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One-year assessment of the CHAOS two-way coupled atmosphere-ocean wave modelling system over the Mediterranean and Black Seas

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GEORGE VARLAS (http://orcid.org/0000-0001-7929-9452), CHRISTOS SPYROU, ANASTASIOS PAPADOPOULOS, GERASIMOS KORRES, PETROS KATSAFADOS (http://orcid.org/0000-0001-7452-0138)


It is currently clear that the atmosphere and ocean should be simulated by integrated modelling systems resolving interconnected physical factors that determine the Earth’s energy balance. Waves play a key role in the interfacial interaction between the atmosphere and the ocean, regulating momentum, heat and moisture exchange. This study aims to evaluate the CHAOS two-way coupled atmosphere-ocean wave system (Chemical Hydrological Atmospheric Ocean wave System) over the Mediterranean and Black Seas. The evaluation is performed against in situ and remote sensing data for the period from 1 December 2013 to 1 December 2014. CHAOS includes the Weather Research Forecasting (WRF) model, version 3.8, as atmospheric component and the Wave model (WAM) cycle 4.5.4 as ocean wave component, coupled through the OASIS3-MCT coupler, version 3.0. Two continuous model simulation approaches were followed to assess the impact of atmosphere ocean waves coupling. In the first approach (1-way coupling mode), the ocean wave component uses the winds produced by the atmospheric component, while in the second approach (2-way coupling mode) the atmospheric component additionally uses sea state information estimated by the ocean wave component through wave-dependent Charnock parameter computations. In the 2-way coupling mode, the attenuation of the atmospheric flow has a damping effect on wind-generated waves. The simulations in 2-way coupling mode produce more realistic results yielding statistical improvements. Compared against buoy observations, the 2-way mode reduces the root mean square error (RMSE) 1.2% for wind speed and 6.3% for significant wave height, while against Jason-2 satellite retrievals the reduction is 0.5% and 2.4%, respectively. Additionally, the 2-way coupling mode outperformed the 1-way mode under intense wind and wave conditions during the one-year period considered.


Air-sea interaction; WRF; WAM; sea surface roughness; wind-wave coupling; statistical evaluation.

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Abdalla, S., Janssen, P.A., Bidlot, J. R., 2010. Jason-2 OGDR wind and wave products: Monitoring, validation and assimilation. Marine Geodesy, 33 (S1), 239-255.

Amante, C., Eakins, B.W., 2009. ETOPO1 1 arc-minute global relief model: procedures, data sources and analysis. Colorado: US Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data, and Information Service, National Geophysical Data Center, Marine Geology and Geophysics Division, 19 pp.

Andreas, E.L., 2011. Fallacies of the enthalpy transfer coefficient over the ocean in high winds. Journal of the Atmospheric Sciences, 68 (7), 1435-1445.

Bao, J.W., Fairall, C.W., Michelson, S.A., Bianco, L., 2011. Parameterizations of sea-spray impact on the air-sea momentum and heat fluxes. Monthly Weather Review, 139 (12), 3781-3797.

Barbariol, F., Benetazzo, A., Bertotti, L., Cavaleri, L., Durrant, T. et al., 2019. Large waves and drifting buoys in the Southern Ocean. Ocean Engineering, 172, 817-828.

Battjes, J.A., Janssen, J.P.F.M., 1978. Energy loss and set-up due to breaking of random waves. p. 569-587. In Proceedings of the 16th International Conference on Coastal Engineering. American Society of Civil Engineers, New York.

Bell, M.M., Montgomery, M.T., Emanuel, K.A., 2012. Air–sea enthalpy and momentum exchange at major hurricane wind speeds observed during CBLAST. Journal of the Atmospheric Sciences, 69 (11), 3197-3222.

Benetazzo, A., Bergamasco, A., Bonaldo, D., Falcieri, F. M., Sclavo, M. et al., 2014. Response of the Adriatic Sea to an intense cold air outbreak: dense water dynamics and wave-induced transport. Progress in Oceanography, 128, 115-138.

Black, P.G., D'Asaro, E.A., Sanford, T.B., Drennan, W.M., Zhang, J.A. et al., 2007. Air-sea exchange in hurricanes: synthesis of observations from the coupled boundary layer air-sea transfer experiment. Bulletin of the American Meteorological Society, 88 (3), 357-374.

