scholarly journals A Ternary Mixing Model Approach Using Benthic Foraminifer δ 13 C‐δ 18 O Data to Reconstruct Late Pliocene Deep Atlantic Water Mass Mixing

2020 ◽  
Vol 35 (12) ◽  
Author(s):  
Carolien M. H. Weijst ◽  
Josse Winkelhorst ◽  
Lucas Lourens ◽  
Maureen E. Raymo ◽  
Francesca Sangiorgi ◽  
...  
Keyword(s):  
Water Mass ◽  
Atlantic Water ◽  
Mixing Model ◽  
Benthic Foraminifer ◽  
Late Pliocene ◽  
Model Approach

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

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.

scholarly journals Impact of the Kuroshio intrusion on the nutrient inventory in the upper northern South China Sea: insights from an isopycnal mixing model

2013 ◽  
Vol 10 (10) ◽  
pp. 6419-6432 ◽  
Author(s):  
C. Du ◽  
Z. Liu ◽  
M. Dai ◽  
S.-J. Kao ◽  
Z. Cao ◽  
...  
Keyword(s):  
South China Sea ◽  
Water Column ◽  
South China ◽  
Water Mass ◽  
Northern South China Sea ◽  
Mixing Model ◽  
Nutrient Concentrations ◽  
Kuroshio Intrusion ◽  
China Sea ◽  
The Kuroshio

Abstract. Based on four cruises covering a seasonal cycle in 2009–2011, we examined the impact of the Kuroshio intrusion, featured by extremely oligotrophic waters, on the nutrient inventory in the central northern South China Sea (NSCS). The nutrient inventory in the upper 100 m of the water column in the study area ranged from ∼200 to ∼290 mmol m−2 for N + N (nitrate plus nitrite), from ∼13 to ∼24 mmol m−2 for soluble reactive phosphate and from ∼210 to ∼430 mmol m−2 for silicic acid. The nutrient inventory showed a clear seasonal pattern with the highest value appearing in summer, while the N + N inventory in spring and winter had a reduction of ∼13 and ∼30%, respectively, relative to that in summer. To quantify the extent of the Kuroshio intrusion, an isopycnal mixing model was adopted to derive the proportional contribution of water masses from the SCS proper and the Kuroshio along individual isopycnal surfaces. The derived mixing ratio along the isopycnal plane was then employed to predict the genuine gradients of nutrients under the assumption of no biogeochemical alteration. These predicted nutrient concentrations, denoted as Nm, are solely determined by water mass mixing. Results showed that the nutrient inventory in the upper 100 m of the NSCS was overall negatively correlated to the Kuroshio water fraction, suggesting that the Kuroshio intrusion significantly influenced the nutrient distribution in the SCS and its seasonal variation. The difference between the observed nutrient concentrations and their corresponding Nm allowed us to further quantify the nutrient removal/addition associated with the biogeochemical processes on top of the water mass mixing. We revealed that the nutrients in the upper 100 m of the water column had a net consumption in both winter and spring but a net addition in fall.

Paleoceanographic evolution of the SW Svalbard margin (76°N) since 20,000 14C yr BP

2007 ◽  
Vol 67 (1) ◽  
pp. 100-114 ◽  
Author(s):  
Tine L. Rasmussen ◽  
Erik Thomsen ◽  
Marta A. Ślubowska ◽  
Simon Jessen ◽  
Anders Solheim ◽  
...  
Keyword(s):  
Surface Water ◽  
Water Mass ◽  
Atlantic Water ◽  
Subsurface Water ◽  
Planktic Foraminifera ◽  
Surface Conditions ◽  
Polar Surface ◽  
Warm Core ◽  
Heinrich Event ◽  
Benthic Environment

AbstractTwo cores from the southwestern shelf and slope of Storfjorden, Svalbard, taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera, oxygen isotopes, and ice-rafted debris. The results show that over the last 20,000 yr, Atlantic water has been continuously present on the southwestern Svalbard shelf. However, from 15,000 to 10,000 14C yr BP, comprising the Heinrich event H1 interval, the Bølling–Allerød interstades and the Younger Dryas stade, it flowed as a subsurface water mass below a layer of polar surface water. In the benthic environment, the shift to interglacial conditions occurred at 10,000 14C yr BP. Due to the presence of a thin upper layer of polar water, surface conditions remained cold until ca. 9000 14C yr BP, when the warm Atlantic water finally appeared at the surface. Neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of Atlantic water. Its warm core was merely submerged below the cold polar surface water.

