scholarly journals Life in the Fast Lane: Modeling the Fate of Glass Sponge Larvae in the Gulf Stream

2021 ◽  
Vol 8 ◽  
Author(s):  
Shuangqiang Wang ◽  
Ellen Kenchington ◽  
Zeliang Wang ◽  
Andrew J. Davies
Keyword(s):  
United States ◽  
Gulf Stream ◽  
Deep Sea ◽  
Larval Settlement ◽  
Diffusion Constant ◽  
Ocean Model ◽  
Source Population ◽  
Distribution Models ◽  
The North ◽  
Cape Hatteras

Effective conservation management of deep-sea sponges, including design of appropriate marine protected areas, requires an understanding of the connectivity between populations throughout a species’ distribution. We provide the first consideration of larval connectivity among deep-sea sponge populations along the southeastern coast of North America, illustrate the influence of the Gulf Stream on dispersal, and complement published distribution models by evaluating colonization potential. Connectivity among known populations of the hexactinellid sponge Vazella pourtalesii was simulated using a 3-D biophysical dispersal model throughout its distribution from Florida, United States to Nova Scotia, Canada. We found no exchange with an estimated pelagic larval duration of 2 weeks between populations north and south of Cape Hatteras, North Carolina at surface, mid-water and seabed release depths, irrespective of month of release or application of a horizontal diffusion constant specific to cross-Gulf Stream diffusivity. The population north of Cape Hatteras and south of Cape Cod was isolated. There was some evidence that Gulf Stream eddies formed near Cape Hatteras could travel to the northwest, connecting the populations in the two sub-regions, however that would require a much longer pelagic duration than what is currently known. More likely almost all larval settlement will be in the immediate area of the adults. At sub-regional scales, connectivity was found from the Strait of Florida through to the Blake Plateau, southeastern United States, with the latter area showing potential for recruitment from more than one source population. The influence of the Charleston Bump, a shallow feature rising from the Blake Plateau, was substantial. Particles seeded just north of the Bump were transported greater distances than those seeded to the south, some of which were caught in an associated gyre, promoting retention at the seabed. To the north on the Scotian Shelf, despite weaker currents and greater distances between known occurrences, unidirectional transport was detected from Emerald Basin to the Northeast Channel between Georges and Browns Banks. These major conclusions remained consistent through simulations run with different averaging periods for the currents (decades to daily) and using two ocean model products (BNAM and GLORYS12V1).

scholarly journals The Icelandic Low as a Predictor of the Gulf Stream North Wall Position

2016 ◽  
Vol 46 (3) ◽  
pp. 817-826 ◽  
Author(s):  
Alejandra Sanchez-Franks ◽  
Sultan Hameed ◽  
Robert E. Wilson
Keyword(s):  
Gulf Stream ◽  
Southern Oscillation ◽  
Time Lags ◽  
Grand Banks ◽  
The North ◽  
Cape Hatteras ◽  
Pressure Anomaly ◽  
Icelandic Low ◽  
North Wall ◽  
Wall Position

AbstractThe Gulf Stream’s north wall east of Cape Hatteras marks the abrupt change in velocity and water properties between the slope sea to the north and the Gulf Stream itself. An index of the north wall position constructed by Taylor and Stephens, called Gulf Stream north wall (GSNW), is analyzed in terms of interannual changes in the Icelandic low (IL) pressure anomaly and longitudinal displacement. Sea surface temperature (SST) composites suggest that when IL pressure is anomalously low, there are lower temperatures in the Labrador Sea and south of the Grand Banks. Two years later, warm SST anomalies are seen over the Northern Recirculation Gyre and a northward shift in the GSNW occurs. Similar changes in SSTs occur during winters in which the IL is anomalously west, resulting in a northward displacement of the GSNW 3 years later. Although time lags of 2 and 3 years between the IL and the GSNW are used in the calculations, it is shown that lags with respect to each atmospheric variable are statistically significant at the 5% level over a range of years. Utilizing the appropriate time lags between the GSNW index and the IL pressure and longitude, as well as the Southern Oscillation index, a regression prediction scheme is developed for forecasting the GSNW with a lead time of 1 year. This scheme, which uses only prior information, was used to forecast the GSNW from 1994 to 2015. The correlation between the observed and forecasted values for 1994–2014 was 0.60, significant at the 1% level. The predicted value for 2015 indicates a small northward shift of the GSNW from its 2014 position.

