Fabien Roquet

University of Gothenburg | GU · Department of Marine Sciences

Large-scale breeding failures, such as offspring die-offs, can disproportionately impact wildlife populations that are characterized by a few large colonies. However, breeding monitoring—and thus investigations of such die-offs—is especially challenging in species with long reproductive cycles. We investigate two unresolved dramatic breeding failur...

A thermodynamic potential is found for seawater as a function of Conservative Temperature, Absolute Salinity and pressure. From this thermodynamic potential, all the equilibrium thermodynamic properties of seawater can be derived, just as all these thermodynamic properties can be found from the TEOS-10 Gibbs function (which is a function of in situ...

The region of Maud Rise, a seamount in the Weddell Sea, is known for the occurrence of irregular polynya openings during the winter months. Hydrographic observations have shown the presence of a warmer water mass below the mixed layer along the seamount's flanks, commonly termed the warm‐water Halo, surrounding a colder region above the rise, the T...

We analyze 15‐year of observational data and a 5‐year Southern Ocean model simulation to quantify the transformation rates of Circumpolar Deep Water (CDW) and the associated heat loss to the surface. This study finds that over the continental shelves of East Antarctica and the Weddell and Ross Seas, surface buoyancy fluxes transform ∼4.4 Sv of surf...

The Southern Ocean greatly contributes to the regulation of the global climate by controlling important heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal timescales are therefore impacted by oceanic processes taking place in the Southern Ocean, yet too little is known about these processes. Limitatio...

The ocean's internal pycnocline is a layer of elevated stratification that separates the well‐ventilated upper ocean from the more slowly renewed deep ocean. Despite its pivotal role in organizing ocean circulation, the processes governing the formation of the internal pycnocline remain little understood. Classical theories on pycnocline formation...

Coastal polynyas are key formation regions for dense shelf water (DSW) that ultimately contributes to the ventilation of the ocean abyss. However, not all polynyas form DSW. We examine how the physiographic setting, water-mass distribution and transformation, water column stratification, and sea-ice production regulate DSW formation in four East An...

The formation of sea ice in polar regions is possible because a salinity gradient or halocline keeps the water column stable despite intense cooling. Here, we demonstrate that a unique water property is central to the maintenance of the polar halocline, namely, that the thermal expansion coefficient (TEC) of seawater increases by one order of magni...

Collapse of the Atlantic Meridional Overturning Circulation (AMOC) is often invoked as an explanation of major past climate changes and as a major risk for future climate. Many of these arguments appear, from an observer’s point of view, as far-more definitive than is warranted. In the hypothetical event of a future collapse, the implications may b...

Despite the ever-growing number of ocean data, the interior of the ocean remains undersampled in regions of high variability such as the Gulf Stream. In this context, neural networks have been shown to be effective for interpolating properties and understanding ocean processes. We introduce OSnet (Ocean Stratification network), a new ocean reconstr...

The stratification is primarily controlled by temperature in subtropical regions (alpha-ocean), and by salinity in subpolar regions (beta-ocean). Between these two regions lies a transition zone, often characterized by deep mixed layers in winter and responsible for the ventilation of intermediate or deep layers. While of primary interest, no conse...

Animal-Borne Ocean Sensors—AniBOS—is an emerging network of the Global Ocean Observing System (GOOS). AniBOS makes freely available oceanographic measurements across the hard-to-observe world's polar and tropical oceans from miniaturized sensors attached to marine animals. These data complement conventional approaches by providing both physical and...

Southern Ocean bathymetry constrains the path of the Antarctic Circumpolar Current (ACC), but the bathymetric influence on the coupled ocean–atmosphere system is poorly understood. Here, we investigate this impact by respectively flattening large topographic barriers around the Kerguelen Plateau, Campbell Plateau, Mid-Atlantic Ridge, and Drake Pass...

Despite the ever-growing amount of ocean’s data, the interior of the ocean remains under sampled in regions of high variability such as the Gulf Stream. In this context, neural networks have been shown to be effective for interpolating properties and understanding ocean processes. We introduce OSnet (Ocean Stratification network), a new ocean recon...

We provide a detailed description of the spatial distribution, seasonality and transformation of the main water masses within MacKenzie Polynya (MP) in Prydz Bay, East Antarctica, using data from instrumented southern elephant seals. Dense Shelf Water (DSW) formation in MP shows large spatial variability that is related to the (i) local bathymetry,...

