Decadal variability of MJO teleconnections in a coupled climate model

Skinner, Daniel T., Matthews, Adrian J. and Stevens, David P. (2025) Decadal variability of MJO teleconnections in a coupled climate model. Quarterly Journal of the Royal Meteorological Society. ISSN 0035-9009 (In Press)

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Abstract

The Madden-Julian Oscillation (MJO) is a key source of predictability for global weather. Through both tropospheric and stratospheric teleconnection pathways, the MJO is able to alter the extratropical circulation, and in turn cause shifts in other modes of variability such as the Pacific-North American Pattern and North Atlantic Oscillation. MJO teleconnections are known to vary on a range of time scales, but their variability on decadal and multi-decadal time scales is not well understood. Using the UKESM1 coupled climate model, we show that both Atlantic Multi-decadal Variability (AMV) and the Pacific Decadal Oscillation (PDO) alter MJO teleconnection patterns and their impact on extratropical modes of variability. AMV and the PDO modulate the mean state of the atmosphere, in particular the Aleutian Low, which controls how the circulation respondes to the MJO. When the Aleutian Low is deepened, for example during the positive phase of the PDO, this provides the conditions necessary for the MJO teleconnection to project onto the climatological low, either constructively or destructively. During the positive phase of the AMV and negative phase of the PDO, which favour a weak Aleutian Low, the MJO cannot drive a significant cyclonic response in the region. Changes in the Stratospheric Polar Vortex, preceded by MJO related anomalies in the Aleutian Low, also control extratropical weather. We hypothesise that this stratospheric teleconnection pathway is also modulated by both AMV and the PDO. These results have implications for improving the predictability of extratropical weather patterns over the coming decades. By understanding how MJO teleconnections are altered by internal modes of decadal and multi-decadal variability, the impact of anthropogenic climate change can be better identified in future projections. This context will improve both long-range forecasts of MJO-driven variability, and short-term forecasts in different SST conditions.

Item Type:	Article
Additional Information:	Data availability statement: UKESM1 data provided by the CEDA archive (Tang et al., 2019) and accessed through JASMIN (Lawrence et al., 2013). MJO RMM index principal components calculated by Wheeler and Hendon (2004) and provided by Dr Prince Xavier. PDO EOF pattern provided by the NOAA PSL (https://psl.noaa.gov/pdo/). Funding information: Natural Environment Research Council, Grant/Award Number: NE/R016704/1 (TerraMaris). University of East Anglia, Faculty of Science Studentship.
Faculty \ School:	Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA Faculty of Science > School of Engineering, Mathematics and Physics
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Climatic Research Unit Faculty of Science > Research Groups > Fluids & Structures
Depositing User:	LivePure Connector
Date Deposited:	16 Jul 2025 10:33
Last Modified:	16 Jul 2025 10:33
URI:	https://ueaeprints.uea.ac.uk/id/eprint/99945
DOI:	10.1002/qj.5071

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