American and International Whaling, c. 1770–1820

2019 ◽  
pp. 25-48
Author(s):  
James R. Fichter
Keyword(s):  
United States ◽  
Environmental History ◽  
Deep Sea ◽  
The United States ◽  
Primary Sources ◽  
Full Understanding ◽  
The North ◽  
History Of ◽  
The North Atlantic ◽  
National Boundaries

This chapter outlines an international environmental history of whaling in the South Seas (the Southern Atlantic, Indian and Pacific Oceans). Pelagic (ie., deep-sea) whaling was not discretely national. “American” whaling, as traditionally understood, existed as part of a broader ecological and economic phenomenon which included whalers from other nations. Application of “American,” “British” and other national labels to an ocean process that by its nature crossed national boundaries has occluded a full understanding of whaling’s international nature, a fullness which begins with whaling community diaspora spread across the North Atlantic from the United States to Britain and France, and which extends to the varied locations where whalers hunted and the yet other locations to which they returned with their catch. Ocean archives—the Saint Helena Archive, the Cape Town Archive Repository, and the Brazilian Arquivo Nacional—and a reinterpretation of published primary sources and national whaling historiographies reveal the fundamentally international nature of “American” pelagic whaling, suggesting that an undue focus on US whaling data by whaling historians has likely underestimated the extent of turn-of-the-nineteenth-century pelagic whaling.

scholarly journals Loop Current Variability as Trigger of Coherent Gulf Stream Transport Anomalies

2019 ◽  
Vol 49 (8) ◽  
pp. 2115-2132 ◽  
Author(s):  
Joël J.-M. Hirschi ◽  
Eleanor Frajka-Williams ◽  
Adam T. Blaker ◽  
Bablu Sinha ◽  
Andrew Coward ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Gulf Stream ◽  
Time Lag ◽  
Ocean Model ◽  
Surface Velocity ◽  
Loop Current ◽  
Intrinsic Variability ◽  
Cape Hatteras ◽  
Florida Straits ◽  
Stream Transport

AbstractSatellite observations and output from a high-resolution ocean model are used to investigate how the Loop Current in the Gulf of Mexico affects the Gulf Stream transport through the Florida Straits. We find that the expansion (contraction) of the Loop Current leads to lower (higher) transports through the Straits of Florida. The associated surface velocity anomalies are coherent from the southwestern tip of Florida to Cape Hatteras. A simple continuity-based argument can be used to explain the link between the Loop Current and the downstream Gulf Stream transport: as the Loop Current lengthens (shortens) its path in the Gulf of Mexico, the flow out of the Gulf decreases (increases). Anomalies in the surface velocity field are first seen to the southwest of Florida and within 4 weeks propagate through the Florida Straits up to Cape Hatteras and into the Gulf Stream Extension. In both the observations and the model this propagation can be seen as pulses in the surface velocities. We estimate that the Loop Current variability can be linked to a variability of several Sverdrups (1Sv = 106 m3 s−1) through the Florida Straits. The exact timing of the Loop Current variability is largely unpredictable beyond a few weeks and its variability is therefore likely a major contributor to the chaotic/intrinsic variability of the Gulf Stream. However, the time lag between the Loop Current and the flow downstream of the Gulf of Mexico means that if a lengthening/shortening of the Loop Current is observed this introduces some predictability in the downstream flow for a few weeks.

scholarly journals XXVII. On Holtenia, a genus of vitreous sponges

1869 ◽  
Vol 159 ◽  
pp. 701-720 ◽  
Keyword(s):  
Surface Temperature ◽  
North Atlantic ◽  
Small Proportion ◽  
Gulf Stream ◽  
Deep Sea ◽  
Minimum Temperature ◽  
The North ◽  
The Mean ◽  
The North Atlantic ◽  
Amorphous Particles

During the deep-sea dredging cruise of Her Majesty’s Ship 'Lightning' in the autumn of the year 1868, the 6th of September was occupied in dredging at the depth of 530 fathoms in latitude 59° 36' N., and longitude 7° 20' W., only about 20 miles beyond the 100-fathom line of the Coast Survey of Scotland, slightly to the westward of north of the Butt of the Lews. The minimum temperature indicated by the mean of three thermometers (which registered 47°, 47°∙5, and 47°∙5 Fahr. respectively) was 47°∙3 Fahr, the surface-temperature being 52°5 Fahr. During the day there were four successful hauls of the dredge, which came up each time full of a pale-grey tenacious mud, consisting in a great measure of minute amorphous particles of carbonate of lime mixed with “coccoliths” and “coccospheres.” There was only a small proportion of the Globigerinæ and other minute Rhizopods which are so abundant and characteristic over the whole of the warm or “Gulf-stream” area of the North Atlantic. The mud was glairy, as if it had been mixed with white of egg; and it contained disseminated through it an immense quantity of extremely delicate siliceous organisms, spicules of sponges, and the shells of Radiolarians and Diatoms. Large Rhizopods of the genera Astrorhiza, Rhabdammina, Cristellaria, Cornuspira , and others were abundant; and there was a somewhat scanty sprinkling of small forms belonging to the higher groups, Echinoderms, Annulosa, and Mollusca. Besides a number of dead shells, chiefly of the Boreal or Scandinavian type, and several undescribed Echinoderms and Crustaceans, the following species were procured living.

