Authors: Timothy M. Merlis, Paul O'Gorman, Tapio Schneider
It is commonly held that multiple extratropical jets form as a result of an inverse cascade of eddy kinetic energy to large scales. Here we show that multiple jets in baroclinic atmospheres can form when the nonlinear eddy-eddy interactions that give rise to an inverse energy cascade are weak or entirely absent. We use two versions of a dry primitive equation general circulation model: one with the full nonlinear equations of motion and one in which only eddy-mean flow interactions are retained but nonlinear eddy-eddy interactions are suppressed. Over a wide range of flows, the jet widths are similar to eddy length scales, to the length scale of the linearly most unstable wave, and to the Rossby radius.
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