Sargassum algae are historically known to populate the center of the North Atlantic subtropical gyre, off Florida. However, since 2011 their region of presence has expanded drastically. Sargassum now also proliferate in a large tropical region of the Atlantic, from the Antilles to West Africa. During the 2020 edition of the Vendée Globe race, the skippers were surprised to encounter large amounts of Sargassum off the Cape Verde Islands in mid-November 2020, while sailing southwards, and on their return route northwards in January 2021.
The high-resolution (20 m) image below acquired by MSI onboard the European satellite Sentinel-2 (Copernicus/ESA) on January 26, 2021 reveals Sargassum aggregations near Brava Island at the southernmost end of the Cape Verde achipelago in the Atlantic. Pushed by winds and currents, Sargassum are transported over long distances, forming long thin structures (“windrows”) aligned with the wind (visible south of the island). They also accumulate along the coast in the lee of the island (darker area south-west of the island), shielded from winds and currents.

Click here to discover Sargassum detection from space at the AERIS/ICARE Data and Services Center.

Source: Copernicus/Sentinel Hub/ESA

Source: NASA/Worldview

Sargassum observed by Sentinel-2/MSI near Brava Island, Cape Verde, on January 26, 2021 (left image above). The bottom right image acquired by MODIS on board the Terra satellite on the same day shows the geographic location the Cape Verde archipelago off West Africa (source: NASA/Worldview). The top right image acquired by Sentinel-2/MSI at 20-m resolution shows a closer view to Brava and Fogo Islands (source: Copernicus/Sentinel Hub/ESA). The left  larger image was enhanced to reveal Sargassum aggregations near Brava.