Sargassum outlook update, by USF Optical Oceanography Lab – July 2019 update

The maps below show Sargassum abundance, with warm colors representing high abundance. The July 2019 situation is similar to June 2019 for all regions. Specifically, the following regions continued to experience large amounts of Sargassum: Central West Atlantic (CWA), entire Caribbean Sea (CS), eastern Gulf of Mexico (GoM), northern Florida Straits, and waters off east coast of Florida. In addition to numerous reports of Sargassum beaching in the Caribbean, beaching events have also been reportedalong the southeast coast of Florida. In the CS, the amount is lower than the historical record in 2018for the same month, but higher than the second highest record year of 2015 for the same month. In all regions combined, the total amount is estimated to be > 10 million metric tons, similar to the amountin July 2015 (~11 million metric tons) but lower than in July 2018 (> 17 million tons).

Looking ahead, because the amount of Sargassum in the CWA in July 2019 is higher than most previousyears (except 2018 and 2015), the amount transported to the CS is expected to be higher than most previous years, and possibly resemble the conditions in 2015. In general, the amount in the CS in August and September 2019 will continue to be high. Meanwhile, the transport to the GoM and east coast of Florida will continue, meaning that beaching events in the Florida Keys and along the east coast of Florida will also continue. The exact Sargassum amount, timing, and location of the beaching will depend on local ocean circulations and winds.

For October and later months of 2019, because the amount of Sargassum east of the CWA region has decreased since early July, it’s possible that beaching events in the CS and around south Florida may also reduce from of the current and previous months. Whether the decrease east of the CWA continues in August will be closely monitored, and more updates will be provided by the end of August 2019.

More information and near real–‐time imagery can be found under the Sargassum Watch System (SaWS, https://optics.marine.usf.edu/projects/saws.html and https://www.caricoos.org/oceans/observation/modis_aqua/ECARIBE/afai)