Evaluation of global monitoring and forecasting systems at Mercator Océan

Lellouche, J. M.; Galloudec, O. Le; Drévillon, Marie; Régnier, Charly; Greiner, Eric; Garric, Gilles; Ferry, Nicolas; Desportes, Charles; Testut, Charles-Emmanuel; Bricaud, Clément; Bourdallé‐Badie, Romain; Tranchant, B.; Benkiran, Mounir; Drillet, Yann; Daudin, A.; Nicola, C. de

doi:10.5194/os-9-57-2013

Cited by 258 publications

(282 citation statements)

References 56 publications

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“…2.1), we apply a coastal surface mask within which the salinity observations are artificially replace by the hindcast value. This concept of pseudo observation near the coast has already been used in Lellouche et al (2013) …”

Section: Observational Data Setsmentioning

confidence: 99%

“…In addition to the quality check done by CORIOLIS, SAM2 carries out a supplementary quality control on in situ observations. In order to minimize the risk of erroneous data being assimilated, the system automatically removes, through different criteria, the data too far from a seasonal climatology (Lellouche et al, 2013). On average over the whole period, 79 observations of temperature per year and 16 observations of salinity per year are rejected by this supplementary quality control performed by SAM2.…”

Section: Observational Data Setsmentioning

confidence: 99%

“…Moreover, as the analysis increment is a linear combination of the anomalies, a large amount of anomalies is desirable in order to better span the oceanic variability. In the original formulation of SAM2, SSH increments are analytically computed from temperature and salinity increments through barotropic/dynamic height balances (Lellouche et al, 2013). This assumption is only valid far from the coast and in open seas, where the local SSH variations due to the remote wind are negligible.…”

Section: Data Assimilation Schemementioning

confidence: 99%

“…The Mercator Océan monitoring and forecasting system has demonstrated its skills for the global ocean forecast (Lellouche et al, 2013) and we used it in a regional configuration. As the main part of the assimilation scheme used in this paper is already described by Lellouche et al (2013), we will summarize the assimilation methodology and focus on the specifications inherent to the Mediterranean configuration.…”

Section: Data Assimilation Schemementioning

confidence: 99%

“…The observation error is then artificially increased within 50 km of the whole Mediterranean coast. The mean surface reference used is a hybrid product between the CNES-CLS09 MDT (Rio et al, 2011) adjusted with the data from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) and from the Mercator Océan 1/4 • Reanalysis GLORYS2V1 (Lellouche et al, 2013) representing the 1993-2012 period. In MEDRYS, the volume correction consists in adding a term in the SLA observation operator, representing the effect of the glacial isostatic ad- justment (GIA) and the barystatic effect due to the mass intake of continental ice melting.…”

Section: Observational Data Setsmentioning

confidence: 99%

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Design and validation of MEDRYS, a Mediterranean Sea reanalysis over the period 1992–2013

Hamon

Beuvier

Somot³

et al. 2016

Ocean Sci.

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Abstract. The French research community in the Mediterranean Sea modeling and the French operational ocean forecasting center Mercator Océan have gathered their skill and expertise in physical oceanography, ocean modeling, atmospheric forcings and data assimilation to carry out a MEDiterranean sea ReanalYsiS (MEDRYS) at high resolution for the period 1992-2013. The ocean model used is NEMOMED12, a Mediterranean configuration of NEMO with a 1/12 • (∼ 7 km) horizontal resolution and 75 vertical z levels with partial steps. At the surface, it is forced by a new atmospheric-forcing data set (ALDERA), coming from a dynamical downscaling of the ERA-Interim atmospheric reanalysis by the regional climate model ALADIN-Climate with a 12 km horizontal and 3 h temporal resolutions. This configuration is used to carry a 34-year hindcast simulation over the period 1979, which is the initial state of the reanalysis in October 1992. MEDRYS uses the existing Mercator Océan data assimilation system SAM2 that is based on a reduced-order Kalman filter with a threedimensional (3-D) multivariate modal decomposition of the forecast error. Altimeter data, satellite sea surface temperature (SST) and temperature and salinity vertical profiles are jointly assimilated. This paper describes the configuration we used to perform MEDRYS. We then validate the skills of the data assimilation system. It is shown that the data assimilation restores a good average temperature and salinity at intermediate layers compared to the hindcast. No particular biases are identified in the bottom layers. However, the reanalysis shows slight positive biases of 0.02 psu and 0.15 • C above 150 m depth. In the validation stage, it is also shown that the assimilation allows one to better reproduce water, heat and salt transports through the Strait of Gibraltar. Finally, the ability of the reanalysis to represent the sea surface high-frequency variability is shown.

