Assimilation of ocean sea-surface height observations of mesoscale eddies

Weiss, Jeffrey B.; Grooms, Ian

doi:10.1063/1.4986088

Cited by 8 publications

(12 citation statements)

References 36 publications

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“…The model is configured exactly as in Weiss and Grooms (2017) and Grooms and Zanna (2017) except for the use of eighth-order hyperviscosity instead of biharmonic hyperviscosity. The code is freely available (Grooms, 2017).…”

Section: Quasigeostrophic Reference and Eddy-permitting Modelsmentioning

confidence: 99%

“…The Reference and eddy‐permitting models are nondimensional, and it is valuable to choose dimensional units to facilitate comparison with real ocean models. In Weiss and Grooms (), dimensional units for this model were chosen by comparing the size and strength of the eddies in this nondimensional model to the size and strength of real eddies observed via satellite. Following the observational results of Chelton et al (), the radius of an eddy was set to 75 km, and the maximum current speed was set to 18 cm/s.…”

Section: Quasigeostrophic Reference and Eddy‐permitting Modelsmentioning

confidence: 99%

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Comparing Eddy‐Permitting Ocean Model Parameterizations via Lagrangian Particle Statistics in a Quasigeostrophic Setting

2018

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This paper uses Lagrangian statistics—absolute dispersion, pair dispersion, and particle forecasting—to compare four eddy‐permitting models of idealized mesoscale ocean dynamics. The baseline model uses scale‐selective biharmonic damping of momentum to keep the velocity field smooth at the grid scale without overly smearing the partially resolved eddies. The second model uses a nonlinear space‐ and time‐varying Leith viscosity to absorb enstrophy near the grid scale without dissipating too much energy. The last two models use a strong biharmonic damping of momentum to keep the velocity field smooth at the grid scale; this dissipates an unrealistically large amount of kinetic energy, and the models add either deterministic or stochastic forcing to reinject this energy at larger scales. These models are called Jansen and Held models after Jansen and Held (2014, https://doi.org/10.1016/j.ocemod.2014.06.002). All four models correctly model the diffusive transport of particles over time scales more than a few weeks, as measured by the Lagrangian absolute dispersion, showing that all models correctly reproduce the large scales of coherent eddies. The Lagrangian relative dispersion (or pair dispersion) is more sensitive to structure at smaller scales in the velocity field. The Leith model has the least‐accurate relative dispersion, while the two Jansen and Held models have the most accurate. In initialized forecast experiments, there is very little difference in performance between the models.

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Section: Quasigeostrophic Reference and Eddy-permitting Modelsmentioning

confidence: 99%

Section: Quasigeostrophic Reference and Eddy‐permitting Modelsmentioning

confidence: 99%

Comparing Eddy‐Permitting Ocean Model Parameterizations via Lagrangian Particle Statistics in a Quasigeostrophic Setting

2018

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“…To address these embarrassments, it is essential to thin the data and devise an appropriate assimilating strategy to highly and effectively initialize numerical models associated with SSHA forecasting (Li et al, 2010;Zanna et al, 2018;Fraser et al, 2019). Weiss and Grooms (2017) demonstrated that assimilating the observations on mesoscale eddies can achieve a more accurate ocean state than doing it over the whole model field; especially, they found that when fewer sea surface height (SSH) observations on the mesoscale eddies are assimilated, it improves the accuracy of the initial field more effectively and reduces more errors of the SSH predictions made by a two-layer quasigeostrophic (QG) model. Therefore, appropriate initialization of mesoscale eddies can lead to a much greater improvement in the prediction of the future SSH.…”

Section: Introductionmentioning

confidence: 99%

“…However, mesoscale eddies are usually irregular in shape and asymmetric in the flow field, which reduces the stability of the vortex structure and presents a highly non-linear nature (Tang et al, 2020). Considering this point, Jiang et al (2022) inferred that there should exist an area where the data assimilation should be preferentially implemented for the initialization of irregular eddies, rather than the evenly distributed regular grids on the eddies suggested by Weiss and Grooms (2017). Furthermore, they adopted an advanced approach of conditional non-linear optimal perturbation (CNOP; Mu et al, 2003) and revealed such area by using the two-layer QG model as adopted in Weiss and Grooms (2017).…”

Section: Introductionmentioning

confidence: 99%

“…Considering this point, Jiang et al (2022) inferred that there should exist an area where the data assimilation should be preferentially implemented for the initialization of irregular eddies, rather than the evenly distributed regular grids on the eddies suggested by Weiss and Grooms (2017). Furthermore, they adopted an advanced approach of conditional non-linear optimal perturbation (CNOP; Mu et al, 2003) and revealed such area by using the two-layer QG model as adopted in Weiss and Grooms (2017). Exactly, this area is located on the eddies and presents a clear high-to low-velocity gradient along the eddy rotation.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the sensitivity on mesoscale eddy associated with the sea surface height anomaly forecasting in the Kuroshio Extension

et al. 2023

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The sensitivity of the sea surface height anomaly (SSHA) forecasting on the accuracy of mesoscale eddies over the Kuroshio Extension region, which was determined by the conditional non-linear optimal perturbation (CNOP) method using a two-layer quasigeostrophic model, is evaluated by adopting multiply realistic marine datasets through an advanced particle filter assimilation method. It is shown that, if additional observations are preferentially assimilated to the sensitive area of mesoscale eddies identified by the CNOP, where the eddies present a clear high- to low-velocity gradient along the eddy rotation, the forecasting skill of the SSHA can be more significantly improved. It is also demonstrated that the forecasts of the SSHA in the region where the large-scale mean flow possesses much stronger barotropic and/or baroclinic instability tend to exhibit stronger sensitivity to the accuracy of the initial field in the sensitive area of mesoscale eddies. Therefore, more attention should be preferentially paid to the assimilation of the additional observations of the mesoscale eddies for the SSHA forecast in the region with a strong velocity shear of ocean circulation. The present study verifies the sensitivity on mesoscale eddies of SSHA forecasts derived by the two-layer quasigeostrophic model using multiply sets of realistic oceanic data, especially including observation and reanalysis data, which further additionally demonstrates the importance of targeted observations of mesoscale eddies to the SSHA forecast in the regions of strong velocity shear of ocean circulation and provides a more credible scientific basis for the field campaign of the targeted observations for mesoscale eddies associated with the SSHA forecasting.

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Model sensitivity experiments on data assimilation, downscaling and tides for the representation of the Cape São Tomé Eddies

et al. 2019

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Assimilation of ocean sea-surface height observations of mesoscale eddies

Cited by 8 publications

References 36 publications

Comparing Eddy‐Permitting Ocean Model Parameterizations via Lagrangian Particle Statistics in a Quasigeostrophic Setting

Comparing Eddy‐Permitting Ocean Model Parameterizations via Lagrangian Particle Statistics in a Quasigeostrophic Setting

Evaluation of the sensitivity on mesoscale eddy associated with the sea surface height anomaly forecasting in the Kuroshio Extension

Model sensitivity experiments on data assimilation, downscaling and tides for the representation of the Cape São Tomé Eddies

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