Transient chaotic mixing during a baroclinic life cycle

We discuss how atmospheric eddies affect transport and mixing of tracers at midlatitudes. To this purpose, we study baroclinic life cycles in a simple dynamical model of the atmosphere. We consider the trapping properties of the developing eddies and the characteristics of meridional transport, and we identify regions of increased mixing. Although the flow is in principle three-dimensional, we illustrate how some of the concepts developed in the study of two-dimensional chaotic advection provide useful information on tr acer dynamics in more complicated flows. (C) 2000 American Institute of Phy sics. [S1054-1500(00)02401-0].