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We carry out an inter-comparison of four different altimeters: Cryosat, Jason-2, Jason-3, and Sentinel-3. This inter-comparison is undertaken by checking the altimeter data against the wind and wave model results of a given area, the Mediterranean Sea, for a 1-year period. The four data sets are consistent for wind speed, but they show substantial differences with respect to wave heights. The verification of a Sentinel-3 pass close to the coast in the northern Adriatic Sea shows irregular, spiky, large, wave height values close to the coast. This problem worsens when using high-frequency altimeter data.

In February 2017, a wave buoy was deployed in the Southern Ocean, south of New Zealand at 52°45.71′S, 169°02.54′E. For 170 days, the moored buoy transmitted spectral and time domain observations, including measurements during a storm with a particularly large individual wave of 19.4-m crest-to-trough height. We present a detailed analysis of this storm and the measured and modelled spectra, also considering the probability of the occurrence of single large waves. After 170 days, the buoy broke free of its mooring and started drifting eastwards, still transmitting the essential data, thereby providing a unique opportunity to examine large wave events and their corresponding spectral conditions in the Southern Ocean on both moored and free-drifting platforms. The results are discussed quantitatively.

On December 15, 2009, a very high wave crest was recorded by a local camera at the CNR-ISMAR oceanographic tower, 15 km offshore Venice in the Northern Adriatic Sea (Italy). The height of the estimated crest elevation appears well beyond the value (1,25·Hs) 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., Measurement(s) atmospheric wind direction • atmospheric wind speed • wave Technology Type(s) weather station • acoustic AWAC system • waverider buoy • Camera Device Sample Characteristic - Environment coastal sea water Sample Characteristic - Location Adriatic Sea Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.13415780

Principles of the spatio-temporal statistics are used to investigate the characteristics of short-term/range extreme sea waves and related sea-state parameters under cyclone winds (northern hemisphere). We base our analysis upon consistent stereo-imaging observations of the 3D (2D space + time) sea surface elevation field, and spectral wave model results in the Northwestern Pacific during tropical storm Kong-rey (2018). The focus is on the extreme value analysis of individual maximum sea surface elevations (crest heights) and maximum crest-to-trough wave heights. Results highlight the sea areas around the storm centre where the spatio-temporal highest waves are more likely, and, via scale analysis, the principal mechanisms responsible for the occurrence of extreme conditions in bimodal (composed of wind-sea and swell) and short-crested storm seas. We find that individual waves are the highest to the north-east of the translating cyclone, where sea states are more energetic. However, in the south/south-west of the centre, where opposing wind-sea/swell sea states dominate, directional spread and bound nonlinear interactions are enhanced. In this area, more extreme waves may occur, having the maximum crest and wave heights mean values in excess of 1.3 and 2.1 times the significant wave height, respectively. This set of results provides insights into the role of the dispersive and directional focusing enhanced by nonlinearities up to the second order as an effective mechanism for the formation of extreme waves under cyclone winds. To examine what physical mechanism is behind the generation of extreme waves in different regions around the cyclone, we also explore for comparison areas where nonlinear four-wave interactions are more likely to occur.

Reliable prediction of oceanic waves during severe marine storms has always been foremost for offshore platform design, coastal activities, and navigation safety. Indeed, many damaging accidents and casualties during storms were ascribed to the impact with abnormal and unexpected waves. However, predicting extreme wave occurrence is a challenging task, at first, because of their inherent randomness, and because the observation of large ocean waves, of primary importance to assess theoretical and numerical models, is limited by the costs and risks of deployment during severe open-ocean sea-state conditions.In the context of the EU-based Copernicus Marine Environment Monitoring Service (CMEMS) evolution, the LATEMAR project (https://www.mercator-ocean.fr/en/portfolio/latemar/) aimed at improving the modelling of large wave events during marine storms. Indeed, at present, operational systems only provide average and peak wave parameters, with no information on individual waves whatsoever. However, developments of the state-of-the-art third-generation wave models demonstrated that using the directional wave spectrum moments into theoretical statistical models for wave extremes, forecasters are able to accurately infer the expected shape and likelihood of the maximum waves during storms.The main purpose of the activity is therefore to provide the wave models WAM and WAVEWATCH III with common procedures to explicitly estimate the maximum wave heights for each sea state. LATEMAR achieved this goal by: performing an extensive assessment of the model maximum waves using field observations collected from an oceanographic tower; comparing WAM and WAVEWATCH III maximum wave estimates in the Mediterranean Sea; investigating the sensitivity of the maximum waves on the main sea state parameters. All model developments and evaluations resulting from this research project will be directly applicable to the wave model forecasting systems to expand their catalogue.

