Publication Date:
2014-01-05
Description:
[1] Here we ask, what controls the horizontal scale of the Madden-Julian Oscillation, i.e., what controls its zonal wavenumber k ? We present a new one-dimensional (1D) β-plane model that successfully simulates the MJO with the same governing mechanism as the 2D shallow water model of Yang and Ingersoll (2013). Convection is parameterized as a short-duration localized mass source that is triggered when the layer thickness falls below a critical value. Radiation is parameterized as a steady uniform mass sink. Both models tend toward a statistically steady state—a state of radiative-convective equilibrium, not just on a global scale but also on the scale of each MJO event. This gives k ~ ( S c / c ) 1/2 , where S c is the spatial-temporal frequency of convection events and c is the Kelvin wave speed. We offer this scaling as a prediction of how the MJO would respond to climate change.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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