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

2013 ◽  
Vol 99 ◽  
pp. 29-44 ◽  
Author(s):  
Ekaterina Taldenkova ◽  
Henning A. Bauch ◽  
Anna Stepanova ◽  
Yaroslav Ovsepyan ◽  
Irina Pogodina ◽  
...  
Keyword(s):  
Water Mass ◽  
Atlantic Water ◽  
The North ◽  
Community Changes ◽  
Last Deglacial

scholarly journals Isotopic reconstruction of the weaning process in the archaeological population of Canímar Abajo, Cuba: A Bayesian probability mixing model approach

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0176065 ◽  
Author(s):  
Yadira Chinique de Armas ◽  
Mirjana Roksandic ◽  
Dejana Nikitović ◽  
Roberto Rodríguez Suárez ◽  
David Smith ◽  
...  
Keyword(s):  
Mixing Model ◽  
Bayesian Probability ◽  
Model Approach

scholarly journals Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago

2020 ◽  
Author(s):  
Chantal Mears ◽  
Helmuth Thomas ◽  
Paul B. Henderson ◽  
Matthew A. Charette ◽  
Hugh MacIntyre ◽  
...  
Keyword(s):  
Water Exchange ◽  
Water Mass ◽  
Dissolved Inorganic Carbon ◽  
Canadian Arctic ◽  
Atlantic Water ◽  
Radioactive Isotopes ◽  
Total Alkalinity ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Wide Range

Abstract. As a shelf dominated basin, the Arctic Ocean and its biogeochemistry are heavily influenced by continental and riverine sources. Radium isotopes (226Ra, 228Ra, 224Ra, 223Ra), are transferred from the sediments to seawater, making them ideal tracers of sediment-water exchange processes and ocean mixing. 226Ra and 228Ra are the two longer-lived isotopes of the Radium Quartet (226Ra, t1/2 = 1600 y and 228Ra, t1/2 = 5.8 y). Because of their long half-lives they can provide insight into the water mass compositions, distribution patterns, as well as mixing processes and the associated timescales throughout the Canadian Arctic Archipelago (CAA). The wide range of 226Ra, 228Ra, and of the 228Ra / 226Ra ratio, measured in water samples collected during the 2015 GEOTRACES cruise, complemented by additional chemical tracers (dissolved inorganic carbon (DIC), total alkalinity (AT), barium (Ba), and the stable oxygen isotope composition of water (δ18O)) highlight the dominant biogeochemical, hydrographic and bathymetric features of the CAA. Bathymetric features, such as the continental shelf and shallow coastal sills, are critical in modulating circulation patterns within the CAA, including the bulk flow of Pacific waters and the inhibited eastward flow of denser Atlantic waters through the CAA. Using a Principal Component Analysis, we unravel the dominant mechanisms and the apparent water mass end-members that shape the tracer distributions. We identify two distinct water masses located above and below the upper halocline layer throughout the CAA, as well as distinctly differentiate surface waters in the eastern and western CAA. Furthermore, we identify water exchange across 80° W, inferring a draw of Atlantic water, originating from Baffin Bay, into the CAA. In other words, this implies the presence of an Atlantic water U-turn located at Barrow Strait, where the same water mass is seen along the northernmost edge at 80° W as well as along south-easternmost confines of Lancaster Sound. Overall, this study provides a stepping stone for future research initiatives within the Canadian Arctic Archipelago, revealing how quantifying disparities in radioactive isotopes can provide valuable information on the potential effects of climate change within vulnerable areas such as the CAA.

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