Microstructure measurements along a quasi-meridional transect in the northeastern Atlantic Ocean

This study presents vertical profiles of turbulence parameters obtained in the upper 100 m of the northeastern Atlantic Ocean along a transect from tropical permanently stratified waters to subpolar seasonally stratified waters in July-August 2009. The focus is to fully characterize the vertical mixing along this transect for further studies related to phytoplankton and nutrient distributions. Derived values of temperature eddy diffusivity K_T, of temperature variance dissipation rate Χ_T, and of turbulent kinetic energy dissipation rate ε indicate a northward increase of turbulent mixing below the mixed layer. In the northern stations where the wind stress is sufficiently high, the vertical distributions of ε in the mixed layer follow the wind stress scaling. The related low wind-scaling factors, and the low values of encountered at this cruise, are in agreement with a strongly stratified upper water column at midday in summer.