This study aims at characterizing the distinctive features of a spatio-temporal nonlinear wave surface. We analyze wind-generated 3-D wave fields observed during the passage of an atmospheric front, which led to a wide directional spreading of wave energy. Data were acquired from the ocean research station Socheongcho-ORS (Yellow Sea) with a stereo wave imaging system. They include 3-D (i.e. 2-D + time) measurements of the sea surface elevation with high spatial and temporal resolution over a swath larger than any previous similar deployment. We examine the shape and the nonlinear properties of the wavenumber/frequency 3-D wave spectrum, and the characteristic spatial, temporal and spatio-temporal length scales of the wave field. We then focus on analyzing the probability of occurrence and the spatio-temporal size of the rogue waves we identified in the data. In particular, we provide for the first time an empirical estimate of the extent of the horizontal sea surface spanned by rogue waves. We also propose and assess a novel strategy to determine from the 3-D wave spectrum the vertical current profile, to be then used to map the spectrum on intrinsic frequencies.

We use our previous numerical and measuring experience and the evidence from a rather unique episode at sea to summarise our doubts on the present physical approach in wave modelling. The evidence strongly suggests that generation by wind and dissipation by white-capping have a different physics than presently considered. Most of all they should be viewed as part of a single physical process.

Within the progressive improvement in wave modeling we focus on the attenuation of swell waves by rain. Till now ignored, the process is shown to be relevant, especially for the correct estimate of swell. Following the practical impossibility of devoted field experiments, we exploit the global model results over a period of more than four years to extract the tiny signal associated to the attenuation by rain. A direct comparison of the ratio model by altimeter significant wave heights versus the encountered rain amount hints to a marked related dependence. A proper quantification of the related physical effect requires a multiple step procedure that we describe in detail. We check the reliability of the results, and we provide the related source function ready for implementation in operational wave models.

We analyse high rate (20 Hz) altimeter derived sea level information, both from Synthetic Aperture Radar (SAR) altimetry missions and Low Resolution Mode missions, in an inner sea and coastal environment. They are compared versus measured and high resolution model data. After a compact description of the relevant physical processes affecting the local sea level values, we focus on three specific passes on the Adriatic Sea, East of Italy. Our main finding is that altimeters and models provide both valuable, partially overlapping, but complementary, information to be exploited in parallel with a double purpose: to progressively approach the truth and to ensure the parallel improvement of both sources. From altimeter data there is a very strong suggestion that the spatial, and implicitly temporal, variability of the fields is much higher than shown by models. The reasons are discussed.

The wind climatology of the Red Sea is described based on a 30-year high-resolution regional reanalysis generated using the Advanced Weather Research Forecasting model. The model was reinitialized on a daily basis with ERA-Interim global data and regional observations were assimilated using a cyclic three-dimensional variational approach. The reanalysis products were validated against buoy and scatterometers data. We describe the wind climatology and identify four major systems that determine the wind patterns in the Red Sea. Each system has a well-defined origin, and consequently different characteristics along the year. After analysing the relevant features of the basin in terms of their climatology, we investigate possible long-term trends in each system. It is found that there is a definite tendency towards lowering the strength of the wind speed, but at a different rate for different systems and periods of the year.

