Doug Wilson
NOAA/AOML, Miami FL
26 August 1998
The Gulf Stream is one of the most well-known, closely studied, and significant features of the world ocean. For centuries those traveling the seas have used or avoided the Gulf Stream and other strong currents. Palm trees along the coast of the British Isles at the latitude of Moscow stand as a tribute to the Gulf Stream's ability to transport its warm water over long distances and impact coastal climates.
For a good basic review of the Gulf Stream system, check out
http://www.k12science.org/curriculum/gulfstream/.
This powerful North Atlantic ocean current has a relatively humble beginning in the Caribbean Sea. Water flowing through the passes between the islands of the Caribbean converge, head west and then north toward the Yucatan Channel. Passing through the Yucatan Channel, flow may loop into the Gulf of Mexico or head out through the Straits of Florida and enter the Gulf Stream proper. But where the water comes from, how the currents flow in the Caribbean Sea, and how these patterns vary remains poorly understood.
At its maximum, east of the New England coast, the Gulf Stream transports 150 million tons of water per second (106 ton/sec = 1 Sverdrup (Sv)) - WOW!. We think that about 20 Sv of this enters the Caribbean Sea through narrow island passages between Trinidad and Puerto Rico (the Lesser Antilles). Another 8 - 10 Sv may enter through the Mona (Puerto Rico - Hispaniola) and Windward (Hispaniola - Cuba) Passages in the Greater Antilles. While the flows through any of these passages may be quite variable (sometimes with flow back out into the North Atlantic) they always concentrate into a strong current in the western Caribbean (the Caribbean Current) that eventually moves out through the Straits of Florida as the Florida Current at a roughly constant rate of 32 Sv. For information on long-term monitoring of the flow in the Florida Current, see
http://www.pmel.noaa.gov/wbcurrents/cabletransport.html
Since the YOTO Drifter Project began in March, three drifter deployments have been carried out in the Lesser Antilles by merchant ships, and several drifters have been deployed in the Greater Antilles by U. S. Coast Guard and research vessels. We hope to use these buoys to study the how the Caribbean Current forms and to better understand current patterns to determine how and where nutrients or larvae are distributed. YOTO drifter deployments in the island passages have highlighted an important problem in oceanographic studies - the difficulty in separating instantaneous (short-term) conditions from average conditions (long-term). As opposed to the SW Caribbean drifters, whose tracks have nicely defined the clockwise Panama - Colombia gyre (see Kevin Leaman's project from the drifter home page on currents in the Southwestern Caribbean or look under drifter results)
The YOTO Drifters in the eastern Caribbean Sea and those released in the passages so far show a complex and highly variable pattern of water flow. We expect that as more drifters are tracked, circulation patterns will become clearer. Until then, here's some commentary on a few of the more interesting tracks seen so far. This will be a good geography lesson, too - get out your map of the Caribbean and name those islands!
Go to Project Results.