On the implementation and consequences of the oceanic currents feedback in ocean–atmosphere coupled models

Renault, Lionel; Lemarié, Florian; Arsouze, Thomas

doi:10.1016/j.ocemod.2019.101423

Cited by 19 publications

(21 citation statements)

References 32 publications

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“…Note that to properly take into account the impact of the oceanic surface current in the atmosphere, we must also modify the tridiagonal matrix system solved in the vertical turbulent diffusion scheme (Lemarié, 2015;Renault, Lemarié, & Arsouze, 2019).…”

Section: Surface Wind and Stressmentioning

confidence: 99%

“…When estimating the surface stress in a coupled model, the CFB is taken into account by using the wind relative to the oceanic current instead of the absolute wind neglecting surface motion (Renault et al, ). From an oceanic perspective, coupled simulations are computationally expensive because of the high computational cost of atmospheric models with respect to oceanic ones.…”

Section: Introductionmentioning

confidence: 99%

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Recipes for How to Force Oceanic Model Dynamics

Renault

Masson

Arsouze

et al. 2020

J Adv Model Earth Syst

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The current feedback to the atmosphere (CFB) contributes to the oceanic circulation by damping eddies. In an ocean‐atmosphere coupled model, CFB can be correctly accounted for by using the wind relative to the oceanic current. However, its implementation in a forced oceanic model is less straightforward as CFB also enhances the 10‐m wind. Wind products based on observations have seen real currents that will not necessarily correspond to model currents, whereas meteorological reanalyses often neglect surface currents or use surface currents that, again, will differ from the surface currents of the forced oceanic simulation. In this study, we use a set of quasi‐global oceanic simulations, coupled or not with the atmosphere, to (i) quantify the error associated with the different existing strategies of forcing an oceanic model, (ii) test different parameterizations of the CFB, and (iii) propose the best strategy to account for CFB in forced oceanic simulation. We show that scatterometer wind or stress are not suitable to properly represent the CFB in forced oceanic simulation. We furthermore demonstrate that a parameterization of CFB based on a wind‐predicted coupling coefficient between the surface current and the stress allows us to reproduce the main characteristics of a coupled simulation. Such a parameterization can be used with any forcing set, including future coupled reanalyses, assuming that the associated oceanic surface currents are known. A further assessment of the thermal feedback of the surface wind in response to oceanic surface temperature gradients shows a weak forcing effect on oceanic currents.

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Section: Surface Wind and Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recipes for How to Force Oceanic Model Dynamics

Renault

Masson

Arsouze

et al. 2020

J Adv Model Earth Syst

Self Cite

View full text Add to dashboard Cite

show abstract

“…Seo et al, 2016;Seo, 2017;Renault et al, 2016;Jullien et al, 2020). Renault et al (2017Renault et al ( , 2019 showed a damping of the eddy kinetic energy due to the current feedback modulation of the energy transfer between the ocean and the atmosphere leading to more realistic simulations. These current-wind interactions need to be further investigated in our coupled system with the insertion of the current terms in the AROME turbulence scheme.…”

Section: Discussionmentioning

confidence: 99%

Towards kilometer-scale ocean-atmosphere-wave coupled forecast: a case study on a Mediterranean heavy precipitation event

