 May 2025

Research article |

| 08 May 2025

Interdecadal cycles in Australian annual rainfall

Tobias F. Selkirk, Andrew W. Western, and J. Angus Webb

Supplement

https://doi.org/10.5194/hess-29-2167-2025-supplement

Data sets

Weather station networks and details Australian Bureau of Meteorology http://www.bom.gov.au/climate/data/lists_by_element/alphaAUS_139.txt

SILO Climate Data Scientific Information for Land Owners https://www.longpaddock.qld.gov.au/silo/view-point-data/

Daily total sunspot number since 1818 (taches solaires) Royal Observatory of Belgium https://data.opendatasoft.com/explore/embed/dataset/daily-sunspot-number@datastro/table/?sort=-column_4

Model code and software

PyWavelets/pywt: v1.1.1 G. R. Lee et al. https://doi.org/10.5281/zenodo.3510098

scaleogram: v0.9.5 A. Sauvé and D. Nowacki https://github.com/alsauve/scaleogram

PyCWT: v0.3.0a22 S. Krieger et al. https://github.com/regeirk/pycwt

Short summary

This study investigated rainfall in eastern Australia to search for patterns that may aid in predicting flood and drought. The current popular consensus is that such cycles do not exist. We analysed 130 years of rainfall using a very modern technique for identifying cycles in complex signals. The results showed strong evidence of three clear cycles of 12.9, 20.4 and 29.1 years with a confidence of 99.99 %. When combined, they showed an 80 % alignment with years of extremely high and low rainfall.