On the linear approximation of velocity and density profiles in the problem of baroclinic instability

The linear approximation of density and velocity profiles is compared to more realistic models with vertically inhomogeneous density gradients and nonzero anomalous vorticity (i.e., the nonplanetary part of potential vorticity). Calculations based on the parameters of 'real life' currents in the Northern Pacific demonstrate that these effects, acting together, can make baroclinic instability 2.5-6 times stronger and dramatically expand the spectral range of unstable disturbances toward the short-wave region (by a factor of more than 20-30).