A new Sargassum drift model derived from features tracking in MODIS images

Type Article
Date 2023-03
Language English
Author(s) Podlejski Witold1, 2, Berline Léo1, Nerini David1, Doglioli Andrea1, Lett Christophe2
Affiliation(s) 1 : Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
2 : Marbec, Université de Monpellier, CNRS, Ifremer, IRD, Sète, France
Source Marine Pollution Bulletin (0025-326X) (Elsevier BV), 2023-03 , Vol. 188 , P. 114629 (9p.)
DOI 10.1016/j.marpolbul.2023.114629
WOS© Times Cited 3
Keyword(s) Sargassum algae, Computer vision, Regression, Tracking, Remote sensing, Drift, Collocation, Drifter, Tropical North Atlantic, Time series
Abstract

Massive Sargassum stranding events affect erratically numerous countries from the Gulf of Guinea to the Gulf of Mexico. Forecasting transport and stranding of Sargassum aggregates require progress in detection and drift modelling. Here we evaluate the role of currents and wind, i.e. windage, on Sargassum drift. Sargassum drift is computed from automatic tracking using MODIS 1 km Sargassum detection dataset, and compared to reference surface current and wind estimates from collocated drifters and altimetric products. First, we confirm the strong total wind effect of ≈3 % (≈2 % of pure windage), but also show the existence of a deflection angle of ≈10° between Sargassum drift and wind directions. Second, our results suggest reducing the role of currents on drift to 80 % of its velocity, likely because of Sargassum resistance to flow. These results should significantly improve our understanding of the drivers of Sargassum dynamics and the forecast of stranding events.

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