Pathways for advective transport

Advective transport in the ocean fundamentally is Lagrangian in nature. At model grid scales, this transport is parameterized by eddy or turbulent exchange coefficients in analogy to molecular diffusion. Nevertheless, much of the transport is by advection on scales larger than the grid cell yet smaller than basin scale. Moreover, flow at these scales tends to be nonstationary in time and irregularly distributed in space. Recently we have successfully used concepts from dynamical systems theory to analyze observations of such flows. The analysis is based on constructing, from synoptic observations of currents, material boundaries within the flow field that are not apparent in time varying Eulerian velocity fields. Here a short description of the approach is given and an application to the Gulf of Mexico is described where the analysis precisely identifies the boundaries of coherent vortical structures as well as pathways for advective transport.