Diapycnal diffusivity at the upper boundary of the tropical North Atlantic oxygen minimum zone.

Banyte, Donata, Tanhua, Toste , Visbeck, Martin , Wallace, Douglas W.R., Karstensen, Johannes , Krahmann, Gerd , Schneider, Anke, Stramma, Lothar and Dengler, Marcus (2012) Diapycnal diffusivity at the upper boundary of the tropical North Atlantic oxygen minimum zone. Open Access Journal of Geophysical Research: Oceans, 117 (C9). C09016. DOI 10.1029/2011JC007762.

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Abstract

A deliberate tracer release experiment in 2008–2010 was used to study diapycnal mixing in the tropical northeastern Atlantic. The tracer (CF3SF5) was injected on the isopycnal surface σΘ = 26.88 kg m−3, which corresponds to about 330 m depth. Three surveys, performed 7, 20, and 30 months after the release, sampled the vertically and laterally expanding tracer patch. The mean diapycnal mixing estimate over the entire region occupied by the tracer and the period of 30 months was found to be (1.19 ± 0.18) × 10−5 m2 s−1, or, alternatively, (3.07 ± 0.58) × 10−11 (kg m−3)2 s−1 as computed from the advection-diffusion equation in isopycnal coordinates with the thickness-weighted averaging. The latter method is preferable in the regions of different stratification for it yields local diapycnal mixing estimates varying less with stratification than their Cartesian coordinate counterparts. Results of this study are comparable to the results of the North Atlantic tracer release experiment (NATRE). However, the internal wave-wave interaction models predict reduced mixing from the breaking of internal waves at low latitudes. Thus, the diapycnal diffusivity found in this study is higher than parameterized by the low latitude of the site (4°N–12°N).

Document Type: Article
Additional Information: WOS:000308894100001
Keywords: North Atlantic OMZ , diapycnal diffusivity ; tracer release experiment
Research affiliation: OceanRep > SFB 754 > A5
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > SFB 754 > A8
OceanRep > SFB 754 > A4
OceanRep > SFB 754 > A3
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > SFB 754
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2011JC007762
ISSN: 2169-9275
Projects: SFB754, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 18 Sep 2012 07:03
Last Modified: 27 Feb 2018 09:06
URI: http://oceanrep.geomar.de/id/eprint/15279

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