Can wave coupling improve operational regional ocean forecasts for the north-west European Shelf?

Lewis, Huw; Sanchez, Juan Manuel Castillo; Siddorn, John; King, Robert R.; Tonani, Marina; Saulter, Andrew; Sykes, Peter; Péquignet, Christine; Weedon, Graham P.; Palmer, Tamzin; Staneva, Joanna; Bricheno, Lucy

doi:10.5194/os-15-669-2019

Cited by 34 publications

(52 citation statements)

References 47 publications

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“…Here, it is interesting to notice that sea-state-dependent processes showed their contribution to sea-level variability over the shelf areas, as well as in the open ocean. This was in agreement with the findings of Lewis et al (2019) who, analyzing the sea-surface height variability over a 3-month period (DJF) during 2017, found similar spatial patterns associated with the minimum and maximum instantaneous differences between two assimilative experiments due to ocean-wave coupling. In the shelf areas (shallower than 200 m), wave coupling enhanced the model simulation and large-scale positive surge differences (>20 cm) were observed in the North Sea (German Bight) and the Baltic Sea during OND, while smaller values were observed in JAS over the same areas.…”

Section: Signature Of Wave-induced Processessupporting

confidence: 92%

“…When assessing the surge signals in the EXPs using power spectra comparison and coherence analysis with the in situ records, the results showed that WIPs significantly contribute (10-40%) to resolve the surge variability, mainly due to a better representation of processes that act at temporal scales up to 12 h. This is in agreement with Lewis et al (2019), who observed an improved representation of the physical signals at a semidiurnal frequency in North West European Shelf due to ocean-wave coupling.…”

Section: Discussionsupporting

confidence: 82%

“…Considering EXP1 (blue lines), the impact of wave-induced processes is noticeable down to 12 h, while the impact is weaker at higher frequencies. This was in agreement with The column values show basic statistics of the compared datasets: correlation coefficient (C), RMSE (expressed as cm) and the error reduction (expressed as a percentage; ER) with respect to the reference experiment Lewis et al (2019), who investigating the impact of wavecoupling in the North West European Shelf, observed an improved representation of the physical signals at semidiurnal frequency due to the coupling. At frequencies between 1 and 5 days, the largest ER spec were observed in the SNS (∼40%).…”

Section: Synergy With In Situ and Remote-sensing Observationssupporting

confidence: 85%

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Sea-state contributions to sea-level variability in the European Seas

et al. 2020

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The contribution of sea-state-induced processes to sea-level variability is investigated through ocean-wave coupled simulations. These experiments are performed with a high-resolution configuration of the Geestacht COAstal model SysTem (GCOAST), implemented in the Northeast Atlantic, the North Sea and the Baltic Sea which are considered as connected basins. The GCOAST system accounts for wave-ocean interactions and the ocean circulation relies on the NEMO (Nucleus for European Modelling of the Ocean) ocean model, while ocean-wave simulations are performed using the spectral wave model WAM. The objective is to demonstrate the contribution of wave-induced processes to sea level at different temporal and spatial scales of variability. When comparing the ocean-wave coupled experiment with in situ data, a significant reduction of the errors (up to 40% in the North Sea) is observed, compared with the reference. Spectral analysis shows that the reduction of the errors is mainly due to an improved representation of sea-level variability at temporal scales up to 12 h. Investigating the representation of sea-level extremes in the experiments, significant contributions (> 20%) due to wave-induced processes are observed both over continental shelf areas and in the Atlantic, associated with different patterns of variability. Sensitivity experiments to the impact of the different wave-induced processes show a major impact of wave-modified surface stress over the shelf areas in the North Sea and in the Baltic Sea. In the Atlantic, the signature of wave-induced processes is driven by the interaction of wave-modified momentum flux and turbulent mixing, and it shows its impact to the occurrence of mesoscale features of the ocean circulation. Wave-induced energy fluxes also have a role (10%) in the modulation of surge at the shelf break.

