Sack Lunch Seminar (SLS)

Stirring in certain regions of the ocean and atmosphere is controlled by coherent, long-lived eddies or waveforms. Stirring is most rapid where fluid trajectories are chaotic, and this process, known as chaotic advection, has been documented and studied in depth in connection with two-dimensional (or quasi 2D) flow fields. I will discuss the applicability of these ideas in a fully 3D flow that contains a horizontal swirling circulation plus an overturning circulation, as in certain ocean eddies. The numerically generated flow fields contain a rich mixture of chaotic and non-chaotic regions, so the stirring can be highly non-homogeneous. Various regimes are mapped out in the space of geophysically relevant ranges of Ekman and Rossby numbers.