The North Atlantic Current (NAC), also known as North Atlantic Drift and North Atlantic Sea Movement, is a powerful warm western boundary current within the Atlantic Ocean that extends the Gulf Stream northeastward.[1]
The North Atlantic Current is the first leg in the North Atlantic Subpolar Gyre.
The NAC originates from where the Gulf Stream turns north at the Southeast Newfoundland Rise, a submarine ridge that stretches southeast from the Grand Banks of Newfoundland. The NAC flows northward east of the Grand Banks, from 40°N to 51°N, before turning sharply east to cross the Atlantic. It transports more warm tropical water to northern latitudes than any other boundary current; more than 40 Sv (40 million m3/s, 1.4 billion cu ft/s) in the south and 20 Sv (20 million m3/s, 710 million cu ft/s) as it crosses the Mid-Atlantic Ridge. It reaches speeds of 2 knots (3.7 km/h; 2.3 mph) near the North American coast. Directed by topography, the NAC meanders heavily, but in contrast to the meanders of the Gulf Stream, the NAC meanders remain stable without breaking off into eddies.[1]
The colder parts of the Gulf Stream turn northward near the "tail" of the Grand Banks at 50°W where the Azores Current branches off to flow south of the Azores. From there the NAC flows northeastward, east of the Flemish Cap (47°N, 45°W). Approaching the Mid-Atlantic Ridge, it then turns eastward and becomes much broader and more diffuse. It then splits into a colder northeastern branch and a warmer eastern branch. As the warmer branch turns southward, most of the subtropical component of the Gulf Stream is diverted southward, and as a consequence, the North Atlantic is mostly supplied by subpolar waters, including a contribution from the Labrador Current recirculated into the NAC at 45°N.[2]
West of Continental Europe, it splits into two major branches. One branch goes southeast, becoming the Canary Current as it passes northwest Africa and turns southwest. The other major branch continues north along the coast of Northwestern Europe. Other branches include the Irminger Current and the Norwegian Current. Driven by the global thermohaline circulation, the North Atlantic Current is part of the wind-driven Gulf Stream, which goes further east and north from the North American coast across the Atlantic and into the Arctic Ocean.
The North Atlantic Current, together with the Gulf Stream, have a long-lived reputation for having a considerable warming influence on European climate. However, the principal cause for differences in winter climate between North America and Europe seems to be winds rather than ocean currents (although the currents do exert influence at very high latitudes by preventing the formation of sea ice).[3]
Modelled 21st century warming under the "intermediate" climate change scenario (top). The potential collapse of the subpolar gyre in this scenario (middle). The collapse of the entire AMOC (bottom).
Unlike the AMOC, the observations of Labrador Sea outflow showed no negative trend from 1997 to 2009,[4] and the Labrador Sea convection began to intensify in 2012, reaching a new high in 2016.[5] As of 2022, the trend of strengthened Labrador Sea convection appears to hold, and is associated with observed increases in marine primary production.[6] Yet, a 150-year dataset suggests that even this recently strengthened convection is anomalously weak compared to its baseline state.[7]
Some climate models indicate that the deep convection in Labrador-Irminger Seas could collapse under certain global warming scenarios, which would then collapse the entire circulation in the North subpolar gyre. It is considered unlikely to recover even if the temperature is returned to a lower level, making it an example of a climate tipping point. This would result in rapid cooling, with implications for economic sectors, agriculture industry, water resources and energy management in Western Europe and the East Coast of the United States.[8] Frajka-Williams et al. 2017 pointed out that recent changes in cooling of the subpolar gyre, warm temperatures in the subtropics and cool anomalies over the tropics, increased the spatial distribution of meridional gradient in sea surface temperatures, which is not captured by the AMO Index.[9]
A 2021 study found that this collapse occurs in only four CMIP6 models out of 35 analyzed. However, only 11 models out of 35 can simulate North Atlantic Current with a high degree of accuracy, and this includes all four models which simulate collapse of the subpolar gyre. As the result, the study estimated the risk of an abrupt cooling event over Europe caused by the collapse of the current at 36.4%, which is lower than the 45.5% chance estimated by the previous generation of models [10] In 2022, a paper suggested that previous disruption of subpolar gyre was connected to the Little Ice Age.[11]
A 2022 Science Magazine review study on climate tipping points noted that in the scenarios where this convection collapses, it is most likely to be triggered by 1.8 degrees of global warming. However, model differences mean that the required warming may be as low as 1.1 degrees or as high as 3.8 degrees. Once triggered, the collapse of the current would most likely take 10 years from start to end, with a range between 5 and 50 years. The loss of this convection is estimated to lower the global temperature by 0.5 degrees, while the average temperature in Europe decreases by around 3 degrees. There are also substantial impacts on regional precipitation.[12][13]
^Fischer, Jürgen; Visbeck, Martin; Zantopp, Rainer; Nunes, Nuno (31 December 2010). "Interannual to decadal variability of outflow from the Labrador Sea". Geophysical Research Letters. 37 (24): 3204–3210. Bibcode:2010GeoRL..3724610F. doi:10.1029/2010GL045321. S2CID 54768522. Retrieved 3 October 2022.
