References of "Deep-Sea Research Part II, Topical Studies in Oceanography"
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See detailVariability in North Pacific intermediate and deep water ventilation during Heinrich events in two coupled climate models
Chikamoto, M. O.; Menviel, L.; Abe-Ouchi, A. et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2012), 61-64

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See detailRemoving the North Pacific halocline: effects on global climate, ocean circulation and the carbon cycle
Menviel, L.; Timmermann, A.; Timm, O. et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2012), 61-64

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See detailInterannual variability of Black Sea’s hydrodynamics and connection to atmospheric patterns
Capet, Arthur ULg; Barth, Alexander ULg; Beckers, Jean-Marie ULg et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2012)

The long term variability (1962–2000) of the Black Sea physical processes (e.g. temperature, main circulation, cold intermediate layer, sea level) and its relation to atmospheric conditions and large ... [more ▼]

The long term variability (1962–2000) of the Black Sea physical processes (e.g. temperature, main circulation, cold intermediate layer, sea level) and its relation to atmospheric conditions and large scale climate patterns are investigated using an eddy-resolving tridimensional model in ombination with statistical tools (e.g. Empirical Orthogonal Functions, Self Organizing Maps). First, the ability of the model to represent the interannual dynamics of the system is assessed by comparing the modeled and satellite sea surface temperature (SST) and sea level anomaly (SLA) decomposed into their dominant Empirical Orthogonal Functions (EOFs). The correlation between the spatial and temporal EOFs modes derived from model and satellite data is usually satisfactory and this gives some confidence in using the model as a tool to investigate not only the SST and SLA dynamics but also the dynamics of connected variables. Then, the long term variability (1962–2000) of the Black Sea hydrodynamics is assessed by decomposing into their dominant EOFs modeled SST, SLA and selected key hydrodynamical variables associated to the main circulation and vertical structure of the water column. Significant correlations between the EOFs associated to these variables are investigated in order to link the variability of surface fields and the internal dynamics of the system. In particular, the intensity of the general cyclonic circulation (the Rim Current) is shown to impact strongly (1) the mean sea level, (2) the SST response to air temperature (AT), (3) the formation of the cold intermediate layer, (4) the meridional repartition of the SST anomaly and (5) the exchanges of heat between the north-western shelf and the open basin. In order to appraise the variability of atmospheric conditions over the Black Sea during 1962–2000 and their role in driving the hydrodynamics, a self-organizing maps technique is used to identify spatial recurrent patterns of atmospheric fields (i.e., AT, wind stress and curl). The impact on these patterns of large scale climatic variability over the north Atlantic, Eurasia and the Pacific Ocean (estimated by respectively the north Atlantic oscillation (NAO), the east Atlantic/west ̃Russia oscillation (EA/WR) and the El Nino southern oscillation (ENSO) indexes) is assessed. Distinct time scales of influence of the large scale teleconnection patterns on the AT are identified: EA/WR drives the short scale (1–5 years) variations of SST, while the long term (4-5 years) trends of the NAO drive the long term SST trends. The drastic changes that have occurred in the Black Sea deep sea ecosystem at the end of the 80s are connected to an intensification of the general circulation that has promoted an export of riverine materials from the eutrophicated north-western shelf to the deep sea. Finally, in the last two decades, we find an increased duration of persistent atmospheric anomalies regime that has the potential to drive the system away from its average state as occurred in the late 80s. If persistent in the future, such long lasting atmospheric anomalies may have a significant impact on the ecosystem functioning. [less ▲]

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See detailSea ice and snow cover characteristics during the winter-spring transition in the Bellingshausen Sea: an overview of SIMBA 2007
Lewis, M. J.; Tison, Jean-Louis; Weissling et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2011), 58(9-10), 10191038

The Sea Ice Mass Balance in the Antarctic (SIMBA) experiment was conducted from the RVIB N.B. Palmer in September and October 2007 in the Bellingshausen Sea in an area recently experiencing considerable ... [more ▼]

