On open ocean baroclinic instability in the Arctic

A simple linear model is used to investigate the possibility of baroclinic instability in the Arctic. The basic state consists of a barotropic flow directed along depth contours, a baroclinic component uniform in horizontal directions which decreases exponentially with depth, and an exponentially decaying stratification. With no β-effect there is always a shortwave cutoff for wavelengths shorter than the radius of deformation based on the surface N² and total depth. With β there appears to be no shortwave cutoff but the growth rate peaks near the same values of wavelength. The results suggest that the 10- to 20-km eddies observed in the Arctic are probably not generated by baroclinic instability in the open ocean but may arise from instability in the shallow regions.