Mechanism of the Madden-Julian Oscillation (MJO) Viewed from Scale Interactions in the Frequency Domain

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The project will investigate the evolution of the Madden-Julian Oscillation (MJO) in the tropics from diagnostic analysis of observations and numerical modeling of the atmosphere and the coupled atmosphere-ocean system. MJO is a key component of intra-seasonal variability, and plays a significant role in modulating the circulation and precipitation variability in the tropics and the extratropical Pacific/North American region. MJO also influences the Asian-Australian summer monsoons. Because of being sandwiched between two notable fluctuation time-scales--the shorter time-scale weather and the longer time-scale seasonal-to-interannual variability--MJO has not received the needed research attention up until recently. Dr. Krishnamurti (FSU) will investigate the role of intra-frequency interactions in MJO genesis and evolution. High-resolution numerical models of the atmosphere and the atmosphere-ocean system will be integrated to understand the spatio-temporal structure of the boundary layer fluxes of moisture, sensible heat, and momentum, in context of MJO variability. The project is driven by the PI's hypothesis that MJO time-scale flow components amplify from frequency interactions with a pair of synoptic time-scale (2-to-6 days) circulation features, particularly in the planetary boundary layer. The socio-economic impacts of Asian monsoon forecasts are felt by more than two billion people on the earth. The passage of intra-seasonal waves seems to have substantial impact on the wet and dry spells of the monsoon. This work has the potential to lead to real time prediction models of the MJO that can provide important guidance for sustained wet and dry spells of the monsoon.