Marine animals equipped with biological and physical electronic sensors have produced long-term data streams on key marine environmental variables, hydrography, animal behavior and ecology. These data are an essential component of the Global Ocean Observing System (GOOS). The Animal Borne Ocean Sensors (AniBOS) network aims to coordinate the long-t...

The Southern Ocean is responsible for the majority of the global oceanic heat uptake that contributes to global sea level rise. At the same time, ocean temperatures do not change at the same rate in all regions and sea level variability is also affected by changes in salinity. This study investigates ten years of steric height variability (2008 to...

Understanding the physical mechanisms behind the transport and accumulation of floating objects in the ocean is crucial to efficiently tackle the issue of marine pollution. The main sinks of marine plastic are the coast and the bottom sediment. This study focuses on the former, investigating the timescales of dispersal from the ocean surface and on...

Rapid and regionally contrasting climate changes have been observed around Antarctica. However, our understanding of the impact of these changes on ecosystems remains limited, and there is an urgent need to better identify habitats of Antarctic species. The Weddell seal ( Leptonychotes weddellii ) is a circumpolar mesopredator and an indicative spe...

The Southern Ocean is responsible for the majority of the global oceanic heat uptake that contributes to global sea level rise. At the same time, ocean temperatures do not change at the same rate in all regions and sea level variability is also affected by changes in salinity. This study investigates ten years of steric height variability (2008 to...

Plain Language Summary When tidal ocean currents flow over bumpy seafloor, they generate internal tidal waves. Internal waves are the subsurface analog of surface waves that break on beaches. Like surface waves, internal tidal waves often become unstable and break into turbulence. This turbulence is a primary cause of mixing between stacked ocean l...

The first 2000 m of the global thermohaline structure of the ocean are statistically decomposed into vertical thermohaline modes, using a multivariate Functional Principal Component Analysis (FPCA). This method is applied on the Monthly Isopycnal & Mixed-layer Ocean Climatology (MIMOC). The first three modes account for 92% of the joint temperature...

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers,...

Temperature and salinity measurements obtained from sensors deployed on Weddell seals (Leptonychotes weddellii) between late austral summer and the following spring for 2010–2012 were used to describe the temporal and spatial variability of hydrographic conditions in the western Ross Sea, with particular emphasis on the inner-shelf region off Victo...

Internal tides power much of the observed small-scale turbulence in the ocean interior. To represent mixing induced by this turbulence in ocean climate models, the cascade of internal tide energy to dissipation scales must be understood and mapped. Here, we present a framework for estimating the geography of internal tide energy sinks. The mapping...

Most available CTD–Satellite Relay Data Logger (CTD–SRDL) profiles are heavily compressed before satellite transmission. High-resolution profiles recorded at the sampling frequency of 0.5 Hz are however available upon physical retrieval of the logger. Between 2014 and 2018, several loggers deployed on elephant seals in the Southern Ocean have been...

The dataset contains global estimates of barotropic-to-baroclinic tidal energy conversion at 1/30-degree resolution. Three types of estimates are available: 1. Non-modal conversion rates calculated by Falahat et al. (2014) following the method of Nycander (2005). A map for each of the eight most energetic tidal constituents (M2, S2, K1, O1, N2, K...

The dataset consists of global two-dimensional maps of internal tide energy sources and sinks, at half-degree horizontal resolution. Estimated energy sources are provided for the three most energetic tidal constituents: M2, S2 and K1. They are decomposed into vertical normal modes. Units are Watts per square meter. Estimated energy sinks are prov...

The location of the Antarctic Polar Front (PF) is mapped in the Southern Indian Ocean by decomposing the shape of temperature and salinity profiles into vertical modes using a functional Principal Component Analysis. We define the PF as the northernmost minimum of temperature at the subsurface, and represent it as a linear combination of the first...

While the Atlantic Ocean is ventilated by high-latitude deep water formation and exhibits a pole-to-pole overturning circulation, the Pacific Ocean does not. This asymmetric global overturning pattern has persisted for the past 2–3 million years, with evidence for different ventilation modes in the deeper past. In the current climate, the Atlantic-...

In the Amundsen Sea, warm saline Circumpolar Deep Water (CDW) crosses the con- tinental shelf toward the vulnerable West Antarctic ice shelves, contributing to their basal melting. Due to lack of observations, little is known about the spatial and temporal variability of CDW, particularly seasonally. A new dataset of 6704 seal-tag temperature and s...

