Tritium distributions in Weddell Sea water masses

Abstract. We assessed and evaluated the performance of five ocean reanalysis products in reproducing essential hydrographic properties and their associated temporal variability for the Weddell Sea, Antarctica. The products used in this assessment were ECMWF ORAS4 (European Centre for Medium-Range Weather Forecasts Ocean Reanalysis System 4), CFSR (Climate Forecast System Reanalysis), MyOcean UR025.4 (University of Reading), ECCO2 (Estimating the Circulation and Climate of the Ocean, Phase II) and SODA (Simple Ocean Data Assimilation). The present study focuses on the Weddell Sea deep layer, which is composed of the following three main water masses: Warm Deep Water (WDW), Weddell Sea Deep Water (WSDW) and Weddell Sea Bottom Water (WSBW). The MyOcean UR025.4 product provided the most accurate representation of the structure and thermohaline properties of the Weddell Sea water masses when compared with observations. All the ocean reanalysis products analyzed exhibited limited capabilities in representing the surface water masses in the Weddell Sea. The CFSR and ECCO2 products were not able to represent deep water masses with a neutral density ≥ 28.40 kg m−3, which was considered the WSBW's upper limit throughout the simulation period. The expected WDW warming was only reproduced by the SODA product, whereas the ECCO2 product was able to represent the trends in the WSDW's hydrographic properties. All the assessed ocean reanalyses were able to represent the decrease in the WSBW's density, except the SODA product in the inner Weddell Sea. Improvements in parameterization may have as much impact on the reanalyses assessed as improvements in horizontal resolution primarily because the Southern Ocean lacks in situ data, and the data that are currently available are summer-biased. The choice of the reanalysis product should be made carefully, taking into account the performance, the parameters of interest, and the type of physical processes to be evaluated.

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Water masses in the Atlantic Ocean: characteristics and distributions

Ocean Science ◽

10.5194/os-17-463-2021 ◽

2021 ◽

Vol 17 (2) ◽

pp. 463-486

Author(s):

Mian Liu ◽

Toste Tanhua

Keyword(s):

Atlantic Ocean ◽

Deep Water ◽

Bottom Water ◽

Water Mass ◽

Sea Water ◽

Weddell Sea ◽

Water Masses ◽

Global Ocean ◽

Intermediate Water ◽

The North

Abstract. A large number of water masses are presented in the Atlantic Ocean, and knowledge of their distributions and properties is important for understanding and monitoring of a range of oceanographic phenomena. The characteristics and distributions of water masses in biogeochemical space are useful for, in particular, chemical and biological oceanography to understand the origin and mixing history of water samples. Here, we define the characteristics of the major water masses in the Atlantic Ocean as source water types (SWTs) from their formation areas, and map out their distributions. The SWTs are described by six properties taken from the biased-adjusted Global Ocean Data Analysis Project version 2 (GLODAPv2) data product, including both conservative (conservative temperature and absolute salinity) and non-conservative (oxygen, silicate, phosphate and nitrate) properties. The distributions of these water masses are investigated with the use of the optimum multi-parameter (OMP) method and mapped out. The Atlantic Ocean is divided into four vertical layers by distinct neutral densities and four zonal layers to guide the identification and characterization. The water masses in the upper layer originate from wintertime subduction and are defined as central waters. Below the upper layer, the intermediate layer consists of three main water masses: Antarctic Intermediate Water (AAIW), Subarctic Intermediate Water (SAIW) and Mediterranean Water (MW). The North Atlantic Deep Water (NADW, divided into its upper and lower components) is the dominating water mass in the deep and overflow layer. The origin of both the upper and lower NADW is the Labrador Sea Water (LSW), the Iceland–Scotland Overflow Water (ISOW) and the Denmark Strait Overflow Water (DSOW). The Antarctic Bottom Water (AABW) is the only natural water mass in the bottom layer, and this water mass is redefined as Northeast Atlantic Bottom Water (NEABW) in the north of the Equator due to the change of key properties, especially silicate. Similar with NADW, two additional water masses, Circumpolar Deep Water (CDW) and Weddell Sea Bottom Water (WSBW), are defined in the Weddell Sea region in order to understand the origin of AABW.

