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

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.

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Quantifying Antarctic Bottom Water and North Atlantic Deep Water volumes

Journal of Geophysical Research Atmospheres ◽

10.1029/2007jc004477 ◽

2008 ◽

Vol 113 (C5) ◽

Cited By ~ 151

Author(s):

Gregory C. Johnson

Keyword(s):

North Atlantic ◽

Deep Water ◽

Bottom Water ◽

North Atlantic Deep Water ◽

Antarctic Bottom Water ◽

Water Volumes

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Source water distribution and quantification of North Atlantic Deep Water and Antarctic Bottom Water in the Atlantic Ocean

Progress In Oceanography ◽

10.1016/j.pocean.2017.04.003 ◽

2017 ◽

Vol 153 ◽

pp. 66-83 ◽

Cited By ~ 19

Author(s):

Maria Luiza de Carvalho Ferreira ◽

Rodrigo Kerr

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

Deep Water ◽

Water Distribution ◽

Bottom Water ◽

North Atlantic Deep Water ◽

Source Water ◽

Antarctic Bottom Water

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North Atlantic Deep Water and Antarctic Bottom Water: Their interaction and influence on the variability of the global ocean circulation

Journal of Geophysical Research Atmospheres ◽

10.1029/2002jc001335 ◽

2003 ◽

Vol 108 (C2) ◽

pp. n/a-n/a ◽

Cited By ~ 23

Author(s):

H. Brix ◽

R. Gerdes

Keyword(s):

Ocean Circulation ◽

North Atlantic ◽

Deep Water ◽

Bottom Water ◽

North Atlantic Deep Water ◽

Global Ocean ◽

Antarctic Bottom Water ◽

Global Ocean Circulation

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Review of “Tracking water masses using passive-tracer transport in NEMO v3.4 with NEMOTAM: application to North Atlantic Deep Water and North Atlantic Subtropical Mode Water” by Stephenson et al

10.5194/gmd-2019-245-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

North Atlantic ◽

Deep Water ◽

North Atlantic Deep Water ◽

Water Masses ◽

Passive Tracer ◽

Tracer Transport ◽

Mode Water ◽

Subtropical Mode Water

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

Aquatic Microbial Ecology ◽

10.3354/ame01934 ◽

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.

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

10.5194/os-2018-139 ◽

2019 ◽

Cited By ~ 1

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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