On the influence of resolution on wave modelled results in the Mediterranean Sea

We have explored the sensitivity of the wave modelled results in the Mediterranean Sea to the grid and integration time step resolutions. The results show that in areas with a complicated coastal shape an improved grid resolution provides often substantial local differences, mostly associate to the effect of, but not necessarily close to, the coasts. Some smaller differences are associated also to the accuracy of the numerical procedure. The use of different time steps did not provide appreciable differences. We have also explored how the quality of the wind fields in the Mediterranean Sea is going to improve with the shift of the resolution of the ECMWF meteorological model from T511 (40 km) to T799 (25 km)

An exceptionally high wave at the CNR-ISMAR oceanographic tower in the Northern Adriatic Sea

On December 15, 2009, a very high wave crest was recorded by a local camera at the CNR-ISMAR oceanographic tower, 15km offshore Venice in the Northern Adriatic Sea (Italy). The height of the estimated crest elevation appears well beyond the value (1,25.H-s) commonly used to identify a wave as freak. We document the wave event with a full description of the corresponding met-ocean conditions and related measurements, of which we provide a critical analysis

The 2015 exceptional swell in the Southern Pacific: Generation, advection, forecast and implied extremes

A very severe storm in the Antarctic belt is analysed that sent a very large swell throughout the South-Pacific Ocean. The reasons for the storm were a deep depression passing over an anomalous warm sea area, with consequent increased intensity, more active wind input, gustiness, with also dynamical generation. Wind and wave model results are verified with scatterometer and altimeter data. We follow the swell evolution during the five days required to reach the Galapagos Islands and a buoy off the Peruvian coast. The first forerunners peaked at 0.032 Hz at these locations, well represented in the model thanks to a purposely extended frequency range used in the WAM model. A nonlinear combined analysis is carried out to estimate the overall maximum single wave heights that may have impinged on the Galapagos coasts. Single wave heights up to 6 m have been estimated. Once generated, the swell conditions at Galapagos and the buoy are perfectly anticipated. Including generation, useful forecasts extend till at least eight days before the event. The lack of any local communication is discussed. An analysis using ERA5 winds, but a respectively higher resolution long-term wave hindcast, shows that a similar, actually stronger, event happened in 2006. A simple, but sound method, based on physical principles and elementary geometry, is proposed to estimate, firsthand and after any time, the maximum height of a once generated swell. The results for the 2015 storm are correct within 5% of the model values

Accuracy of global and high resolution models in stormy conditions

We analyse the performance of two top level meteorological models and their associated analyses versus the corresponding results obtained with high resolution nesting both for wind and for the derived wave field using the same advanced wave model. The comparison is also done versus both locally (buoys) and large scale (altimeter and scatterometer) measured data. It turns out that nested high resolution modelling does in general lead to a lower bias, but at the expense of larger root mean square errors and scatter indexes when compared with measured data. The reasons for this are discussed and a possible solution is indicated. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE)

Nettuno: Analysis of a Wind and Wave Forecast System for the Mediterranean Sea

Nettuno is a wind and wave forecast system for the Mediterranean Sea. It has been operational since 2009 producing twice-daily high-resolution forecasts for the next 72 h. The authors have carried out a detailed analysis of the results, both in space and time, using scatterometer and altimeter data from four different satellites. The findings suggest that there are appreciable differences in the measurements from the different instruments. Within the overall positive results, there is also evidence of differences in Nettuno performance for the various subbasins. The related geographical distributions in Nettuno performance are consistent with the various satellite instruments used in the comparisons. The extensive system of buoys around Italy is used to highlight the difficulties involved in a correct modeling of wave heights in Italy's coastal areas.status: publishe

