Deep Water Masses of the South and North Atlantic

2021 ◽  
pp. 1-42
Author(s):  
Eugene G. Morozov ◽  
Roman Y. Tarakanov ◽  
Dmitry I. Frey
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Water Masses ◽  
The South

Deep Water Masses of the South and North Atlantic

2010 ◽  
pp. 25-50 ◽  
Author(s):  
Eugene G. Morozov ◽  
Alexander N. Demidov ◽  
Roman Y. Tarakanov ◽  
Walter Zenk
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Water Masses ◽  
The South

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).

Deep water circulation patterns in the Atlantic during MISs 12-11

2020 ◽  
Author(s):  
Jasmin M. Link ◽  
Norbert Frank
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Glacial Maximum ◽  
Water Circulation ◽  
Water Masses ◽  
Overturning Circulation ◽  
The Past ◽  
The North ◽  
Circulation Patterns ◽  
The North Atlantic

<p>Glacial Termination V is one of the most extreme glacial-interglacial transitions of the past 800 ka [1]. However, the changes in orbital forcing from Marine Isotope Stage (MIS) 12 to 11 are comparatively weak. In addition, MIS 11c is exceptionally distinct compared to other interglacials with for example a longer duration [2] and a higher-than-present sea level [3] despite a relative low incoming insolation. Therefore, the term “MIS 11 paradox” was coined [4]. However, only little is known about the Atlantic overturning circulation during this time interval [e.g. 5,6].</p><p>Here, we present Atlantic-wide deep water circulation patterns spanning the glacial maximum of MIS 12, Termination V, and MIS 11. Therefore, sediment cores throughout the Atlantic were analyzed regarding their Nd isotopic composition of authigenic coatings to reconstruct the provenance of the prevailing bottom water masses.</p><p>During the glacial maximum of MIS 12, the deep Atlantic Ocean was bathed with a higher amount of southern sourced water compared to the following interglacial. Termination V is represented by a sharp transition in the high-accumulating sites from the North Atlantic with a switch to northern sourced water masses. MIS 11 is characterized through an active deep water formation in the North Atlantic with active overflows from the Nordic Seas, only disrupted by a short deterioration. A strong export of northern sourced water masses to the South Atlantic points to an overall strong overturning circulation.</p><p> </p><p>[1] Lang and Wolff 2011, Climate of the Past 7: 361-380.</p><p>[2] Candy et al. 2014, Earth-Science Reviews 128: 18-51.</p><p>[3] Dutton et al. 2015, Science 349: aaa4019.</p><p>[4] Berger and Wefer 2003, Geophysical Monograph 137: 41-60.</p><p>[5] Dickson et al. 2009, Nature Geoscience 2: 428-433.</p><p>[6] Vázquez Riveiros et al. 2013, EPSL 371-372: 258-268.</p>

scholarly journals Glacial–interglacial Nd isotope variability of North Atlantic Deep Water modulated by North American ice sheet

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ning Zhao ◽  
Delia W. Oppo ◽  
Kuo-Fang Huang ◽  
Jacob N. W. Howe ◽  
Jerzy Blusztajn ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Deep Water ◽  
North American ◽  
Isotope Composition ◽  
Ice Sheet ◽  
North Atlantic Deep Water ◽  
Water Masses ◽  
Nd Isotope ◽  
Nd Isotope Composition

AbstractThe Nd isotope composition of seawater has been used to reconstruct past changes in the contribution of different water masses to the deep ocean. In the absence of contrary information, the Nd isotope compositions of endmember water masses are usually assumed constant during the Quaternary. Here we show that the Nd isotope composition of North Atlantic Deep Water (NADW), a major component of the global overturning ocean circulation, was significantly more radiogenic than modern during the Last Glacial Maximum (LGM), and shifted towards modern values during the deglaciation. We propose that weathering contributions of unradiogenic Nd modulated by the North American Ice Sheet dominated the evolution of the NADW Nd isotope endmember. If water mass mixing dominated the distribution of deep glacial Atlantic Nd isotopes, our results would imply a larger fraction of NADW in the deep Atlantic during the LGM and deglaciation than reconstructed with a constant northern endmember.

scholarly journals The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

2018 ◽  
Vol 15 (18) ◽  
pp. 5663-5676 ◽  
Author(s):  
Jill N. Sutton ◽  
Gregory F. de Souza ◽  
Maribel I. García-Ibáñez ◽  
Christina L. De La Rocha
Keyword(s):  
Stable Isotope ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Ocean ◽  
Water Masses ◽  
Labrador Sea ◽  
The North ◽  
The North Atlantic ◽  
Eastern North Atlantic

Abstract. The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60∘ N) and Labrador Sea. Variations in δ30SiDSi below 500 m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution.

