Influence of the QBO on MJO prediction skill in the subseasonal-to-seasonal prediction models
Recent studies have shown that the Madden-Julian Oscillation (MJO) is significantly modulated by the stratospheric Quasi-Biennial Oscillation (QBO). In general, boreal winter MJO becomes more active during the easterly phase of the QBO (EQBO) than during the westerly phase (WQBO). Based on this finding, here we examine the possible impacts of the QBO on MJO prediction skill in the operational models that participated in the WCRP/WWRP subseasonal-to-seasonal (S2S) prediction project. All models show a higher MJO prediction skill during EQBO winters than during WQBO winters. For the bivariate anomaly correlation coefficient of 0.5, the MJO prediction skill during EQBO winters is enhanced by up to 10 days. This enhancement is insensitive to the initial MJO amplitude, indicating that the improved MJO prediction skill is not simply the result of a stronger MJO. Instead, a longer persistence of the MJO during EQBO winters likely induces a higher prediction skill by having a higher prediction limit.
KeywordsQuasi-Biennial Oscillation (QBO) Madden-Julian Oscillation (MJO) QBO–MJO link Subseasonal-to-Seasonal (S2S) prediction
This work is supported by the Korea Meteorological Institute under Grant KMI 2018-01011. We thank the operational centers for supplying their model output through the S2S database. We also appreciate the three anonymous reviewers for their constructive comments.
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