Modelling deep-water formation in the north-west Mediterranean Sea with a new air–sea coupled model: sensitivity to turbulent flux parameterizations

Seyfried, Léo; Marsaleix, Patrick; Richard, Évelyne; Estournel, Claude

doi:10.5194/os-13-1093-2017

Cited by 11 publications

(13 citation statements)

References 57 publications

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“…This is mainly attributed to the Charnock parameter and roughness length being larger in the OWA simulation than the OA one (Figures 10c and 10f). However, divergences in turbulent flux parameterizations at high wind speeds imply a need to revisit them (Lebeaupin Brossier et al, 2008;Seyfried et al, 2017) and meaning that this sensitivity of turbulent fluxes to oceanic waves is not generalizable. Further studies with longer simulations and statistical diagnoses (as in Lengaigne et al, 2018;Samson et al, 2014) are necessary to address the physical origin of these differences.…”

Section: Turbulent Surface Fluxesmentioning

confidence: 99%

A New Coupled Ocean‐Waves‐Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013–2014) in the South‐West Indian Ocean

Pianezze

Barthe

Bielli

et al. 2018

J Adv Model Earth Syst

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Ocean‐Waves‐Atmosphere (OWA) exchanges are not well represented in current Numerical Weather Prediction (NWP) systems, which can lead to large uncertainties in tropical cyclone track and intensity forecasts. In order to explore and better understand the impact of OWA interactions on tropical cyclone modeling, a fully coupled OWA system based on the atmospheric model Meso‐NH, the oceanic model CROCO, and the wave model WW3 and called MSWC was designed and applied to the case of tropical cyclone Bejisa (2013–2014). The fully coupled OWA simulation shows good agreement with the literature and available observations. In particular, simulated significant wave height is within 30 cm of measurements made with buoys and altimeters. Short‐term (< 2 days) sensitivity experiments used to highlight the effect of oceanic waves coupling show limited impact on the track, the intensity evolution, and the turbulent surface fluxes of the tropical cyclone. However, it is also shown that using a fully coupled OWA system is essential to obtain consistent sea salt emissions. Spatial and temporal coherence of the sea state with the 10 m wind speed are necessary to produce sea salt aerosol emissions in the right place (in the eyewall of the tropical cyclone) and with the right size distribution, which is critical for cloud microphysics.

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Section: Turbulent Surface Fluxesmentioning

confidence: 99%

A New Coupled Ocean‐Waves‐Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013–2014) in the South‐West Indian Ocean

Pianezze

Barthe

Bielli

et al. 2018

J Adv Model Earth Syst

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“…Uncertainties on heat and water fluxes, in particular related to uncertainties in the parameterization of turbulent fluxes under strong wind conditions, remain an important problem for ocean modeling in the Mediterranean, as shown by the sensitivity study by Seyfried et al () on the modeling of the convection during winter 2012–2013. Unfortunately, no direct observation of the turbulent fluxes was available during the strong wind events of DeWEX/HyMeX SOP2.…”

Section: Major Outcomesmentioning

confidence: 99%

Preface to the Special Section: Dense Water Formations in the Northwestern Mediterranean: From the Physical Forcings to the Biogeochemical Consequences

