On the dynamics of oceanic gap-traversing boundary currents
Rotating-table laboratory experiments of oceanic gap-traversing boundary currents are considered. The experimental setup is designed to mimic a predominantly inertial boundary current, which impinges on a quasigeostrophic interior when encountering a gap in its supporting boundary. The current separates from the boundary, negotiates the gap and reattaches to the boundary. This is the case in oceanic situations such as the Kuroshio encountering the Luzon Strait and the Gulf Stream in the mouth of the Gulf of Mexico. Observation of such regions have shown the current to either leap directly across the gap or penetrate into the gap, forming a loop current, before continuing along the boundary (Caruso et al. 2006). Transitions between these states are observed to be irregular and difficult to predict. ^ The results of our experiments confirm the hypothesis of Sheremet (2001), that variations in the inertia of the current can cause transitions between states and that there is a hysteresis associated with those transitions. It is further confirmed that when a two-dimensional parameter space, representing the current's inertia and vorticity constraints of the system, is considered, the system admits a cusp catastrophe geometry of solutions. These findings are confirmed for both single- and two-layer experiments as well as supported by numerics and theory. The cusp framework may provide a means to understand the behavior of oceanic gap-traversing boundary currents. ^
Joseph J Kuehl,
"On the dynamics of oceanic gap-traversing boundary currents"
Dissertations and Master's Theses (Campus Access).