Bonaldo, D., Antonioli, F., Archetti, R., Bezzi, A., Correggiari, A. et al., 2019. Integrating multidisciplinary instruments for assessing coastal vulnerability to erosion and sea level rise: Lessons and challenges from the Adriatic Sea, Italy. Journal of Coastal Conservation, 23 (1), 19-37.

Breivik, Ø., Mogensen, K., Bidlot, J.R., Balmaseda, M.A., Janssen, P.A., 2015. Surface wave effects in the NEMO ocean model: Forced and coupled experiments. Journal of Geophysical Research: Oceans, 120 (4), 2973-2992.

Bruneau, N., Toumi, R., 2016. A fully-coupled atmosphere-ocean-wave model of the Caspian Sea. Ocean Modelling, 107, 97-111.

Carniel, S., Benetazzo, A., Bonaldo, D., Falcieri, F.M., Miglietta, M.M. et al., 2016. Scratching beneath the surface while coupling atmosphere, ocean and waves: Analysis of a dense water formation event. Ocean Modelling, 101, 101-112.

Chen, S.S., Zhao, W., Donelan, M.A., Tolman, H.L., 2013. Directional wind-wave coupling in fully coupled atmosphere-wave-ocean models: Results from CBLAST-Hurricane. Journal of the Atmospheric Sciences, 70 (10), 3198-3215.

Christakos, K., Cheliotis, I., Varlas, G., Steeneveld, G.J., 2016. Offshore wind energy analysis of cyclone Xaver over North Europe. Energy Procedia, 94, 37-44.

Christakos, K., Varlas, G., Reuder, J., Katsafados, P., Papadopoulos, A., 2014. Analysis of a low-level coastal jet off the western coast of Norway. Energy Procedia, 53, 162-172.

Danielson, J.J., Gesch, D.B., 2011. Global multi-resolution terrain elevation data 2010 (GMTED2010). US Geological Survey, No 2011-1073, 34 pp. (Online available at: https://pubs.usgs.gov/of/2011/1073/pdf/of2011-1073.pdf, accessed 19.11.2018)

Desjardins, S., Mailhot, J., Lalbeharry, R., 2000. Examination of the impact of a coupled atmospheric and ocean wave system. Part I: Atmospheric aspects. Journal of Physical Oceanography, 30 (2), 385-401.

Donelan, M.A., Haus, B.K., Reul, N., Plant, W.J., Stiassnie, M. et al., 2004. On the limiting aerodynamic roughness of the ocean in very strong winds. Geophysical Research Letters, 31 (18).

Doyle, J.D., 1995. Coupled ocean wave/atmosphere mesoscale model simulations of cyclogenesis. Tellus A, 47 (5), 766-778.

Drennan, W.M., Zhang, J.A., French, J.R., McCormick, C., Black, P.G., 2007. Turbulent fluxes in the hurricane boundary layer. Part II: Latent heat flux. Journal of the Atmospheric Sciences, 64 (4), 1103-1115.

Dudhia, J., 1989. Numerical study of convection observed during the winter monsoon experiment using a mesoscale two-dimensional model. Journal of the Atmospheric Sciences, 46 (20), 3077-3107.

Fairall, C.W., Bradley, E.F., Hare, J.E., Grachev, A.A., Edson, J.B., 2003. Bulk parameterization of air-sea fluxes: Updates and verification for the COARE algorithm. Journal of Climate, 16 (4), 571-591.

French, J.R., Drennan, W.M., Zhang, J.A., Black, P.G., 2007. Turbulent fluxes in the hurricane boundary layer. Part I: Momentum flux. Journal of the Atmospheric Sciences, 64 (4), 1089-1102.

Friedl, M.A., Sulla-Menashe, D., Tan, B., Schneider, A., Ramankutty, N. et al., 2010. MODIS Collection 5 global land cover: Algorithm refinements and characterization of new datasets. Remote sensing of Environment, 114 (1), 168-182.

