Baroclinic adjustment observed in the Southern Hemisphere

A SG model is used to seek evidence of baroclinic adjustment in the observed Southern Hemisphere flows. To avoid complications associated with orographic effects, the analysis is restricted to the Southern Hemisphere. The study focuses on a local singel "life cycle event," in which the working of baroclinic adjustment is most likely to be detected. The change in the local mean flow during the life cycle of baroclinic eddy is analyzed first. The SG model is then used to capture the essence of this change in the mean flow and stability analysis is performed on the flow. It is found that mixing associated with baroclinic eddies tends to distort the baroclinic zone on the tropopause, while leaving the surface potential temperature relatively undisturbed. While care must be exercised in generalizing the result of this "case study," it appears that similar separation events occur quite frequently on the tropopause in both Northern and Southern Hemispheres. The existence of downstream development will also be considered in the study. This study represents one of the few direct observational evidence of baroclinic adjustment at work, be it regional or global.