Centrifugal-dissipative instability of Rossby vortices and their cyclonic-anticyclonic asymmetry

A new linear centrifugal-dissipative mechanism is proposed that explains the vortex asymmetry observed, in particular, in the structure of low-frequency anticyclonic Rossby vortices. It is shown that the relevant centrifugal-dissipative instability, which spontaneously breaks the chiral symmetry of the vortices, takes place only in the range $\omega<\Omega$, where $\omega$ is the frequency of small oscillations corresponding to the effective solid-body rotation of a vortex and $\Omega$ is the rotation rate of a noninertial frame of reference. The onset of the instability is associated with the existence of an optimum magnitude of the frictional force. In the vortex model based on a two-dimensional oscillator with the natural frequency $\omega$ in a noninertial reference frame rotating at the rate $\Omega$, the instability shows up as an exponential increase in the total angular momentum. It is noted that the centrifugal dissipative instability may also manifest itself in the seismically active regions of the world.