Gochis, D.J., Yu, W., Yates, D.N., 2015. The WRF-Hydro model technical description and user’s guide, version 3.0. NCAR Technical Document, Boulder, Colorado, USA, 123 pp. (Online available at: https://ral.ucar.edu/sites/default/files/public/images/project/WRF_Hydro_User_Guide_v3.0.pdf, accessed 19.11.2018)

Grell, G.A., Peckham, S.E., Schmitz, R., McKeen, S.A., Frost, G. et al., 2005. Fully coupled “online” chemistry within the WRF model. Atmospheric Environment, 39 (37), 6957-6975.

Hodur, R.M., 1997. The Naval Research Laboratory’s coupled ocean/atmosphere mesoscale prediction system (COAMPS). Monthly Weather Review, 125 (7), 1414-1430.

Hong, S.-Y., Noh, Y., Dudhia, J., 2006. A new vertical diffusion package with an explicit treatment of entrainment processes. Monthly Weather Review, 134, 2318-2341.

Janssen, P., 2004. The interaction of ocean waves and wind. Cambridge University Press, London, UK, 310 pp.

Janssen, P.A., 1989. Wave-induced stress and the drag of air flow over sea waves. Journal of Physical Oceanography, 19 (6), 745-754.

Janssen, P.A.E.M., 1991. The Quasi-linear theory of wind wave generation applied to wave forecasting. Journal of Physical Oceanography, 21, 1631-1642.

Janssen, P.A.E.M., Doyle, J.D., Bidlot, J., Hansen, B., Isaksen, L. et al., 2002. Impact and feedback of ocean waves on the atmosphere. Advances in Fluid Mechanics, 33, 155-198.

Jenkins, A.D., Paskyabi, M.B., Fer, I., Gupta, A., Adakudlu, M., 2012. Modelling the effect of ocean waves on the atmospheric and ocean boundary layers. Energy Procedia, 24, 166-175.

Jiménez, P.A., Dudhia, J., González-Rouco, J.F., Navarro, J., Montávez, J.P. et al., 2012. A revised scheme for the WRF surface layer formulation. Monthly Weather Review, 140 (3), 898-918.

Kain, J. S., 2004. The Kain-Fritsch convective parameterization: an update. Journal of Applied Meteorology, 43 (1), 170-181.

Katsafados, P., Papadopoulos, A., Korres, G., Varlas, G., 2016. A fully coupled atmosphere-ocean wave modeling system for the Mediterranean Sea: interactions and sensitivity to the re-solved scales and mechanisms. Geoscientific Model Development, 9 (1), 161-173.

Katsafados, P., Papadopoulos, A., Mavromatidis, E., Gikas, N., 2011. Quantitative verification statistics of WRF predictions over the Mediterranean region. In: 12th Annual WRF Users’ Event, 20-24 June 2011. Boulder, Colorado, USA, 6 pp.

Katsafados, P., Varlas, G., Papadopoulos, A., Korres, G., 2017. Implementation of a Hybrid Surface Layer Parameterization Scheme for the Coupled Atmosphere-Ocean Wave System WEW. p. 159-165. In: Perspectives on Atmospheric Sciences. Karacostas, T., Bais, A., Nastos, P. (Eds), Springer, Cham.

Katsafados, P., Varlas, G., Papadopoulos, A., Spyrou, C., Korres, G., 2018. Assessing the implicit rain impact on sea state during hurricane Sandy (2012). Geophysical Research Letters, 45, 12015-12022.

Komen, G. J., Cavaleri, L., Donelan, M., Hasselmann, K., Hasselmann, S. et al., 1994. Dynamics and modeling of ocean waves. Cambridge university press, Cambridge, UK, 532 pp.

Korres, G., Papadopoulos, A., Katsafados, P., Ballas, D., Perivoliotis, L. et al., 2011. A 2-year intercomparison of the WAM-Cycle4 and the WAVEWATCH-III wave models implemented within the Mediterranean Sea. Mediterranean Marine Science, 12 (1), 129-152.

Ličer, M., Smerkol, P., Fettich, A., Ravdas, M., Papapostolou, A. et al., 2016. Modeling the ocean and atmosphere during an extreme bora event in northern Adriatic using one-way and two-way atmosphere-ocean coupling. Ocean Science, 12 (1), 71-86.

