Abstract 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). The 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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使用热带大西洋海洋漂流者和捕鱼设备的轨迹评估拉格朗日模型

摘要 在热带大西洋，我们评估了拉格朗日模型 (Ichthyop) 的准确性，该模型使用来自流体动力学模型 (CROCO) 的速度场和两种不同的遥感产品（GlobCurrent 和 OSCAR），使用海洋漂流者的轨迹。此外，我们评估了使用配备 GPS 浮标的漂流鱼聚集设备 (FAD) 的轨迹来扩展漂流者数据的可能性。观察到的和模拟的轨迹在空间分布、速度分布和无量纲技能分数方面进行了比较。对于漂移器和 FAD，GlobCurrent 和 OSCAR 产品在广泛的研究领域具有与 CROCO 模型输出相似的性能。然而，在几内亚湾，CROCO 模型的表现明显优于其他两个模型，因为 CROCO 的父解决方案受益于它与该区域分辨率更高的子网格的通信。平均而言，模拟导致对漂流器和 FAD 速度的低估，这可能是因为强迫产品的空间分辨率不足，而且它们产生的时间频率太低，无法正确解决相关的海洋过程。我们发现所有模型模拟 FAD 轨迹的技能都很低，这可能是因为设备的垂直结构可以防止 FAD 像水包一样漂移。因此，我们的结果表明，在热带大西洋，FAD 数据集可能不适合用于证实拉格朗日模拟。