The wave climatology of the Red Sea is described based on a 30-year hindcast generated using WAVEWATCH III configured on a 5-km resolution grid and forced by Red Sea reanalysis surface winds from the advanced Weather Research and Forecasting model. The wave simulations have been validated using buoy and altimeter data. The four main wind systems in the Red Sea characterize the corresponding wave climatology. The dominant ones are the two opposite wave systems with different genesis, propagating along the axis of the basin. The highest waves are generated at the centre of the Red Sea as a consequence of the strong seasonal winds blowing from the Tokar Gap on the African side. There is a general long-term trend toward lowering the values of the significant wave height over the whole basin, with a decreasing rate depending on the genesis of the individual systems.

Improving intensity simulation and forecast of tropical cyclones has always been a challenge, although in recent years the track forecasts have been remarkably improved. In this study, we explore the sensitivity of typhoon simulation to three physical processes using a fully coupled atmosphere-ocean-wave model. Two storms, a strong and a weak one, have been chosen. The effects of wave breaking induced sea spray, ocean vertical mixing associated with nonbreaking surface waves, and sea surface cooling due to intense rainfall are assessed by means of a set of numerical experiments. The results show and confirm that sea spray leads to an increase of typhoon intensity by enhancing the air-sea heat flux, while nonbreaking wave-induced vertical mixing and rainfall lead to a decrease. Each process can be relevant, depending on wind and wave conditions. These can vary dramatically when typhoons interact with not sufficiently well-defined coastal areas, typically an archipelago. Compared with the control runs, when all the three physical processes are considered, the (absolute) difference between the modeled sea level pressure and best track data is reduced from 26.05 to 0.70 hPa for typhoon Haiyan, and from −9.42 to −8.67 hPa for typhoon Jebi. We have found a steady overestimate of the dimensions of the typhoons. We have verified an extreme sensitivity to the initial conditions, especially when small differences in the typhoon track may imply different relevance of the physical processes, like the ones we have considered, governing the evolution of the storm.

On October 29, 2018 a very severe storm affected Northern Italy, including the Adriatic Sea. The ensuing surge and wave conditions at and in front of Venice stand at the extreme tail of the respective historical return period distributions. The large set of available measured data, at the coast and at the offshore oceanographic tower, coupled with detailed numerical simulations, allows a keen analysis of the storm, its predictability and in particular of the ensuing enhanced coastal processes. These include the coastal set-up, the input information for tidal prediction in Venice, the documented passage of an atmospheric cold front and, using the local tidal data, the derived possibility of estimating the surface wind stress, the evidence of reflected waves from the coast and the associated seismometers signal 40 km inland. The highest crest and wave heights measured at the tower are beyond what is suggested by non-linear statistics. The relative out-of-scale magnitude of the three major storms since 1966 suggests the possibility that they belong to a self-standing family of events.

Following evidence derived in the field and from previous numerical experiments, we carry out wave modeling tests where the white-capping and wind input source functions are modified to be functions of also the rain rate and the wind speed. We show the high sensitivity of the results to these parameterizations and how related physically sound, but purely intuitive, choices can reproduce almost perfectly the original results also in extreme conditions. We discuss the related physical and numerical implications.

We consider the effect of rain on wind wave generation and dissipation. Rain falling on a wavy surface may have a marked tendency to dampen the shorter waves in the tail of the spectrum, the related range increasing with the rain rate. Historical and sailors’ reports suggest that this leads to calmer wave conditions, certainly so for the action of breakers. We have explored this situation using a fully coupled meteorological-wave model system, adding an artificial rain rate-dependent damping of the tail. Contrarily to direct marine experience, the experimental results show higher wind speeds and wave heights. A solid indication of the truth is achieved with the direct comparison between operational model (where rain effect is ignored) and measured data. These strongly support the sailors’ claims of less severe wave conditions under heavy rain. This leads to a keen analysis of the overall process, in particular on the role of the tail of the spectrum in modulating the wind input and the white-capping, and how this is presently modeled in operational activity. We suggest that some revision is due and that the relationship between white-capping and generation by wind is deeper and more implicative than presently generally assumed.

