The relevance of deep chlorophyll maximum in the open Mediterranean Sea evaluated through 3D hydrodynamic-biogeochemical coupled simulations

Macías, Diego; Adolf, Stips; García-Górriz, Elisa

doi:10.1016/j.ecolmodel.2014.03.002

Cited by 46 publications

(47 citation statements)

References 67 publications

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“…This same model configuration has been used to successfully represent the sea surface temperature patterns in the Mediterranean Sea during the last 50 years and also the present day conditions of the pelagic ecosystem when coupled to a biogeochemical model (Macías et al 2014b). To avoid the effects of initial conditions, only the final 16 years (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) of the simulation period are used to compare with satellite data (see below).…”

Section: Model Descriptionmentioning

confidence: 99%

“…No horizontal currents were imposed at the open boundary. It has been demonstrated that for basinwide studies the location of this western boundary is not crucial (e.g., Macías et al 2013Macías et al , 2014c, but it does affects the performance of the model in the Alboran Sea in terms of absolute values of hydrological and biogeochemical properties (e.g., Macías et al 2014b). In those previous works, the open boundary of the model was located right on the strait itself as their focus was on the basin-wide properties and not on regional scales.…”

Section: Model Descriptionmentioning

confidence: 99%

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The seasonal cycle of the Atlantic Jet dynamics in the Alboran Sea: direct atmospheric forcing versus Mediterranean thermohaline circulation

2016

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The Atlantic Jet (AJ) is the inflow of Atlantic surface waters into the Mediterranean Sea. This geostrophically adjusted jet fluctuates in a wide range of temporal scales from tidal to subinertial, seasonal, and interannual modifying its velocity and direction within the Alboran Sea. At seasonal scale, a clearly defined cycle has been previously described, with the jet being stronger and flowing towards the northeast during the first half of the year and weakening and flowing more southwardly towards the end of the year. Different hypothesis have been proposed to explain this fluctuation pattern but, up to now, no quantitative assessment of the importance of the different forcings for this seasonality has been provided. Here, we use a 3D hydrodynamic model of the entire Mediterranean Sea forced at the surface with realistic atmospheric conditions to study and quantify the importance of the different meteorological forcings on the velocity and direction of the AJ at seasonal time scale. We find that the direct effects of local zonal wind variations are much more important to explain extreme collapse events when the jet dramatically veers southward than to the seasonal cycle itself while sea level pressure variations over the Mediterranean seem to have very little direct effect on the AJ behavior at monthly and longer time scales. Further model results indicate that the annual cycle of the thermohaline circulation is the main driver of the seasonality of the AJ dynamics in the model simulations.The annual cycles in local wind forcing and SLP variations over the Mediterranean have no causal relationship with the AJ seasonality.

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Section: Model Descriptionmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

The seasonal cycle of the Atlantic Jet dynamics in the Alboran Sea: direct atmospheric forcing versus Mediterranean thermohaline circulation

2016

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“…The biogeochemical model used here is quite similar to the one developed for different regions of the Mediterranean Sea by Oguz et al (2013) on a 1D configuration and also to the one used by Macias et al (2014) to simulate the 3D dynamics of the pelagic ecosystem of the open Mediterranean basin. Our comparison of observed and simulated biological variables (Chla and mesozooplankton biomass) indicates that the proposed biogeochemical model is also suitable for representing the different ecosystems found in this particular region.…”

Section: Discussionmentioning

confidence: 78%

A high-resolution hydrodynamic-biogeochemical coupled model of the Gulf of Cadiz – Alboran Sea region.

Macías¹,

Guerreiro²,

Prieto³

et al. 2014

Medit. Mar. Sci.

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The southern Iberia regional seas comprise the Gulf of Cadiz and the Alboran Sea sub-basins connected by the narrow Strait of Gibraltar. Both basins are very different in their hydrological and biological characteristics but are, also, tightly connected to each other. Integrative studies of the whole regional oceanic system are scarce and difficult to perform due to the relative large area to cover and the different relevant time-scales of the main forcing in each sub-basin. Here we propose, for the first time, a fully coupled, 3D, hydrodynamic-biogeochemical model that covers, in a single domain (~2km resolution) both marine basins for a 20-year simulation (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008). Model performance is assessed against available data in terms of spatial and temporal distribution of biological variables. In general, the proposed model is able to represent the climatological distribution of primary and secondary producers and also the main seasonality of primary production in the various sub-regions of the analyzed basins. Potential causes of the observed mismatches between model and data are identified and some solutions are proposed for future model development. We conclude that most of these mismatches could be attributed to the missing tidal forcing in the actual model configuration. This model is a first step towards obtaining a meaningful tool to study past and future oceanographic conditions in this important marine region, which constitutes the unique connection between the Mediterranean Sea and the open ocean.

