Interaction of the North Atlantic Current with the Deep Charlie Gibbs Fracture Zone Throughflow

Schott, Friedrich; Stramma, Lothar; Fischer, Jürgen

doi:10.1029/1998gl900223

Cited by 39 publications

(63 citation statements)

References 16 publications

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“…The monthly transport values are more variable than upstream and a seasonal cycle no longer exists. Rather, the variation appears to be associated with the horizontal location and vertical extension of the eastward flow through the southern part of the CGFZ, somewhat similar to variations discussed by Saunders [1994] and Schott et al [1999]. Both T and S exhibit a small trend that continues through the end of the 20 year simulation.…”

Section: Variation Of the Model-based Nsow At Mooring Arraysmentioning

confidence: 68%

Transport of Nordic Seas overflow water into and within the Irminger Sea: An eddy‐resolving simulation and observations

Schmitz²,

Hurlburt

et al. 2010

J. Geophys. Res.

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[1] Results from a climatologically forced, eddy-resolving (1/12°) Atlantic simulation using the Hybrid Coordinate Ocean Model help clarify some presently unresolved connections between volume transports of Nordic Seas overflow water at key locations in the northernmost North Atlantic Ocean. The model results demonstrate that, in addition to the known westward flow through the Charlie Gibbs Fracture Zone (CGFZ), some Iceland Scotland overflow water (ISOW) flows westward through gaps in the Reykjanes Ridge north of the CGFZ into the Irminger Sea, and some flows southward along the eastern flank of the Mid-Atlantic Ridge into the West European Basin. These results provide insights into the well-known inconsistency between observed westward transport of ISOW through the CGFZ (2.4 Sv) and the transports upstream at Southeast of Iceland section (3.2 Sv) and downstream in the western Irminger Sea (4.5 Sv). Although the portion of the simulated ISOW that flows through CGFZ is about 500 m deeper than observed, the model results also show two ISOW pathways of this flow into the Irminger Sea, one northward along the western flank of the Reykjanes Ridge and the other westward before turning north-eastward on the western side of the Irminger Basin. Comparisons with the long-term moored instrument database in the Irminger Sea show that the model-based mean circulation is in reasonable agreement with observed volume transports of overflow water and that it gives approximately correct temperature and salinity characteristics.

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Section: Variation Of the Model-based Nsow At Mooring Arraysmentioning

confidence: 68%

Transport of Nordic Seas overflow water into and within the Irminger Sea: An eddy‐resolving simulation and observations

Schmitz²,

Hurlburt

et al. 2010

J. Geophys. Res.

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“…It should be noted that the NAC is usually defined as a surface intensified jet with the baroclinic structure reaching down to about 1000 m (Krauss 1986). However, in the western subpolar North Atlantic we observed much deeperreaching extensions of the NAC at various places (e.g., Schott et al 1999), by direct current profiling, that were not visible in traditional geostrophic analyses.…”

Section: The Flemish Cap Areamentioning

confidence: 93%

“…The floats crossed the MAR about one degree south of the location where the NAC axis was found a year earlier in the shipboard observations of Schott et al (1999), but approximately along the axis of high eddy kinetic energy deduced from altimetry (White and Heywood 1995). After passing over the MAR the float trajectories split into a northeastward path, represented by float 8636, that reaches the Rockall Plateau about 900 days after its deployment and a more southward path roughly along the MAR, represented by float 8628.…”

Section: E Eastward Spreading Toward the Charlie Gibbs Fracture Zonementioning

confidence: 99%

Labrador Sea Water Tracked by Profiling Floats—From the Boundary Current into the Open North Atlantic

Fischer¹,

Schott²

2002

J. Phys. Oceanogr.

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Fifteen profiling floats were injected into the deep boundary current off Labrador. They were ballasted to drift in the core depth of Labrador Sea Water (LSW) at 1500-m depth and were deployed in two groups during March and July/August 1997. Initially, for about three months, the floats were drifting within the boundary current, and the flow vectors were used to determine the mean horizontal structure of the Deep Labrador Current, which was found to be about 100 km wide with an average core speed of 18 cm s Ϫ1 . North of Flemish Cap the boundary current encounters complicated topography around ''Orphan Knoll,'' and there the LSW outflow splits up into different routes. One obvious LSW path is eastward through the Charlie Gibbs Fracture Zone and another route is a narrow recirculation toward the central Labrador Sea. A surprising result was that none of the floats were able to follow the boundary current southward to the Grand Banks area and exit into the subtropics. Trajectories and temperature profiles of the eastward drifting floats indicate the importance of the North Atlantic Current for dispersing the floats, even at the level of LSW.

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“…Of particular interest here are the studies of variability in NAC pathways and its relationship to changing wind stress patterns. Heywood et al (1994) and General circulation patterns at the surface and at depth in the northern North Atlantic (reproduced from Schott et al 1999). Study area around the Mid-Atlantic Ridge is indicated by the rectangular box.…”

Section: Introductionmentioning

confidence: 99%

Interannual Variability in the Pathways of the North Atlantic Current over the Mid-Atlantic Ridge and the Impact of Topography

Bower

Appen

2008

Journal of Physical Oceanography

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Recent studies have indicated that the North Atlantic Ocean subpolar gyre circulation undergoes significant interannual-to-decadal changes in response to variability in atmospheric forcing. There are also observations, however, suggesting that the southern limb of the subpolar gyre, namely, the eastward-flowing North Atlantic Current (NAC), may be quasi-locked to particular latitudes in the central North Atlantic by fracture zones (gaps) in the Mid-Atlantic Ridge. This could constrain the current's ability to respond to variability in forcing. In the present study, subsurface float trajectories at 100-1000 m collected during 1997-99 and satellite-derived surface geostrophic velocities from 1992 to 2006 are used to provide an improved description of the detailed pathways of the NAC over the ridge and their relationship to bathymetry. Both the float and satellite observations indicate that in 1997-99, the northern branch of the NAC was split into two branches as it crossed the ridge, one quasi-locked to the Charlie-Gibbs Fracture Zone (CGFZ; 52°-53°N) and the other to the Faraday Fracture Zone (50°-51°N). The longer satellite time series shows, however, that this pattern did not persist outside the float sampling period and that other branching modes persisted for one or more years, including an approximately 12-month time period in 2002-03 when the strongest eastward flow over the ridge was at ϳ49°N. Schott et al. showed how northward excursions of the NAC can temporarily block the westward flow of the Iceland-Scotland Overflow Water through the CGFZ. From the 13-yr time series of surface geostrophic velocity, it is estimated that such blocking may occur on average 6% of the time, although estimates for any given 12-month period range from 0% to 35%.

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Interaction of the North Atlantic Current with the Deep Charlie Gibbs Fracture Zone Throughflow

Cited by 39 publications

References 16 publications

Transport of Nordic Seas overflow water into and within the Irminger Sea: An eddy‐resolving simulation and observations

Transport of Nordic Seas overflow water into and within the Irminger Sea: An eddy‐resolving simulation and observations

Labrador Sea Water Tracked by Profiling Floats—From the Boundary Current into the Open North Atlantic

Interannual Variability in the Pathways of the North Atlantic Current over the Mid-Atlantic Ridge and the Impact of Topography

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