Publications of Marilaure Grégoire
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See detailMultidisciplinary Observing in the World Ocean’s Oxygen Minimum Zone regions: from climate to fish- the VOICE initiative
Garçon, Véronique; Karstensen, Johannes; Palacz, Artur et al

in Frontiers in Marine Science (2020)

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See detailThe chlorophyll seasonal dynamics in the Black Sea as inferred from Biogeochemical-Argo floats
Ricour, Florian ULiege; Capet, Arthur ULiege; Delille, Bruno ULiege et al

Poster (2019, April)

Biogeochemical-Argo (BGC-Argo) floats offer the opportunity to investigate the spatial and temporal dynamics of chlorophyll a (Chla) profiles. In the Black Sea, the unusual abundance of colored dissolved ... [more ▼]

Biogeochemical-Argo (BGC-Argo) floats offer the opportunity to investigate the spatial and temporal dynamics of chlorophyll a (Chla) profiles. In the Black Sea, the unusual abundance of colored dissolved organic matter (CDOM) and the absence of oxygen below ∼80-100m require a revision of the classic formulation used to link the fluorescence signal and the algal chlorophyll concentration (e.g. Xing et al., 2017). Indeed, the very high content of CDOM in the basin is thought to be responsible for the apparent increase of Chla concentrations at depth, where it should be zero due to the absence of light. Here, the classic formulation to link fluorescence and Chla is revised based on a reference Chla dataset sampled during a scientific cruise onboard RV Akademik and analysed with High Performance Liquid Chromatography (HPLC). Then, using the established equation to remove the contribution of CDOM to the fluorescence signal, we estimated the Chla profiles from 4 BGC-Argo floats during the period 2014-2017. All Chla profiles were thus highly quality controlled by using the Argo documentation (Schmechtig et al., 2015). Especially, we removed bad data (e.g. spikes, outliers) and we corrected the Non-Photochemical Quenching effect, a photoprotective mechanism resulting in a decrease in the fluorescence signal at the surface. The Chla profiles are categorized based on fitting algorithms (e.g. sigmoid, exponential, gaussian) and empirical criteria. They display a large variety of shapes across the seasons (e.g. homogeneity in the mixed layer, subsurface maximum, double peaks below the surface, etc.) with roughly homogeneous profiles dominating between November and February while subsurface maxima are present during the rest of the year, with in summer a clearly-marked deep chlorophyll maximum (DCM). We then investigate the formation mechanism of DCMs based on the hysteresis hypothesis for the temperate ocean proposed by Navarro et al., (2013). For this, we looked at the correlation between the position of DCMs and the potential density anomaly of the mixed layer when it is maximum in winter, usually between February and March. We show that DCMs are highly correlated with the potential density anomaly of the previous winter mixed layer where a winter bloom initiated while the correlation with the 10% and 1% light levels is poor. This is in agreement with the hysteresis hypothesis that assumes that in regions where a bloom forms in late winter/early spring, this bloom remains established at a fixed density (i.e. the density of the mixed layer when it is maximum) until the end of summer acting as a barrier for the diffusion of nutrients from below and preventing the occurrence of deeper blooms due to a shading effect. This bloom is finally progressively eroded in autumn, when the depth of the mixed layer increases again. [less ▲]

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See detailWhat is ocean deoxygenation?
Grégoire, Marilaure ULiege; Gilbert, Denis; Oschlies, Andreas et al

in Baxter, John; Lafolley, Daniel (Eds.) Ocean deoxygenation: everyone’s problem. Causes, impacts, consequences and solutions (2019)

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See detailAdvancing marine biogeochemical and ecosystem reanalyses and forecasts as tools for monitoring and managing ecosystem health
Fennel, K.; Gehlen, M.; Brasseur, P. et al

in Frontiers in Marine Science (2019), 6(MAR),

Ocean ecosystems are subject to a multitude of stressors, including changes in ocean physics and biogeochemistry, and direct anthropogenic influences. Implementation of protective and adaptive measures ... [more ▼]

