Explained: Our recent low tides

The recent spate of unusually low tides in Bermuda is due to a large cyclonic eddy in the Sargasso Sea, according to scientists.

The Bermuda Institute of Ocean Sciences discovered the cyclone in January 2010 between 300km and 400km east of Bermuda.

Studies showed the eddy intensified in late March and brought with it a sea level depression of around 35cm at its centre. This in turn began to influence the tides around Bermuda as the anticlockwise eddy got closer.

Scientists are still trying to work out the source of the eddies that form in the Sargasso Sea.

But their formation is usually associated with areas of unstable ocean density.

Eddies that form in the ocean off Bermuda can be hundreds of kilometres in diameter.

BIOS scientist Dr. Rod Johnson said: “It is perhaps too early to make any conclusions.

“But I think this analysis of eddies illustrates how our long-term studies of the open ocean at BATS and Hydrostation can shed light on questions we have about both global ocean dynamics and more localized affects such as the low tide levels that Bermuda has been experiencing.”

Scientists at BIOS are constantly monitoring eddies in the Sargasso Sea using both remote sensing techniques and ship-based observations from BIOS’ research vessel Atlantic Explorer.

Most of the monitoring takes place at two long-term open-ocean observation sites, Hydrostation ‘S’ and Bermuda Atlantic Time-series Study (BATS), near Bermuda.