^Yashayaev, Igor; Loder, John W. (8 December 2016). "Further intensification of deep convection in the Labrador Sea in 2016". Geophysical Research Letters. 44 (3): 1429–1438. doi:10.1002/2016GL071668. S2CID 133577687. Retrieved 3 October 2022.
^Tesdal, Jan-Erik; Ducklow, Hugh W.; Goes, Joaquim I.; Yashayaev, Igor (August 2022). "Recent nutrient enrichment and high biological productivity in the Labrador Sea is tied to enhanced winter convection". Geophysical Research Letters. 44 (3): 102848. Bibcode:2022PrOce.20602848T. doi:10.1016/j.pocean.2022.102848. S2CID 249977465. Retrieved 3 October 2022.
^Thornalley, David JR; et al. (11 April 2018). "Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years". Nature. 556 (7700): 227–230. Bibcode:2018Natur.556..227T. doi:10.1038/s41586-018-0007-4. PMID 29643484. S2CID 4771341. Retrieved 3 October 2022.
^Sgubin; et al. (2017). "Abrupt cooling over the North Atlantic in modern climate models". Nature Communications. 8. Bibcode:2017NatCo...8.....S. doi:10.1038/ncomms14375. PMC5330854. PMID 28198383.
^Eleanor Frajka-Williams; Claudie Beaulieu; Aurelie Duchez (2017). "Emerging negative Atlantic Multidecadal Oscillation index in spite of warm subtropics". Scientific Reports. 7 (1): 11224. Bibcode:2017NatSR...711224F. doi:10.1038/s41598-017-11046-x. PMC5593924. PMID 28894211.
^Swingedouw, Didier; Bily, Adrien; Esquerdo, Claire; Borchert, Leonard F.; Sgubin, Giovanni; Mignot, Juliette; Menary, Matthew (2021). "On the risk of abrupt changes in the North Atlantic subpolar gyre in CMIP6 models". Annals of the New York Academy of Sciences. 1504 (1): 187–201. Bibcode:2021NYASA1504..187S. doi:10.1111/nyas.14659. PMID 34212391. S2CID 235712017.
^Arellano-Nava, Beatriz; Halloran, Paul R.; Boulton, Chris A.; Scourse, James; Butler, Paul G.; Reynolds, David J.; Lenton, Timothy (25 August 2022). "Destabilisation of the Subpolar North Atlantic prior to the Little Ice Age". Nature Communications. 13 (1): 5008. Bibcode:2022NatCo..13.5008A. doi:10.1038/s41467-022-32653-x. PMC9411610. PMID 36008418.
^Armstrong McKay, David (9 September 2022). "Exceeding 1.5°C global warming could trigger multiple climate tipping points – paper explainer". climatetippingpoints.info. Retrieved 2 October 2022.
Sources
Lozier, M. S.; Owens, W. B.; Curry, R. G. (1995). "The climatology of the North Atlantic" (PDF). Progress in Oceanography. 36 (1): 1–44. Bibcode:1995PrOce..36....1L. doi:10.1016/0079-6611(95)00013-5. Retrieved 19 November 2016.
Rossby, T. (1996). "The North Atlantic Current and surrounding waters: At the crossroads" (PDF). Reviews of Geophysics. 34 (4): 463–481. Bibcode:1996RvGeo..34..463R. doi:10.1029/96RG02214. Retrieved 19 November 2016.
Seager, R.; Battisti, D. S.; Yin, J.; Gordon, N.; Naik, N.; Clement, A. C.; Cane, M. A. (2002). "Is the Gulf Stream responsible for Europe's mild winters?" (PDF). Quarterly Journal of the Royal Meteorological Society. 128 (586): 2563–2586. Bibcode:2002QJRMS.128.2563S. doi:10.1256/qj.01.128. S2CID 8558921. Retrieved 25 October 2010.
