Assessment of a Lagrangian model using trajectories of oceanographic drifters and fishing devices in the Tropical Atlantic Ocean

Type Article
Date 2020-10
Language English
Author(s) Amemou H.1, 2, 3, 4, Koné V., Aman A.2, Lett Christophe3
Affiliation(s) 1 : Centre de Recherches Océanologiques (CRO), 29 Rue des Pêcheurs, BPV 18, Abidjan, Côte d’Ivoire
2 : Laboratoire de Physique de l’Atmosphére et Mécanique des fluides, LAPA-MF, Université Félix Houphouet Boigny, Côte d’Ivoire
3 : MARBEC, Univ Montpellier, CNRS, IFREMER, IRD, Séte, France
4 : Sorbonne Université, IRD, Unité de Modélisation Mathématique et Informatique des Systémes Complexes, UMMISCO, F-93143, Bondy, France
Source Progress In Oceanography (0079-6611) (Elsevier BV), 2020-10 , Vol. 188 , P. 102426 (21p.)
DOI 10.1016/j.pocean.2020.102426
WOS© Times Cited 2
Keyword(s) Drifter, Fish aggregating device, Particle, Trajectory, Velocity, Model performance

In the Tropical Atlantic Ocean, we assessed the accuracy of a Lagrangian model (Ichthyop) forced with velocity fields from a hydrodynamical model (CROCO) and two different remote sensing products (GlobCurrent and OSCAR) using trajectories of oceanographic drifters. Additionally, we evaluated the possibility to expand the drifters data using trajectories of GPS-buoy equipped drifting Fish Aggregating Devices (FADs). Tehe observed and simulated trajectories were compared in terms of spatial distribution, velocity distribution and a nondimensional skill score. For the drifters and FADs, the GlobCurrent and OSCAR products lead to similar performances as the CROCO model-ouputs in the broad studied domain. In the Gulf of Guinea, however, the CROCO model performed significantly better than the other two because the parent solution of CROCO benefited from its communication with a child grid of finer resolution in this region. On average, the simulations lead to an underestimation of the drifter and FAD velocities, likely because the spatial resolutions of the forcing products were insufficient and the time frequency at which they were produced were too low to resolve the relevant oceanic processes properly. We found a low skill for all models to simulate FAD trajectories, possibly because of the devices vertical structure that prevent FADs from drifting like water parcels. Our results therefore suggest that in the Tropical Atlantic the FAD dataset may not be appropriate to use for corroborating Lagrangian simulations.

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