讲座简介

The Madden-Julian Oscillation (MJO), a planetary-scale eastward propagating coherent structure with periods of 30-60 days, is a prominent manifestation of intraseasonal variability in the tropical atmosphere.It is widely presumed that small-scale moist cumulus convection is a critical part of its dynamics.However, the recent results from high-resolution modeling as wellas data analysis suggest that the MJO may be understood by dry dynamics to a leading--order approximation.Simple, further theoretical considerations presented herein suggestthat the MJO is most likely a strongly nonlinear solitary Rossby wave, if it is to be understood by dry dynamics. Under a global quasi-geostrophic equivalent-barotropic formulation, the modontheory provides such analytical solutions. Stability and the longevity of the modon solutions are investigated with a global shallow water model.The preferred modon solutions with the highest longevities comparerelatively well with the observed MJO in scale and phase velocity within the factors.

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