Reprint of: Benthic and planktic community changes at the North Siberian margin in response to Atlantic water mass variability since last deglacial times

AbstractOver 90% of the build up of additional heat in the earth system over recent decades is contained in the ocean. Since 2006 new observational programs have revealed heterogeneous patterns of ocean heat content change. It is unclear how much of this heterogeneity is due to heat being added to and mixed within the ocean leading to material changes in water mass properties or due to changes in circulation which redistribute existing water masses. Here we present a novel diagnosis of the ‘material’ and ‘redistributed’ contributions to regional heat content change between 2006 and 2017 based on a new Minimum Transformation Method informed by both water mass transformation and optimal transportation theory. We show that material warming has large spatial coherence. The material change tends to be smaller than the redistributed change at any geographical location, however it sums globally to the net warming of the ocean, while the redistributed component sums, by design, to zero. Material warming is robust over the time period of this analysis, whereas the redistributed signal only emerges from the variability in a few regions. In the North Atlantic, water mass changes indicate substantial material warming while redistribution cools the subpolar region due to a slowdown in the Meridional Overturning Circulation. Warming in the Southern Ocean is explained by material warming and by anomalous southward heat transport of 118 ± 50 TWdue to redistribution. Our results suggest near termprojections of ocean heat content change and therefore sea level change will hinge on understanding and predicting changes in ocean redistribution.

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Observed trends of anthropogenic acidification in North Atlantic water masses

Biogeosciences Discussions ◽

10.5194/bgd-9-3003-2012 ◽

2012 ◽

Vol 9 (3) ◽

pp. 3003-3030

Author(s):

M. Vázquez-Rodríguez ◽

F. F. Pérez ◽

A. Velo ◽

A. F. Ríos ◽

H. Mercier

Keyword(s):

North Atlantic ◽

Water Mass ◽

Deep Convection ◽

Temporal Trends ◽

Atlantic Water ◽

Water Masses ◽

The North ◽

Iceland Basin ◽

The North Atlantic ◽

Atmospheric Co2 Concentrations

Abstract. The lack of observational pH data has made difficult assessing recent rates of ocean acidification, particularly in the high latitudes. Here we present a time series of high-quality carbon system measurements in the North Atlantic, comprising fourteen cruises spanning over 27 yr (1981–2008) and covering important water mass formation areas like the Irminger and Iceland basins. We provide direct quantification of anthropogenic acidification rates in upper and intermediate North Atlantic waters by removing the natural variability of pH from the observations. Bottle data were normalised to basin-average conditions using climatological data and further condensed into averages per water mass and year to examine the temporal trends. The highest acidification rates of all inspected water masses were associated with surface waters in the Irminger Sea (−0.0018 ± 0.0001 yr−1) and the Iceland Basin (−0.0012 ± 0.0002 yr−1) and, unexpectedly, with Labrador Seawater (LSW) which experienced an unprecedented pH drop of −0.0015 ± 0.001 yr−1. The latter stems from the formation by deep convection and the rapid propagation in the North Atlantic subpolar gyre of this well-ventilated water mass. The high concentrations of anthropogenic CO2 are effectively transported from the surface into intermediate waters faster than via downward diffusion, thus accelerating the acidification rates of LSW. An extrapolation of the observed lineal trends of acidification suggests that the pH of LSW could drop 0.45 units with respect to pre-industrial levels by the time atmospheric CO2 concentrations double the present ones.

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Water mass transport variability to the North Icelandic shelf, 1994–2010

ICES Journal of Marine Science ◽

10.1093/icesjms/fss024 ◽

2012 ◽

Vol 69 (5) ◽

pp. 809-815 ◽

Cited By ~ 40

Author(s):

Steingrímur Jónsson ◽

Héðinn Valdimarsson

Keyword(s):

Mass Transport ◽

Heat Transport ◽

Water Mass ◽

Atlantic Water ◽

Hydrographic Data ◽

The North ◽

East Greenland Current ◽

Denmark Strait ◽

Irminger Current ◽

Polar Water

Abstract Jónsson, S., and Valdimarsson, H. 2012. Water mass transport variability to the North Icelandic shelf, 1994–2010. – ICES Journal of Marine Science, 69: 809–815. In the Denmark Strait between Greenland and Iceland, the north-flowing warm, saline Atlantic Water (AW) of the Irminger Current meets the south-flowing cold, relatively fresh Polar Water (PW) of the East Greenland Current. A mixture of these two surface water masses then flows along the shelf north of Iceland. The mixture can vary from being almost pure AW to consisting, to a large extent, of PW. The relative quantities of each water mass to some extent determine the productivity and the living conditions on the shelf north of Iceland. The flow has been monitored with current meters on a section north of Iceland since 1994, and these measurements, together with hydrographic data, are used to study its structure and variability. The amount of AW carried by the flow is calculated along with the associated heat transport. In the period 1994–2010, the flow consisted on average of 68% of AW with a transport of 0.88 Sv and an associated heat transport of 24 TW. There is notable seasonal variation in the flow and strong interannual variability.