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Assessment of the structure and variability of Weddell Sea water masses in distinct ocean reanalysis products

Ocean Science Discussions ◽

10.5194/osd-11-497-2014 ◽

2014 ◽

Vol 11 (1) ◽

pp. 497-542 ◽

Cited By ~ 1

Author(s):

T. S. Dotto ◽

R. Kerr ◽

M. M. Mata ◽

M. Azaneu ◽

I. Wainer

Keyword(s):

Deep Water ◽

Sea Water ◽

Horizontal Resolution ◽

Weddell Sea ◽

Water Masses ◽

Ocean Reanalysis ◽

In Situ Data ◽

Sea Bottom ◽

Warm Deep Water ◽

Deep Layers

Abstract. We assessed and evaluated the performance of five ocean reanalysis in reproducing essential hydrographic properties and their associated temporal variability for the Weddell Sea, Antarctica. The products used in this assessment were ECMWF ORAS4, CFSR, MyOcean UR025.4, ECCO2 and SODA. The present study focuses on the Weddell Sea deep layer, which is composed of the following three main water masses: Warm Deep Water (WDW), Weddell Sea Deep Water (WSDW) and Weddell Sea Bottom Water (WSBW). Moreover, all the ocean reanalysis products analyzed showed limited capabilities in representing the surface water masses in the Weddell Sea. The MyOcean UR025.4 product provided the most accurate representation of the structure of the Weddell Sea water masses when compared to observations. The CFSR and ECCO2 products were not able to represent the WSBW throughout the simulation period. The expected WDW warming was only reproduced by the SODA product, while the ECCO2 product was able to represent the WSDW's hydrographic properties trends. All of these ocean reanalysis systems were able to represent the decrease in the WSBW's density. Our results also showed that a simple increase in horizontal resolution does not necessarily imply better representation of the deep layers. Rather, it is needed to observe the physics involved in each model and their parameterizations because the Southern Ocean suffers from the lack of in situ data, and it is biased by summer observations. The choice of the reanalysis product should be made carefully, taking into account the performance, the parameters of interest, and the type of physical processes to be evaluated.

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Oxygen and carbon stable isotope tracers of Weddell Sea water masses: new data and some paleoceanographic implications

Deep Sea Research Part I Oceanographic Research Papers ◽

10.1016/s0967-0637(00)00093-5 ◽

2001 ◽

Vol 48 (6) ◽

pp. 1401-1422 ◽

Cited By ~ 35

Author(s):

A. Mackensen

Keyword(s):

Stable Isotope ◽

Sea Water ◽

Weddell Sea ◽

Water Masses ◽

Carbon Stable Isotope ◽

Stable Isotope Tracers ◽

Isotope Tracers

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The role of tides on the carbonate chemistry of a coastal polynya in the south-eastern Weddell Sea

10.5194/egusphere-egu21-8978 ◽

2021 ◽

Author(s):

Elise Droste ◽

Melchor González Dávila ◽

Juana Magdalena Santana Casiano ◽

Mario Hoppema ◽

Gerd Rohardt ◽

...

Keyword(s):

Southern Ocean ◽

Weddell Sea ◽

Water Masses ◽

Total Alkalinity ◽

The South ◽

Carbonate Chemistry ◽

Large Variability ◽

South Eastern ◽

Coastal Polynya ◽

Eastern Weddell Sea

Tides have a large impact on coastal polynyas around Antarctica. We investigate the effect of semi-diurnal tidal cycles on the seawater carbonate chemistry in a coastal polynya hugging the Ekstr&#246;m Ice Shelf in the south-eastern Weddell Sea. This region experiences some of the strongest tides in the Southern Ocean. We assess the implications for the contribution of coastal polynyas to the carbon dioxide (CO2) air-sea flux of the Weddell Sea.Two site visits, in January 2015 and January 2019, are intercompared in terms of the dissolved inorganic carbon (DIC) concentration, total alkalinity, pH, and CO2 partial pressure (pCO2). The tides induce large variability in the carbonate chemistry of the coastal polynya in the austral summer: DIC concentrations vary between 2174 and 2223 umol kg-1.The tidal fluctuation in the DIC concentration can swing the polynya from a sink to a source of atmospheric CO2 on a semi-diurnal timescale. We attribute these changes to the mixing of different water masses. The amount of variability induced by tides depends on &#8211; and is associated with &#8211; large scale oceanographic and biogeochemical processes that affect the characteristics and presence of the water masses being mixed, such as the rate of sea ice melt.Sampling strategies in Antarctic coastal polynyas should always take tidal influences into account. This would help to reduce biases in our understanding of how coastal polynyas contribute to the CO2 uptake by the Southern Ocean.