Lo, J.C.F., Yang, Z.L., Pielke, R.A., 2008. Assessment of three dynamical climate downscaling methods using the Weather Research and Forecasting (WRF) model. Journal of Geophysical Research: Atmospheres, 113 (D9).

Mlawer, E. J., Taubman, S. J., Brown, P. D., Iacono, M. J., Clough, S. A., 1997. Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated‐k model for the longwave. Journal of Geophysical Research: Atmospheres, 102 (D14), 16663-16682.

Myneni, R.B., Hoffman, S., Knyazikhin, Y., Privette, J.L., Glassy, J. et al., 2002. Global products of vegetation leaf area and fraction absorbed PAR from year one of MODIS data. Remote Sensing of Environment, 83 (1), 214-231.

Papadopoulos, A., Katsafados, P., 2009. Verification of operational weather forecasts from the POSEIDON system across Eastern Mediterranean. Natural Hazards and Earth System Sciences, 9 (4), 1299-1306.

Papadopoulos, A., Korres, G., Katsafados, P., Ballas, D., Perivoliotis, L. et al., 2011. Dynamic downscaling of the ERA-40 data using a mesoscale meteorological model. Mediterranean Marine Science, 12 (1), 183-198.

Powers, J.G., Klemp, J.B., Skamarock, W.C., Davis, C.A., Dudhia, J. et al., 2017. The weather research and forecasting model: Overview, system efforts, and future directions. Bulletin of the American Meteorological Society, 98, 1717-1737.

Ricchi, A., Miglietta, M.M., Barbariol, F., Benetazzo, A., Bergamasco, A. et al., 2017. Sensitivity of a Mediterranean tropical-like cyclone to different model configurations and coupling strategies. Atmosphere, 8 (5), 92.

Ricchi, A., Miglietta, M.M., Bonaldo, D., Cioni, G., Rizza, U. et al., 2019. Multi-physics ensemble versus Atmosphere-Ocean coupled model simulations for a tropical-like cyclone in the Mediterranean Sea. Atmosphere, 10 (4), 202.

Rizza, U., Canepa, E., Ricchi, A., Bonaldo, D., Carniel, S. et al., 2018. Influence of wave state and sea spray on the roughness length: Feedback on medicanes. Atmosphere, 9 (8), 301.

Rutgersson, A., Nilsson, E.O., Kumar, R., 2012. Introducing surface waves in a coupled wave-atmosphere regional climate model: Impact on atmospheric mixing length. Journal of Geophysical Research: Oceans, 117 (C11).

Shimada, S., Ohsawa, T., 2011. Accuracy and characteristics of offshore wind speeds simulated by WRF. Sola, 7, 21-24.

Sikirić, M.D., Roland, A., Janeković, I., Tomaz̆ić, I., Kuzmić, M., 2013. Coupling of the Regional Ocean Modeling System (ROMS) and Wind Wave Model. Ocean Modelling, 72, 59-73.

Skamarock, W.C., Klemp, J.B., Dudhia, J., Gill, D.O., Barker, D.M. et al., 2008. A description of the advanced research WRF Ver. 3.0. NCAR Technical Note, Boulder, Colorado, USA, 125 pp. (Online available at: http://www2.mmm.ucar.edu/wrf/users/docs/arw_v3.pdf, accessed 19.11.2018)

Soukissian, T., Denaxa, D., Karathanasi, F., Prospathopoulos, A., Sarantakos, K. et al., 2017. Marine renewable energy in the Mediterranean Sea: status and perspectives. Energies, 10 (10), 1512.

Staneva, J., Wahle, K., Günther, H., Stanev, E., 2016. Coupling of wave and circulation models in coastal-ocean predicting systems: a case study for the German Bight. Ocean Science, 12 (3), 797-806.

Strajnar, B., Cedilnik, J., Fettich, A., Ličer, M., Pristov, N. et al., 2019. Impact of two‐way coupling and sea‐surface temperature on precipitation forecasts in regional atmosphere and ocean models. Quarterly Journal of the Royal Meteorological Society, 145 (718), 228-242.

Sullivan, P.P., Edson, J.B., Hristov, T., McWilliams, J.C., 2008. Large-eddy simulations and observations of atmospheric marine boundary layers above nonequilibrium surface waves. Journal of the Atmospheric Sciences, 65 (4), 1225-1245.

