Direct measurements of the mean flow and eddy kinetic energy structure of the upper ocean circuletion in the NE Atlantic

Abstract

The upper ocean circulation in the sub-polar northeast Atlantic has been a challenge to quantify due to strong and variable wind-forcing, and strong and variable deep currents that lead to large uncertainties in the use of the standard dynamical method. Since 1999 we have been operating an acoustical Doppler current profiler on a container vessel that operates between Denmark and Greenland to repeatedly sample upper ocean currents across the northeast Atlantic. Individual transects exhibit a highly energetic mesoscale variability, but ensemble-averaging of the sections reveals a striking organization of the mean field along the Reykjanes Ridge: a distinct southward flow along its eastern slope and two clearly defined peaks with seasonal modulation flowing to the north along its western slope. Higher values of eddy kinetic energy (about 150–600 cm2 s−2) are observed along the transect, O(1.5) greater than surface drifter estimates.