Interaction of a Glacial Water Outflow with the Gulf Stream

2021 ◽  
Author(s):  
Olivier Marchal ◽  
Alan Condron
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Gulf Stream ◽  
Circulation Model ◽  
Liquid Form ◽  
Sea Levels ◽  
Grand Banks ◽  
The North ◽  
Cape Hatteras ◽  
Water Outflow

<p>A popular hypothesis in paleoclimatology posits that the episodic discharges of glacial water from the Laurentide Ice Sheet (LIS) to the North Atlantic caused abrupt changes in ocean circulation and climate during the last (de)glacial periods. Implicit in this hypothesis is that the glacial water spread away from the coast and reached critical sites of deep water formation. Among the processes that could favour the offshore export of glacial water released along the eastern North American coast is the entrainment with the Gulf Stream near Cape Hatteras, where the Stream is observed to detach from the coast in the modern climate, or at other locations between Cape Hatteras and the Grand Banks of Newfoundland.</p><p>Here we investigate the fate of glacial water released in the western North Atlantic from the Laurentian Channel, which geologic evidence suggests to have been the main route of ice discharge from the Québec-Labrador Ice Dome of the LIS. To this end, we conduct numerical experiments with an ocean circulation model with eddy-resolving resolution and configured to represent the region north of Bermuda and west of the Grand Banks. Experiments with different regional sea levels are performed which correspond to different estimates of global sea level since the Last Glacial Maximum. In each experiment, glacial water in liquid form is discharged from the Laurentian Channel, providing a paleoceanographic analogue of the dam-break problem. As expected from the action of the Coriolis force and from the properties of the glacial water inflow, the discharged water turns to the right of the Channel and then produces a narrow buoyant current that flows along the coast to the southwest towards Cape Hatteras. Our presentation will focus on the interaction of this current with the Gulf Stream, particularly with its meanders and rings, and on the role of this interaction both in the seaward export of glacial water and in the modification of the Stream itself.</p>

Decomposing barotropic transport variability in a high-resolution ocean model of the North Atlantic Ocean

2020 ◽  
Author(s):  
Yuan Wang ◽  
Richard Greatbatch ◽  
Martin Claus ◽  
Jinyu Sheng
Keyword(s):  
High Resolution ◽  
North Atlantic ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Momentum Equation ◽  
Ocean Model ◽  
Recirculation Region ◽  
Mean Flow ◽  
The North ◽  
Stream Transport

<p>Temporal variability of the annual mean barotropic streamfunction in a high-resolution model configuration (VIKING20) for the northern North Atlantic is analyzed using a decomposition technique based on the vertically-averaged momentum equation. The method is illustrated by examining how the Gulf Stream transport in the recirculation region responds to the winter North Atlantic Oscillation (NAO). While no significant response is found in the year overlapping with the winter NAO index, a tendency is found for the Gulf Stream transport to increase as the NAO becomes more positive, starting in lead years 1 and 2 when the mean flow advection (MFA) and eddy momentum flux (EMF) terms associated with the nonlinear terms dominate in the momentum equations. Only after 2 years, the potential energy (PE) term, associated with the density field, starts to play a role and it is only after 5 years that the transport dependence on the NAO ceases to be significant. The PE contribution to the transport streamfunction has significant memory of up to 5 years in the Labrador and Irminger Seas. However, it is only around the northern rim of these seas that VIKING20 and the transport reconstruction exhibit similar memory. This is due to masking by the nonlinear MFA and EMF contributions.</p>

Hydrokinetic Energy Resource Assessment of the Gulf Stream Near Cape Hatteras, North Carolina

