Title :

Coastal current convergence structures in the Bay of Biscay from optimized high-frequency radar and satellite data

Author(s) :

Bertin, S. [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Rubio, A. [Auteur]
Hernández-Carrasco, I. [Auteur]
Solabarrieta, L. [Auteur]
Ruiz, I. [Auteur]
Orfila, A. [Auteur]
Sentchev, Alexei [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Université du Littoral Côte d'Opale [ULCO]

Journal title :

Science of the Total Environment

Pages :

174372

Publisher :

Elsevier

Publication date :

2024-10-15

ISSN :

0048-9697

English keyword(s) :

Current convergence structures
High-Frequency Radar
Surface drifters
Lagrangian dispersion
Southeastern Bay of Biscay

English abstract : [en]

The southeastern Bay of Biscay has been described as a “dead end” for floating marine litter, often accumulatingalong small-scale linear streaks. Coastal Current Convergence Structures (CCS), often associated with ...
Show more >The southeastern Bay of Biscay has been described as a “dead end” for floating marine litter, often accumulatingalong small-scale linear streaks. Coastal Current Convergence Structures (CCS), often associated with verticalmotions at river plume edges, estuarine fronts, or other physical processes, can be at the origin of the accumulation.Understanding the formation of CCS and their role in the transport of marine litter is essential to betterquantify and to help mitigate marine litter pollution. The Lagrangian framework, used to estimate the absolutedispersion, and the finite-size Lyapunov exponents (FSLE), have proved very effective for identifying CCS in thecurrent velocity field. However, the quality of CCS identification depends strongly on the Eulerian fields. Twosurface current velocity data sets were used in the analysis: the remotely sensed velocities from the EuskOOSHigh-Frequency Radar (HFR) network and velocities from three-dimensional model outputs. They were complementedby drifting buoy velocity measurements. An optimization method, involving the fusion of driftingbuoys and HFR velocities is proposed to better reconstruct the fine-scale structure of the current velocity field.Merging these two sources of velocity data reduced the mean Lagrangian error and the Root Mean Square Error(RMSE) by 50 % and 30 % respectively, significantly improving velocity reconstruction. FSLE ridgelines obtainedfrom the Lagrangian analysis of optimized velocities were compared with remotely sensed concentrations ofChlorophyll-a. It was shown that ridgelines control the spatial distribution of phytoplankton. They fundamentally represent the CCS which can potentially affect marine litter aggregation. Analysis of the absolute dispersionrevealed large stirring in the alongshore direction which was also confirmed by spatial distribution of FSLEridgelines. The alignment between FSLE ridgelines and patterns of high Chlorophyll-a concentration wasobserved, often determining the limits of river plume expansion in the study area.Show less >

Language :

Anglais

Popular science :

Non

ANR Project :

Transdisciplinary graduate school for marIne, Fisheries and SEAfood sciences

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL