Maxwave final meeting and summary symposium.

Time : 8 - 10 October 2003.
Venue: Salle B, ground floor,
World Meteorological Organization,7 bis, avenue de la Paix, Geneva.

 The meeting was hosted by the World Meteorological Organization (WMO)

Symposium theme:

The Maxwave project, funded by EU, has revealed new and ground breaking knowledge about extremes of ocean waves, their crest heights and trough lows, their spectral shapes, their groupiness and their classification according to wind patterns. The findings of Maxwave are believed to be inherited by marine designers, maritime classification societies, accident investigators, maritime education, and in particular in operational wave forecasting as organized within the Global Maritime Distress Safety System (GMDSS).

Participants:

• Opening, WMO welcome (Peter Dexter) (TOP 1)
• WMO/IOC engagement in operational wave forecasting (Peter Dexter) (TOP 1)
• The EU’s 5th and 6th RTD Framework Programmes, including GMES (Alan Edwards) (TOP 1)
• Requirements of MetOcean data. Johannes Guddal, co-president of JCOMM. (TOP 1)
• Requirements from JIPs (Chris Shaw) (TOP 1)
• Maxwave overview (WR) (TOP 2)
• Presentations by consortium WP leaders  (TOP 2)
• WP1 – WP 10
• SAP internal meeting after 17.00

• Continued presentations by Maxwave WP leaders (TOP 2)
• WMO roles and facilities regarding ocean satellite data (Don Hinsman) (TOP 1)
• MetOcean Aspects of TerraSAR-X (R. Bamler) (TOP 1)
• Presentations by Maxwave expert teams (TOP 3)
• Kristian Dysthe: Simulation of extreme waves..." a short resume' of the project’s philosophy and some results on spectral evolution and crest height distribution
• Harald Krogstad: Some comments about spatial extremes
• Igor Lavrenov: Wind wave measurements and numerical modelling in typhoons
• Hans Moes: 10-minute overview of what is done with regard to waves in South Africa
• Søeren Peter Kjeldsen: Slamming pressures measured, in a full scale experiment
• Carl Trygve Stansberg: Experimental Studies on Extreme Waves and Impact on Marine Structures
• Vision for the future approaches (WR)

• Presentations by Maxwave SAP. (TOP 4)
• The SAP approach and conclusions (JG)
• Summary discussion.
• Adjourn 1600.

Day 1, October 8

Peter Dexter (WMO) (TOP 1)

An overview on the organization of the WMO with focus on the Joint WMO/IOC technical commission for
oceanography and marine meteorology (JCOMM) was given. Information can be found under http://www.wmo.ch/web/aom/marprog/marprog.html

Finally  the JCOMM Workshop on New Ocean Products & MPERSS in Toulouse, May 2004 was anounced.

Hans Graber asked whether JCOMM data standard exists and/or a quality control is performed and how much the data cost.
P.Dexter: Standardisation and quality control need further improvements. JCOMM basic data is free of charge.

Alan Edward (European commission) (TOP 1)

Johannes Guddal (MaxWave participant, co-president of JCOMM) (TOP 1)

Chris Shaw (Shell International, Chairman OGP , Metocean Committee) (TOP 1)

S.Lehner:  WP 1+3 Detection of extreme single waves and wave statistics;(TOP 2)  (PDF1) (PDF2)

Within the framework of the MaxWave project, new algorithms to detect extreme wave events from
radar images have been developed. This work shows results obtained in the project concerning the detection of extreme waves, which produce serious damages to navigation and off shore industry, by using microwave remote sensing techniques. In addition, the paper contains a description of all the different sets of sea surface radar measurements acquired and processed for periods and different geographical areas, where different sea state conditions were presented.

W. Sulisz: WP 1.1 Propagation and transformation of nonlinear waves in a wave train (TOP 2) (PDF)
The nonlinear Schroedinger equation, which is often applied to explain the formation of extreme individual waves, seems to be inadequate for this problem due to simplifications applied in the derivation of this equation. A more adequate approach is to investigate the development of extreme waves and wave groups by mathematical modeling of the problem of the propagation of nonlinear waves and wave groups in a wave train.
Several nonlinear wave models were derived to study this phenomena. The results show that for certain wave sequences a large wave can be formed in a wave train and can propagate over a long distance. Theoretical results are in reasonable agreement with experimental data. In this work, a theoretical approach is applied to investigate the propagation and transformation of nonlinear waves in a wave train. First, several nonlinear wave models are derived to study the propagation of water waves in a wave train. Then, laboratory experiments are conducted in a wave flume to verify
theoretical results. Finally, theoretical results are compared with experimental data and the conclusions are specified.

