Salinity intrusion and convective mixing in the Atlantic Equatorial Undercurrent


  • Mariona Claret Departament d’Oceanografia Física, Institut de Ciències del Mar, CSIC
  • Rocío Rodríguez Departament d’Oceanografia Física, Institut de Ciències del Mar, CSIC
  • Josep L. Pelegrí Departament d’Oceanografia Física, Institut de Ciències del Mar, CSIC



Equatorial Undercurrent, high-salinity core, horizontal advection, convective mixing, step-like features


This study investigates the advection of positive-salinity anomalies by the Equatorial Undercurrent (EUC) and their potential importance in inducing vertical convective mixing. For this purpose we use hydrographic and velocity observations taken in April 2010 along the western Atlantic equatorial ocean (32 to 43°W). The high-salinity EUC core is a few tens of metres thick and occupies the base of the surface mixed layer and the upper portion of the surface thermocline. It leads to high positive values of the vertical salinity gradient, which in many instances cause statically unstable conditions in otherwise well-stratified regions. The unstable regions result in vertical convection, hence favouring the occurrence of step-like features. We propose that this combination of horizontal advection and vertical-instability leads to a sequence of downward-convective events. As a result the EUC salinity is diffused down to a potential density of 26.43, or about 200 m deep. This mechanism is responsible for water-mass and salt downwelling in the equatorial Atlantic Ocean, with a potentially large influence on the tropical and subtropical cells.


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How to Cite

Claret M, Rodríguez R, Pelegrí JL. Salinity intrusion and convective mixing in the Atlantic Equatorial Undercurrent. scimar [Internet]. 2012Sep.30 [cited 2023Dec.3];76(S1):117-29. Available from:




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