Dynamical Systems Analysis of IAS-ROMS Near-surface Velocity Field

Fernando Andrade, Julio Sheinbaum and Oscar Velasco-Fuentes
Physical Oceanography, CICESE, Ensenada, Baja California, Mexico

Dynamical systems techniques are used to analyze the near-surface velocity (30 m depth) of the Intra-Americas (Caribbean and Gulf of Mexico) ROMS model and understand the transport and mixing of particles in the system. Finite Size Lyapunov Exponents (FSLE) and the double time slice method are used to identify stable and unstable manifolds (or repelling and attracting material lines) of the flow field which define directions of transport. Lobes arising from intersection of these manifolds at vortex edges indicate regions of exchange in and out of the vortices, whereas barriers to transport are identified by their tangency. A particular condition consisting of two interacting vortices near the Yucatan Channel is investigated in detail. Time-averaged FSLE maps and of the Okubo-Weiss invariant are used to identify areas of strong and weak mixing in the region.