NEMO on the shelf: assessment of the Iberia–Biscay–Ireland configuration

Maraldi, C.; Chanut, Jérôme; Levier, Bruno; Reffray, Guillaume; Ayoub, Nadia; Mey, P. De; Lyard, Florent; Cailleau, S.; Drévillon, Marie; Fanjul, Enrique Álvarez; Sotillo, Marcos García; Marsaleix, Patrick

doi:10.5194/osd-9-499-2012

Cited by 31 publications

(43 citation statements)

References 116 publications

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“…The model was initialized and forced at its lateral boundaries with daily analyses provided by the Mercator‐Ocean operational system based on the NEMO model (Maraldi et al, ). The configuration of this model was the PSY2V2R4 prototype based on the NEMO ocean modeling platform and the SAM data assimilation system (Lellouche et al, ) at a resolution of 1/12° over the Atlantic and the Mediterranean from 20°S to 80°N.…”

Section: Methodsmentioning

confidence: 99%

Vertical Mixing Effects on Phytoplankton Dynamics and Organic Carbon Export in the Western Mediterranean Sea

et al. 2018

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A 3‐D high‐resolution coupled hydrodynamic‐biogeochemical model of the western Mediterranean was used to study phytoplankton dynamics and organic carbon export in three regions with contrasting vertical regimes, ranging from deep convection to a shallow mixed layer. One month after the initial increase in surface chlorophyll (caused by the erosion of the deep chlorophyll maximum), the autumnal bloom was triggered in all three regions by the upward flux of nutrients resulting from mixed layer deepening. In contrast, at the end of winter, the end of turbulent mixing favored the onset of the spring bloom in the deep convection region. Low grazing pressure allowed rapid phytoplankton growth during the bloom. Primary production in the shallow mixed layer region, the Algerian subbasin, was characterized by a long period (4 months) of sustained phytoplankton development, unlike the deep convection region where primary production was inhibited during 2 months in winter. Despite seasonal variations, annual primary production in all three regions is similar. In the deep convection region, total organic carbon export below the photic layer (150 m) and transfer to deep waters (800 m) was 5 and 8 times, respectively, higher than in the Algerian subbasin. Although some of the exported material will be injected back into the surface layer during the next convection event, lateral transport, and strong interannual variability of MLD in this region suggest that a significant amount of exported material is effectively sequestrated.

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Section: Methodsmentioning

confidence: 99%

Vertical Mixing Effects on Phytoplankton Dynamics and Organic Carbon Export in the Western Mediterranean Sea

et al. 2018

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“…In order to make a quantitative assessment of the tides, comparisons against tide‐gauge data located on the shelf, and processed by BODC, have been made. These results can be compared with other studies which have used the same data set (Holt et al, ; Maraldi et al, ; O'Dea et al, ). Since many of the gauged data are from secluded harbors their locations, when interpolated onto the model grid, are located within land grid boxes.…”

Section: Assessment Of the Configurationsmentioning

confidence: 99%

Kilometric Scale Modeling of the North West European Shelf Seas: Exploring the Spatial and Temporal Variability of Internal Tides

et al. 2018

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The North West European Shelf break acts as a barrier to the transport and exchange between the open ocean and the shelf seas. The strong spatial variability of these exchange processes is hard to fully explore using observations, and simulations generally are too coarse to simulate the fine‐scale processes over the whole region. In this context, under the FASTNEt program, a new NEMO configuration of the North West European Shelf and Atlantic Margin at 1/60° (∼1.8 km) has been developed, with the objective to better understand and quantify the seasonal and interannual variability of shelf break processes. The capability of this configuration to reproduce the seasonal cycle in SST, the barotropic tide, and fine‐resolution temperature profiles is assessed against a basin‐scale (1/12°, ∼9 km) configuration and a standard regional configuration (7 km resolution). The seasonal cycle is well reproduced in all configurations though the fine‐resolution allows the simulation of smaller scale processes. Time series of temperature at various locations on the shelf show the presence of internal waves with a strong spatiotemporal variability. Spectral analysis of the internal waves reveals peaks at the diurnal, semidiurnal, inertial, and quarter‐diurnal bands, which are only realistically reproduced in the new configuration. Tidally induced pycnocline variability is diagnosed in the model and shown to vary with the spring neap cycle with mean displacement amplitudes in excess of 2 m for 30% of the stratified domain. With sufficiently fine resolution, internal tides are shown to be generated at numerous bathymetric features resulting in a complex pycnocline displacement superposition pattern.