2014 ◽  
Author(s):  
Asif Kabir ◽  
Ivan J. Lemongo ◽  
Arturo Fernandez
Keyword(s):  
North Carolina ◽  
Gulf Stream ◽  
Energy Resource ◽  
Resource Assessment ◽  
Ocean Model ◽  
Likelihood Method ◽  
Ocean Current ◽  
Hydrokinetic Energy ◽  
Cape Hatteras ◽  
Promising Source

The Gulf Stream near the coasts of North Carolina is considered a promising source of hydrokinetic energy. A statistical analysis is conducted to assess the energy available for extraction in this region. Weibull distribution is used as the Probability Density Function (PDF) for this purpose. The ocean current velocity data are collected from the ‘HYbrid Coordinate Ocean Model (HYCOM)’. The data are collected at a depth of 20 m from the sea surface which is considered a good position for energy extraction. The Weibull parameters from the analysis are calculated using the maximum likelihood method. The direction of the ocean current was found to be mostly uniform in this region. The theoretical power density of this region was estimated to be more than 275 W/m2 around 70% of the time and exceeded 2000 W/m2 around 10% of the time.

The penetration of Labrador Slope Water to Cape Hatteras and its role in Gulf Stream Dynamics

2020 ◽  
Author(s):  
Adrian New ◽  
David Smeed ◽  
Adam Blaker ◽  
Jenny Mecking
Keyword(s):  
Gulf Stream ◽  
Water Mass ◽  
Gulf Of Maine ◽  
Meridional Overturning Circulation ◽  
Western Boundary ◽  
Boundary Current ◽  
The North ◽  
The Us ◽  
Cape Hatteras ◽  
Northern Side

<p>Labrador Slope Water is known to exist in the Slope Sea off the US eastern shelf as a relatively fresh and cool water mass deriving from the Labrador Current further north, and is present between the upper layer US shelf-derived water masses and the deeper Deep Western Boundary current waters, typically near 400-600m. This LSLW  is investigated in the EN4 database and shown to penetrate as far south as Cape Hatteras (74-75°W), having previously only been described as far west as the Gulf of Maine (66°W). We then examine, using both EN4 and Line W observations, the changes of this water mass between 2005-2008, when the strength of Atlantic Meridional Overturning Circulation (AMOC) measured by the RAPID array at 26°N, was high, and 2009-2015, when the AMOC was low. We show that in the AMOC high period, there was a larger volume of the LSSW present on the northern side of the Gulf Stream system which resulted in an increased meridional slope of the isopycnals near these depths, commensurate with increased geostrophic transport, and also in a more southerly position, of the Gulf Stream after separation at Cape Hatteras. The LSLW could therefore play an important role in decadal timescale variations in the North Atlantic climate system through its impact on the Gulf Stream and AMOC.</p>

scholarly journals On the Nature of Temporal Variability of the Gulf Stream Path from 75° to 55°W

2016 ◽  
Vol 20 (9) ◽  
pp. 1-17 ◽  
Author(s):  
Avijit Gangopadhyay ◽  
Ayan H. Chaudhuri ◽  
Arnold H. Taylor
Keyword(s):  
Interannual Variability ◽  
North Atlantic ◽  
Gulf Stream ◽  
Temporal Variability ◽  
Low Frequency ◽  
The West ◽  
The North ◽  
Basin Scale ◽  
Cape Hatteras ◽  
The North Atlantic Oscillation

Abstract The response of the Gulf Stream (GS) system to atmospheric forcing is generally linked either to the basin-scale winds on the subtropical gyre or to the buoyancy forcing from the Labrador Sea. This study presents a multiscale synergistic perspective to describe the low-frequency response of the GS system. The authors identify dominant temporal variability in the North Atlantic Oscillation (NAO), in known indices of the GS path, and in the observed GS latitudes along its path derived from sea surface height (SSH) contours over the period 1993–2013. The analysis suggests that the signature of interannual variability changes along the stream’s path from 75° to 55°W. From its separation at Cape Hatteras to the west of 65°W, the variability of the GS is mainly in the near-decadal (7–10 years) band, which is missing to the east of 60°W, where a new interannual (4–5 years) band peaks. The latter peak (4–5 years) was missing to the west of 65°W. The region between 65° and 60°W seems to be a transition region. A 2–3-yr secondary peak was pervasive in all time series, including that for the NAO. This multiscale response of the GS system is supported by results from a basin-scale North Atlantic model. The near-decadal response can be attributed to similar forcing periods in the NAO signal; however, the interannual variability of 4–5 years in the eastern segment of the GS path is as yet unexplained. More numerical and observational studies are warranted to understand such causality.

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