Scientists are still debating what drives the interannual variation of the Madden-Julian Oscillation (MJO)—a global-scale pattern of tropical winds and rain that can have dramatic impacts in the mid-latitudes. One existing theory is the moisture mode theory, or the idea that the MJO’s behavior can be explained by changes in the background moisture over the tropical ocean. Recent work funded by CPO’s Climate Variability and Predictability (CVP) program took a closer look at this theory and revealed its strong influence on the MJO’s global trek.
Specifically, the study, published in the Journal of Climate, investigated the role of background moisture on the MJO’s eastward movement across the maritime continent region. The authors found that in years with higher mean moisture, the MJO travels eastward more quickly. In years with lower mean moisture, the MJO travels eastward more slowly.
This study could help improve the representation of the MJO in climate models. However, the authors note that El Niño/La Niña years can impact background moisture available to the MJO, so further work is necessary.
This work is part CVP’s Years of the Maritime Continent research activity. See the webinar series for more.
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