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Section: Signature Of Wave-induced Processessupporting

confidence: 92%

Section: Discussionsupporting

confidence: 82%

Section: Synergy With In Situ and Remote-sensing Observationssupporting

confidence: 85%

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Sea-state contributions to sea-level variability in the European Seas

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“…The surface currents are affecting the wave computations, but the wave dynamics are not fed back into the current field. Wave fields have been shown to influence current fields in dynamically coupled wave-ocean models (Lewis et al, 2019). This effect is neglected as the focus is on the effect that the Agulhas Current has on the wave field for operational wave forecasting applications.…”

Section: Modeling Processmentioning

confidence: 99%

Toward Operational Wave‐Current Interactions Over the Agulhas Current System

Barnes

Rautenbach

2020

JGR Oceans

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A computationally inexpensive operational wave forecasting system taking wave‐current interactions over the fast‐flowing Agulhas Current into account is explored. Spectral wave model hindcasts at 1/16 of a geographical degree are employed using the Simulating Waves in the Nearshore (SWAN) wave model. Unidirectional wave‐current coupling, with currents affecting waves, is performed using both Operational Mercator 1/12 degree (ORCA12) and GLOBCURRENT 1/4 degree currents. Comparisons between the coupled and uncoupled simulations indicate that wave amplification or lowering is highly dependent on the current magnitude and wave incident angle. In opposing current scenarios, the significant wave height can increase by 20–40% and by 60% in extreme cases. Model validation is performed using Jason‐3 satellite altimetry measurements and in situ directional wave buoy measurements. The nearshore wave directional dispersion is found to be significantly influenced by the core of the Agulhas Current. This is especially prominent in current‐following cases with wave‐current direction differences of up to 20°. The findings are all corroborated by simplistic, idealized models.

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“…Tonani et al: The impact of a new high-resolution ocean model tial results but is still far from meeting operational requirements. A coupled ocean-atmosphere version of this model has already been developed for research (Lewis et al, 2019b) and studies will continue toward a fully coupled prediction system with an ocean, atmosphere, land, and wave model. Data availability.…”

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confidence: 99%

The impact of a new high-resolution ocean model on the Met Office North-West European Shelf forecasting system

et al. 2019

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Abstract. The North-West European Shelf ocean forecasting system has been providing oceanographic products for the European continental shelf seas for more than 15 years. In that time, several different configurations have been implemented, updating the model and the data assimilation components. The latest configuration to be put in operation, an eddy-resolving model at 1.5 km (AMM15), replaces the 7 km model (AMM7) that has been used for 8 years to deliver forecast products to the Copernicus Marine Environment Monitoring Service and its precursor projects. This has improved the ability to resolve the mesoscale variability in this area. An overview of this new system and its initial validation is provided in this paper, highlighting the differences with the previous version. Validation of the model with data assimilation is based on the results of 2 years (2016–2017) of trial experiments run with the low- and high-resolution systems in their operational configuration. The 1.5 km system has been validated against observations and the low-resolution system, trying to understand the impact of the high resolution on the quality of the products delivered to the users. Although the number of observations is a limiting factor, especially for the assessment of model variables like currents and salinity, the new system has been proven to be an improvement in resolving fine-scale structures and variability and provides more accurate information on the major physical variables, like temperature, salinity, and horizontal currents. AMM15 improvements are evident from the validation against high-resolution observations, available in some selected areas of the model domain. However, validation at the basin scale and using daily means penalized the high-resolution system and does not reflect its superior performance. This increment in resolution also improves the capabilities to provide marine information closer to the coast even if the coastal processes are not fully resolved by the model.

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Can wave coupling improve operational regional ocean forecasts for the north-west European Shelf?

Cited by 34 publications

References 47 publications

Sea-state contributions to sea-level variability in the European Seas

Sea-state contributions to sea-level variability in the European Seas

Toward Operational Wave‐Current Interactions Over the Agulhas Current System

The impact of a new high-resolution ocean model on the Met Office North-West European Shelf forecasting system

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