On The Capacity of A Shipboard X-Band Marine Radar in Detecting Free-Floating Sargassum Seaweed

Abstract

Sargassum seaweed is a macroalgae that drifts in the Atlantic and massively washes ashore under the influence of winds, ocean currents and waves. Despite its benefits to open ocean ecology, invasive coastal Sargassum influxes affect negatively coastal communities. Thus, more observations are needed to monitor Sargassum motion from sea to shore. This work highlights the capacity of X-band radars to detect free-floating Sargassum in the open-ocean, a completely novel use of this technology. Radar data was collected during M181 Transatlantic Equatorial Cruise on 21st May 2022 (13:40-17:25 UTC). Results show shipboard X-band radars are able to detect local Sargassum rafts, while measuring waves and near-surface wave currents in near real-time. A qualitative comparison of radar images to in-situ photographs and satellite data shows concordance between radar-detected Sargassum and in-situ observations. Thus, X-band radars are potential monitoring tools to provide data for Sargassum motion forecasting and local biomass calculation, which can support Sargassum sinking initiatives for climate change mitigation. This paper is thereby a step further to develop solutions for trying to turn the crisis into an opportunity.