Riconstruzione e previsione della tempesta del parsifal

[IT] Il 2 novembre 1995 l'imbarcazione a vela di 16 m "Parsifal" affondò durante una tempesta di Maestrale al largo di Minorca nel Golfo del Leone provocando la morte di sei dei nove membri dell 'equipaggio. Si analizza la tempesta con differenti modelli numerici meteorologici e di moto ondoso, confrontando i risultati con le misure disponibili da boe e da satellite. Si prendono poi in considerazione le previsioni della tempesta e le informazioni disponibili durante i giorni precedenti all 'incidente. Infine si discute sulla situazione attuale dei sistemi di ricostruzione e previsione del campo di vento e del moto ondoso nel Mar Mediterraneo, nonché sulla distribuzione di queste informazioni al pubblico.Le elaborazioni con il vento ECMWF sono state parzialmente eseguite presso il centro ECMWF di Reading, U.K.. Si ringrazia il Direttore, dr. Dave Burridge, per la sua cortese disponibilità. Si ringraziano anche: il SIMN (Roma) per la messa a disposizione delle misure della boa di Alghero, il Puerto del Estado (Spagna) per i dati delle boe spagnole e la Soc.Meteomer (Francia) per i dati del satellite Topex. Una versione preliminare del presente studio è sttata publicatta negli Atti del 4° Congresso AIOM, Padova ottobre 1996.Bertotti, L.; Cavaleri, L.; Girolamo, PD.; Magnaldi, S.; Franco, L. (1997). Riconstruzione e previsione della tempesta del parsifal. Ingeniería del Agua. 4(3):17-26. https://doi.org/10.4995/ia.1997.2726SWORD172643Cavaleri, L., G.J.H.Burgers (1992) Wind gustiness and wave growth, KNMI Afdeling Oceanografisch Onderzoek memo, 00-92-18, De Bilt, 38p.Cullen, M.J.P., (1991), The unified forecast/climate model, Scientific Paper No. 1, U.K. Meteor. Office, 35 pp.Franco, L., P. Contini, (1997) Wavemeasurements and climatology in the Italian seas, PIANC Bulletin n.94.Golding, B. (1983) A wave prediction system for real-time sea state forecasting, QJR Meteorol. Soc., 109, p.393-416.Hasselmann, K., T.P. Barnett, E. Bouws, H. Carlson, D.E. Cartwright, K. Enke, J.A. Ewing, H. Gienapp, D.E. Hasselmann, A. Meerburg, P. Muller, D.J. Olbers, K. Richter, W. Sell and H. Walden, (1973) Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP), Dtsch. Hydrogr. Z. Suppl.A. 8(12), 95p.Komen, G.J., L. Cavaleri, M. Donelan, K. Hasselmann, S. Hasselmann, P.A.E.M. Janssen, (1994) Dynamics and Modelling of Ocean Waves, Cambridge Univ. Press, 532pMagnaldi, S, F.Ferrauto, (1996) Un nuovo modello spettrale di generazione e propagazione del moto ondoso in acqua profonda, Atti 25 Convegno Nazionale di Idraulica e Costruzioni Idrauliche, Torino, ed.CNRPontes, T.et al. (1996) WERATLAS: Atlas of the Wave Energy Resource in Europe. Report to the Euopean Commission, JOULE II Programme, 96p.PCM, Programa de Clima Marítimo (1991) Predicción del oleaje efectuada con el modelo WAM. Análisis estadístico de un mes de predicción (nov. 1988). Direccion General de Puertos. Publicacion n.48, pp.102.Simmons, A., (1991) Development of the operational 31-level T213 version of the ECMWF forecast model, ECMWF Newsletter 56, p.3-13.WAMDI Group: S. Hasselmann, K. Hasselmann, E. Bauer, P.A.E.M. Janssen, G.J. Komen, L. Bertotti, P. Lionello, A. Guillaume, V.C. Cardone, J.A. Greenwood, M. Reistad, L. Zambresky, J.A. Ewing, (1988), The WAM model- a third generation ocean wave prediction model, J. Phys. Oceanogr.,18, p.1775-181

Waverider buoy processed wave parameters and raw data of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009

Waverider buoy processed wave parameters and raw data of an exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. In: Pomaro, A et al. (2020): An exceptionally high wave at the Acqua Alta Oceanographic Tower on December 15, 2009. Istituto di Scienze Marine - CNR, PANGAEA, https://doi.org/10.1594/PANGAEA.91546