Drifters dispersion in the Adriatic Sea: Lagrangian data and chaotic model

TL;DR

This paper investigates drifter trajectories in the Adriatic Sea using nonlinear dynamics techniques, highlighting the limitations of traditional dispersion analysis and proposing alternative indicators and a chaotic model to better understand sub-basin scale advection.

Contribution

It introduces the use of Finite-Scale Lyapunov Exponent and Lagrangian Structure Function as non-asymptotic indicators for dispersion analysis in quasi-enclosed basins and presents a simple chaotic model for drifter motion.

Findings

Relative dispersion can be distorted in quasi-enclosed basins.

FSLE and LSF provide intrinsic physical insights at specific scales.

Lagrangian dispersion is mainly driven by advection at sub-basin scales.

Abstract

We analyze characteristics of drifter trajectories from the Adriatic Sea with recently introduced nonlinear dynamics techniques. We discuss how in quasi-enclosed basins, relative dispersion as function of time, a standard analysis tool in this context, may give a distorted picture of the dynamics. We further show that useful information may be obtained by using two related non-asymptotic indicators, the Finite-Scale Lyapunov Exponent (FSLE) and the Lagrangian Structure Function (LSF), which both describe intrinsic physical properties at a given scale. We introduce a simple chaotic model for drifter motion in this system, and show by comparison with the model that Lagrangian dispersion is mainly driven by advection at sub-basin scales until saturation sets in.