The Sea Ice Mass Balance in the Antarctic (SIMBA) experiment was conducted from the RVIB N.B. Palmer in September and October 2007 in the Bellingshausen Sea in an area recently experiencing considerable changes in both climate and sea ice cover. Snow and ice properties were observed at 3 short-term stations and a 27-day drift station (Ice Station Belgica, ISB) during the winter-spring transition. Repeat measurements were performed on sea ice and snow cover at 5 ISB sites, each having different physical characteristics, with mean ice (snow) thicknesses varying from 0.6m (0.1m) to 2.3m (0.7m). Ice cores retrieved every five days from 2 sites and measured for physical, biological, and chemical properties. Three ice mass-balance buoys (IMBs) provided continuous records of snow and ice thickness and temperature. Meteorological conditions changed from warm fronts with high winds and precipitation followed by cold and calm periods through four cycles during ISB. The snow cover regulated temperature flux and controlled the physical regime in which sea ice morphology changed. Level thin ice areas had little snow accumulation and experienced greater thermal fluctuations resulting in brine salinity and volume changes, and winter maximum thermodynamic growth of ~0.6m in this region. Flooding and snow-ice formation occurred during cold spells in ice and snow of intermediate instead nearly isothermal, highly permeable ice persisted. In spring, short-lived cold air episodes did not effectively penetrate the sea ice nor overcome the effect of ocean heat flux, thus favoring net ice thinning from bottom melt over ice thickening from snow-ice growth, in all cases. These warm ice conditions were consistent with regional remote sensing observations of earlier ice breakup and a shorter sea ice season, more recently observed in the Bellingshausen Sea. [less ▲]

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See detailReconciling opposing views on carbon cycling in the coastal ocean: continental shelves as sinks and near-shore ecosystems as sources of atmospheric CO2
Chen, C. T. A.; Borges, Alberto ULg

in Deep-Sea Research Part II, Topical Studies in Oceanography (2009), 56(8-10), 578-590

Despite their moderately-sized surface area, continental marginal seas play a significant role in the biogeochemical cycles of carbon, as they receive huge amounts of upwelled and riverine inputs of ... [more ▼]

Despite their moderately-sized surface area, continental marginal seas play a significant role in the biogeochemical cycles of carbon, as they receive huge amounts of upwelled and riverine inputs of carbon and nutrients, sustaining a disproportionate large biological activity compared to their relative surface area. A synthesis of worldwide measurements of the partial pressure of CO2 (pCO2) indicates that most open shelves in the temperate and high latitude regions are under-saturated with respect to atmospheric CO2 during all seasons, although the low latitude shelves seem to be over-saturated. Most inner estuaries and near-shore coastal areas on the other hand are over-saturated with respect to atmospheric CO2. The scaling of air-sea CO2 fluxes based on pCO2 measurements and carbon mass balance calculations indicate that the continental shelves absorb atmospheric CO2 ranging between 0.33 to 0.36 Pg C yr-1 that corresponds to an additional sink of 27% to ~30% of the CO2 uptake by the open oceans based on the most recent pCO2 climatology (Takahashi et al., 2008; Deep-Sea Research II, this issue). Inner estuaries, salt marshes and mangroves emit up to 0.50 Pg C yr-1, although these estimates are prone to large uncertainty due to poorly constrained ecosystem surface area estimates. Nevertheless, the view of continental shelves as sinks and near-shore ecosystems as sources of atmospheric CO2 allows reconciling long-lived opposing views on carbon cycling in the coastal ocean. [less ▲]

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See detailClimatological Mean and Decadal Change in Surface Ocean pCO2, and Net Sea-air CO2 Flux over the Global Oceans
Takahashi, Taro; Sutherland, Stewart C.; Wanninkhof, Rik et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2009), in press

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See detailTemporal evolution of decaying summer first-year sea ice in the Western Weddell Sea, Antarctica
Tison, J. L.; Worby, A.; Delille, Bruno ULg et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2008), 55(8-9), 975-987

The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international ... [more ▼]