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Arctic vs. North Atlantic water mass exchanges in Fram Strait from Pb isotopes in sedimentsThis article is one of a series of papers published in this Special Issue on the theme Polar Climate Stability Network.

Canadian Journal of Earth Sciences ◽

10.1139/e08-050 ◽

2008 ◽

Vol 45 (11) ◽

pp. 1253-1263 ◽

Cited By ~ 10

Author(s):

Jean Carignan ◽

Claude Hillaire-Marcel ◽

Anne de Vernal

Keyword(s):

North Atlantic ◽

Water Mass ◽

North Atlantic Ocean ◽

Atlantic Water ◽

The Arctic ◽

Fram Strait ◽

The North ◽

Anthropogenic Inputs ◽

North Atlantic Water ◽

The North Atlantic

Surface sediment samples (n = 10), collected between Spitzbergen and Greenland, and two cores raised east (C04) and west (C16) from Fram Strait were analyzed for their chemical and isotopic (Pb) compositions to trace the source of sediments and water masses exchanging between the Arctic and the North Atlantic oceans. In surface sediments, variable major and trace element concentrations suggest variations in both the mineralogy (carbonate and quartz dilution of other silicate minerals) and source regions of detrital supplies, based on Th/Zr and, to a lesser extent, on Th/U ratios. Each core site shows specific but nearly constant Th/Zr ratios, indicating homogeneous source supplies. At both core sites, Pb concentrations and isotopic compositions display similar patterns: homogeneous low Pb and radiogenic crustal signals below 5–10 cm, contrasting with high Pb and less radiogenic anthropogenic inputs at core-tops. However, the differing pre-anthropogenic Pb isotopic ratios in C04 and C16 confirm the involvement of distinct source supplies east and west of Fram Strait. We suggest that this isotopic specificity is mainly owing to inputs of material carried from northwestern Europe by the North Atlantic water mass and from the Laptev Sea by the Transpolar Drift, respectively. Some material from the Greenland margin and possibly from the North Atlantic Ocean may reach this zone as well. Sediments from the western Arctic are not significantly transported into the Fram Strait area, suggesting that the Canadian and the Eurasian basins remained decoupled, at least during the time span of the cored sediments (∼2000 years).

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Study of water storage variations at the Pantanal wetlands area from GRACE monthly mass grids

Journal of Geodetic Science ◽

10.1515/jogs-2019-0013 ◽

2019 ◽

Vol 9 (1) ◽

pp. 133-143

Author(s):

Ayelen Pereira ◽

Cecilia Cornero ◽

Ana C. O. C. Matos ◽

M. Cristina Pacino ◽

Denizar Blitzkow

Keyword(s):

Water Mass ◽

Spatial Scales ◽

Water Storage ◽

Transport Processes ◽

Satellite Gravity ◽

The North ◽

Paraguay River ◽

Gravity Recovery ◽

Grace Mission ◽

Phase Differences

Abstract The continental water storage is significantly in-fluenced by wetlands, which are highly affected by climate change and anthropogenic influences. The Pantanal, located in the Paraguay river basin, is one of the world’s largest and most important wetlands because of the environmental biodiversity that represents. The satellite gravity mission GRACE (Gravity Recovery And Climate Experiment) provided until 2017 time-variable Earth’s gravity field models that reflected the variations due to mass transport processes-like continental water storage changes-which allowed to study environments such as wetlands, at large spatial scales. The water storage variations for the period 2002-2016, by using monthly land water mass grids of Total Water Storage (TWS) derived from GRACE solutions, were evaluated in the Pantanal area. The capability of the GRACE mission for monitoring this particular environment is analyzed, and the comparison of the water mass changes with rainfall and hydrometric heights data at different stations distributed over the Pantanal region was carried out. Additionally, the correlation between the TWS and river gauge measurements, and the phase differences for these variables, were also evaluated. Results show two distinct zones: high correlations and low phase shifts at the north, and smaller correlation values and consequently significant phase differences towards the south. This situation is mainly related to the hydrogeological domains of the area.

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Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

Scientific Reports ◽

10.1038/s41598-021-88517-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rebecca Jackson ◽

Anna Bang Kvorning ◽

Audrey Limoges ◽

Eleanor Georgiadis ◽

Steffen M. Olsen ◽

...

Keyword(s):

Sediment Cores ◽

Active Role ◽

Atlantic Water ◽

The Arctic ◽

Negative Consequences ◽

Baffin Bay ◽

The North ◽

North Water ◽

History Of ◽

Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

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Latest Miocene restriction of the Mediterranean Outflow Water: a perspective from the Gulf of Cádiz

Geo-Marine Letters ◽

10.1007/s00367-021-00693-9 ◽

2021 ◽

Vol 41 (2) ◽

Author(s):

Zhi Lin Ng ◽

F. Javier Hernández-Molina ◽

Débora Duarte ◽

Francisco J. Sierro ◽

Santiago Ledesma ◽

...

