Comments on “Reconstruction of the Gulf Stream from 1940 to the Present and Correlation with the North Atlantic Oscillation”

2019 ◽  
Vol 49 (10) ◽  
pp. 2731-2734
Author(s):  
Lequan Chi ◽  
Sultan Hameed ◽  
Christopher L. P. Wolfe
Keyword(s):  
Continental Shelf ◽  
Gulf Stream ◽  
Error Function ◽  
Labrador Sea ◽  
Subjective Analysis ◽  
The North ◽  
Shelf Slope ◽  
Cape Hatteras ◽  
North Wall ◽  
The North Atlantic Oscillation

AbstractThe path of the Gulf Stream as it leaves the continental shelf near Cape Hatteras is marked by a sharp gradient in ocean temperature known as the North Wall. The latitude location of the Gulf Stream North Wall (GSNW) has previously been estimated by subjective analysis of daily maps of sea surface temperatures. Recently, Watelet et al. (2017) presented an objective procedure by fitting an error function to the SST profile across the Gulf Stream at 81 longitude positions. The fit smooths over not only the GSNW but also the much colder waters from the Labrador Sea on the continental shelf. Watelet et al.’s procedure is therefore likely to misidentify the shelf-slope front as the Gulf Stream North Wall, leading to a systematic northward bias the in North Wall position.

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.

scholarly journals Seven copepod species considered as indicators of water-mass influence and changes: results from a Northumberland coastal station

2004 ◽  
Vol 61 (4) ◽  
pp. 485-491 ◽  
Author(s):  
D Bonnet ◽  
C Frid
Keyword(s):  
North Atlantic ◽  
Gulf Stream ◽  
Water Mass ◽  
Zooplankton Community ◽  
Copepod Species ◽  
Coastal Station ◽  
The North ◽  
North Wall ◽  
The North Atlantic Oscillation

Abstract Zooplankton has been sampled monthly since 1969 at Station Z off the Northumberland coast. Seven copepod species were chosen as potential indicators of specific water masses. Data have been analysed to provide information about seasonal and interannual changes in the zooplankton community with special reference to the indicator taxa and to the possible role of hydrographic and climate drivers, including variations in the position of the Gulf Stream North Wall position and the North Atlantic Oscillation. Results show that, at this Northumberland coastal station, some copepod species are likely to be good indicators of water-mass influence and changes.

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.

scholarly journals Impact of the Atlantic Meridional Mode on Gulf Stream North Wall Position

2018 ◽  
Vol 31 (21) ◽  
pp. 8875-8894 ◽  
Author(s):  
Sultan Hameed ◽  
Christopher L. P. Wolfe ◽  
Lequan Chi
Keyword(s):  
Gulf Stream ◽  
Cold Water ◽  
Meridional Overturning Circulation ◽  
Major Influence ◽  
Tropical Atlantic ◽  
The North ◽  
Meridional Mode ◽  
North Wall ◽  
Atlantic Meridional Mode ◽  
Wall Position

The path of the Gulf Stream as it leaves the continental shelf near Cape Hatteras is marked by a sharp gradient in ocean temperature known as the North Wall. Previous work in the literature has considered processes related to the North Atlantic Oscillation (NAO) in triggering latitudinal displacements of the North Wall position. This paper presents evidence that the Atlantic meridional mode (AMM) also impacts interannual variations of the North Wall position. The AMM signal from the tropics propagates to the Gulf Stream near the 200-m depth, and there are two time scales for this interaction. Anomalous Ekman suction induced by AMM cools the tropical Atlantic. The cold water in the Caribbean Sea is entrained into the currents feeding the Gulf Stream, and this cooling signal reaches the North Wall within a year. A second mechanism involves cold anomalies in the western tropical Atlantic, which initially propagate westward as baroclinic planetary waves, reaching the Gulf Stream and resulting in a southward shift in the North Wall position after a delay of about one year. In an analysis for the period 1961–2015, AMM’s signal dominates North Wall fluctuations in the upper 300 m, while NAO is the major influence below ~500 m; the influence of both the teleconnections is seen between 300 and 500 m. The relationship between the Atlantic meridional overturning circulation (AMOC) and the North Wall is investigated for the 2005–15 period and found to be statistically significant only at the sea surface in one of the three North Wall indices used.

Observations of cross-frontal exchange associated with submesoscale features along the North Wall of the Gulf Stream

2020 ◽  
Vol 163 ◽  
pp. 103342
Author(s):  
Alejandra Sanchez-Rios ◽  
R. Kipp Shearman ◽  
Jody Klymak ◽  
Eric D'Asaro ◽  
Craig Lee
Keyword(s):  
Gulf Stream ◽  
The North ◽  
North Wall

The Role of Extratropical Air–Sea Interaction in the Autumn Subseasonal Variability of the North Atlantic Oscillation

2019 ◽  
Vol 32 (22) ◽  
pp. 7697-7712 ◽  
Author(s):  
Yu Nie ◽  
Hong-Li Ren ◽  
Yang Zhang
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Gulf Stream ◽  
Low Frequency ◽  
Mean Flow ◽  
The North ◽  
Subseasonal Variability ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Considerable progress has been made in understanding the internal eddy–mean flow feedback in the subseasonal variability of the North Atlantic Oscillation (NAO) during winter. Using daily atmospheric and oceanic reanalysis data, this study highlights the role of extratropical air–sea interaction in the NAO variability during autumn when the daily sea surface temperature (SST) variability is more active and eddy–mean flow interactions are still relevant. Our analysis shows that a horseshoe-like SST tripolar pattern in the North Atlantic Ocean, marked by a cold anomaly in the Gulf Stream and two warm anomalies to the south of the Gulf Stream and off the western coast of northern Europe, can induce a quasi-barotropic NAO-like atmospheric response through eddy-mediated processes. An initial southwest–northeast tripolar geopotential anomaly in the North Atlantic forces this horseshoe-like SST anomaly tripole. Then the SST anomalies, through surface heat flux exchange, alter the spatial patterns of the lower-tropospheric temperature and thus baroclinicity anomalies, which are manifested as the midlatitude baroclinicity shifted poleward and reduced baroclinicity poleward of 70°N. In response to such changes of the lower-level baroclinicity, anomalous synoptic eddy generation, eddy kinetic energy, and eddy momentum forcing in the midlatitudes all shift poleward. Meanwhile, the 10–30-day low-frequency anticyclonic wave activities in the high latitudes decrease significantly. We illustrate that both the latitudinal displacement of midlatitude synoptic eddy activities and intensity variation of high-latitude low-frequency wave activities contribute to inducing the NAO-like anomalies.

Flushing of the continental shelf south of Cape Hatteras by the Gulf Stream

1978 ◽  
Vol 5 (6) ◽  
pp. 495-498 ◽  
Author(s):  
Jackson O. Blanton ◽  
Leonard J. Pietrafesa
Keyword(s):  
Continental Shelf ◽  
Gulf Stream ◽  
Cape Hatteras
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