The evolution of the main physico-chemical properties of the unflooded 90-cm-thick first-year sea-ice cover at the Ice Station POLarstern (ISPOL) "clean site" is described. ISPOL was an international experiment of the German research icebreaker R.V. Polarstern. The vessel was anchored to an ice floe for an observation period of 5 weeks, during the early summer melt onset in the Western Weddell Sea. The "clean site" was specially designed and accessed so as to prevent any trace metal contamination of the sampling area. Observations were made at 5-day intervals during December 2004 in the central part of the main floe. Results show the succession of two contrasting phases in the behavior of the brine network (brine channels, pockets, and tubes). Initially, brine salinity was higher than that of sea-water, leading to brine migration and a decrease in the mean bulk salinity of the ice cover. This process is highly favored by the already high bulk porosity (14%), which ensures full connectivity of the brine network. Gravity drainage rather than convection seems to be the dominant brine transfer process. Half-way through the observation period, the brine salinity became lower than that of the sea-water throughout the ice column. The brine network therefore switched to a "stratified" regime in which exchange with sea-water was limited to molecular diffusion, strongly stabilizing the bulk mean sea-ice salinity. During the transition between the two regimes, and in areas closer to ridges, slush water (resulting from a mixture of snow meltwater and sea water accumulated at the snow-ice interface) penetrated through the growing "honeycomb-like structure" and replaced the downward draining brines. This resulted in a slight local replenishment of nutrients (as indicated by dissolved silicic acid). However, as a whole, the described decaying regime in this globally unflooded location with limited snow cover should be unfavorable to the development of healthy and active surface and internal microbial communities. The switch from gravity to diffusion controlled transport mechanisms within the ice column also should affect the efficiency of gas exchange across the sea-ice cover. The observed late build-up of a continuous, impermeable, superimposed ice layer should further significantly hamper gas exchange. Statistical estimates of the evolution of the ice thickness during the observation period and salinity trends of the under-ice water salinity down to 30m corroborate model predictions of a moderate bottom melting (5-10cm) from ocean heat fluxes. (C) 2008 Elsevier Ltd. All rights reserved. [less ▲]

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See detailGlacial–interglacial rain ratio changes: Implications for atmospheric CO2 and ocean–sediment interaction
Munhoven, Guy ULg

in Deep-Sea Research Part II, Topical Studies in Oceanography (2007), 54(5-7), 722-746

A reduction of the carbonate-carbon to organic-carbon export rain ratio during glacial times has been advanced to explain the glacial–interglacial atmospheric CO2 variations. This hypothesis is tested and ... [more ▼]

A reduction of the carbonate-carbon to organic-carbon export rain ratio during glacial times has been advanced to explain the glacial–interglacial atmospheric CO2 variations. This hypothesis is tested and implications for the dynamics of sedimentary carbonate preservation and dissolution are explored with a multi-box model (MBM) of the ocean carbon cycle, fully coupled to a new transient early diagenesis model (called MEDUSA). A peak reduction of the rain ratio by 40% at the Last Glacial Maximum (LGM) was found to produce a net atmospheric pCO2 reduction of about 40 ppm. Changing shelf carbonate accumulation rates and continental weathering inputs produced a 55–60 ppm reduction. The combination of the two mechanisms generates a pCO2 change of 90–95 ppm, which compares well with the observed data. However, the resulting model sedimentary record does not conform to actual sedimentary records. The changes related to continental shelf processes and variable weathering flux depress the calcite saturation horizon (CSH) by about 1 km at the LGM; if rain ratio variations are also considered, that depression increases by another km. In addition to this large amplitude for the CSH, possibly due to the adopted box-model approach, the changing rain ratio also leads to transition zone changes in the model sedimentary record that are opposite in phase with data-based reconstructions. Realistic changes in the aragonite fraction of the carbonate rain were found to have only a minimal impact on atmospheric pCO2. Finally, chemical erosion of deep-sea sediment was shown to reduce the amplitude of variation of the sedimentary CCD by about 10–20%. It may provide a mechanism to improve the model-data agreement. [less ▲]

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See detailThe crustacean scavenger guild in Antarctic shelf, bathyal and abyssal communities
De Broyer, Claude; Nyssen, Fabienne ULg; Dauby, Patrick ULg

in Deep-Sea Research Part II, Topical Studies in Oceanography (2004), 51(14-16), 1733-1752

Peracarid crustaceans form a significant part of the macrobenthic community that is responsible for scavenging on large food falls onto the sea floor. Although several studies are available about ... [more ▼]