W. Sulisz: WP 2.1 Extreme waves and wave events in the Baltic Sea (TOP 2)  (PDF)
Records of free-surface elevations from the Polish territorial waters are analyzed with emphases on the presence of extreme waves, wave groups and extreme wave events occurring in the Baltic Sea. The results are applied to derive extreme wave statistics and to eventually indicate periods and areas where extreme waves occur more frequently.

Anne Karin Magnusson : WP 2 Extreme wave statistics from time-series data (TOP 2) (PDF)

J. Gunson: WP 4 Analysis ship accidents - data bases and hindcasts (TOP 2) (PDF)
The objectives of the Met Office’s contribution to workpackage 4 were to screen the casualty databases to identify the most important graveyards and trading routes. The wave conditions for several selected ship casualties were then hindcast using a global spectral wave model. With input from WP1,2 and 3 the model spectra were assessed to identify the characteristics leading to a high likelihood of extreme waves occurring. Finally the potential for improving wave model predictions by incorporating SAR data was assessed.

Day 2, October 9:

Jack Monbaliu: WP 5 Regional distribution of extreme waves (TOP 2)  (PDF)
The European research program “MaxWave” aims at investigating the occurrence and properties of rogue waves. In particular the investigation of the risk for their encounter is the main objective of the work package 5 (WP5). To this end a database with 650 ship accidents reported as being due to heavy seas was extracted from the Lloyd’s global database. For these accidents wave conditions were downloaded from the ECMWF-archive, and a correlation analysis was performed. The work is aimed by the need to find some common features that might lead to a clear definition of risk – defined herein as probability of occurrence – for the encounter of abnormal sea phenomena in general and “freak” waves in particular.

Carlos Guedes-Soares: WP 6 An approach of the structural design of ships and offshore platforms in abnormal waves (TOP 2) (PDF)
The paper proposes an approach to use freak, abnormal or episodic waves as additional wave conditions to be considered in determining design loads for ships and offshore platforms. It describes the present approaches of determining extreme values of wave induced loads, including the recent advances of adopting time series of wave elevation as reference design conditions to calculate the wave induced structural loads on ships and offshore platforms in heavy weather. It is shown how this procedure can be extended to account for abnormal or episodic waves.

G. Clauss: WP 7 Simulations of rough waves and their impact on marine structures (TOP 2) (PDF)

The design of safe and economic offshore structures and ships requires detailed knowledge of the extreme wave environment and the corresponding loads and motions. For the investigation of wave/structure interaction and for the analysis of extreme wave events this paper describes techniques to synthesize nonlinear gravity waves in irregular seas. Extreme waves registered in nature are simulated in a physical wave tank. Furthermore, the impact of one of these rogue waves, the so called New Year Wave, on a semisubmersible and two stationary ships is investigated.

Henri Savina and Jean-Michel Lefevre: WP8 Definition of warning Criteria (TOP 2) (PDF)
In order to promote the use of sea-sate related parameters and in particular to introduce new warning criteria for rogues waves and dangerous sea-states within GMDSS, WP8 main tasks consisted in to propose updates of WMO regulations and to interact with some end users to define specific products with the aid of physical, statistical and deterministic wave models. To find the appropriate parameters and related thresholds, a specific database issued from ECMWF was prepared for WP5 to find correlations with ship accidents. Major updates of MMMS (Manual of Marine Meteorological Services, including sea-state as a mandatory parameter in MSI (Marine Safety Information) and dangerous sea-state/rogue waves and as a potential criterion for warning, has been agreed by JCOMM (The Joint Commission for Oceanography and Marine Meteorology) Expert Team on Maritime Safety Services. They will be presented for formal adoption by the next plenary session of JCOMM, planned in June 2005 in Halifax. ETMSS (Expert Team on Maritime Safety Services) and ETWS (Expert Team on Wind Waves and Storm Surges) will continue to work together to take into account the future research results, in particular to include in the future specific thresholds.New real time specific products are presented in the paper, which are currently in calibration and validation phase by some selected professional end users.

