Weekly CASPO Seminar: join us on Zoom every Wednesday at 3:30 pm to hear about the latest and greatest in Climate, Atmospheric Sciences, and Physical Oceanography!
Daehyun Kim, Assisstant Professor of Atmospheric Sciences at the University of Washington, will give a talk titled Propagation of the Madden-Julian Oscillation over the Maritime Continent: the Role of the Basic State.
The Madden-Julian oscillation, or MJO, is the dominant mode of tropical intraseasonal (20-100 days) variability. It influences a wide range of Earth system phenomena, including high-impact weather and climate events. Despite its unmatched significance in the Earth system on the intraseasonal timescale, our understanding of the MJO remains incomplete.
My talk will focus on a particular aspect of the MJO that recently drew much attention from the research and forecast community: how MJO influences and is influenced by the world’s largest archipelago – the Indo-Pacific Maritime Continent, or MC. The MJO tends to detour around the MC region into the summer hemisphere. Moreover, the MJO’s propagation comes to an end most frequently over the MC, which is often referred to as the ‘MC barrier effect’. These peculiar behaviors of the MJO in the MC is poorly represented in weather and climate models.
I will review existing hypotheses for the MJO detour and the MC barrier effect and then focus on the role of the basic state. Our results from observations and models strongly suggest that a sharper peak in the basic state moisture, hence a greater meridional moisture gradient near MC, provides a favorable condition for MJO to cross MC more smoothly (i.e. weaker MC barrier effect). The role of the meridional moisture gradient on the propagation of the MJO will be discussed in the context of the moisture mode theory.
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