Circulation and water masses on the southern Weddell Sea shelf

1985 ◽  
pp. 5-20 ◽  
Author(s):  
A. Foldvik ◽  
T. Gammelsrød ◽  
T. Tørresen
Keyword(s):  
Weddell Sea ◽  
Water Masses

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

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

<p>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 Ekström 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 (CO<sub>2</sub>) air-sea flux of the Weddell Sea.</p><p>Two site visits, in January 2015 and January 2019, are intercompared in terms of the dissolved inorganic carbon (DIC) concentration, total alkalinity, pH, and CO<sub>2</sub> partial pressure (pCO<sub>2</sub>). 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<sup>-1</sup>.</p><p>The tidal fluctuation in the DIC concentration can swing the polynya from a sink to a source of atmospheric CO<sub>2 </sub>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 – and is associated with – 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.</p><p>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 CO<sub>2</sub> uptake by the Southern Ocean.</p>

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

Ocean Science ◽  
2014 ◽  
Vol 10 (3) ◽  
pp. 523-546 ◽  
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 ◽  
Ocean Data Assimilation ◽  
Sea Bottom ◽  
Warm Deep Water

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.

scholarly journals Modelling the impact of ocean warming on melting and water masses of ice shelves in the Eastern Weddell Sea

2010 ◽  
Vol 60 (3) ◽  
pp. 479-489 ◽  
Author(s):  
Malte Thoma ◽  
Klaus Grosfeld ◽  
Keith Makinson ◽  
Manfred A. Lange
Keyword(s):  
Ocean Warming ◽  
Weddell Sea ◽  
Water Masses ◽  
Ice Shelves ◽  
The Impact ◽  
Eastern Weddell Sea

scholarly journals Water masses in the Atlantic Ocean: characteristics and distributions

Ocean Science ◽  
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.

scholarly journals Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201447
Author(s):  
Theoni Photopoulou ◽  
Karine Heerah ◽  
Jennifer Pohle ◽  
Lars Boehme
Keyword(s):  
Habitat Use ◽  
Continental Shelf ◽  
Weddell Sea ◽  
Water Masses ◽  
Shelf Water ◽  
Top Predator ◽  
Marine Animals ◽  
Deep Diving ◽  
Continental Shelf Water ◽  
Oceanographic Conditions

Patterns of habitat use are commonly studied in horizontal space, but this does not capture the four-dimensional nature of ocean habitats (space, depth, and time). Deep-diving marine animals encounter varying oceanographic conditions, particularly at the poles, where there is strong seasonal variation in vertical ocean structuring. This dimension of space use is hidden if we only consider horizontal movement. To identify different diving behaviours and usage patterns of vertically distributed habitat, we use hidden Markov models fitted to telemetry data from an air-breathing top predator, the Weddell seal, in the Weddell Sea, Antarctica. We present evidence of overlapping use of high-density, continental shelf water masses by both sexes, as well as important differences in their preferences for oceanographic conditions. Males spend more time in the unique high-salinity shelf water masses found at depth, while females also venture off the continental shelf and visit warmer, shallower water masses. Both sexes exhibit a diurnal pattern in diving behaviour (deep in the day, shallow at night) that persists from austral autumn into winter. The differences in habitat use in this resident, sexually monomorphic Antarctic top predator suggest a different set of needs and constraints operating at the intraspecific level, not driven by body size.

Multiproxy climate and sea ice reconstruction of the industrial era at the Western Antarctic Peninsula

2020 ◽  
Author(s):  
Maria-Elena Vorrath ◽  
Paola Cárdenas ◽  
Lorena Rebolledo ◽  
Xiaoxu Shi ◽  
Juliane Müller ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
System Analysis ◽  
Ice Cover ◽  
Weddell Sea ◽  
Water Masses ◽  
Western Antarctic Peninsula ◽  
Climate Conditions ◽  
Ice Conditions ◽  
Bransfield Basin

<p>Recent changes and variability in climate conditions leave a significant footprint on the distribution and properties of sea ice, as it is sensitive to environmental variations. We investigate the rapidly transforming region of the Western Antarctic Peninsula (WAP) focusing on the conditions and development of sea ice in the pre-satellite era. For this study on past sea ice cover we apply the novel proxy IPSO<sub>25</sub> (Ice Proxy for the Southern Ocean with 25 carbon atoms; Belt et al., 2016). Three sampling sites were selected to cover areas near the Antarctic mainland, in the Bransfield Basin (2000 m depth) and the deeper shelf under an oceanographic frontal system. Analysis of short cores (multicores) resolving the last 200 years (based on <sup>210</sup>Pb<sub>ex</sub> dating) focused on geochemical bulk parameters, biomarkers (highly branched isoprenoids, GDGTs, sterols) and diatoms. These results are compared to multiple climate archives and modelled data. This multiproxy based approach provides insights on changes in spring sea ice cover, primary production regimes, subsurface ocean temperature (SOT based on TEX<sup>L</sup><sub>86</sub>) and oceanographic as well as atmospheric circulation patterns. While environmental proxies preserved in two cores near the coast and in the Bransfield Basin reflect the properties of water masses from the Bellingshausen Sea and Weddell Sea, respectively, data from the third core at the deeper shelf depict mixed signals of both water masses. Our study reveals clear evidence for warm and cold periods matching with ice core records and other marine sediment data at the WAP. We observe a general decrease in SOT and an increase in sea ice cover overprinted by high decadal fluctuations. Trends in SOT seem to be decoupled from atmospheric temperatures in the 20<sup>th</sup> century, and this is supported by previous studies (e.g. Barbara et al., 2013), and may be related to the Southern Annual Mode. We consider numerical modelling of sea ice conditions, sea surface temperature and SOT for further support of our findings.</p><p> </p><p>References:</p><p>Barbara, L., Crosta, X., Schmidt, S. and Massé, G.: Diatoms and biomarkers evidence for major changes in sea ice conditions prior the instrumental period in Antarctic Peninsula, Quat. Sci. Rev., 79, 99–110, doi:10.1016/j.quascirev.2013.07.021, 2013.</p><p>Belt, S. T., Smik, L., Brown, T. A., Kim, J. H., Rowland, S. J., Allen, C. S., Gal, J. K., Shin, K. H., Lee, J. I. and Taylor, K. W. R.: Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25, Nat. Commun., 7, 1–10, doi:10.1038/ncomms12655, 2016.</p>

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

2014 ◽  
Vol 11 (1) ◽  
pp. 497-542 ◽  
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.

scholarly journals FRIS revisited in 2018: On the circulation and water masses at the Filchner and Ronne Ice Shelves in the southern Weddell Sea

2021 ◽  
Author(s):  
Markus Janout ◽  
Hartmut H Hellmer ◽  
Tore Hattermann ◽  
Oliver Huhn ◽  
Jürgen Sültenfuss ◽  
...  
Keyword(s):  
Weddell Sea ◽  
Water Masses ◽  
Ice Shelves
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