  We study the Lagrangian dynamics of passive tracers in a simple model of a
driven two-dimensional vortex resembling real-world geophysical flow patterns.
Using a discrete approximation of the system's transfer operator, we construct
a directed network that characterizes the exchange of mass between distinct
regions of the flow domain. By studying different measures characterizing flow
network connectivity at different time-scales, we are able to identify the
location of dynamically invariant structures and regions of maximum dispersion.
Specifically, our approach allows to delimit co-existing flow regimes with
different dynamics. To validate our findings, we compare several network
characteristics to the well-established finite-time Lyapunov exponents and
apply a receiver operating characteristic (ROC) analysis to identify network
measures that are particularly useful for unveiling the skeleton of Lagrangian
chaos.