scholarly journals Changes in North Atlantic Deep Water strength and bottom water masses during Marine Isotope Stage 3 (45–35kaBP)

2010 ◽  
Vol 29 (19-20) ◽  
pp. 2451-2461 ◽  
Author(s):  
Marcus Gutjahr ◽  
Babette A.A. Hoogakker ◽  
Martin Frank ◽  
I. Nicholas McCave
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Bottom Water ◽  
North Atlantic Deep Water ◽  
Water Masses ◽  
Marine Isotope Stage ◽  
Marine Isotope Stage 3

scholarly journals Viral infection of prokaryotic plankton during early formation of the North Atlantic Deep Water

2020 ◽  
Vol 84 ◽  
pp. 175-189
Author(s):  
MG Weinbauer ◽  
C Griebler ◽  
HM van Aken ◽  
GJ Herndl
Keyword(s):  
Viral Infection ◽  
North Atlantic ◽  
Deep Water ◽  
North Atlantic Deep Water ◽  
Water Masses ◽  
Life Strategy ◽  
Viral Abundance ◽  
The North ◽  
Early Formation ◽  
The North Atlantic

Viral abundance was assessed in different water masses of the NW Atlantic, and the development of viral abundance, lytic viral infection and lysogeny was followed for the first ca. 5000 km (corresponding to ca. 50 yr in the oceanic conveyor belt) of the western branch of the North Atlantic Deep Water (NADW). Viral abundance was significantly higher in the 100 m layer than in the NADW (2400-2700 m depth) and the Denmark Strait Overflow Water (2400-3600 m depth). The virus-to-prokaryote ratio (VPR) increased with depth, ranging from 32-43 for different water masses of the bathypelagic ocean, thus corroborating the enigma of high viral abundance in the dark ocean. The O2-minimum layer (250-600 m) also showed high viral abundance and VPRs. Viral abundance, a viral subgroup and VPRs decreased in a non-linear form with distance from the NADW origin. Viral production (range: 0.2-2.4 × 107 viruses l-1) and the fraction of lytically infected cells (range: 1-22%) decreased with increasing distance from the formation site of the NADW. Conservative estimations of virus-mediated mortality of prokaryotes in the NADW averaged 20 ± 12%. The fraction of the prokaryotic community with lysogens (i.e. harboring a functional viral DNA) in the NADW averaged 21 ± 14%. Hence, we conclude that (1) viral abundance and subgroups differ between water masses, (2) virus-mediated mortality of prokaryotes as well as lysogeny are significant in the dark ocean and (3) the lysogenic life strategy became more important than the lytic life style during the early formation of the NADW.

scholarly journals Characteristics of Water Masses in the Atlantic Ocean based on GLODAPv2 data

2019 ◽  
Author(s):  
Mian Liu ◽  
Toste Tanhua
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
Bottom Water ◽  
South Atlantic ◽  
Weddell Sea ◽  
Water Masses ◽  
Intermediate Water ◽  
South Atlantic Central Water ◽  
The North

Abstract. The characteristics of the main water masses in the Atlantic Ocean are investigated and defined as Source Water Types (SWTs) from their formation area by six key properties based on the GLODAPv2 observational data. These include both conservative (potential temperature and salinity) and non-conservative (oxygen, silicate, phosphate and nitrate) variables. For this we divided the Atlantic Ocean into four vertical layers by distinct potential densities in the shallow and intermediate water column, and additionally by concentration of silicate in the deep waters. The SWTs in the upper/central water layer originates from subduction during winter and are defined as central waters, formed in four distinct areas; East North Atlantic Central water (ENACW), West North Atlantic Central Water (WNACW), East South Atlantic Central Water (ESACW) and West South Atlantic Central Water (WSACW). Below the upper/central layer the intermediate layer consist of three main SWTs; Antarctic Intermediate Water (AAIW), Subarctic Intermediate Water (SAIW) and Mediterranean Overflow Water (MOW). The North Atlantic Deep Water (NADW) is the dominating SWT in the deep and overflow layer, and is divided into upper and lower NADW based on the different origins and properties. The origin of both the upper and lower NADW is the Labrador Sea Water (LSW), the Iceland–Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW). Antarctic Bottom Water (AABW) is the only natural SWT in the bottom layer and this SWT is redefined as North East Atlantic Bottom Water (NEABW) in the north of equator due to the change of key properties, especial silicate. Similar with NADW, two additional SWTS, Circumpolar Deep Water (CDW) and Weddell Sea Bottom Water (WSBW), are defined in the Weddell Sea in order to understand the origin of AABW. The definition of water masses in biogeochemical space is useful for, in particular, chemical and biological oceanography to understand the origin and mixing history of water samples.

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