Ocean ecosystems are subject to a multitude of stressors, including changes in ocean physics and biogeochemistry, and direct anthropogenic influences. Implementation of protective and adaptive measures for ocean ecosystems requires a combination of ocean observations with analysis and prediction tools. These can guide assessments of the current state of ocean ecosystems, elucidate ongoing trends and shifts, and anticipate impacts of climate change and management policies. Analysis and prediction tools are defined here as ocean circulation models that are coupled to biogeochemical or ecological models. The range of potential applications for these systems is broad, ranging from reanalyses for the assessment of past and current states, and short-term and seasonal forecasts, to scenario simulations including climate change projections. The objectives of this article are to illustrate current capabilities with regard to the three types of applications, and to discuss the challenges and opportunities. Representative examples of global and regional systems are described with particular emphasis on those in operational or pre-operational use. With regard to the benefits and challenges, similar considerations apply to biogeochemical and ecological prediction systems as do to physical systems. However, at present there are at least two major differences: (1) biogeochemical observation streams are much sparser than physical streams presenting a significant hinderance, and (2) biogeochemical and ecological models are largely unconstrained because of insufficient observations. Expansion of biogeochemical and ecological observation systems will allow for significant advances in the development and application of analysis and prediction tools for ocean biogeochemistry and ecosystems, with multiple societal benefits. © 2019 Fennel, Gehlen, Brasseur, Brown, Ciavatta, Cossarini, Crise, Edwards, Ford, Friedrichs, Gregoire, Jones, Kim, Lamouroux, Murtugudde, Perruche and the GODAE OceanView Marine Ecosystem Analysis and Prediction Task Team. [less ▲]

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See detailBlack Sea observing System
Palazov, Atanas; Ciliberti, S; Peneva, E et al

in Frontiers in Marine Science (2019)

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See detailFrom observation to information and users: The Copernicus Marine Service Perspective
Le Traon, P. Y.; Reppucci, A.; Fanjul, E. A. et al

in Frontiers in Marine Science (2019), 6(May),

The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical ocean and sea-ice state for the global ocean and the ... [more ▼]

The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical ocean and sea-ice state for the global ocean and the European regional seas. CMEMS serves a wide range of users (more than 15,000 users are now registered to the service) and applications. Observations are a fundamental pillar of the CMEMS value-added chain that goes from observation to information and users. Observations are used by CMEMS Thematic Assembly Centres (TACs) to derive high-level data products and by CMEMS Monitoring and Forecasting Centres (MFCs) to validate and constrain their global and regional ocean analysis and forecasting systems. This paper presents an overview of CMEMS, its evolution, and how the value of in situ and satellite observations is increased through the generation of high-level products ready to be used by downstream applications and services. The complementary nature of satellite and in situ observations is highlighted. Long-term perspectives for the development of CMEMS are described and implications for the evolution of the in situ and satellite observing systems are outlined. Results from Observing System Evaluations (OSEs) and Observing System Simulation Experiments (OSSEs) illustrate the high dependencies of CMEMS systems on observations. Finally future CMEMS requirements for both satellite and in situ observations are detailed. © 2019 Le Traon, Reppucci, Alvarez Fanjul, Aouf, Behrens, Belmonte, Bentamy, Bertino, Brando, Kreiner, Benkiran, Carval, Ciliberti, Claustre, Clementi, Coppini, Cossarini, De Alfonso Alonso-Muñoyerro, Delamarche, Dibarboure, Dinessen, Drevillon, Drillet, Faugere, Fernández, Fleming, Garcia-Hermosa, Sotillo, Garric, Gasparin, Giordan, Gehlen, Gregoire, Guinehut, Hamon, Harris, Hernandez, Hinkler, Hoyer, Karvonen, Kay, King, Lavergne, Lemieux-Dudon, Lima, Mao, Martin, Masina, Melet, Buongiorno Nardelli, Nolan, Pascual, Pistoia, Palazov, Piolle, Pujol, Pequignet, Peneva, Pérez Gómez, Petit de la Villeon, Pinardi, Pisano, Pouliquen, Reid, Remy, Santoleri, Siddorn, She, Staneva, Stoffelen, Tonani, Vandenbulcke, von Schuckmann, Volpe, Wettre and Zacharioudaki. [less ▲]

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See detail3.6 Decline of the Black Sea oxygen inventory. In: Copernicus Marine Service Ocean State Report, Issue 2
Capet, Arthur ULiege; Vandenbulcke, Luc ULiege; Veselka, Marinova et al

in Journal of Operational Oceanography (2018), 11(sup1),

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See detailGlobal Ocean Oxygen Network 2018. The ocean is losing its breath: Declining oxygen in the world’s ocean and coastal waters.
Breitburg, Denise; Grégoire, Marilaure ULiege; Isensee, Kirsten et al

in IOC-UNESCO, IOC Technical Series, (2018), 137

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See detailEvolution of the Black Sea ventilation regime during the last decades
Capet, Arthur ULiege; Vandenbulcke, Luc ULiege; Grégoire, Marilaure ULiege

in Ocean Deoxygenation : Drivers and Consequences, Past, Present, Future, Kiel, Sept 2018 (2018)

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See detailThe Ocean is lossing its breath: declining oxygen in the global and coastal ocean
Breitburg, Denise; Grégoire, Marilaure ULiege; Isensee, Kirsten

Book published by IOC-Unesco (2018)