Sauvage¹,

Brossier²,

Bouin³

2021

Preprint

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Abstract. The Western Mediterranean Sea area is frequently affected in autumn by heavy precipitation events (HPEs). These severe meteorological episodes, characterized by strong offshore low-level winds and heavy rain in a short period of time, can lead to severe flooding and wave-submersion events. This study aims to progress towards integrated short-range forecast system via coupled modelling for a better representation of the processes at the air–sea interface. In order to identify and quantify the coupling impacts, coupled ocean–atmosphere–wave simulations were performed for a HPE that occurred between October 12 and 14, 2016 in the South of France, using the coupled AROME-NEMO-WaveWatchIII system and notably compared to atmosphere only, coupled atmosphere–wave and ocean–atmosphere simulations. The results showed that the HPE fine-scale forecast is sensitive to both couplings: The interactive coupling with the ocean leads to significant changes in the heat and moisture supply of the HPE that intensify the convective systems, while coupling with a wave model mainly leads to changes in the low-level dynamics, affecting the location of the convergence that triggers convection over sea. Even if this first case study with the AROME-NEMO-WaveWatchIII system does not clearly show major changes in the forecasts with coupling and highlights some attention points to follow (ocean initialisation notably), it illustrates the higher realism and potential benefits of kilometer-scale coupled numerical weather prediction systems, in particular in case of severe weather events over sea and/or in coastal areas, and shows their affordability to confidently progress towards operational coupled forecasts.

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“…As far as the current feedback is concerned, Renault et al (2016b) showed that the reduction of wind power input to the ocean is systematically overestimated in oceanic simulations based on an ASL forcing strategy compared to air-sea coupled simulations. A simulation that neglects the MABL adjustment to the current feedback cannot represent the partial re-energization of the ocean by the atmosphere and hence overestimates the drag effect by more than 30 % (e.g., Renault et al, 2016bRenault et al, , 2019a. The ASL forcing strategy used in most oceanic models will thus overestimate the current feedback effect and underestimate the downward momentum mixing.…”

Section: Air-sea Interactions At Oceanic Mesoscalesmentioning

confidence: 99%

A simplified atmospheric boundary layer model for an improved representation of air-sea interactions in eddying oceanic models: implementation and first evaluation in NEMO (4.0)

Lemarié¹,

Samson²,

Redelsperger³

et al. 2020

Preprint

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Abstract. A simplified model of the Atmospheric Boundary Layer (ABL) of intermediate complexity between a bulk parameterization and a three-dimensional atmospheric model is developed and integrated to the Nucleus for European Modelling of the Ocean (NEMO) general circulation model. An objective in the derivation of such simplified model called ABL1d is to reach an apt representation in ocean-only numerical simulations of some of the key processes associated to air/sea interactions at the characteristic scales of the oceanic mesoscale. In this paper we describe the formulation of the ABL1d model and the strategy to constrain this model with large-scale atmospheric data available from reanalysis or real-time forecasts. A particular emphasis is on the appropriate choice and calibration of a turbulent closure scheme for the atmospheric boundary layer. This is a key ingredient to properly represent the air/sea interaction processes of interest. We also provide a detailed description of the NEMO-ABL1d coupling infrastructure and its computational efficiency. The resulting simplified model is then tested for several boundary-layer regimes relevant to either ocean/atmosphere or sea-ice/atmosphere coupling. The coupled system is also tested with a realistic 0.25&degree; resolution global configuration. The numerical results are evaluated using standard metrics from the literature to quantify the wind/sea surface temperature (a.k.a. thermal feedback effect), wind/currents (a.k.a. current feedback effect) and ABL/sea-ice couplings. With respect to these metrics, our results show very good agreement with observations and fully coupled ocean-atmosphere models for a computational overhead of about 9% in term of elapsed time compared to standard uncoupled simulations. This moderate overhead, largely due to I/O operations, leaves room for further improvement to relax the assumption of horizontal homogeneity behind ABL1d and thus to further improve the realism of the coupling while keeping the flexibility of ocean-only modelling.

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On the implementation and consequences of the oceanic currents feedback in ocean–atmosphere coupled models

Cited by 19 publications

References 32 publications

Recipes for How to Force Oceanic Model Dynamics

Recipes for How to Force Oceanic Model Dynamics

Towards kilometer-scale ocean-atmosphere-wave coupled forecast: a case study on a Mediterranean heavy precipitation event

A simplified atmospheric boundary layer model for an improved representation of air-sea interactions in eddying oceanic models: implementation and first evaluation in NEMO (4.0)

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