Atlantic Current Apparently is Holding Its Own

and now we know what a Sverdrup is—

from Physorg.com

In March 2004, the scientists deployed an instrument array across the Atlantic at 26°N from the Saharan coast of Africa to the Bahamas. Since then, the instruments have provided a continuous record of the temperature, salinity and density of the ocean. In combination with current measurements of the Gulf Stream in the Straits of Florida (provided by scientists from AOML) and satellite measurements of the wind-driven flow across 26°N, the MOC [Atlantic Meridional Overturning Circulation] has been calculated on a daily basis.

The publications in Science show that the remarkable instrument array is working effectively and is bringing in some surprising results. The full range of variability measured in the Atlantic MOC is large. It can range from as little as 4 Sverdrups to as much as 35 Sverdrups. (A Sverdrup is a measure of ocean flow, with one Sverdrup equivalent to one million tonnes of water a second.) The year–long average of the MOC calculates at around 19 Sverdrups, in agreement with earlier estimates.
Prof. Marotzke explains, “There is no indication of an MOC slowdown. And the large fluctuations explain why previously it was diagnosed that a slowdown had already happened. By chance, measurements were taken at a time when the MOC happened to be quite weak.”

With the instrument array it is feasible to monitor the annual average MOC to a resolution of about 1.5 Sverdrups, or about 8 percent of the mean value. This would be sufficient to detect any large, abrupt changes in the circulation, critical to planning for future climate change.