Keyword(s):

Mass Exchange ◽

Water Mass ◽

Atlantic Water ◽

Meridional Overturning Circulation ◽

Gulf Of Cadiz ◽

Mediterranean Outflow Water ◽

Gulf Of Cádiz ◽

Mediterranean Outflow ◽

The Mediterranean ◽

Water Mass Exchange

AbstractThe Mediterranean-Atlantic water mass exchange provides the ideal setting for deciphering the role of gateway evolution in ocean circulation. However, the dynamics of Mediterranean Outflow Water (MOW) during the closure of the Late Miocene Mediterranean-Atlantic gateways are poorly understood. Here, we define the sedimentary evolution of Neogene basins from the Gulf of Cádiz to the West Iberian margin to investigate MOW circulation during the latest Miocene. Seismic interpretation highlights a middle to upper Messinian seismic unit of transparent facies, whose base predates the onset of the Messinian salinity crisis (MSC). Its facies and distribution imply a predominantly hemipelagic environment along the Atlantic margins, suggesting an absence or intermittence of MOW preceding evaporite precipitation in the Mediterranean, simultaneous to progressive gateway restriction. The removal of MOW from the Mediterranean-Atlantic water mass exchange reorganized the Atlantic water masses and is correlated to a severe weakening of the Atlantic Meridional Overturning Circulation (AMOC) and a period of further cooling in the North Atlantic during the latest Miocene.

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Interdecadal Baroclinic Sea Level Changes in the North Pacific Based on Historical Ocean Hydrographic Observations

Journal of Climate ◽

10.1175/jcli-d-13-00103.1 ◽

2015 ◽

Vol 28 (11) ◽

pp. 4585-4594 ◽

Cited By ~ 4

Author(s):

Tatsuo Suzuki ◽

Masayoshi Ishii

Keyword(s):

Sea Level ◽

Wind Stress ◽

North Pacific ◽

Water Mass ◽

Mass Density ◽

Baroclinic Mode ◽

Sea Level Changes ◽

The North ◽

Basin Scale ◽

The North Pacific

Abstract Using historical ocean hydrographic observations, decadal to multidecadal sea level changes from 1951 to 2007 in the North Pacific were investigated focusing on vertical density structures. Hydrographically, the sea level changes could reflect the following: changes in the depth of the main pycnocline, density gradient changes across the pycnocline, and modification of the water mass density structure within the pycnocline. The first two processes are characterized as the first baroclinic mode. The changes in density stratification across the pycnocline are sufficiently small to maintain the vertical profile of the first baroclinic mode in this analysis period. Therefore, the first mode should represent mainly the dynamical response to the wind stress forcing. Meanwhile, changes in the composite of all modes of order greater than 1 (remaining baroclinic mode) can be attributed to water mass modifications above the pycnocline. The first baroclinic mode is associated with 40–60-yr fluctuations in the subtropical gyre and bidecadal fluctuations of the Kuroshio Extension (KE) in response to basin-scale wind stress changes. In addition to this, the remaining baroclinic mode exhibits strong variability around the recirculation region south of the KE and regions downstream of the KE, accompanied by 40–60-yr and bidecadal fluctuations, respectively. These fluctuations follow spinup/spindown of the subtropical gyre and meridional shifts of the KE shown in the first mode, respectively. A lag correlation analysis suggests that interdecadal sea level changes due to water mass density changes are a secondary consequence of changes in basin-scale wind stress forcing related to the ocean circulation changes associated with the first mode.

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Multidecadal to millennial marine climate oscillations across the Denmark Strait (~ 66° N) over the last 2000 cal yr BP

Climate of the Past ◽

10.5194/cp-10-325-2014 ◽

2014 ◽

Vol 10 (1) ◽

pp. 325-343 ◽

Cited By ~ 13

Author(s):

J. T. Andrews ◽

A. E. Jennings

Keyword(s):

North Atlantic ◽

Low Frequency ◽

Atlantic Water ◽

Ice Age ◽

The North ◽

Denmark Strait ◽

Water Stratification ◽

The North Atlantic Oscillation ◽

Frequency Variations ◽

Marine Climate

Abstract. In the area of Denmark Strait (~66° N), the two modes of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) are expressed in changes of the northward flux of Atlantic water and the southward advection of polar water in the East Iceland current. Proxies from marine cores along an environmental gradient from extensive to little or no drift ice, capture low frequency variations over the last 2000 cal yr BP. Key proxies are the weight% of calcite, a measure of surface water stratification and nutrient supply, the weight% of quartz, a measure of drift ice transport, and grain size. Records from Nansen and Kangerlussuaq fjords show variable ice-rafted debris (IRD) records but have distinct mineralogy associated with differences in the fjord catchment bedrock. A comparison between cores on either side of the Denmark Strait (MD99-2322 and MD99-2269) show a remarkable millennial-scale similarity in the trends of the weight% of calcite with a trough reached during the Little Ice Age. However, the quartz records from these two sites are quite different. The calcite records from the Denmark Strait parallel the 2000 yr Arctic summer-temperature reconstructions; analysis of the detrended calcite and quartz data reveal significant multi-decadal–century periodicities superimposed on a major environmental shift occurring ca. 1450 AD.

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