Program and Agenda

Abstract

DEAD-ZONE EDDIES IN THE OXYGEN MINIMUM ZONE OF THE TROPICAL EASTERN NORTH ATLANTIC OCEAN

Oxygen minimum zones (OMZs) are oceanic regions with low dissolved oxygen content, typically located at the eastern boundary of the subtropical oceans. Because oxygen is a fundamental property for biogeochemical cycling and ecosystem functioning, OMZs are extreme regions with global importance as well. Therefore all processes that control the oxygen supply and removal within OMZs are of major interest – for understanding the functioning of the OMZs but ultimately also for predicting OMZ variability. We report on extreme low-oxygen environments in open ocean waters of the eastern tropical North Atlantic OMZ, a region so far considered fairly well ventilated with oxygen concentration hardly below 40µM. With the aid of autonomous instrumentation we observed the existence of severe hypoxia (oxygen <20µM) and anoxia (no detectable oxygen) that were present in cyclonic and intrathermocline eddies. In particular, the formation of anoxia in the open ocean - typically known as “dead zone” in coastal area only - is a new aspect for oxygen cycling. We found some evidence that the integrated vertical transport within the eddies is in line with a linear eddy/wind interaction process. However, a high-resolution survey across the front of a particular intense dead zone eddy suggests that submesoscale processes are at work. Although simple eddy statistics are available from satellite altimetry, it is the interior structure that ultimately qualifies the observed feature as a dead zone eddy.

ePoster:

Authors

Karstensen, J., Helmholtz Centre for Ocean Research Kiel GEOMAR, Germany, jkarstensen@geomar.de

Schütte, F., Helmholtz Centre for Ocean Research Kiel GEOMAR, Germany, fschuette@geomar.de

Pietri, A., Helmholtz Centre for Ocean Research Kiel GEOMAR, Germany, apietri@geomar.de

Fiedler, B., Helmholtz Centre for Ocean Research Kiel GEOMAR, Germany, bfiedler@geomar.de

Brandt, P., Helmholtz Centre for Ocean Research Kiel GEOMAR, Germany, pbrandt@geomar.de

Details

Poster presentation

Session #:015
Date: 2/24/2014
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 913