Webinar – Sargassum Mapping in the Caribbean Sea

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Thursday 26th of August 2021

In this webinar, we will download and process in the SNAP software Sentinel-3 products to detect and map Sargassum rafts in the Caribbean Sea in June 2018.


Pelagic Sargassum seaweed is a large brown algae floating at the ocean surface thanks to its gas-filled bladders. When present in reasonable amount, it provides a safe habitat to many marine species such as the threatened loggerhead sea turtle. A large panel of fish species like mahi-mahi, jacks and amberjacks also use these floating vegetation as nursery.

In the North Atlantic, pelagic Sargassum floats and grows at the sea surface during its entire lifetime, aggregating and forming mats carried by winds, waves and currents on very long distances. Since 2011, Sargassum algae have been aggregating in kilometres wide rafts. Massive stranding episodes have increased in periodicity and intensity in the Caribbean Sea, summer 2018 being the historical record so far.  Once on the beaches, the rafts rot and decompose, leading to dramatic consequences on the environment, the tourism economy and the human health.

It has hence become of prime importance to monitor these disastrous events but their irregularity makes their forecasting complex. Moreover, the mechanisms at stake in the apparition and arrivals of the rafts on shores still need more studies. In situ observation means such as drones or boats constitute key tools to quantify the algae amount available for stranding but their coverage in space and time remains limited.

With their high spatial and temporal resolution and coverage, ocean colour satellites can help filling in the gaps. For example, the satellite based Sargassum Watch System (SaWS) provides with monthly reports on the Sargassum situation based on MODIS, VIIRS and Landsat 8 images. It has not incorporated data from OLCI so far. This webinar will demonstrate a simple and powerful way of detecting Sargassum rafts with Sentinel-3 OLCI instrument.


Attendees must be in possession of their own computer with an internet connexion.

Cost & Participation

Attendance to the webinar course is free of charge.

Audience & Selection

Everyone is welcome to attend ! Do not hesitate, register now !

Application opening – closing

Thursday 8th of July 2021 – Friday 20th of August 2021

Repeat the webinar

Here is the recording of the session:

Previous RUS webinar on Ocean Colour

Feel free to check the previous RUS webinar on Sentinel-3 data processing to monitor the ocean colour

OCEA04 – Ocean Colour Monitoring with Sentinel-3


Remote Sensing Engineer


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Webinar – Sargassum Mapping in the Caribbean Sea

Training date & time:

Thursday 26th of August 2021

14:30 – 16:00 CEST Q&A included


This webinar will be held fully online.