An introduction to GODAE OceanView

Bell, Michael; Schiller, A.; Traon, Pierre‐Yves Le; Smith, Neville; Dombrowsky, E.; Wilmer-Becker, Kirsten

doi:10.1080/1755876x.2015.1022041

Cited by 64 publications

(56 citation statements)

References 55 publications

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“…Le and Argo observations are required to constrain the temperature and salinity fields. OSEs carried out in the context of the GODAE OceanView international programme (Bell et al, 2015) have demonstrated the impact of assimilating several altimeters and Argo (e.g. Lea et al, 2014;Oke et al, 2015;Turpin et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Assessing the impact of multiple altimeter missions and Argo in a global eddy-permitting data assimilation system

2017

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Abstract. A series of observing system simulation experiments (OSSEs) is carried out with a global data assimilation system at 1/4 • resolution using simulated data derived from a 1/12 • resolution free-run simulation. The objective is to not only quantify how well multiple altimeter missions and Argo profiling floats can constrain the global ocean analysis and 7-day forecast at 1/4 • resolution but also to better understand the sensitivity of results to data assimilation techniques used in Mercator Ocean operational systems. The impact of multiple altimeter data is clearly evidenced even at a 1/4 • resolution. Seven-day forecasts of sea level and ocean currents are significantly improved when moving from one altimeter to two altimeters not only on the sea level, but also on the 3-D thermohaline structure and currents. In high-eddy-energy regions, sea level and surface current 7-day forecast errors when assimilating one altimeter data set are respectively 20 and 45 % of the error of the simulation without assimilation. Seven-day forecasts of sea level and ocean currents continue to be improved when moving from one altimeter to two altimeters with a relative error reduction of almost 30 %. The addition of a third altimeter still improves the 7-day forecasts even at this medium 1/4 • resolution and brings an additional relative error reduction of about 10 %. The error level of the analysis with one altimeter is close to the 7-day forecast error level when two or three altimeter data sets are assimilated. Assimilating altimeter data also improves the representation of the 3-D ocean fields. The addition of Argo has a major impact on improving temperature and demonstrates the essential role of Argo together with altimetry in constraining a global data assimilation system. Salinity fields are only marginally improved. Results derived from these OSSEs are consistent with those derived from experiments with real data (observing system evaluations, OSEs) but they allow for more detailed characterisation of errors on analyses and 7-day forecasts. Both OSEs and OSSEs should be systematically used and intercompared to test data assimilation systems and quantify the impact of existing observing systems.

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Section: Introductionmentioning

confidence: 99%

Assessing the impact of multiple altimeter missions and Argo in a global eddy-permitting data assimilation system

2017

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“…Development of ocean forecasting has since been consolidated and extended under GODAE OceanView (GOV) (Bell et al 2014). There are now several agencies and centres supporting first-or second-generation global and basinscale pre-operational and operational ocean prediction systems as described in this special issue.…”

Section: Introductionmentioning

confidence: 99%

Progress and challenges in short- to medium-range coupled prediction

Brassington

Martin

Tolman³

et al. 2015

Journal of Operational Oceanography

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“…The growing capacities of new products developed in operational oceanography (Schiller and Brassington, 2011;Bell et al, 2015;Chakraborty et al, 2015;Le Traon et al, 2015;Hernandez et al, 2015;Kaurkin et al, 2016;Sotillo et al, 2016) imply a need for ongoing assessment using independent high-resolution in situ data sets. Such efforts help ensure the provision of high quality services by, for example, the Copernicus Marine Service.…”

Section: Introductionmentioning

confidence: 99%

Comparing a Multivariate Global Ocean State Estimate With High-Resolution in Situ Data: An Anticyclonic Intrathermocline Eddy Near the Canary Islands

et al. 2018

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The provision of high-resolution in situ oceanographic data is key for the ongoing verification, validation and assessment of operational products, such as those provided by the Copernicus Marine Core Service (CMEMS). Here we analyze the ability of ARMOR3D-a multivariate global ocean state estimate that is available from CMEMS-to reconstruct a mesoscale anticyclonic intrathermocline eddy that was previously sampled with high-resolution independent in situ observations. ARMOR3D is constructed by merging remote sensing observations with in situ vertical profiles of temperature and salinity obtained primarily from the Argo network. In situ data from CTDs and an Acoustic Doppler Current Profiler were obtained during an oceanographic cruise near the Canary Islands (Atlantic ocean). The analysis of the ARMOR3D product using the in situ data is done over (i) a high-resolution meridional transect crossing the eddy center and (ii) a three-dimensional grid centered on the eddy center. An evaluation of the hydrographic eddy signature and derived dynamical variables, namely geostrophic velocity, vertical vorticity and quasi-geostrophic (QG) vertical velocity, demonstrates that the ARMOR3D product is able to reproduce the vertical hydrographic structure of the independently sampled eddy below the seasonal pycnocline, with the caveat that the flow is surface intensified and the seasonal pycnocline remains flat. Maps of ARMOR3D density show the signature of the eddy, and agreement with the elliptical eddy shape seen in the in situ data. The major eddy axes are oriented NW-SE in both data sets. The estimated radius for the in situ eddy is ∼46 km; the ARMOR3D radius is significantly larger at ∼ 92 km and is considered an overestimation that is inherited from an across-track altimetry sampling issue. The ARMOR3D geostrophic flow is underestimated by a factor of 2, with maxima of 0.11 (−0.19) m s −1 at the surface, which implies an underestimation of the local Rossby number by a factor of 3. Both the in situ and ARMOR3D eddies have decelerating flows at their northern edges. The ARMOR3D QG vertical velocity distribution has upwelling/downwelling cells located along the eddy periphery and similar magnitudes to the in situ-derived QG vertical velocity.

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An introduction to GODAE OceanView

Cited by 64 publications

References 55 publications

Assessing the impact of multiple altimeter missions and Argo in a global eddy-permitting data assimilation system

Assessing the impact of multiple altimeter missions and Argo in a global eddy-permitting data assimilation system

Progress and challenges in short- to medium-range coupled prediction

Comparing a Multivariate Global Ocean State Estimate With High-Resolution in Situ Data: An Anticyclonic Intrathermocline Eddy Near the Canary Islands

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