Dataset: Results from Finite Time Lyapunov Exponent calculations using High Frequency Radar observed surface currents around Palmer Deep Canyon from January to March of 2020

Methods for these LCS results can be found in Veatch, et al., (2024), In revision.

Finite Time Lyapunov Exponents assign scalar values to points on a gridded velocity field that characterizes the horizontal separation distance between two drifters about a point over a defined

 time interval. From particle trajectories in a velocity field, FTLE will define stretching as the integrated separation rate between two particles. To calculate repelling FTLEs, a forward trajectory is used, and to calculate attracting FTLEs, a backward trajectory is used. In this study, attracting FTLEs were calculated. FTLE differs from the instantaneous separation rate (Weiss 1991; Okubo 1970) by integrating over trajectories, providing a more realistic interpretation (one with particle position “memory”) of transport in the velocity field. Coherent structures are defined by the FTLE metric as ridges in the flow field where neighboring particles are converged toward, and then diverged along the ridge. This relative motion between two

neighboring particles is the key way in which the FTLE metric differs from the RPD metric. FTLE will vary over space and time when applied to a discrete set of velocity data. FTLE calculations result in a material surface that then can be projected at a set resolution back onto the study region. FTLE results were projected at the resolution of the HFR so as to not stretch the observations further than the input data should be able to resolve. FTLE calculations were performed using a MATLAB software toolbox (Haller) that was modified for use on HFR data and available at https://github.com/JackieVeatch/SWARM_LCS.
* Curatorial note: See supplemental file SWARM_LCS-related_to_bcodmo_917926_917914_v1.zip which contains a release corresponding to commit (10931d9).