A novel implementation of parameters estimating the space-time wave extremes within the spectral wave modelWAVEWATCH III (WW3) is presented. The new output parameters, available in WW3 version 5.16, rely on the theoretical model of Fedele (J Phys Oceanogr 42( 9): 1601-1615, 2012) extended by Benetazzo et al. (J Phys Oceanogr 45( 9): 2261-2275, 2015) to estimate the maximum secondorder nonlinear crest height over a given space-time region. In order to assess the wave height associated to the maximum crest height and the maximum wave height (generally different in a broad-band stormy sea state), the linear quasi-determinism theory of Boccotti (2000) is considered. The new WW3 implementation is tested by simulating sea states and space-time extremes over the Mediterranean Sea ( forced by the wind fields produced by the COSMO-ME atmospheric model). Model simulations are compared to space-time wave maxima observed on March 10th, 2014, in the northern Adriatic Sea (Italy), by a stereo camera system installed on-board the "Acqua Alta" oceanographic tower. Results show that modeled space-time extremes are in general agreement with observations. Differences are mostly ascribed to the accuracy of the wind forcing and, to a lesser extent, to the approximations introduced in the space-time extremes parameterizations. Model estimates are expected to be even more accurate over areas larger than the mean wavelength (for instance, the model grid size).

A novel implemtation of parameters estimating the space-time extremes within the spectral wave model WAVEWATCH III (WW3) is presented. The new output parameters, available in WW3 version 5.16, rely on the theoretical model of Fedele (J Phys Oceanogr 42(9): 1601-1615, 2012) extended by Benetazzo et al (J Phys Oceanogr 45(9):2261-2275, 2015) to estimate the maximum second-order nonlinear crest height over a given space-time region. In order to assess the wave height associated to the maximum crest height and the maximum wave height (generally different in a broad-band storrmy sea state), the linear quasi-deterministic theory of Boccotti (2000) is considered. The new WW3 implementation is tested in simulating sea states and space-time extremes over the Mediterranean Sea (forced by the wind fields produced by the COSMO-ME atmospheric model). Model simulations are compared to space-time wave maxima observed on March 10th, 2014, in the northern Adriatic Sea (Italy), by the stereo camera system installed on board of the "Acqua Alta" oceanographic tower. Results show that modeled space-time extremes are in general agreement with observations. Differences are mostly ascribed to the accuracy of the wind forcing and, to a lesser extent, to the approximations introduced in the space-time extremes parameterizations. Model estimates are expected to be even more accurate over areas larger than the mean wavelength (for instance, the model grid size)

We discuss the performance of two global meteorological models in a difficult enclosed sea area and the possible improvements using two respectively nested high resolution local models. Each of the four sets of wind fields has been used to drive the same wave model. The performances are judged on the base of measured, buoys and satellites, wind and wave data. The analysis shows clearly the general benefits of a higher resolution. However, it also highlights the sensitivity of the nested models to apparently minor changes in the input information from the global models and their consequent possibility of larger errors, particularly in complex meteorological situations. © 2014 Elsevier Ltd. All rights reserved.