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INTEGRATED SYNOPTICAL METHOD FOR CALCULATING ASSIMILATION CAPACITY OF SEA WATERS

VESTNIK OF ASTRAKHAN STATE TECHNICAL UNIVERSITY SERIES MARINE ENGINEERING AND TECHNOLOGIES ◽

10.24143/2073-1574-2017-4-115-120 ◽

2017 ◽

pp. 115-120

Author(s):

Hikmat Hamid oglu Asadov ◽

Sima Ajdar gizi Askerova

Keyword(s):

Sea Water ◽

Water Masses ◽

Optimum Regime ◽

Optimization Task ◽

Maximum Value ◽

Long Time ◽

Negative Effect ◽

Optimum Order ◽

Assimilation Capacity ◽

The Given

Pollution of sea waters is one of major attributes of coastal industrial centers and the norming of such emissions is one of major countermeasures. The assimilation capacity of sea waters is a major factor relevant at norming and planning of outflows into sea waters. At present time the synoptical method has been developed, which doesn’t require carrying out long time and repeated observing of the level of pollution of sea waters. This method has formed the basis for developing the integrated synoptical method for calculating sea water assimilation capacity. The suggested method provides for division of the sea waters into separated homogenous water masses. The aim of the study is to develop an inverse integrated synoptical method allowing synthesizing of such an optimum order for loading separate water masses with pollutants upon, at which the calculated total value of assimilation capacity would reach its maximum. The article shows the possibility of utilization of known synoptical method for determining assimilation capacity of sea waters in the inverse order, i.e. for calculating the maximum value of pollutant put into the fixed zone of sea waters, upon a condition of reaching the given amount of assimilation capacity and absence of essential negative effect on ecosystem. The task of calculating an optimum regime function of discrete type, upon which the integrated value of assimilation capacity would reach the maximum value, has been formulated. The solution of analogue equivalent of the formed optimization task is carried out using the Euler equation for a non-conditional variation optimization task, taking into account the accepted limitation condition. The recommendations on optimum loading of different sea water zones with determined type of pollutant have been given.

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Controls on Weddell Sea water mass Nd isotope signatures and their export to the subantarctic Southern Ocean

10.7185/gold2021.4674 ◽

2021 ◽

Author(s):

Marcus Gutjahr ◽

Huang Huang ◽

Jörg Rickli ◽

Gerhard Kuhn ◽

Anton Eisenhauer

Keyword(s):

Southern Ocean ◽

Water Mass ◽

Sea Water ◽

Weddell Sea ◽

Nd Isotope

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WATER MASSES CHARACTERISTICS AT THE SANGHIE TALAUD ENTRY PASSAGE OF INDONESIAN THROUGHFLOW USING INDEX SATAL DATA 2010

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v6i2.9027 ◽

2015 ◽

Vol 6 (2) ◽

Author(s):

Ivonne M Radjawane ◽

Paundra P Hadipoetranto

Keyword(s):

North Pacific ◽

Water Mass ◽

Sea Water ◽

Core Layer ◽

South Pacific ◽

New Guinea ◽

Water Masses ◽

Coastal Current ◽

Indonesian Throughflow ◽

Pacific Water

ABSTRACT Measurement of ocean physical parameters using the CTD was conducted by deep water expedition INDEX-SATAL 2010 (Indonesian Expedition Sangihe-Talaud) in July-August 2010. The aim of this study was to determine the characteristics of water masses around the Sangihe Talaud Water where there was an entry passage of Indonesian throughflow (ITF) at the west pathway that passed through the primary pathway i.e., the Sulawesi Sea and Makassar Strait and the secondary pathway (east pathway) that passed through the Halmahera Sea. The analyses were performed by the method of the core layer and was processed with software Ocean Data View (ODV). The results showed that in the Sangihe Talaud waters there was a meeting water masses from the North Pacific and the South Pacific. The water mass characteristics in main pathway through the Sulawesi Sea was dominated by surface and intermediate North Pacific water masses and carried by the Mindanao Currents. While the Halmahera Sea water mass was dominated by surface and intermediate South Pacific water masses carried by the New Guinea Coastal Current that moved along the Papua New Guinea and Papua coast enters to the Halmahera Sea. Keywords: Index-Satal 2010, Northern Pacific Water Masses, Southern Pacific Water Masses, Sangihe Talaud

