Mamidi, K.; Mathew, V. Minimal Mechanisms Responsible for the Dispersive Behavior of the Madden–Julian Oscillation. Climate2023, 11, 236.
Mamidi, K.; Mathew, V. Minimal Mechanisms Responsible for the Dispersive Behavior of the Madden–Julian Oscillation. Climate 2023, 11, 236.
Mamidi, K.; Mathew, V. Minimal Mechanisms Responsible for the Dispersive Behavior of the Madden–Julian Oscillation. Climate2023, 11, 236.
Mamidi, K.; Mathew, V. Minimal Mechanisms Responsible for the Dispersive Behavior of the Madden–Julian Oscillation. Climate 2023, 11, 236.
Abstract
An attempt has been made to explore the relative contributions of moisture feedback processes on tropical intraseasonal oscillation or Madden Julian Oscillation (MJO). We focused on moisture feedback processes, including evaporation wind feedback (EWF) and moisture convergence feedback (MCF), which integrates the mechanisms of convective interactions in the tropical atmosphere. The dynamical framework considered here is a moisture-coupled, single-layer linear shallow-water model on an equatorial beta-plane with zonal momentum damping. With this simple approach, we aimed to recognize the minimal physical mechanisms responsible for the existence of the essential dispersive characteristics of the MJO, including its eastward propagation(k>0), the planetary-scale (small zonal wavenumbers) instability, and the slow phase speed of about ≈ 5 m/sec. Further, we extended our study to determine each feedback mechanism’s influence on the simulated eastward dispersive mode. Our model emphasized that the MJO-like eastward mode is a possible outcome of the combined effect of moisture feedback processes without requiring additional complex mechanisms such as cloud radiative feedback and boundary layer dynamics. The results substantiate the importance of EWF as an energy source for developing eastward moisture mode with a planter-scale instability. Moreover, our model endorses that the MCF alone could not produce instability without surface fluxes, although it has a significant role in developing deep convection. It is found that the MCF exhibits a damping mechanism by regulating the frequency and growth rate of the eastward moisture mode at shorter wavelengths.
Keywords
Madden Julian Oscillation; shallow water model; moisture interactions
Subject
Environmental and Earth Sciences, Atmospheric Science and Meteorology
Copyright:
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