The increasing maritime activity can be seriously affected by severe weather and sea conditions. To avoid serious damages to ships, marine structures and humans, a good weather and wave forecast is of primary importance. In general the meteorological and the wave models are used to produce forecasts at large scale like the global or the medium-size inner seas. For much smaller environments like the Greek maritime areas, characterized by complicated features like the orography and the presence of islands, the modelisation becomes a not simple task. This study is devoted to the validation of the performance of the WAM wave model over the Ionian and Aegean Seas. The period of validation refers to the first 12 months of operational use of the model at the National Observatory of Athens. The wave model is applied at a resolution of 1/16 degrees and is driven by the 10 m wind, produced by the BOLAM meteorological model operationally run over the same area. Two different sources of data have been used for the verification of the model results. The first dataset is provided by a network of buoys deployed over the Greek maritime areas and the second consists of altimeter data, provided by the OSTM/Jason-2 satellite platform. Although the study area is characterized by complex topography and a large number of islands, the implementation of the WAM model provides very encouraging results. In general, with the exception of the two buoys located in the Ionian Sea, the WAM model tends to underestimate the wave energy in the region of the Aegean Sea. The comparison with the altimeter data shows that the model has a tendency to overestimate the height for waves lower than 2.5 m and to underestimate the waves higher than 3 m.

We have explored the possibility of deriving coastal wave conditions from the archived data of operational large scale modelling. Starting from this data, a high resolution nested grid has been used to derive wave results at two locations where buoy data is available. The comparison suggests that the used solution can be used to provide long term statistics or reliable forecasts at desired coastal locations. The accuracy and the limitations of the approach have been explored by analysing the sensitivity of the results to the frequency of the archived information and of the wave model spectral shape. The problems connected to inputting the correct spectral shapes are discussed.

We consider an exceptional storm—‘Klaus’ (January 2009)—its evolution on the Western Mediterranean Sea, and how the associated wind and wave conditions were modelled by seven of the major systems presently operational in this area. We intercompare the model results and then verify them and the related model ensemble versus the available measured data. Working with short-term forecasts (24 h) only, as expected, each model correctly anticipates the incoming of an exceptional storm. However, even at such limited range, we have found substantial differences among the results of the different models. The differences concern the time the storm should have entered the Western Mediterranean Sea, the peak values of wind speed and significant wave height, the general distribution of the fields, and the locations where the maxima were achieved. We have compared the model results versus the available measured data, wind from scatterometer, waves from altimeter, plus a few buoy data. We have found some inconsistencies in the results, model wind data being on average larger than the measured one, while the opposite was true for wave heights. However, the limited amount of data available and its different times and positions, at and off the centre of the storm, impede the drawing of any definite conclusion in this respect. On the whole we feel that our results, although related to a single storm, cast doubts on the reliability of a single forecast system to provide sufficiently reliable and accurate forecasts in case of an incoming exceptional storm. The results, both for wind and waves, have improved using an ensemble of the seven considered models. This suggests that there is no relevant systematic error in the used models except, as possibly suggested by our results, in the case of wave generation under very strong wind and very young sea conditions. Copyright © 2011 Royal Meteorological Society and British Crown Copyright, the Met Office

The accuracy of deterministic and probabilistic forecasts of storms in the Adriatic Sea that lead to the flooding of Venice is discussed. We consider ECMWF state-of-the-art high-resolution single deterministic and lower-resolution ensemble-based forecasts of meteorological and sea states (waves) for five storms that affected Venice between 1966 and 2008. Notwithstanding the complicated local orographic situation, it is shown that ECMWF single, deterministic forecasts provide accurate information up to 3–4 days in advance. This range is further extended to between 4 and 6 days if ensemble-based, probabilistic forecasts are considered. The assessment of the quality of Ensemble Prediction System (EPS) probabilistic forecasts during the winters of 2008–2009 and 2009–2010 over the Adriatic and the Mediterranean Seas, and the North Atlantic Ocean, is also discussed to provide a proper statistical evaluation of the accuracy of EPS-based probabilistic forecasts of the wind over the sea. Average results indicate that EPS probabilistic forecasts over these areas are skilful for the whole forecast range considered in this study. Copyright © 2011 Royal Meteorological Society

We have explored the predictability of storms in a small enclosed basin with a complicated surrounding orography. We have considered two exceptional storms in the far past and three mild events happened in recent years. A posteriori forecasts have been done up to 6 days before the events. The results have been compared versus measured data and the related analysis. Good predictability (10-15% error in surface wind speed and wave height) have been found up to day 4, mildly larger (< 30%) up to day 6 before the event. In no case was a storm missed. This suggests that the effective predictability in more open basins may extend to even larger ranges.

