Ocean surface hidden structures in the Lofoten area of the Norwegian Sea

Abstract

We investigate the structure of surface lateral mixing in the Lofoten area in the Norwegian Sea using surface velocity field derived from a 1/12o reanalysis data. We compute a Lagrangian diagnostic based on the evolution of Finite Time Lyapunov Exponents (FTLEs) by advecting (backward in time) a large number of particles to quantify the hidden skeleton of different dynamical regions in the study area. By constructing maps of deterministic Lagrangian Coherent Structures (LCSs), four dynamical regions are generally identified: (i) regions of maximal dynamical attraction along the west coast of Norway and Barents Sea Opening; (ii) area of quasi-prominent anticyclonic eddy located at the centre of Lofoten Basin (LB); (iii) mid-ocean system of the Mohn Ridge which separates the Atlantic and Arctic waters: (iv) areas expanded between shallow continental shelf and deep basins populated with multiscale structures. We further construct a climatology of LCSs and FTLE statistical distributions with 11-year of reanalysis data to investigate the seasonal variability of Lagrangian circulations and to classify further their dynamical properties. The FTLE and LCS analyses in the present study can contribute to better understand the key transport barriers to the fate of larval dispersion and ocean contaminants, and marine population connectivity.