NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-12-485-2012 Implementation and validation of a coastal forecasting system for wind waves in the Mediterranean Sea Inghilesi R. 1 Catini F. 2 Bellotti G. 3 Franco L. 3 Orasi A. 1 Corsini S. 1 4 ISPRA, Istituto Superiore per la Protezione e la Ricerca Ambientale, Roma, Italy Consorzio per le Attività di Supercalcolo per Universita e Ricerca, Roma, Italy Dipartimento di Scienze dell'Ingegneria Civile, Università Roma Tre, Roma, Italy now at: CIPE, Presidenza del Consiglio, Roma, Italy 29 02 2012 12 2 485 494 Copyright: © 2012 R. Inghilesi et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/12/485/2012/nhess-12-485-2012.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/12/485/2012/nhess-12-485-2012.pdf

A coastal forecasting system was implemented to provide wind wave forecasts over the whole Mediterranean Sea area, and with the added capability to focus on selected coastal areas. The goal of the system was to achieve a representation of the small-scale coastal processes influencing the propagation of waves towards the coasts. The system was based on a chain of nested wave models and adopted the WAve Model (WAM) to analyse the large-scale, deep-sea propagation of waves; and the Simulating WAves Nearshore (SWAN) to simulate waves in key coastal areas. Regional intermediate-scale WAM grids were introduced to bridge the gap between the large-scale and each coastal area. Even applying two consecutive nestings (Mediterranean grid → regional grid → coastal grid), a very high resolution was still required for the large scale WAM implementation in order to get a final resolution of about 400 m on the shores. In this study three regional areas in the Tyrrhenian Sea were selected, with a single coastal area embedded in each of them. The number of regional and coastal grids in the system could easily be modified without significantly affecting the efficiency of the system. The coastal system was tested in three Italian coastal regions in order to optimize the numerical parameters and to check the results in orographically complex zones for which wave records were available. Fifteen storm events in the period 2004–2009 were considered.

 References Accadia, C., Mariani, S., Casaioli, M., Lavagnini, A., and Speranza, A.: Sensitivity of Precipitation Forecast Skill Scores to Bilinear Interpolation and a Simple Nearest-Neighbor Average Method on High-Resolution Verification Grids, Weather Forecast., 18, 918–932, 2002. Buzzi, A., Fantini, M., Malguzzi, P., and Nerozzi, F.: Validation of a limited area model in cases of Mediterranean cyclogenesis: surface fields and precipitation scores., Meteorol. Atmos. Phys., 53, 137–153, 1994. Bertotti, L. and Cavaleri, L.: On the influence of resolution on wave modeled results in the Mediterranean Sea, Il Nuovo Cimento, 29, 9 pp., <a href="http://dx.doi.org/10.1393/ncc/i2005-10210-6">https://doi.org/10.1393/ncc/i2005-10210-6</a>, 2006. Bertotti, L. and Cavaleri, L.: Large and small scale wave forecast in the Mediterranean Sea, Nat. Hazards Earth Syst. Sci., 9, 779–788, <a href="http://dx.doi.org/10.5194/nhess-9-779-2009">https://doi.org/10.5194/nhess-9-779-2009</a>, 2009. Booij, N., Ris, R. C., and Holthuijsen, L. H.: A third-generation wave model for coastal regions, J. Geo. Res., 104, 7649–7666, 1999 Cavaleri, L. and Sclavo, M.: The calibration of wind and wave model data in the Mediterranean Sea, Coast. Eng., 53, 613–627, 2006. ECMWF: ECMWF WAVE MODEL, IFS Documentation, part VII – Cy33r1 Operational implementation, 2009. Franco, L., Piscopia, R., Corsini, S., and Inghilesi, R.: L'Atlante delle onde nei mari italiani - Italian Wave Atlas, Full Final Report, University of Roma TRE – APAT, 2004 Holthuijsen, L. H.: Waves in Oceanic and Coastal Waters, CUP, 2007. Holthuijsen, L. H., Booji, N., and Bertotti, L.: The propagation of wind errors through ocean wave hind casts, J. Offshore Mech. Arct. Eng., 118, 184–189, 1996. Janssen, P. A. E. M.: The Interaction of Ocean Waves and Wind, CUP, 2004. Janssen, P. A. E. M.: Progress in ocean wave forecasting, J. Comput. Phys., 227, 3572–3594, 2008. Komen, G. J., Hasselmann, S., and Hasselmann, K.: On the Existence of a Fully Developed Wind-Sea Spectrum, J. Phys. Ocean., 14, 1271–1285, 1984. Komen, G. J., Cavaleri, L., Donelan, M., Hasselmann, K., Hasselmann, S., and Janssen, P. A. E. M.: Dynamics and Modeling of Ocean Waves, Cambridge University Press, 1994. Lavrenov, I. V.: Wind Waves in Oceans – Dynamics and Numerical Simulations, Springer, 2003. Lagouvardos, K., Kotroni, V., Koussis, A., and Feidas, H.: The Meteorological Model BOLAM at the National Observatory of Athens: Assessment of Two-Year Operational Use, J. Appl. Met., 42, 1667–1678, 2003. Lionello, P., Malanotte-Rizzoli, P., and Boscolo, R.: Mediterranean Climate Variability, Elsevier, Chapter 6, 325–372, 2006. Miles, J. W.: On the generation of surface waves by shear flow, J. Fluid Mech., 3, 185–204, 1957. Phillips, O. M.: On the generation of waves by turbulent wind, J. Fluid. Mech., 2, 417–445, 1957. Polnikov, V. G., Dymov, V. I., Pasechnik, T. A., Lavrenov, I. V., Abuzyarov, Z. K., and Sannasiraj, S. A.: Testing and verifying the wind wave model with an optimized source function, Oceanology, 48, 7–14, 2008. The SWAN Team: SWAN Technical Manual, SWAN Cycle III version 40.81, Delft University of Technology, 1993. The WISE Group: Wave Modeling – The State of the Art, Progress in Oceanography, 75, 603–674, 2007. Van der Westhuysen, A. J., Zijlema, M., and Battjes, J. A.: Nonlinear saturation based white capping dissipation in SWAN for deep and shallow water, Coast. Eng., 54, 151–170, 2007.