Overturning Circulation of the North Atlantic Subtropical Gyre Computed in Density Coordinates at 26°N

The RAPID-MOCHA-WBTS array in the subtropical gyre of the North Atlantic has measured the Atlantic Meridional Overturning Circulation (AMOC) and the overturning streamfunction in depth coordinates since 2004. Here we show that the overturning streamfunction in density coordinates can be estimated by combining data from the RAPID-MOCHA-WBTS array with repeated shipboard measurements from the Florida Straits and Argo data. The streamfunction in density coordinates highlights the shallow overturning cell associated with the subtropical gyre circulation, a feature that is obscured in depth coordinates. The AMOC calculated in density space is slightly greater than in depth space, but the variability of the time series are very similar with differences occurring when the streamfunction maximum occasionally switches from the main overturning cell to the shallow cell.