A barotropic model of storm tracks

A simple model of a tropospheric storm track consists of a barotropic atmosphere on a sphere which supports Rossby wave propagation. A localised region of instability is introduced. As disturbances propagate into the unstable region, they amplify and excite further Rossby wave activity. On a periodic domain, these disturbances eventually re-enter the unstable region and generate further amplification events. The resulting signature of eddy activity can be similar to that observed in the upper troposphere in the vicinity of the Atlantic or Pacific storm tracks. Many of its features can be understood in terms of linear theories of Rossby wave propagation. Provided the instability is sufficiently strong, the resulting flow is highly unsteady and aperiodic. The aperiodicity is related to the two dimensional geometry of the system.