north, atlantic, current, north, atlantic, drift, redirects, here, 2003, rock, album, ocean, colour, scene, north, atlantic, drift, album, also, known, north, atlantic, drift, north, atlantic, movement, powerful, warm, western, boundary, current, within, atlan. North Atlantic Drift redirects here For the 2003 rock album by Ocean Colour Scene see North Atlantic Drift album The North Atlantic Current NAC also known as North Atlantic Drift and North Atlantic Sea Movement is a powerful warm western boundary current within the Atlantic Ocean that extends the Gulf Stream northeastward 1 The North Atlantic Current is the first leg in the North Atlantic Subpolar Gyre The NAC originates from where the Gulf Stream turns north at the Southeast Newfoundland Rise a submarine ridge that stretches southeast from the Grand Banks of Newfoundland The NAC flows northward east of the Grand Banks from 40 N to 51 N before turning sharply east to cross the Atlantic It transports more warm tropical water to northern latitudes than any other boundary current more than 40 Sv 40 million m3 s 1 4 billion cu ft s in the south and 20 Sv 20 million m3 s 710 million cu ft s as it crosses the Mid Atlantic Ridge It reaches speeds of 2 knots 3 7 km h 2 3 mph near the North American coast Directed by topography the NAC meanders heavily but in contrast to the meanders of the Gulf Stream the NAC meanders remain stable without breaking off into eddies 1 The colder parts of the Gulf Stream turn northward near the tail of the Grand Banks at 50 W where the Azores Current branches off to flow south of the Azores From there the NAC flows northeastward east of the Flemish Cap 47 N 45 W Approaching the Mid Atlantic Ridge it then turns eastward and becomes much broader and more diffuse It then splits into a colder northeastern branch and a warmer eastern branch As the warmer branch turns southward most of the subtropical component of the Gulf Stream is diverted southward and as a consequence the North Atlantic is mostly supplied by subpolar waters including a contribution from the Labrador Current recirculated into the NAC at 45 N 2 West of Continental Europe it splits into two major branches One branch goes southeast becoming the Canary Current as it passes northwest Africa and turns southwest The other major branch continues north along the coast of Northwestern Europe Other branches include the Irminger Current and the Norwegian Current Driven by the global thermohaline circulation the North Atlantic Current is part of the wind driven Gulf Stream which goes further east and north from the North American coast across the Atlantic and into the Arctic Ocean The North Atlantic Current together with the Gulf Stream have a long lived reputation for having a considerable warming influence on European climate However the principal cause for differences in winter climate between North America and Europe seems to be winds rather than ocean currents although the currents do exert influence at very high latitudes by preventing the formation of sea ice 3 Contents 1 Climate change 2 See also 3 References 4 External linksClimate change Edit Modelled 21st century warming under the intermediate climate change scenario top The potential collapse of the subpolar gyre in this scenario middle The collapse of the entire AMOC bottom See also Tipping points in the climate system Unlike the AMOC the observations of Labrador Sea outflow showed no negative trend from 1997 to 2009 4 and the Labrador Sea convection began to intensify in 2012 reaching a new high in 2016 5 As of 2022 the trend of strengthened Labrador Sea convection appears to hold and is associated with observed increases in marine primary production 6 Yet a 150 year dataset suggests that even this recently strengthened convection is anomalously weak compared to its baseline state 7 Some climate models indicate that the deep convection in Labrador Irminger Seas could collapse under certain global warming scenarios which would then collapse the entire circulation in the North subpolar gyre It is considered unlikely to recover even if the temperature is returned to a lower level making it an example of a climate tipping point This would result in rapid cooling with implications for economic sectors agriculture industry water resources and energy management in Western Europe and the East Coast of the United States 8 Frajka Williams et al 2017 pointed out that recent changes in cooling of the subpolar gyre warm temperatures in the subtropics and cool anomalies over the tropics increased the spatial distribution of meridional gradient in sea surface temperatures which is not captured by the AMO Index 9 A 2021 study found that this collapse occurs in only four CMIP6 models out of 35 analyzed However only 11 models out of 35 can simulate North Atlantic Current with a high degree of accuracy and this includes all four models which simulate collapse of the