The performance of state-of-the-art meteorological and oceanographic numerical systems in predicting the sea state in the Adriatic Sea during intense storms is assessed. Two major storms that affected Venice are discussed. The first storm occurred on 4 November 1966, when Venice suffered its most dramatic flood event. The damage and loss of life caused by the storm and the associated flood were extremely high also because the event was poorly forecast. The 1966 event is reanalysed using state-of-the-art meteorological and oceanographic numerical systems to investigate whether the poor forecast quality was due to a lack of data or of suitable numerical modelling. The second severe storm took place on 22 December 1979, when Venice experienced the second-worst ‘acqua-alta’ conditions in recorded history. Results show that with the present numerical systems both storms and associated wave and surge conditions could have been forecast several days in advance. Potential implications for the prediction of more frequent less intense storms are discussed, and a suitably enhanced system based on a global meteorological model and a limited area one is outlined. Copyright © 2010 Royal Meteorological Society

In the framework of RISKMED project, three different high-resolution limited area meteorological models (BOLAM, MOLOCH and WRF) have been run over southern Italy for the retrospective analysis of three case studies characterized by strong winds and severe wave conditions in the Ionian, southern Adriatic and southern Tyrrhenian seas. All the models were able to reproduce the main meteorological features of each event. The wind fields simulated by the meteorological models and those provided by the ECMWF analysis have been ingested into a wave model (WAM) for the hindcast of the main wave parameters. The results have been compared with the observations of three buoys whose measurements were available in the area of interest. A remarkable improvement in the representation of the significant wave height came out using the limited area model data with respect to the simulations where the ECMWF analyses were used as forcing. Among the limited area models, the BOLAM-MOLOCH modelling system provided slightly better performances. From the limited set of simulations, the different model predictions came out closer to each other and more skilful in areas where the waves approach the coastline perpendicularly from the open sea.

We describe the implementation of an operational high resolution wind and wave forecasting system in the Mediterranean Sea, and then on a limited area centred on the south-east part of Italy, covering parts of the Adriatic and the Ionian seas. We analyse the performance at the two different resolutions during the first four months of operation, using the wind and wave data provided by the QuikSCAT scatterometer, and the Jason and Envisat altimeters. Useful accurate forecasts are found up to 72 h range, the maximum operational one. As expected, we find that the limited area models outperform both the wind and wave global or larger scale model results. However, we still find an appreciable underestimate by the models for surface wind speed and hence wave height, often concentrated on specific events.

On 14 February 2005 a severe mistral storm caused substantial damage to the passenger cruiser "Voyager" between Balearic Islands and Sardinia. The storm had been well predicted. However, the ship was hit by one or more, apparently unexpected, large waves. Our aim was to understand if this was a freak event or it was within the expectable probability. At this aim we use our best estimate of the local wave conditions, obtained combining modelling and measured data. Starting from these we derive the probability of large waves, considering both linear and non-linear cases. Notwithstanding a correction towards the worse of the, otherwise inconsistent, available reports, on the basis of the data at disposal we conclude that, given the local conditions, the event was within the range of the potentially expectable wave heights. This turns out to be even more the case on the basis of recent results based on theoretical and experimental data.

We have simulated a number of periods using different resolutions of the ECMWF meteorological model. Then we have explored how the quality of the surface wind and wave model results varies with the resolution. The comparisons have been done in the oceans and in the Mediterranean Sea, using measured data from buoys and satellite. At the highest resolution we have used, T799 or 25 km, the biases in the oceans reduce to very small values of the order of a few percent. In enclosed seas, represented in this case by the Mediterranean, the errors decrease with increasing resolution, but a substantial underestimate still remains. The maximum values of both the wind speeds and the wave heights increase with resolution. However, the suggestion is that even T799 fails to model properly the highest peaks of the storms, a fact possibly due to the inaccurate description of physics in these extreme events. This seems particularly true in the case of a cyclone in the Bay of Bengal.

