Closing the loop

On the 8th May we deployed three drifters at the top of a meander in a strong current that coincides with an abrupt change in temperature called the subpolar front. The red circle on the lefthand panel below shows the approximate location where the drifters were deployed and the sea surface temperature (SST) at this time. Notice how the cold water (blue) forms a northward meander that is nearly detached from the subpolar front.

Three days later, the drifters have nearly completed a full loop, passing just north of their original positions. The right hand panel shows the latest drifter tracks and SST. It is now clear that the meander has pinched off to form a closed loop of cold water called an eddy. Although this process happens at many fronts around the world it is very unpredictable, and we all feel extremely lucky to have been here with instruments in the water during the birth of a new eddy!