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Ice-Ocean Interaction On Ronne Ice Shelf, Antarctica

Annals of Glaciology ◽

10.1017/s026030550000906x ◽

1990 ◽

Vol 14 ◽

pp. 341

Author(s):

A. Jenkins ◽

C.S.M. Doake

Keyword(s):

Cold Water ◽

Sea Water ◽

Freezing Point ◽

Accumulation Rate ◽

Weddell Sea ◽

Shear Stresses ◽

Strain Rates ◽

Horizontal Shear ◽

Ice Shelf ◽

Ice Stream

A detailed glaciological study of Ronne Ice Shelf has been undertaken along a flowline extending from Rutford Ice Stream grounding line to the ice front. Measurements of velocity, surface elevation, ice thickness, surface temperature and accumulation rate have been made at a total of 28 sites; at 17 of these ice deformation rates are also known. Although no direct measurements of basal conditions have been made, these can be deduced from observations made at the surface. Assuming the ice shelf to be in a steady state, the basal mass balance can be calculated at points where strain-rates are known. Information on the spatial distribution of basal saline ice layers can also be obtained from radio-echo sounding data. The derived pattern of basal melting and freezing influences both the ice shelf and the underlying ocean. Vertical heat advection modifies the temperature distribution within the ice shelf, which determines its dynamic response to driving and restraining forces through the temperature-dependent ice-flow law. Using measured strain-rates and calculated temperature profiles, the restraint generated by horizontal shear stresses can be derived for points on the flowline. It is the cumulative effect of these forces which controls the discharge of grounded ice from Rutford Ice Stream. Cooling of sea-water to its pressure melting point by melting of ice at depth has two important results. The outflow of cold, dense Ice Shelf Water, produced by this mechanism, is a major source of Antarctic Bottom Water, formed as it mixes at depth with the warmer waters of the Weddell Sea (Foldvik and Gammelsrod, 1988). If the cold water is forced up to shallower depths, frazil ice will be produced as the pressure freezing point rises, resulting in basal accretion if this occurs beneath the ice shelf.

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The Identification and Nomenclature of the Surface Water Masses in the Tasman Sea (Data to the End of 1954)

Marine and Freshwater Research ◽

10.1071/mf9570369 ◽

1957 ◽

Vol 8 (4) ◽

pp. 369 ◽

Cited By ~ 24

Author(s):

DJ Rochford

Keyword(s):

Surface Water ◽

Sea Water ◽

Maximum Velocity ◽

Water Masses ◽

Late Winter ◽

The South ◽

Coral Sea ◽

Tasman Sea ◽

East And West ◽

Western Side

In this paper an examination of all available data on the hydrological characteristics of the Tasman Sea, prior to and including the year 1954, has permitted the identification and naming of eight surface water masses. Certain of their properties and general features of their season and region of occurrence and method of formation are summarized. Although little quantitative data are available some general features of the circulation of these water masses in the Tasman Sea are deduced from a study of their seasonal occurrence in relation to source regions. The Coral Sea water mass (chlorinity 19.60-19.70‰, temperature 20-26� C) flows from a source region in the north-west Coral Sea along the western side of the Tasman Sea and reaches maximum velocity off Sydney in October-December. The South Equatorial (chlorinity 19.50-19.60‰, temperature 24-26� C) also flows south along the western side of the Tasman Sea but reaches maximum velocity between February and March. These two water masses constitute the East Australian current. The Sub-Antarctic (chlorinity 19.15-19.30‰, temperature 10-14°C) is found at the surface in the south-eastern Tasman Sea between July and September. The Central Tasman (chlorinity 19.65-19.75‰, temperature 15-20‰C) flows to the west from its region of formation and generally flows north along the southern New South Wales coast in late winter. The South-west Tasman (chlorinity 19.50- 19.60‰, temperature 12-15°C) flows to the east in latitude 38�S. and curves south in a clockwise gyral off eastern Tasmania between October and December. The Xorth Bass Strait (chlorinity 19.66-19.75‰ temperature 12-17�C) flows from South Australia to the eastern approaches of Bass Strait. The East Central New Zealand (chlorinity 19.10-19.30‰, temperature 15-20°C) flows west through Cook Strait into the Tasman Sea in midsummer. The East and West Tasmanian (chlorinity 19.40- 19.50‰ temperature 10-14°C) form in midwinter in the southern part of Bass Strait and flow along the east and west coasts in the spring.

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