Wolfgang Rosenthal: WP9 Dissemination and exploitation: Wolfgang Rosenthal (TOP 2)

• Terra SAR-X Oceanographic Opportunities; Bammler, DLR (TOP 1) (PDF)
  
Overview on the possibilities of the German Satellite, which will be launched presumable in Oct. 2005. The satellite will be equipped with an X-band SAR. More technical detailes can be found under:
http://www.dlr.de/dlr/raumfahrt/rf-management/erdbeobachtung/terrasar-x

The satellite serves both the scientific community (via DLR) and aims to exploit the commercial application of satellite based remote sensing data (via Infoterra). The most prominent feature of TerraSAR-X is its 3 m spatial resolution in strip-map mode and up to 1 m in spotlight modes. Possible applications are: - high resolution wind data for off-shore wind parks - wave fields - current measurements - surface elevation. 

1st science team meeting:                                                       March 2004. 
Implementation of the Terra SAR Science Panel:                    June2004
Proposal deadline for the announcement for opportunity:         Sep. 2004

• Donald E. Hinsmann: (WMO Satellite Activities Officer) Overview on the global satellite Systems GOS (TOP 1) 

GOS summarizes the satellite activities from different countries who are cooperating with the WMO. The activities cover different aspects like: Atmosphere - Land/Surface - Climate - Forecast - Ocean. The activities of Oceanography are under JCOMM and GOS The space based component of WMO activities is expanding quickly and the WMO wants to interact with the research community. For WMO member states the data is open for research and education.

• Kristian Dysthe: Simulation of extreme waves..." a short resume' of the project's philosophy and some results on spectral evolution and crest height distribution. (TOP 3)
  A numerical model was decribed that is moderately narrow band. It is computationally very efficient, allowing a large computational domain (artificial ocean).
  With the model it is possible to investigate app. 5000 waves at any given time, while buoy samples of 20 minutes cover in general about 100 waves. It was found in the simulations that the an initial JONSWAP type wave spectrum is "relaxing" to a form that seems to become quasi-steady. This "relaxation" takes place very rapidly (in less than 100 waveperiods). The highest waves are found during this relaxation phase.
  

• Harald Krogstad: Some comments about spatial extreme waves..."  (TOP 3)
There exists one fundamental theoretical paper about extremes in Gaussian fields, Vladimir Piterbarg: Asymptotic Methods in the Theory of Gaussian Processes and Fields. Translation of AMS, Vol. 148, Providence Rhode Island, 1996.  Theorem 14.1 is a basic result about extremes of a Gaussian
field in any dimension, and the result may be applied in the extreme value alaysis of both simulated and measured spatial data.
Another interesting tool is the generalization of the Slepian model process to spatial fields (Lindgren, 1970). This model gives an optimal predictor of the shape of the surface around a maximum in the Gaussian case, and an optimal linear prodictor in the general case.
Sufficient sampling resolution for spatial fields is critical for avoiding biased results.
2nd and 3rd order numerical simulations of ocean surfaces using the modified nonlinear Schrödinger equation are all above the gaussian predictions.
Finally, the Lagrangian gaussian model for ocean waves produce steep waves and sharp crests, but the extremes' hight are similar to the regular linear model. The Lagrangian model is often used for movie animation of ocean surfaces.

• Igor Lavrenov: Wind wave measurements and numerical modelling in typhoons  (TOP 3)
Extreme wave generations mechanisms are:
- dispersive focusing
- non linear modulation
- bottom topography, refraction
- wave- current interaction (exp: Angulas Current)
- wind (especially in the case of temporal and spatial winds variabilities)

South of Korea wave measurements exhibit a large discrepancy to WAM wave model data. This is due to location of the buoy as the measurements are influenced by local bathymetry which is not included in the model. Further the buoy measurements were not always correct interpreted. On the other hand the used WAM model application included errors due to the directional resolution. The data set show that in Typhoons freak waves are more frequently observed. This indicates that cross-seas exhibit a higher probability of freak waves. The cross-seas can be generated by different storm systems, wave current interaction and refraction by local bottom topography.
This kind of phenomena are summarized in the new book: Wind-Waves in Oceans� dynamics and numerical simulations. By Igor Lavrenow, Springer Verlag, ISBN 3-540-44015-1

• Allan Edwards He is impressed by the number of experts.
  Practical remarks for the MaxWave participants. - sorry for the payment delay. The money should be transferred to GKSS by now and will then be distributed again.
  -The final report is due at the end of Jan 04, including the management and scientific report together with the technology implementation plan (TIP).
  - All money should be spend before Nov 03, only the coordinator can spend money until end of Jan 04 for the reporting work.
  Finally a very good quality of the project was attested within the EU 5th framework.