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“…Integrated estimates of PP based on glider observations show averages of ∼ 1.3 g C m −2 d −1 along the entire glider path (with a large variance of 2.25 g C m −2 d −1 ), which is twice the largest value extrapolated from satellite products and four times larger than the most conservative satellite estimates (respectively, VGPM and CBPM algorithms, see http:// www.science.oregonstate.edu/ocean.productivity/ for algorithm documentation). The reason for such an underestimation by the satellite PP algorithms in a highly dynamic event during stratified conditions (when most production occurs at the DCM, Macías et al, 2014) is that such algorithms rely on a Gaussian or uniform vertical distribution of the Chl-a over the water column in the upper mixed layer (a situation that is found only during the winter season, when the upper layers are fully mixed by winds). Such an assumption of the vertical distribution of Chl-a is required to deal with the inability of the satellite optical sensors to cover the full euphotic depth (that in the present case extends to between ∼ 60 and ∼ 80 meters depending on the incident light, turbidity and optical properties of the water column).…”

Section: Evidence Of Frontal Impacts On Biogeochemical Observationsmentioning

confidence: 99%

“…The drawback with ocean color is cloud masking and the obvious restriction to the ocean surface. The latter is particularly restrictive in the Mediterranean, where Macías et al (2014) report that the deep Chlorophyll-a (Chl-a, hereinafter) maximum is found between 30 and 120 m. Satellite altimetry has revolutionized our view and understanding of surface ocean mesoscale circulation during the last two decades (e.g., Le Traon, 2013) leading to major breakthroughs such as, for example, eddy kinetic energy (EKE, hereinafter) quantification , mesoscale eddy identification, and tracking (e.g., Isern-Fontanet et al, 2003;Mason et al, 2014), and the estimation of vertical velocities through the quasi-geostrophic approximation (Tintoré et al, 1991;Ruiz et al, 2009;Pascual et al, 2015). However, the ocean is a complex system with multiple processes interacting at a wide range of temporal and spatial scales.…”

Section: Introductionmentioning

confidence: 99%

A Multiplatform Experiment to Unravel Meso- and Submesoscale Processes in an Intense Front (AlborEx)

et al. 2017

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The challenges associated with meso-and submesoscale variability (between 1 and 100 km) require high-resolution observations and integrated approaches. Here we describe a major oceanographic experiment designed to capture the intense but transient vertical motions in an area characterized by strong fronts. Finescale processes were studied in the eastern Alboran Sea (Western Mediterranean) about 400 km east of the Strait of Gibraltar, a relatively sparsely sampled area. In-situ systems were coordinated with satellite data and numerical simulations to provide a full description of the physical and biogeochemical variability. Hydrographic data confirmed the presence of an intense salinity front formed by the confluence of Atlantic Waters, entering from Gibraltar, with the local Mediterranean waters. The drifters coherently followed the northeastern limb of an anticyclonic gyre. Near real time data from acoustic current meter data profiler showed consistent patterns with currents of up to 1 m/s in the southern part of the sampled domain. High-resolution glider data revealed submesoscale structures with tongues of chlorophyll-a and oxygen associated with the frontal zone. Numerical results show large vertical excursions of tracers that could explain the subducted tongues and filaments captured by ocean gliders. A unique aspect of AlborEx is the combination of high-resolution synoptic measurements of vessel-based measurements, autonomous sampling, remote sensing and modeling, enabling the evaluation of the underlying mechanisms responsible for the observed distributions and biogeochemical patchiness. The main findings point to the importance of fine-scale processes enhancing the vertical exchanges between the upper ocean and the ocean interior.

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The relevance of deep chlorophyll maximum in the open Mediterranean Sea evaluated through 3D hydrodynamic-biogeochemical coupled simulations

Cited by 46 publications

References 67 publications

The seasonal cycle of the Atlantic Jet dynamics in the Alboran Sea: direct atmospheric forcing versus Mediterranean thermohaline circulation

The seasonal cycle of the Atlantic Jet dynamics in the Alboran Sea: direct atmospheric forcing versus Mediterranean thermohaline circulation

A high-resolution hydrodynamic-biogeochemical coupled model of the Gulf of Cadiz – Alboran Sea region.

A Multiplatform Experiment to Unravel Meso- and Submesoscale Processes in an Intense Front (AlborEx)

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