subpolar gyre As the result the study estimated the risk of an abrupt cooling event over Europe caused by the collapse of the current at 36 4 which is lower than the 45 5 chance estimated by the previous generation of models 10 In 2022 a paper suggested that previous disruption of subpolar gyre was connected to the Little Ice Age 11 A 2022 Science Magazine review study on climate tipping points noted that in the scenarios where this convection collapses it is most likely to be triggered by 1 8 degrees of global warming However model differences mean that the required warming may be as low as 1 1 degrees or as high as 3 8 degrees Once triggered the collapse of the current would most likely take 10 years from start to end with a range between 5 and 50 years The loss of this convection is estimated to lower the global temperature by 0 5 degrees while the average temperature in Europe decreases by around 3 degrees There are also substantial impacts on regional precipitation 12 13 See also Edit Oceans portalNorth Atlantic Oscillation Ocean gyre Physical oceanographyReferences EditNotes a b Rossby 1996 Abstract Lozier Owens amp Curry 1995 Circulation Figs 10 and 11 pp 20 22 Seager et al 2002 Abstract Fischer Jurgen Visbeck Martin Zantopp Rainer Nunes Nuno 31 December 2010 Interannual to decadal variability of outflow from the Labrador Sea Geophysical Research Letters 37 24 3204 3210 Bibcode 2010GeoRL 3724610F doi 10 1029 2010GL045321 S2CID 54768522 Retrieved 3 October 2022 Yashayaev Igor Loder John W 8 December 2016 Further intensification of deep convection in the Labrador Sea in 2016 Geophysical Research Letters 44 3 1429 1438 doi 10 1002 2016GL071668 S2CID 133577687 Retrieved 3 October 2022 Tesdal Jan Erik Ducklow Hugh W Goes Joaquim I Yashayaev Igor August 2022 Recent nutrient enrichment and high biological productivity in the Labrador Sea is tied to enhanced winter convection Geophysical Research Letters 44 3 102848 Bibcode 2022PrOce 20602848T doi 10 1016 j pocean 2022 102848 S2CID 249977465 Retrieved 3 October 2022 Thornalley David JR et al 11 April 2018 Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years Nature 556 7700 227 230 Bibcode 2018Natur 556 227T doi 10 1038 s41586 018 0007 4 PMID 29643484 S2CID 4771341 Retrieved 3 October 2022 Sgubin et al 2017 Abrupt cooling over the North Atlantic in modern climate models Nature Communications 8 Bibcode 2017NatCo 8 S doi 10 1038 ncomms14375 PMC 5330854 PMID 28198383 Eleanor Frajka Williams Claudie Beaulieu Aurelie Duchez 2017 Emerging negative Atlantic Multidecadal Oscillation index in spite of warm subtropics Scientific Reports 7 1 11224 Bibcode 2017NatSR 711224F doi 10 1038 s41598 017 11046 x PMC 5593924 PMID 28894211 Swingedouw Didier Bily Adrien Esquerdo Claire Borchert Leonard F Sgubin Giovanni Mignot Juliette Menary Matthew 2021 On the risk of abrupt changes in the North Atlantic subpolar gyre in CMIP6 models Annals of the New York Academy of Sciences 1504 1 187 201 Bibcode 2021NYASA1504 187S doi 10 1111 nyas 14659 PMID 34212391 S2CID 235712017 Arellano Nava Beatriz Halloran Paul R Boulton Chris A Scourse James Butler Paul G Reynolds David J Lenton Timothy 25 August 2022 Destabilisation of the Subpolar North Atlantic prior to the Little Ice Age Nature Communications 13 1 5008 Bibcode 2022NatCo 13 5008A doi 10 1038 s41467 022 32653 x PMC 9411610 PMID 36008418 Armstrong McKay David Abrams Jesse Winkelmann Ricarda Sakschewski Boris Loriani Sina Fetzer Ingo Cornell Sarah Rockstrom Johan Staal Arie Lenton Timothy 9 September 2022 Exceeding 1 5 C global warming could trigger multiple climate tipping points Science 377 6611 eabn7950 doi 10 1126 science abn7950 ISSN 0036 8075 PMID 36074831 S2CID 252161375 Armstrong McKay David 9 September 2022 Exceeding 1 5 C global warming could trigger multiple climate tipping points paper explainer climatetippingpoints info Retrieved 2 October 2022 SourcesLozier M S Owens W B Curry R G 1995 The climatology of the North Atlantic PDF Progress in Oceanography 36 1 1 44 Bibcode 1995PrOce 36 1L doi 10 1016 0079 6611 95 00013 5 Retrieved 19 November 2016 Rossby T 1996 The North Atlantic Current and surrounding waters At the crossroads PDF Reviews of Geophysics 34 4 463 481 Bibcode 1996RvGeo 34 463R doi 10 1029 96RG02214 Retrieved 19 November 2016 Seager R Battisti D S Yin J Gordon N Naik N Clement A C Cane M A 2002 Is the Gulf Stream responsible for Europe s mild winters PDF Quarterly Journal of the Royal Meteorological Society 128 586 2563 2586 Bibcode 2002QJRMS 128 2563S doi 10 1256 qj 01 128 S2CID 8558921 Retrieved 25 October 2010 External links Edit The North Atlantic Current Elizabeth Rowe Arthur J Mariano Edward H Ryan Cooperative Institute for Marine and Atmospheric Studies This article about a specific ocean current is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title North Atlantic Current amp oldid 1118658405, wikipedia, wiki, book, books, library,