The meteorological model of the European Centre for Medium-Range Weather Forecasts, run with different resolutions, has been used to explore, with a number of numerical experiments, the underestimate of wind speeds and wave heights found in enclosed basins. Comparisons have been made between the results from the different runs, and also against satellite and buoy data. It is found that the error depends on fetch, i.e. on the distance from the closest land from which the wind is blowing. Large errors are found at short fetches (order of 100 km), gradually decreasing with the distance from the coast. The error is larger and more persistent for waves. Increasing the resolution leads to an improvement of the results. However, the bias does not disappear at the highest resolution we have used (about 25 km). Experiments with the single-point version of the meteorological model do not suggest that a slow development of the marine boundary layer is the main reason for the underestimate of the wind speeds. With respect to the mean orography, the use of envelope orography leads to a substantial increase of the marine wind speeds in the area affected by land.

A number of meteorological situations are studied using the operational models at the European Centre for Medium-Range Weather Forecasts, and a series of short-term forecast experiments is made for four different resolutions of the meteorological model. A comparison with the measurements and between the corresponding results allows an evaluation of the relative benefits of increased resolution. The focus is on the surface wind speeds and on the wave heights. Good quality results are found over the oceans, especially in areas with strong spatial gradients. Consistent with the already good quality of the present operational results, the improvements with increased resolution are small, but significant. In enclosed basins, as in the case of the Mediterranean Sea, it is found that both the surface wind speed and wave height are strongly underestimated. The improvements with increased resolution are greater than over the oceans, but still not sufficient to give agreement with measured data. Copyright © 2003 Royal Meteorological Society

We consider the wind climatology of the Adriatic Sea derived from three different sources: an operational meteorological model, a simplified wind model, and traditional ship reports. The simplified wind model is found to provide reliable results in storm conditions, but it partly smoothes the fields when the meteorological pattern is not well defined and fairly uniform at the basin scale.

The authors analyze the accuracy of the surface wind of the Adriatic Sea from a global model. They find it to be substantially underestimated and propose a calibration by a suitable enhancement of the strength of the fields. The reasons for the underestimate are discussed.

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. ispartof: Monthly Weather Review vol:141 issue:9 pages:3130-3141 status: published

To estimate uncertainties in wave forecast and hindcasts, computations have been carried out for a location in the Mediterranean Sea using three different analyses of one historic wind field. These computations involve a systematic sensitivity analysis and estimated wind field errors. This technique enables a wave modeler to estimate such uncertainties in other forecasts and hindcasts if only one wind analysis is available.

A severe storm in the Adriatic Sea has been hindcast with two meteorological models, respectively at the local (LAMBO) and global scale (T213). We have found that the increase of resolution is not paralleled by a corresponding increase of the overall accuracy. This is particularly true when the wind fields are used to evaluate the corresponding wave fields. The LAMBO data have then been used to validate a simpler wind model that, when properly tuned to the specific basin and starting from the correct pressure fields, is capable to supply surface wind fields of acceptable quality.

[1] We analyze the sea state conditions during which the accident of the cruise ship Louis Majesty took place. The ship was hit by a large wave that destroyed some windows at deck number five and caused two fatalities. Using the wave model (WAM), driven by the Consortium for Small-Scale Modelling (COSMO-ME) winds, we perform a detailed hindcast of the local wave conditions. The results reveal the presence of two comparable wave systems characterized almost by the same frequency. We discuss such sea state conditions in the framework of a system of two coupled Nonlinear Schrodinger (CNLS) equations, each of which describe the dynamics of a single spectral peak. For some specific parameters, we discuss the breather solutions of the CNLS equations and estimate the maximum wave amplitude. Even though, due to the lack of measurements, it is impossible to establish the nature of the wave that caused the accident, we show that the angle between the two wave systems during the accident was close to the condition for which the maximum amplitude of the breather solution is observed.

