Gulf Stream flow field and events near 68°W

Shay, Thomas J.; Bane, John M.; Watts, D. Randolph; Tracey, Karen L.

doi:10.1029/95jc02685

Cited by 41 publications

(43 citation statements)

References 21 publications

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“…While it is presumed that baroclinic instability in strongly baroclinic currents is possible anywhere, the large amplitude Gulf Stream troughs observed appear in this location often enough to result in a slight trough in the mean Gulf Stream axis placement here [Shay et al, 1995 …”

Section: Sea Surface Height Termmentioning

confidence: 99%

Cyclogenesis in the deep ocean beneath the Gulf Stream: 2. Dynamics

Savidge¹,

Bane²

1999

J. Geophys. Res.

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Abstract. Strong cyclones in the deep ocean beneath the Gulf Stream have been observed during the period June 13, 1988, to August 7, 1990, near 68øW, 37øN in data from the Synoptic Ocean Prediction (SYNOP) Experiment. These cyclones developed in association with the evolution of large amplitude, quasi-stationary meander troughs in the Gulf Stream. It is likely that baroclinic instability is responsible for cyclone spin-up. The dynamical analysis of these cyclones indicates the process is analogous with atmospheric cyclogenesis from the perspectives of divergence and conservation of potential vorticity, but not in terms of the density field evolution. Large positive vertical velocities in the thermocline over developing low pressure centers at 3500 rn are consistent with convergence at depth and divergence in the upper ocean, and with stretching of the lower water column and shortening of the upper water column. The stretching of the lower water column accounts for the generation of positive relative vorticity there. However, the evolution of the density field in the oceanic case does not resemble the atmospheric case. In the atmosphere, density field adjustments in the air column above the low pressure center at the Earth's surface are in the correct sense to account for decreasing pressure there. In the ocean, density field adjustments in the water column fail to account for the developing low pressure centers, so sea surface height depressions must be responsible. These depressions must have an approximate magnitude of 0.5 rn depth over a 250 km horizontal extent (the cyclone's diameter).

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Section: Sea Surface Height Termmentioning

confidence: 99%

Cyclogenesis in the deep ocean beneath the Gulf Stream: 2. Dynamics

Savidge¹,

Bane²

1999

J. Geophys. Res.

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“…Rossby and Zhang (2001) presented ADCP data from multiple crossings of the Gulf Stream at about 378N, 708W between 1992 and 1999 by Motor Vessel (M/V) Oleander to characterize its near-surface velocity structure. Shay et al (1995), Bower and Hogg (1996), and Meinen et al (2009) presented results from current meter moorings and associated data from the Synoptic Ocean Prediction (SYNOP) program. Figure 3 shows along-stream velocity profiles based on these papers.…”

Section: A Gulf Stream Velocity Profiles and Wind And Wave Conditionsmentioning

confidence: 99%

A Surface Mooring for Air–Sea Interaction Research in the Gulf Stream. Part I: Mooring Design and Instrumentation

Weller

Bigorre

Lord

et al. 2012

Journal of Atmospheric and Oceanic Technology

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The design of a surface mooring for deployment in the Gulf Stream in the Mid-Atlantic Bight is described. The authors' goals were to observe the surface meteorology; upper-ocean variability; and air-sea exchanges of heat, freshwater, and momentum in and near the Gulf Stream during two successive 1-yr deployments. Of particular interest was quantifying these air-sea fluxes during wintertime events that carry cold, dry air from the land over the Gulf Stream. Historical current data and information about the surface waves were used to guide the design of the surface mooring. The surface buoy provided the platform for both bulk meteorological sensors and a direct covariance flux system. Redundancy in the meteorological sensors proved to be a largely successful strategy to obtain complete time series. Oceanographic instrumentation was limited in size by considerations of drag; and two current meters, three temperature-salinity recorders, and 15 temperature recorders were deployed. Deployment from a single-screw vessel in the Gulf Stream required a controlleddrift stern first over the anchor sites. The first deployment lasted the planned full year. The second deployment ended after 3 months when the mooring was cut by unknown means at a depth of about 3000 m. The mooring was at times in the core of the Gulf Stream, and a peak surface current of over 2.7 m s 21 was observed. The 15-month records of surface meteorology and air-sea fluxes captured the seasonal variability as well as several cold-air outbreaks; the peak observed heat loss was in excess of 1400 W m 22 .

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“…Could there be a precursor advective signal which takes the fastest route, and accounts for some of our observed correlations? Certainly, near-bottom velocities in the region do approach the 10-20 cm s 21 speeds which are at the limit of acceptability in our data (e.g., Shay et al 1995;Bower and Hunt 2000;Pickart and Watts 1990). We investigate this in more detail, using independent Lagrangian data, and Eulerian data from Line W.…”

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confidence: 99%

“…Others such as Shay et al (1995) In conclusion, the analysis of Lagrangian and Eulerian velocity datasets suggests that that advection in the DWBC is too slow to account for the coherence at time scales shorter than six months. At longer periods advection cannot be excluded as a factor, but appears to be unlikely to account for the coherent signals seen here.…”

mentioning

confidence: 99%

Coherence of Western Boundary Pressure at the RAPID WAVE Array: Boundary Wave Adjustments or Deep Western Boundary Current Advection?

Elipot

Hughes

Olhede

et al. 2013

Journal of Physical Oceanography

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This study investigates the coherence between ocean bottom pressure signals at the Rapid Climate Change programme (RAPID) West Atlantic Variability Experiment (WAVE) array on the western North Atlantic continental slope, including the Woods Hole Oceanographic Institution Line W. Highly coherent pressure signals propagate southwestward along the slope, at speeds in excess of 128 m s−1, consistent with expectations of barotropic Kelvin-like waves. Coherent signals are also evidenced in the smaller pressure differences relative to 1000-m depth, which are expected to be associated with depth-dependent basinwide meridional transport variations or an overturning circulation. These signals are coherent and almost in phase for all time scales from 3.6 years down to 3 months. Coherence is still seen at shorter time scales for which group delay estimates are consistent with a propagation speed of about 1 m s−1 over 990 km of continental slope but with large error bounds on the speed. This is roughly consistent with expectations for propagation of coastally trapped waves, though somewhat slower than expected. A comparison with both Eulerian currents and Lagrangian float measurements shows that the coherence is inconsistent with a propagation of signals by advection, except possibly on time scales longer than 6 months.

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Gulf Stream flow field and events near 68°W

Cited by 41 publications

References 21 publications

Cyclogenesis in the deep ocean beneath the Gulf Stream: 2. Dynamics

Cyclogenesis in the deep ocean beneath the Gulf Stream: 2. Dynamics

A Surface Mooring for Air–Sea Interaction Research in the Gulf Stream. Part I: Mooring Design and Instrumentation

Coherence of Western Boundary Pressure at the RAPID WAVE Array: Boundary Wave Adjustments or Deep Western Boundary Current Advection?

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