scholarly journals Species diversity of the deep-water gulper sharks (Squaliformes: Centrophoridae:Centrophorus) in North Atlantic waters - current status and taxonomic issues

2014 ◽  
Vol 172 (4) ◽  
pp. 803-830 ◽  
Author(s):  
Ana Veríssimo ◽  
Charles F. Cotton ◽  
Robert H. Buch ◽  
Javier Guallart ◽  
George H. Burgess
Keyword(s):  
Species Diversity ◽  
North Atlantic ◽  
Deep Water ◽  
Current Status

Late Quaternary palaeo-oceanography of the Denmark Strait overflow pathway, South-East Greenland margin

1998 ◽  
Vol 180 ◽  
pp. 163-167
Author(s):  
Antoon Kuijpers ◽  
Jørn Bo Jensen ◽  
Simon R . Troelstra ◽  
And shipboard scientific party of RV Professor Logachev and RV Dana
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Deep Convection ◽  
Conveyor Belt ◽  
Water Masses ◽  
Labrador Sea ◽  
Greenland Sea ◽  
The North ◽  
Denmark Strait ◽  
The North Atlantic

Direct interaction between the atmosphere and the deep ocean basins takes place today only in the Southern Ocean near the Antarctic continent and in the northern extremity of the North Atlantic Ocean, notably in the Norwegian–Greenland Sea and Labrador Sea. Cooling and evaporation cause surface waters in the latter region to become dense and sink. At depth, further mixing occurs with Arctic water masses from adjacent polar shelves. Export of these water masses from the Norwegian–Greenland Sea (Norwegian Sea Overflow Water) to the North Atlantic basin occurs via two major gateways, the Denmark Strait system and the Faeroe– Shetland Channel and Faeroe Bank Channel system (e.g. Dickson et al. 1990; Fig.1). Deep convection in the Labrador Sea produces intermediate waters (Labrador Sea Water), which spreads across the North Atlantic. Deep waters thus formed in the North Atlantic (North Atlantic Deep Water) constitute an essential component of a global ‘conveyor’ belt extending from the North Atlantic via the Southern and Indian Oceans to the Pacific. Water masses return as a (warm) surface water flow. In the North Atlantic this is the Gulf Stream and the relatively warm and saline North Atlantic Current. Numerous palaeo-oceanographic studies have indicated that climatic changes in the North Atlantic region are closely related to changes in surface circulation and in the production of North Atlantic Deep Water. Abrupt shut-down of the ocean-overturning and subsequently of the conveyor belt is believed to represent a potential explanation for rapid climate deterioration at high latitudes, such as those that caused the Quaternary ice ages. Here it should be noted, that significant changes in deep convection in Greenland waters have also recently occurred. While in the Greenland Sea deep water formation over the last decade has drastically decreased, a strong increase of deep convection has simultaneously been observed in the Labrador Sea (Sy et al. 1997).

Bougainvillia aberrans (Cnidaria, Hydrozoa), a new species of hydroid and medusa from the upper bathyal zone off Bermuda

1993 ◽  
Vol 71 (5) ◽  
pp. 997-1002 ◽  
Author(s):  
Dale R. Calder
Keyword(s):  
New Species ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Deep Water Species ◽  
A New Species ◽  
Water Species

Bougainvillia aberrans n.sp. is described from Bermuda in the western North Atlantic Ocean. Specimens were collected at a depth of 150 fathoms (274 m) from the polypropylene buoy line of a crab trap. The hydroid colony of B. aberrans is erect, with a polysiphonic hydrocaulus, a smooth to somewhat wrinkled perisarc, hydranths having a maximum of about 16 tentacles, and medusa buds arising only from hydranth pedicels. Medusae liberated in the laboratory from these hydroids differ from all other known species of the genus in having a long, spindle-shaped manubrium, lacking oral tentacles, having marginal tentacles reduced to mere stubs, and being very short-lived (surviving for a few hours at most). Gonads develop in medusa buds while they are still attached to the hydroids, and gametes are shed either prior to liberation of the medusae or shortly thereafter. The eggs are surrounded by an envelope bearing nematocysts (heterotrichous microbasic euryteles). The cnidome of both hydroid and medusa stages consists of desmonemes and heterotrichous microbasic euryteles. The diagnosis of the genus Bougainvillia is modified to accommodate this new deep-water species.

scholarly journals Lagrangian perspectives of deep water export from the subpolar North Atlantic

2006 ◽  
Vol 33 (21) ◽  
Author(s):  
K. Getzlaff ◽  
C. W. Böning ◽  
J. Dengg
Keyword(s):  
North Atlantic ◽  
Deep Water

scholarly journals Propagation of North Atlantic Deep Water Anomalies

2018 ◽  
Vol 48 (8) ◽  
pp. 1831-1848 ◽  
Author(s):  
David Nieves ◽  
Michael Spall
Keyword(s):  
Boundary Condition ◽  
Layer Thickness ◽  
Time Scales ◽  
North Atlantic ◽  
Deep Water ◽  
Volume Flux ◽  
Reduced Gravity ◽  
Northern Boundary ◽  
Variable Source ◽  
Gravity Equations

AbstractWe present a simplified theory using reduced-gravity equations for North Atlantic Deep Water (NADW) and its variation driven by high-latitude deep-water formation. The theory approximates layer thickness on the eastern boundary with domain-averaged layer thickness and, in tandem with a mass conservation argument, retains fundamental physics for cross-equatorial flows on interannual and longer forcing time scales. Layer thickness anomalies are driven by a time-dependent northern boundary condition that imposes a southward volume flux representative of a variable source of NADW and damped by diapycnal mixing throughout the basin. Moreover, an outflowing southern boundary condition imposes a southward volume flux that generally differs from the volume flux at the northern boundary, giving rise to temporal storage of NADW within the Atlantic basin. Closed form analytic solutions for the amplitude and phase are provided when the variable source of NADW is sinusoidal. We provide a nondimensional analysis that demonstrates that solution behavior is primarily controlled by two parameters that characterize the meridional extent of the southern basin and the width of the basin relative to the equatorial deformation radius. Similar scaling applied to the time-lagged equations of Johnson and Marshall provides a clear connection to their results. Numerical simulations of reduced-gravity equations agree with analytic predictions in linear, turbulent, and diabatic regimes. The theory introduces a simple analytic framework for studying idealized buoyancy- and wind-driven cross-equatorial flows on interannual and longer time scales.

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