On uniting Eulerian and Lagrangian mesoscale eddy perspectives

Mesoscale eddies play a pivotal role in oceanic dynamics, influencing transport, mixing, and energy distribution. Current detection methods are primarily divided into Eulerian and Lagrangian approaches, each highlighting unique eddy characteristics. Eulerian methods rely on instantaneous fields, such as sea surface height, Okubo–Weiss parameter or vorticity, to identify the eddy boundaries. In contrast, Lagrangian approaches utilize water parcel trajectories to compute metrics like the Lagrangian Average Vorticity Deviation (LAVD) or Finite-Time Lyapunov Exponents (FTLE), identifying rotationally coherent Lagrangian vortices (RCLVs) with minimal exchange across the boundary. Eulerian eddies, however, are inherently "leaky", allowing for fluid exchange due to the fact that their boundaries are non-material. Despite these differences, both approaches capture complementary aspects of the same physical phenomenon. This study aims to bridge the gap between the two eddy detection methods by combining their strengths and leveraging high-resolution simulations from the coupled climate model ICON. Here, we identify daily RCLVs from evolving LAVD fields to find the time at which each Eulerian eddy loses coherence. In doing so, we will be able to explore how eddy coherence changes though its lifecycle and geographical location. This combined methodology can deepen our understanding of mesoscale ocean transport by quantifying realistic eddy trapping ability.