Interdecadal rainfall cycles in spatially coherent global regions and their relationship to the climate modes

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

doi:https://doi.org/10.5194/hess-29-5737-2025

Articles | Volume 29, issue 20

https://doi.org/10.5194/hess-29-5737-2025

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

https://doi.org/10.5194/hess-29-5737-2025

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

Articles | Volume 29, issue 20

Research article

|

24 Oct 2025

Research article |

| 24 Oct 2025

Interdecadal rainfall cycles in spatially coherent global regions and their relationship to the climate modes

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

Supplement

https://doi.org/10.5194/hess-29-5737-2025-supplement

Data sets

GPCC Full Data Monthly Version 2022 at 2.5°: Monthly Land-Surface Precipitation from Rain-Gauges built on GTS-based and Historic Data: Globally Gridded Monthly 655 Totals U. Schneider et al. https://doi.org/10.5676/DWD_GPCC/FD_M_V2022_250

Niño 3.4 645 SST Index from the HadISST1.1 N. A. Rayner et al. https://psl.noaa.gov/data/timeseries/month/DS/Nino34/

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

Dipole Mode Index (DMI) Monthly Time-series N. H. Saji and T. Yamagata https://psl.noaa.gov/data/timeseries/month/DS/DMI/

North Atlantic Oscillation (NAO) index NOAA National Centers for Environmental Information (NCEI) https://www.ncei.noaa.gov/access/monitoring/nao/

Interdecadal Pacific Oscillation, 1871–2016 Ministry for the Environment https://data.mfe.govt.nz/table/89382-interdecadal-pacific-oscillation-18712016

Model code and software

PyWavelets/pywt: v1.7.0 (v1.7.0) Gregory Lee et al. https://doi.org/10.5281/zenodo.13306773

Short summary

This study finds three cycles in yearly rainfall worldwide of approximately 13, 20 and 28 years. The cycles rise and fall together across continents and also appear in the El Niño–Southern Oscillation (ENSO), a major climate driver of rain. However the signal in ENSO is too small to explain the strong local influence, the results point to another, still-unknown force that may shape both the climate modes and global rainfall.