Yano, J. -I., & Tribbia, J. J. (2017). Tropical atmospheric Madden-Julian Oscillation: A strongly nonlinear free solitary Rossby wave? Journal Of The Atmospheric Sciences, 74, 3473-3489. doi:10.1175/JAS-D-16-0319.1
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 it... Show moreThe 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 well as data analysis suggest that the MJO may be understood by dry dynamics to a leading-order approximation. Simple, further theoretical considerations presented herein suggest that if it is to be understood by dry dynamics, the MJO is most likely a strongly nonlinear solitary Rossby wave. Under a global quasigeostrophic equivalent-barotropic formulation, modon theory provides such analytic solutions. Stability and the longevity of the modon solutions are investigated with a global shallow-water model. The preferred modon solutions with the greatest longevities compare well overall with the observed MJO in scale and phase velocity within the factors. Show less