Program and Agenda

Abstract

VENTILATION OF THE EASTERN TROPICAL ATLANTIC OXYGEN MINIMUM ZONE BY MESOSCALE EDDY STIRRING AND TROPICAL ZONAL JETS

Mesoscale eddies and alternating zonal jets are the main pathways ventilating the eastern tropical Atlantic where at about 400 m depth the oxygen minimum zones are situated. Here we report on the lateral mixing coefficients as estimated from the Guinea Upwelling Tracer Release Experiment (GUTRE) and discuss the preliminary results of the second follow-up tracer release experiment (OSTRE). The observations are compared with the simulated tracer release by high-resolution ocean circulation model. The predominantly zonal flow in the tropical Atlantic suggests that the zonal component of the lateral mixing coefficient results from the cumulative effect of mesoscale eddies and alternative zonal jets, while the meridional lateral mixing component is mainly eddy driven. We find that the best estimate of mesoscale eddy diffusivity at about 300 m depth is about 500 m2 s-1. The cumulative effect of zonal advection by alternating tropical zonal jets and mesoscale eddies result in the diffusivity estimate twice as large - about 1200 m2 s-1. Furthermore, about 70% of the total OMZ ventilation is coming by lateral pathways where mesoscale eddies have the largest contribution.

Authors

Banyte, D., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, dbanyte@geomar.de

Visbeck, M., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany

Tanhua, T., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany

Fischer, T., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany

Brandt, P., GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany

Details

Oral presentation

Session #:058
Date: 2/26/2014
Time: 12:00
Location: 315

Presentation is given by student: No