• Hans Moes: Extreme wave conditions and shippng safety around the southern African coast.  (TOP 3)
First, an overview was given of wave and wind measurements around Southern Africa.  These data are accessible by registered users in real-time through the central network WAVENET.  Satellite data indicated that the Aghullas Current amplifies the local wave heights.  This is also an area of many ship accidents, reportedly due to "freak waves". 
In-situ measurements in this area are very difficult, so new remote sensing technology to quantify wave-current interaction is very welcome.

Day 3, October 10:

• Søeren Peter Kjeldsen: Slamming pressures measured, in a full scale experiment   (TOP 3)
Motivation of the investigation on this topic is the loss of the semi-submersible " OCEAN RANGER " near New Foundland in Canada. The reason for the loss of this platform was a breaking wave cruishing into a window so that the ballast control failed. The platform then capsized and all 84 people onboard were lost. The rescue operations that were attempted failed in very severe waves. Hence new research on wave impact forces was carried out in full scale combined with stereo-photogrammetric data acquisition of severe breaking waves. The severe waves were found to be asymmetric in the wind direction with steep fronts and less steep rear sides. Numerical simulations were made to predict both wave crest kinematics in breaking waves and associated wave impact forces. These numerical simulations were calibrated against full scale measurements. First results show that the wave impact on structures increase with wave height, but it was not the highest waves but the breaking waves with air intrusion that produced even higher impacts. Experiments were also performed in a wind-wave flume in order to study the effects of asymmetric wind waves and their influence on wave impact forces. The results have been established in a data bank which can be useful for Max Wave evaluation.
Ref: Kjeldsen S.P. 1997: " Examples of Heavy Weather Damages caused by Giant Waves. " Bulletin of the Society of Naval Architects of Japan, Vol 828 pp. 744-748.
Peter.kjeldsen@c2i.net

• Carl Trygve Stansberg: Carl Trygve Stansberg: Experimental Studies on Extreme Waves and Impact on Marine Structures  (TOP 3) (PDF)
  
 Overview on new wave tank experiments, with some observations.
1) Investigations on wave physics - with focus on extreme and steep wave events. Higher-order wave amplification effects, leading to particularly high waves and crests: Theoretical expectations verified through experiments with wave groups, and through random wave experiments in a long (270m) wave  tank. Nonlinear increase in local, basic wave frequency near crest (apart from higher harmonics).  Group speed of  steepest wave events approximately 30% higher than linear dispersion - this coincides qualitatively with the MaxWave findings from radar measurements.
2) Experiments with extreme and steep waves on ships and floating platforms. Nonlinear wave amplification and slamming forces. Discussion of experimental technique for efficient testing in high waves - without having to always run long time series. Which criteria do we need to specify for actual wave events (groups) used in testing?

• Nigel Barltrop Waves causing bow slap loading  (TOP 3)
Motivation was the Schiehallion FPSO bow damage in a sea of Hs = 14 m and Tp =11 s. This lead to investiagation of wave imapct on FPSO bows which were carried out in the SAEFLOW project. The nature of ship damaging waves are: - high waves with a wave length of the order of the ship length - the bow impact is highest for very long and steep waves Ship model tests should lead to possible recommendations for ship /bow design.

• Helge Rathje Shipboard routing assistance (SRA) system (TOP 4)
The recently developed SRA system shall support the navigating personnel to avoid critical situations in heavy weather by monitoring wave parameters, ship motions and global hull girder stresses on the basis of measured seaway spectra provided by the nautical X-band radar. The ship response is calculated by processing the seaway spectra with pre-calculated hydrodynamic transfer functions stored in a database onboard, taking into account the ship's actual loading condition provided by the loading computer. Results are displayed on a PC in the wheelhouse and updated at regular intervals. Moreover, the SRA is able to process wave data from weather forecasts to yield upcoming ship response. Hence, the SRA actively supports the decision making process for the operation in heavy seas. By comparing SRA predictions with stress measurements and vertical accelerations at the bow on two containerships the sound functionality of the SRA was demonstrated.
For more information please contact Helge Rathje, email rje@gl-group.com

• Mark Donelan Wave number spectra from laser arrays at Ekofisk  (TOP 3)
At the platform Ekofisk a laser array was installed. From the 20 minutes timeseries wave number spectra exhibit a significant difference in the k � decay for upwind and downwind waves. Data comparision with the WaMoS II measurements are planned.

Vision for the future approaches (WR)