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“…Hence, while 1.5 km might be seen as an aspiration, the practicalities of eddy resolving on shelf (when/how this can be reached are discussed below) should not be seen as a particular obstacle to making shorter-term progress in modelling the coastal ocean on a global scale, for example, by using 1/36 • as a compromise resolution (as in many coastal ocean studies; e.g. Maraldi et al, 2012) or focusing on process representation (e.g. Luneva et al, 2015).…”

Section: Coastal Ocean Process Scales In a Global Contextmentioning

confidence: 99%

“…For example, the NEMO model from v3.2 onwards has the capability of simulating both open ocean and shelf sea cases (O'Dea et al, 2012;Maraldi et al, 2012), with capability improving in later versions. This essentially allows these processes to be included by configuration selection as the global model resolution is refined.…”

Section: Process Representationmentioning

confidence: 99%

“…This need to increase resolution in shoaling water, alongside the need for smoothly represented across-isobath flows, has led to a prevalence of s coordinates in coastal ocean models, accepting some exceptions (Maraldi et al, 2012;Daewel and Schrum, 2013) that have used z coordinates. The large majority of global ocean models use z or isopycnal coordinates.…”

Section: Vertical Coordinatesmentioning

confidence: 99%

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Prospects for improving the representation of coastal and shelf seas in global ocean models

et al. 2017

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Abstract. Accurately representing coastal and shelf seas in global ocean models represents one of the grand challenges of Earth system science. They are regions of immense societal importance through the goods and services they provide, hazards they pose and their role in global-scale processes and cycles, e.g. carbon fluxes and dense water formation. However, they are poorly represented in the current generation of global ocean models. In this contribution, we aim to briefly characterise the problem, and then to identify the important physical processes, and their scales, needed to address this issue in the context of the options available to resolve these scales globally and the evolving computational landscape.We find barotropic and topographic scales are well resolved by the current state-of-the-art model resolutions, e.g. nominal 1/12 • , and still reasonably well resolved at 1/4 • ; here, the focus is on process representation. We identify tides, vertical coordinates, river inflows and mixing schemes as four areas where modelling approaches can readily be transferred from regional to global modelling with substantial benefit. In terms of finer-scale processes, we find that a 1/12 • global model resolves the first baroclinic Rossby radius for only ∼ 8 % of regions < 500 m deep, but this increases to ∼ 70 % for a 1/72 • model, so resolving scales globally requires substantially finer resolution than the current state of the art.We quantify the benefit of improved resolution and process representation using 1/12 • global-and basin-scale northern North Atlantic nucleus for a European model of the ocean (NEMO) simulations; the latter includes tides and a k-ε vertical mixing scheme. These are compared with global stratification observations and 19 models from CMIP5. In terms of correlation and basin-wide rms error, the high-resolution models outperform all these CMIP5 models. The model with tides shows improved seasonal cycles compared to the highresolution model without tides. The benefits of resolution are particularly apparent in eastern boundary upwelling zones.To explore the balance between the size of a globally refined model and that of multiscale modelling options (e.g. finite element, finite volume or a two-way nesting approach), we consider a simple scale analysis and a conceptual grid refining approach. We put this analysis in the context of evolving computer systems, discussing model turnaround time, scalability and resource costs. Using a simple cost model compared to a reference configuration (taken to be a 1/4 • global model in 2011) and the increasing performance of the UK Research Councils' computer facility, we estimate an unstructured mesh multiscale approach, resolving process scales down to 1.5 km, would use a comparable share of the computer resource by 2021, the two-way nested multiscale approach by 2022, and a 1/72 • global model by 2026. However, we also note that a 1/12 • global model would not have a comparable computational cost to a 1 • global model in 2017 until 2027. Hence, we conc...

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NEMO on the shelf: assessment of the Iberia–Biscay–Ireland configuration

Cited by 31 publications

References 116 publications

Vertical Mixing Effects on Phytoplankton Dynamics and Organic Carbon Export in the Western Mediterranean Sea

Vertical Mixing Effects on Phytoplankton Dynamics and Organic Carbon Export in the Western Mediterranean Sea

Kilometric Scale Modeling of the North West European Shelf Seas: Exploring the Spatial and Temporal Variability of Internal Tides

Prospects for improving the representation of coastal and shelf seas in global ocean models

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