The WAM model has been run repeatedly for the same storm using different directional resolutions. The results indicate that the overall results are not very sensitive to a further increase of the number of directions in the spectrum. Some minor differences have been found in the lee of sharp coastal features.

This paper presents RISKMED, a project targeted to create an Early Warning System (EWS) in case of severe or extreme weather events in the central and eastern Mediterranean and specifically in southern Italy, northwestern Greece, Malta and Cyprus. As severe or extreme weather events are considered, cases when the values of some meteorological parameters (temperature, wind, precipitation) exceed certain thresholds, and/or a severe weather phenomenon (thunderstorm, snowfall) occurs. For an accurate weather forecast, selected meteorological models have been operated daily, based on a nesting strategy using two or three domains, providing detailed forecasts over the above mentioned areas. The forecast results are further exploited for the evaluation and prediction of human discomfort and fire weather indices. Finally, sea wave models have also been operating daily over the central and eastern Mediterranean Sea. In case a severe or extreme weather event is forecasted within the next 48 or 72 h for selected target areas (sub-regions defined by their morphological and population characteristics), the local authorities and the public are informed via a user-friendly graphic system, the so-called RISK MAP. On the web page of the Project (http://www.riskmed.net), additional information is provided about the real-time values of some meteorological parameters, the latest satellite picture and the time and space distribution of lightning during the last 24 h. The RISKMED project was financed by the EU and the Ministries of National Economy of Greece, Italy, Malta and Cyprus, in the frame of INTERREG IIIB/ARCHIMED programme., peer-reviewed

We analyse the quality of the predictions of wind and waves in the Adriatic Sea considering the corresponding analysis and forecast fields of the European Centre for Medium-Range Weather Forecasts up to 72 h. The whole study is based on a 1-year long period 1st Jan–31st Dec 2006 and two hindcast studies of bora events. Global wind fields are used for the analysis. The marine surface wind speeds are corrected for their underestimate with a procedure based on a long term comparison with measured data. The corrected wind fields are then used to run the WAM wave model and to produce the corresponding analysis and forecast wave fields. These are analysed both among themselves and vs buoy data obtained along the Italian coasts. In particular the detailed analysis of a case of bora highlights the sensitivity of the local wind and wave conditions to small changes in the overall meteorological patterns. This strongly suggests that in an enclosed sea the capability of producing successful forecasts beyond a limited time extent is greatly reduced with respect to the oceans.

We analyse the wind and wave conditions present in the Mediterranean Sea at the time and location when the cruise ship Voyager was reportedly hit by one or more big waves and suffered substantial damage. The analysis is done using wind and wave modelling supported by satellite and buoy wind and wave data. Granted the hindcast of the storm, we also analyse the local conditions for the possibility of freak waves.

We have hindcast the wind and wave conditions in the Mediterranean Sea for two one month periods. Four different meteorological models and three different wave models have been used. The results have been compared with satellite and buoy wind and wave observations. Several conclusions concerning both the instruments and the models have been derived. The quality of both wind and wave results has been assessed. Close to the coasts high resolution, nested wave models are required for sufficient reliability. A wave threshold analysis suggests a sufficient reliability only off the coast, with a substantial decrease for low wave heights.

[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.

We outline here the logical flow of papers that attack the problem of estimating the wave conditions in front of and at the Venetian littoral. We start from the determination of the wind fields, followed by that of the wave fields. The wave data are then transferred to the coast. We end by analysing the wave conditions inside the main inlet to the Venice lagoon. This paper gives a brief account of the logical flow of arguments from paper to paper, indicating the main results and outlining the robust structure of the overall research. We end with a discussion on the accuracy of the results, and with an indication of the possible lines for further research.