Modal Interpretation for the Ekman Destabilization of Inviscidly Stable Baroclinic Flow in the Phillips Model

Ekman boundary layers can lead to the destabilization of baroclinic flow in the Phillips model that, in the absence of dissipation, is nonlinearly stable in the sense of Liapunov. It is shown that the Ekman-induced instability of inviscidly stable baroclinic flow in the Phillips model occurs if and only if the kinematic phase velocity associated with the dissipation lies outside the interval bounded by the greatest and least neutrally stable Rossby wave phase velocities. Thus, Ekman-induced destabilization does not correspond to a coalescence of the barotropic and baroclinic Rossby modes as in classical inviscid baroclinic instability. The differing modal mechanisms between the two instability processes is the reason why subcritical baroclinic shears in the classical theory can be destabilized by an Ekman layer, even in the zero dissipation limit of the theory.

Unemployment in South Africa 1970 – 2002: The development of a configuration concern for future employment

Unemployment in South Africa has reached crisis proportions and does not seem to be decreasing in concurrence with the more propitious economic reality. Indeed, the unemployment process seems to be isolated from economic reality and has developed a life of its own. This paper investigates what initiates and underlies the development of this phenomenon. The Phillips model on endogenously determined long-run equilibrium unemployment is applied, using hysteresis models and autoregressive modelling, to determine the nature of the high and sustained levels of South African unemployment. We find evidence of unemployment in South Africa being a historical inheritance preserved by uncertainty and sunken costs in the labour market.