Closure Modeling of Fully Developed Baroclinic Instability

Abstract

Simple second-order closure models of quasi-geostrophic turbulence are derived, applying either to two-layer flows within isentropic boundaries, or to Eady-type frontogenesis with vanishing potential vorticity; homogeneity and horizontal isotropy are used as simplifying assumptions. Long-term numerical integrations of the two models are performed to obtain the structure of regime flows under stationary large-scale baroclinic forcing. The various cascade processes and the corresponding inertial ranges are discussed and visualized, showing characteristic differences between fully developed baroclinic instability and the linear theory. Further applications of such models may include studies of truncation effects on the efficiency of baroclinic instability.