Meso- to Large-Scale Structure of Subducting Water in the Subtropical Gyre of the Eastern North Atlantic Ocean

Joyce, Terrence M.; Luyten, James R.; Kubryakov, A. I.; Bahr, Frank; Pallant, Julie S.

doi:10.1175/1520-0485(1998)028<0040:mtlsso>2.0.co;2

Cited by 33 publications

(34 citation statements)

References 30 publications

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“…This is generally confirmed by high-resolution model results (Nakano and Hasumi 2005;Richards et al 2006;Eden 2006). Estimates of lateral eddy diffusivities were obtained for the eastern subtropical North Atlantic where an intense field program associated with the North Atlantic Tracer Release Experiment (Ledwell et al 1998) and the Subduction Experiment (Joyce et al 1998) was carried out in 1991-93. Eddy diffusivity coefficients of about 1000 m 2 s 21 were found in the upper 400 m of the water column that drop to 350-500 m 2 s 21 at about 1000 m without zonal-meridional anisotropy (Ferrari and Polzin 2005).…”

Section: B Resultssupporting

confidence: 61%

Changes in the Ventilation of the Oxygen Minimum Zone of the Tropical North Atlantic

Brandt

Hormann

Körtzinger

et al. 2010

Journal of Physical Oceanography

140

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Changes in the ventilation of the oxygen minimum zone (OMZ) of the tropical North Atlantic are studied using oceanographic data from 18 research cruises carried out between 28.58 and 238W during 1999-2008 as well as historical data referring to the period 1972-85. In the core of the OMZ at about 400-m depth, a highly significant oxygen decrease of about 15 mmol kg 21 is found between the two periods. During the same time interval, the salinity at the oxygen minimum increased by about 0.1. Above the core of the OMZ, within the central water layer, oxygen decreased too, but salinity changed only slightly or even decreased. The scatter in the local oxygen-salinity relations decreased from the earlier to the later period suggesting a reduced filamentation due to mesoscale eddies and/or zonal jets acting on the background gradients. Here it is suggested that latitudinally alternating zonal jets with observed amplitudes of a few centimeters per second in the depth range of the OMZ contribute to the ventilation of the OMZ. A conceptual model of the ventilation of the OMZ is used to corroborate the hypothesis that changes in the strength of zonal jets affect mean oxygen levels in the OMZ. According to the model, a weakening of zonal jets, which is in general agreement with observed hydrographic evidences, is associated with a reduction of the mean oxygen levels that could significantly contribute to the observed deoxygenation of the North Atlantic OMZ.

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Section: B Resultssupporting

confidence: 61%

Changes in the Ventilation of the Oxygen Minimum Zone of the Tropical North Atlantic

Brandt

Hormann

Körtzinger

et al. 2010

Journal of Physical Oceanography

140

View full text Add to dashboard Cite

show abstract

“…The Azores Current of the state estimate has similar width and transport found in surveys by research vessels (Rudnick and Luyten 1996;Joyce et al 1998). Most modeled fronts are considerably weaker than the strong current found in this state estimate (Jia 2000;New et al 2001).…”

Section: Regional Circulation and Subduction Pathwayssupporting

confidence: 66%

“…Over 800 standard CTD stations and thirteen surveys with a SeaSoai' towed profileI' were taken (Pallant et al 1995;Joyce et aL. 1998).…”

Section: Woce Hydrography Bobber Sofar and Alace Floatsmentioning

confidence: 99%

Subduction in an eddy-resolving state estimate of the northeast Atlantic Ocean

Gebbie¹

2004

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“…The eastern subtropical North Atlantic was the subject of an intensive series of field programs in 1991-93 as part of the North Atlantic Tracer Release Experiment (Ledwell et al 1998) and the Subduction Experiment (Joyce et al 1998). These observations provide a detailed picture of the mean flow patterns and the thermohaline variability in the region and are used as ground truth for the study of eddy stirring of thermohaline anomalies in the ocean.…”

Section: A Review Of Observationsmentioning

confidence: 99%

The Production and Dissipation of Compensated Thermohaline Variance by Mesoscale Stirring

Smith

Ferrari

2009

Journal of Physical Oceanography

111

146

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Temperature-salinity profiles from the region studied in the North Atlantic Tracer Release Experiment (NATRE) show large isopycnal excursions at depths just below the thermocline. It is proposed here that these thermohaline filaments result from the mesoscale stirring of large-scale temperature and salinity gradients by geostrophic turbulence, resulting in a direct cascade of thermohaline variance to small scales. This hypothesis is investigated as follows: Measurements from NATRE are used to generate mean temperature, salinity, and shear profiles. The mean stratification and shear are used as the background state in a high-resolution horizontally homogeneous quasigeostrophic model. The mean state is baroclinically unstable, and the model produces a vigorous eddy field. Temperature and salinity are stirred laterally in each density layer by the geostrophic velocity and vertical advection is by the ageostrophic velocity. The simulated temperature-salinity diagram exhibits fluctuations at depths just below the thermocline of similar magnitude to those found in the NATRE data. It is shown that vertical diffusion is sufficient to absorb the laterally driven cascade of tracer variance through an amplification of filamentary slopes by small-scale shear. These results suggest that there is a strong coupling between vertical mixing and horizontal stirring in the ocean at scales below the deformation radius.

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Meso- to Large-Scale Structure of Subducting Water in the Subtropical Gyre of the Eastern North Atlantic Ocean

Cited by 33 publications

References 30 publications

Changes in the Ventilation of the Oxygen Minimum Zone of the Tropical North Atlantic

Changes in the Ventilation of the Oxygen Minimum Zone of the Tropical North Atlantic

Subduction in an eddy-resolving state estimate of the northeast Atlantic Ocean

The Production and Dissipation of Compensated Thermohaline Variance by Mesoscale Stirring

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