The effect of thermal mass on the salinity estimate from conductivity–temperature–depth (CTD) tags sensor mounted on marine mammals is documented, and a correction scheme is proposed to mitigate its impact. The algorithm developed here allows for a direct correction of the salinity data, rather than a correction of the sample’s conductivity and tem...

Antarctic coastal polynyas are regions of persistent open water and are thought to be key bio-physical features within the sea-ice zone. However, their use by the upper trophic levels of ecosystems remains unclear. A unique bio-physical dataset recorded by southern elephant seals reveals that East Antarctic polynyas are a key winter foraging habita...

High inputs of nutrients and organic matter make coastal seas places of intense air-sea CO2 exchange. Due to their complexity, the role of coastal seas in the global air-sea CO2 exchange is, however, still uncertain. Here we investigate the role of phytoplankton stoichiometric flexibility and extracellular DOC production for the seasonal nutrient a...

This gridded product consists of a global (80°S-62°N) climatological estimate of radiocarbon content (∆14C) at half-degree horizontal resolution, provided both on neutral density and depth surfaces. It is based on the GLODAPv2 data compilation (Key et al. 2016, Olsen et al. 2016) and the neutral density (γn; Jackett and McDougall 1997) field of the...

The abyssal ocean is broadly characterized by northward flow of the densest waters and southward flow of less-dense waters above them. Understanding what controls the strength and structure of these interhemispheric flows—referred to as the abyssal overturning circulation—is key to quantifying the ocean’s ability to store carbon and heat on timesca...

The Stommel box model elegantly demonstrates that the oceanic response to mixed boundary conditions, combining a temperature relaxation with a fixed salt flux forcing, is non-linear owing to the so-called salt advection feedback. This non-linearity produces a parameter range of bi-stability associated with hysteresis effects characterised by a fast...

The Kerguelen Plateau obstructs the eastward flowing Antarctic Circumpolar Current (ACC) in the Indian sector of the Southern Ocean strongly interacting with the frontal structure. While the Subantarctic Front (SAF) lies north of the plateau and the Southern ACC Front (SACCF) is deflected southward by the Fawn Trough, the position and structure of...

Context: Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. Obj...

Ch 7. Regional Climates: f. Europe and the Middle East

The Sea of Okhotsk is a challenging environment for obtaining in situ data and satellite observation in winter due to sea ice cover. In this study, we evaluated the validity of hydrographic observations by marine mammals (e.g., seals and sea lions) equipped with oceanographic conductivity-temperature-depth (CTD) sensors. During 4-yr operations from...

“Biologging” through temporary attachment of miniaturized data loggers on marine animals is revolutionizing the science of marine ecology (Block et al., 2011; Hussey et al., 2015). It also o ers new capabilities to observe the ocean. In addition to collecting loca- tion and depth information useful for studying foraging behavior, these devices can...

Polar oceans are poorly monitored despite the important role they play in regulating Earth’s climate system. Marine mammals equipped with biologging devices are now being used to fill the data gaps in these logistically difficult to sample regions. Since 2002, instrumented animals have been generating exceptionally large data sets of oceanographic...

The surface mixed layer (ML) governs atmosphere-ocean fluxes, and thereby affects Earth's climate. Accurate representation of ML processes in ocean models remains a challenge, however. The O(100)m deep ML exhibits substantial horizontal thermohaline gradients, despite being near-homogenous vertically, making it an ideal location for processes that...

Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. The importan...

Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. The importan...

Marine mammals help gather information on some of the harshest environments on the planet, through the use of miniaturized ocean sensors glued on their fur. Since 2004, hundreds of diving marine animals, mainly Antarctic and Arctic seals, have been fitted with a new generation of Argos tags developed by the Sea Mammal Research Unit of the Universit...

The thermohaline structure of the Southern Ocean is deeply influenced by the presence of the Antarctic Circumpolar Current (ACC), where water masses of the World Ocean are advected, transformed and redistributed to the other basins. It remains a challenge to describe and visualize the complex 3D pattern of this circulation and its associated tracer...

Marine mammals help gather information on some of the harshest environments on the planet, through the use of miniaturized ocean sensors glued on their fur. Since 2004, hundreds of diving marine animals, mainly Antarctic and Arctic seals, have been fitted with a new generation of Argos tags developed by the Sea Mammal Research Unit of the Universit...

The oceanic mixed-layer is the gateway for the exchanges between the atmosphere and the ocean; in this layer all hydrographic ocean properties are set for months to millennia. A vast area of the Southern Ocean is seasonally capped by sea-ice, which alters the characteristics of the ocean mixed-layer. The interaction between the ocean mixed-layer an...