Fluctuations of the Atlantic North Equatorial Undercurrent and
associated changes in oxygen transports
Abstract
Although the core velocity of the Atlantic North Equatorial Undercurrent
(NEUC) is low (0.1-0.3ms) it has been suggested to act as an important
oxygen supply route towards the oxygen minimum zone in the eastern
tropical North Atlantic. For the first time the intraseasonal to
interannual NEUC variability and its impact on oxygen is investigated
based on shipboard and moored velocity observations around 5°N, 23°W. In
contrast to previous studies that were mainly based on models or
hydrographic data, we find hardly any seasonal cycle of NEUC transports
in the central Atlantic. The NEUC transport variability is instead
dominated by sporadic intraseasonal events. Only some of these events
are associated with high oxygen levels suggesting an occasional eastward
oxygen supply by NEUC transport events. Nevertheless, they likely
contribute to the local oxygen maximum in the mean shipboard section
along 23°W at the NEUC core position.