Peracarid crustaceans form a significant part of the macrobenthic community that is responsible for scavenging on large food falls onto the sea floor. Although several studies are available about scavengers from tropical and temperate seas, very little information has been published about such species living in Antarctic waters, particularly at greater depths. The present paper is based on a collection of 31 baited trap sets deployed in the Weddell Sea, Scotia Sea, and off the South Shetland Islands, and presents results on the geographical and bathymetric distribution of the different taxa and on the eco-functional role of scavengers. <br /> <br />Some 68,000 peracarid crustaceans from 62 species were collected. About 98% of individuals belonged to the amphipod superfamily Lysianassoidea, and 2% to the isopod family Cirolanidae. Of these species, 31, including 26 lysianassoids (1400 individuals), were collected deeper than 1000 m. <br /> <br />High species richness was discerned for the eastern Weddell Sea shelf compared with other Antarctic areas. The Antarctic slope also seems to be richer in species than other areas investigated in the world, while in the abyss, scavenger species richness appears to be lower in Antarctica. A richness gradient was thus observed from the shelf to the deep. For amphipods, a number of species extend their distribution from the shelf to the slope and only one to the abyssal zone. <br /> <br />Amphipod species showed degrees of adaptation to necrophagy. The functional adaptations of the mandible and the storage function of the gut are discussed. Feeding experiments conducted on lysianassoid species collected at great depths and maintained in aquaria showed a mean feeding rate of about 1.4–4.1% dry body weight day−1, which is consistent with data obtained from other species. [less ▲]

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See detailMolecular and pigment studies of the picophytoplankton in a region of the Southern Ocean (42-54 degrees S, 141-144 degrees E) in March 1998
Wilmotte, Annick ULg; Demonceau, Caroline; Goffart, Anne ULg et al

in Deep-Sea Research Part II, Topical Studies in Oceanography (2002), 49(16), 3351-3363

Seven filtered seawater samples (depths between 30 and 55 m) collected during the SAZ project of the Austral summer of 1997-1998 were used for a simultaneous study of the picophytoplankton pigments based ... [more ▼]

Seven filtered seawater samples (depths between 30 and 55 m) collected during the SAZ project of the Austral summer of 1997-1998 were used for a simultaneous study of the picophytoplankton pigments based on high-performance liquid chromatography (HPLC) analyses and flow cytometry, and of the molecular diversity of the picophytoplankton based on their rDNA sequences. The sampling sites could be divided into three temperature zones, distinguished by their proximity to the Sub-Antarctic and Polar Fronts. HPLC analysis of total chlorophylls and carotenoids showed fairly low phytoplankton concentrations (77-262 ng chl al(-1)), with minimal values of the pigments in the two samples of the Polar Front Zone around 54degreesS (water temperature of 4degreesC at time of collection). In this zone, a similar decrease of particles, identified as cyanobacteria on the basis of their fluorescence, was observed by flow cytometry. Sequences very similar to the 16S rDNA sequence of Synechococcus WH8103 were present in all samples. This Synechococcus genotype is thus found in the Southern Ocean in addition to the Atlantic and Pacific locations where it has been previously observed. The yield of PCR products was lower in the two samples taken in the Polar Front Zone, showing a good agreement between molecular and pigment data. 16S rDNA sequences of plastids of eukaryotic algae also were retrieved, mostly related to those of an environmental clone called OM164, which has not been cultivated but has phylogenetic affinities to the Raphidophyceae. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailCirculation of the western Mediterranean: From global to regional scales
Beckers, Jean-Marie ULg; Brasseur, P.; Nihoul, Jacques ULg

in Deep-Sea Research Part II, Topical Studies in Oceanography (1997), 44(3-4), 531-549

A free-surface, three-dimensional, primitive equation model has been implemented with a horizontal resolution of 4.6 km to study the ocean circulation in the Gulf of Lions at time scales ranging from ... [more ▼]

A free-surface, three-dimensional, primitive equation model has been implemented with a horizontal resolution of 4.6 km to study the ocean circulation in the Gulf of Lions at time scales ranging from weeks to seasons. Numerical experiments have been conducted, in which the regional model is nested into a basin-scale model of the whole western Mediterranean. The global model is operated with a relatively coarse resolution (16 km) and provides boundary conditions at the open-sea boundaries of the regional domain. There is, however, no Feedback loop from the regional to the global model. The simulations are consistently driven with atmospheric fluxes computed from the output of the French PERIDOT meteorological forecasting system, between August 1988 and 1989. In addition to the initial conditions, in situ measurements of temperature and salinity are assimilated in the simulation of the general circulation, adopting a simple nudging technique to prevent an excessive drift of the model against climatology. The response of the regional model below and above the thermocline is discussed in the context of the prevailing meteorological situations. Some experiments give indications that a double-gyre system may develop from wind regimes that exhibit a cyclonic/anticyclonic wind stress curl. Advection-diffusion of passive tracers are also examined on the basis of the local hydrodynamic features, because this work has been conceived with the aim of determining the physical conditions in which ecological and biochemical processes develop at the interface between river mouths and the open ocean. (C) 1997 Elsevier Science Ltd. [less ▲]

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