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See detailBenthic hypoxia and early diagenesis in the Black Sea shelf sediments
Plante, Audrey ULiege; Roevros, Nathalie; Capet, Arthur ULiege et al

Poster (2017, April)

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can ... [more ▼]

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can be catastrophic for living species. Between 1970 and 1990, the benthic compartment of the Black Sea underwent modifications due to the occurrence and increase of hypoxia. Indeed, these changes might cause a deterioration of the structure and functioning of the ecosystems. Nowadays, some regions, such as the north-western shelf, are still affected seasonally by this phenomenon.Within the framework of the BENTHOX project, a biogeochemical study focusing on the early diagenesis is conducted in the Black Sea. It aims (1) to obtain a better understanding of the impact of benthic hypoxia on the diagenetic pathways, (2) to contribute to a new dataset of biogeochemical measurements in the sediments including porewaters. During a cruise (Emblas II – May 2016), on board the RV Mare Nigrum, sediment cores were taken at 4 stations on the Ukrainian shelf. Porewaters were extracted on board the ship using Rhizon technique under N2 atmosphere and will be analyzed for dissolved nutrients and major ions. In addition, sediments were sliced and will be determined for major solid phases and trace element contents. A multi-proxies (biological, sedimentological, mineralogical and geochemical) approach will be used to identify the hypoxic events and to reconstruct the history of bottom hypoxia. The results obtained will be presented and discussed with emphasis on the first outcomes and the major biogeochemical processes involved in the early diagenesis. [less ▲]

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See detailContribution of mesoscale eddies to Black Sea ventilation
Capet, Arthur ULiege; Mason, Evan; Pascual, Ananda et al

Poster (2017)

The shoaling of the Black Sea oxycline is one of the most urgent environmental issues in the Black Sea. The permanent oxycline derives directly from the Black Sea permanent stratification and has shoaled ... [more ▼]

The shoaling of the Black Sea oxycline is one of the most urgent environmental issues in the Black Sea. The permanent oxycline derives directly from the Black Sea permanent stratification and has shoaled alarmingly in the last decades, due to a shifting balance between oxygen consumption and ventilation processes (Capet et al. 2016). The understanding of this balance is thus of the utmost importance and requires to quantify 1) the export of nutrients and organic materials from the shelf regions to the open sea and 2) the ventilation processes. These two rocesses being influenced by mesoscale features, it is critical to understand the role of the semi-permanent mesoscale structures in horizontal (center/periphery) and vertical (diapycnal and isopycnal) exchanges. A useful insight can be obtained by merging observations from satellite altimeter and in situ profilers (ARGO). In such composite analyses, eddies are first automatically identified and tracked from altimeter data (Mason et al. 2014, py-eddy-tracker). Vertical ARGO profiles are then expressed in terms of their position relative to eddy centers and radii. Derived statistics indicate how consistently mesoscale eddies alter the vertical structure, and provide a deeper understanding of the associated horizontal and vertical fluxes. However, this data-based approach is limited in the Black Sea due to the lower quality of gridded altimetric products in the vicinity of the coast, where semi-permanent mesoscale structures prevail. To complement the difficult analysis of this sparse dataset, a compositing methodology. is also applied to model outputs from the 5km GHER-BHAMBI Black Sea implementation (CMEMS BS-MFC). Characteristic biogeochemical anomalies associated with eddies in the model are analyzed per se, and compared to the observation-based analysis. Capet, A., Stanev, E. V., Beckers, J.-M., Murray, J. W., and Grégoire, M.: Decline of the Black Sea oxygen inventory, Biogeosciences, 13, 1287-1297, doi:10.5194/bg-13-1287-2016, 2016. Mason, Evan, Ananda Pascual, and James C. McWilliams. "A new sea surface height–based code for oceanic mesoscale eddy tracking." Journal of Atmospheric and Oceanic Technology 31.5 (2014): 1181-1188. [less ▲]

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See detailPotential for Composite Analysis in the Black Sea
Capet, Arthur ULiege; Mason, Evan; Troupin, Charles et al

Conference (2016, October)

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See detailOperational forecasting of the Black sea: merging model simulations and satellite products
Vandenbulcke, Luc ULiege; Capet, Arthur ULiege; Ivanov, Evgeny ULiege et al

Scientific conference (2016, September 29)

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See detailThe two faces of Black Sea deoxygenation
Capet, Arthur ULiege; Stanev, Emil; Beckers, Jean-Marie ULiege et al

Conference (2016, February)

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See detailDecline of the Black Sea oxygen inventory
Capet, Arthur ULiege; Stanev, Emil; Beckers, Jean-Marie ULiege et al

in Biogeosciences (2016), 13

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See detailBenthox Kick-Off Meeting
Capet, Arthur ULiege; Grégoire, Marilaure ULiege

Conference (2015, November)

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