et al. 2018

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The northwestern Mediterranean Sea is one of the few sites of open-sea deep convection and dense water formation. The area is characterized by intense air-sea exchanges favored by the succession of strong northerly and northwesterly winds during autumn and winter that eventually induce deep convection episodes and the formation of the Western Mediterranean Deep Water. This region exhibits a significant spring phytoplankton bloom, which appears to be largely influenced in intensity and diversity by the winter mixing. To understand and resolve the interplay between the atmosphere and ocean, and the impact of ocean circulation and mixing on biogeochemistry, we carried out an unprecedented observational effort during a large experiment between July 2012 and July 2013. A multiplatform approach-combining aircraft, balloons, ships, moorings, floats, and gliders -aimed both at characterizing the dynamics of the atmosphere and at quantifying the physical, biogeochemical, and biological properties of the water masses. Beyond a better understanding of the wind dynamics, the interannual variability of the deep convection, and the seasonal variability of the nutrient distribution and plankton structure in the pelagic ecosystem, the experiment provided a reference data set that was used as a benchmark for advancing the modeling of the surface fluxes, convective processes, dense water formation rates, and physical-biogeochemical coupling processes. It also represented an opportunity for complementary investigations such as evaluating model parameterizations or studying the role of submesoscale eddies in dense water spreading and biogeochemistry. High-resolution, realistic, three-dimensional atmospheric and oceanic models are essential for assessing the intricacy of buoyancy fluxes, horizontal advection, and convective processes, but they need to be validated by data that describe the variability of convection at small spatial scales (a few kilometers) and at high frequency (typically a day), and by accurate concomitant observations throughout the water column and atmosphere, especially during strong wind events. Likewise, the lack of in situ observations simultaneously inferring the main physical and biogeochemical variables was a major obstacle to unify a CONAN ET AL. 6983

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“…To perform the simulation, we used the Meso-NH -SURFEX -Symphonie system (Meso-NH: Lafore et al (1997) (Voldoire et al, 2017). This coupled system was described and validated in Seyfried et al (2017).…”

Section: Air-sea Coupled Simulationmentioning

confidence: 99%

“…Flux calculations are carried out on the atmospheric model grid (after bilinear interpolation of the oceanic fields) and are then bilinearly interpolated on the grid of the ocean model. The atmospheric model covers the whole western Mediterranean basin (same spatial coverage as in Seyfried et al (2017)).…”

Section: Air-sea Coupled Simulationmentioning

confidence: 99%

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Dynamics of North Balearic Front during an autumn Tramontane and Mistral storm: air–sea coupling processes and stratification budget diagnostic

Seyfried¹,

Estournel²,

Marsaleix³

et al. 2018

Preprint

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Abstract. The north Balearic front forms the southern branch of the cyclonic gyre in the North Western Mediterranean Sea. Its dynamics exhibits significant seasonal variability. During autumn, the front spreads northward during the calm wind periods and rapidly moves back southward when it is exposed to strong northerly wind events such as the Tramontane and Mistral. These strong winds considerably enhance the air–sea exchanges. To investigate the role of air–sea exchanges on the dynamics of the North Balearic front, we used observations and a high-resolution air–sea coupled modelling system, and focused on a strong wind event observed in late October 2012, which was well-documented during the Hydrological Cycle Mediterranean Experiment. The coupled model was able to correctly reproduce the 4 °C sea surface temperature drop recorded in the frontal zone together with the observed southwestward displacement of the front. The comparison between the weak wind period preceding the event and the strong wind event itself highlighted the impact of the wind regime on the air–sea coupling, with both thermal and dynamical couplings during the low wind period and mainly thermal coupling during the strong wind period. The effect of air–sea exchanges on the stratification variations in the frontal zone was investigated with a stratification budget diagnosis. The stratification variations are controlled by diabatic air–sea buoyancy flux, adiabatic Ekman buoyancy flux, and advective processes. During the strong wind period, the Ekman buoyancy flux was found to be three times greater than the air–sea buoyancy flux and thus played a major role in the destratification of the frontal zone. The role of Ekman pumping and inertial wave on the advective processes is also discussed.

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Modelling deep-water formation in the north-west Mediterranean Sea with a new air–sea coupled model: sensitivity to turbulent flux parameterizations

Cited by 11 publications

References 57 publications

A New Coupled Ocean‐Waves‐Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013–2014) in the South‐West Indian Ocean

A New Coupled Ocean‐Waves‐Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013–2014) in the South‐West Indian Ocean

Preface to the Special Section: Dense Water Formations in the Northwestern Mediterranean: From the Physical Forcings to the Biogeochemical Consequences

Dynamics of North Balearic Front during an autumn Tramontane and Mistral storm: air–sea coupling processes and stratification budget diagnostic

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