Lagrangian Coherent Structures deduced from HF radar measurements

In the present paper Lagrangian Coherent Structures are detected in the Gulf of Trieste, i.e., a Gulf located in the north-eastern part of the Adriatic Sea. Lagrangian Coherent Structures are usually detected through Lyapunov exponent diagnostic tools. However, such diagnostics lack of a rigorous mathematical background and try to associate well-known classical dynamical system structures of autonomous dynamical systems to the features of fluid flows. Such flows are studied under the perspective of non-autonomous dynamical systems, neglecting diffusion. In this work we try to detect Lagrangian Coherent Structures, i.e., the key material lines that shape trajectory patterns, with both the established Finite-Time Lyapunov Exponents and the recently introduced rigorous mathematical definitions implemented in the publicly available MATLAB LCS Tool. A comparison between real and simulated drifter trajectories is considered, too.