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Section: Observational Data Setsmentioning

confidence: 99%

Section: Observational Data Setsmentioning

confidence: 99%

Section: Data Assimilation Schemementioning

confidence: 99%

Section: Data Assimilation Schemementioning

confidence: 99%

Section: Observational Data Setsmentioning

confidence: 99%

See 3 more Smart Citations

Design and validation of MEDRYS, a Mediterranean Sea reanalysis over the period 1992–2013

Hamon

Beuvier

Somot³

et al. 2016

Ocean Sci.

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Origin and pathways of Winter Intermediate Water in the Northwestern Mediterranean Sea using observations and numerical simulation

et al. 2013

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The study of water masses worldwide (their formation, spreading, mixing, and impact on general circulation) is essential for a better understanding of the ocean circulation and variability. In this paper, the formation and main pathways of Winter Intermediate Water (WIW) in the Northwestern Mediterranean Sea (NWMED) are investigated during the winter‐spring 2011 using observations and numerical simulation. The main results show that the WIW, formed along the continental shelves of the Gulf of Lion and Balearic Sea, circulates southward following five preferential pathways depending on the WIW formation site location and the oceanic conditions. WIW joins the northeastern part of the Balearic Sea, or flows along the continental shelves until joining the Balearic Current (maximum of 0.33 Sv in early‐April) or further south until the Ibiza Channel entrance. Two additional trajectories, contributing to water mass exchanges with the southern part of the Western Mediterranean Sea, bring the WIW through the Ibiza and Mallorca Channels (maxima of 0.26 Sv in late‐March and 0.1 Sv in early‐April, respectively). The circulation of WIW over the NWMED at 50–200 m depth, its mixing and spreading over the Western Mediterranean Sea (reaching the south of the Balearic Islands, the Algero‐Provencal basin, the Ligurian and the Alboran Seas) suggest that the WIW may have an impact on the ocean circulation by eddy blocking effect, exchange of water masses between north and south subbasins of Western Mediterranean Sea through the Ibiza Channel or modification of the ocean stratification.

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Mixed layer heat and salinity budgets during the onset of the 2011 Atlantic cold tongue

Schlundt

Brandt

Dengler

et al. 2014

J. Geophys. Res. Oceans

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The mixed layer (ML) temperature and salinity changes in the central tropical Atlantic have been studied by a dedicated experiment (Cold Tongue Experiment (CTE)) carried out from May to July 2011. The CTE was based on two successive research cruises, a glider swarm, and moored observations. The acquired in situ data sets together with satellite, reanalysis, and assimilation model data were used to evaluate box-averaged ML heat and salinity budgets for two subregions: (1) the western equatorial Atlantic cold tongue (ACT) (23 -10 W) and (2) the region north of the ACT. The strong ML heat loss in the ACT region during the CTE was found to be the result of the balance of warming due to net surface heat flux and cooling due to zonal advection and diapycnal mixing. The northern region was characterized by weak cooling and the dominant balance of net surface heat flux and zonal advection. A strong salinity increase occurred at the equator, 10 W, just before the CTE. During the CTE, ML salinity in the ACT region slightly increased.Largest contributions to the ML salinity budget were zonal advection and the net surface freshwater flux. While essential for the ML heat budget in the ACT region, diapycnal mixing played only a minor role for the ML salinity budget. In the region north of the ACT, the ML freshened at the beginning of the CTE due to precipitation, followed by a weak salinity increase. Zonal advection changed sign contributing to ML freshening at the beginning of the CTE and salinity increase afterward.

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Evaluation of global monitoring and forecasting systems at Mercator Océan

Cited by 258 publications

References 56 publications

Design and validation of MEDRYS, a Mediterranean Sea reanalysis over the period 1992–2013

Design and validation of MEDRYS, a Mediterranean Sea reanalysis over the period 1992–2013

Origin and pathways of Winter Intermediate Water in the Northwestern Mediterranean Sea using observations and numerical simulation

Mixed layer heat and salinity budgets during the onset of the 2011 Atlantic cold tongue

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