Taylor, K.E., 2001. Summarizing multiple aspects of model performance in a single diagram. Journal of Geophysical Research: Atmospheres, 106 (D7), 7183-7192.

Tewari, M., Chen, F., Wang, W., Dudhia, J., LeMone, M.A. et al., 2004. Implementation and verification of the unified NOAH land surface model in the WRF model. p. 2165-2170. In: 20th Conference on Weather Analysis and Forecasting/16th Conference on Numerical Weather Prediction, 12-16 January 2004. American Meteorological Society, Seattle, USA,

Thompson, G., Field, P. R., Rasmussen, R. M., Hall, W. D., 2008. Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part II: Implementation of a new snow parameterization. Monthly Weather Review, 136 (12), 5095-5115.

Thompson, G., Tewari, M., Ikeda, K., Tessendorf, S., Weeks, C. et al., 2016. Explicitly-coupled cloud physics and radiation parameterizations and subsequent evaluation in WRF high-resolution convective forecasts. Atmospheric Research, 168, 92-104.

Tucker, M.J., Pitt, E.G., 2001. Waves in ocean engineering. Vol. 5. Elsevier Science, New York, USA, 548 pp.

Valcke, S., Craig, T., Coquart, L., 2015. OASIS3-MCT_3.0 coupler User Guide. CERFACS/CNRS, Toulouse, France, 58 pp. (Online available at: http://www.cerfacs.fr/oa4web/oasis3-mct_3.0/oasis3mct_UserGuide.pdf, accessed 19.11.2018)

Varlas, G., 2017. Development of an integrated modeling system for simulating the air-ocean wave interactions. PhD Dissertation, Department of Geography, Harokopio University, Athens, Greece, 212 pp. (Online available at: https://www.didaktorika.gr/eadd/handle/10442/41238, accessed 19.11.2018)

Varlas, G., Anagnostou, M., Spyrou, C., Papadopoulos, A., Kalogiros, J. et al., 2019a. A Multi-Platform Hydrometeorological Analysis of the Flash Flood Event of 15 November 2017 in Attica, Greece. Remote Sensing, 11 (1), 45.

Varlas, G., Katsafados, P., Korres, G., Papadopoulos, A., 2019b. Assessing the impact of Argo floats temperature measurements on the numerical weather prediction forecast skill. Mediterranean Marine Science, 20 (2), 331-341.

Varlas, G., Katsafados, P., Papadopoulos, A., Korres, G., 2018a. Implementation of a two-way coupled atmosphere-ocean wave modeling system for assessing air-sea interaction over the Mediterranean Sea. Atmospheric Research, 208, 201-217.

Varlas, G., Papadopoulos, A., Katsafados, P., 2018b. An analysis of the synoptic and dynamical characteristics of hurricane Sandy (2012). Meteorology and Atmospheric Physics, 1-11.

Voldoire, A., Sanchez-Gomez, E., Salas y Mélia, D., Decharme, B., Cassou, C. et al., 2013. The CNRM-CM5. 1 global climate model: description and basic evaluation. Climate Dynamics, 40 (9-10), 2091-2121.

Wahle, K., Staneva, J., Koch, W., Fenoglio-Marc, L., Ho-Hagemann, H. et al., 2017. An atmosphere-wave regional coupled model: improving predictions of wave heights and surface winds in the southern North Sea. Ocean Science, 13 (2), 289-301.

WAMDI group: Hasselmann, S., Hasselmann, K., Bauer, E., Janssen, P.A.E.M., Komen, G.J. et al., 1988. The WAM model - a third generation ocean wave prediction model. Journal of Physical Oceanography, 18, 1775-1810.

Wilks, D.S., 2011. Statistical methods in the atmospheric sciences. Vol. 100. Academic press, Oxford, UK, 704 pp.

Wu, J., 1982. Wind‐stress coefficients over sea surface from breeze to hurricane. Journal of Geophysical Research: Oceans, 87(C12), 9704-9706.

Zhang, J.A., Black, P.G., French, J.R., Drennan, W.M., 2008. First direct measurements of enthalpy flux in the hurricane boundary layer: The CBLAST results. Geophysical Research Letters, 35 (14).


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