Rogue Waves: Results of the MaxWave Project

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
W. Rosenthal ◽  
S. Lehner
Keyword(s):  
Weather Conditions ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Severe Weather ◽  
Sea Surface ◽  
Extreme Waves ◽  
Synthetic Aperture Radar Data ◽  
European Project ◽  
Sea Surface Topography ◽  
The Impact

Safety of shipping is an ever growing concern. In a summary, Faulkner investigated the causes of shipping casualties (2002, “Shipping Safety: A Matter of Concern,” Ingenia, The Royal Academy of Engineering, Marine Matters, pp. 13–20) and concluded that the numbers of unexplained accidents are far too high in comparison to other means of transport. From various sources, including insurers data over 30% of the casualties are due to bad weather (a fact that ships should be able to cope with) and a further 25% remain completely unexplained. The European project MaxWave aimed at investigating ship and platform accidents due to severe weather conditions using different radars and in situ sensors and at suggesting improved design and new safety measures. Heavy sea states and severe weather conditions have caused the loss of more than 200 large cargo vessels within the 20years between 1981 and 2000 (Table 1 in Faulkner). In many cases, single “rogue waves” of abnormal height as well as groups of extreme waves have been reported by crew members of such ships. The European Project MaxWave deals with both theoretical aspects of extreme waves and new techniques to observe these waves using different remote sensing techniques. The final goal is to improve the understanding of the physical processes responsible for the generation of extreme waves and to identify geophysical conditions in which such waves are most likely to occur. Two-dimensional sea surface elevation fields are derived from marine radar and space borne synthetic aperture radar data. Individual wave parameters such as maximum to significant wave height ratios and wave steepness, are derived from the sea surface topography. Several ship and offshore platform accidents are analyzed and the impact on ship and offshore design is discussed. Tank experiments are performed to test the impact of designed extreme waves on ships and offshore structures. This article gives an overview of the different work packages on observation of rogue waves, explanations, and consequences for design.

scholarly journals Numerical modelling of extreme waves by Smoothed Particle Hydrodynamics

2011 ◽  
Vol 11 (2) ◽  
pp. 419-429 ◽  
Author(s):  
M. H. Dao ◽  
H. Xu ◽  
E. S. Chan ◽  
P. Tkalich
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Wave Crest ◽  
Extreme Waves ◽  
Coastal Structures ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact ◽  
The Waves

Abstract. The impact of extreme/rogue waves can lead to serious damage of vessels as well as marine and coastal structures. Such extreme waves in deep water are characterized by steep wave fronts and an energetic wave crest. The process of wave breaking is highly complex and, apart from the general knowledge that impact loadings are highly impulsive, the dynamics of the breaking and impact are still poorly understood. Using an advanced numerical method, the Smoothed Particle Hydrodynamics enhanced with parallel computing is able to reproduce well the extreme waves and their breaking process. Once the waves and their breaking process are modelled successfully, the dynamics of the breaking and the characteristics of their impact on offshore structures could be studied. The computational methodology and numerical results are presented in this paper.

Investigation of Ship and Platform Accidents Due to Severe Weather Events: Results of the MAXWAVE Project

2006 ◽  
Author(s):  
S. Lehner ◽  
W. Rosenthal
Keyword(s):  
Weather Conditions ◽  
Rogue Waves ◽  
Radar Data ◽  
Severe Weather ◽  
Data Sets ◽  
Extreme Waves ◽  
Weather Events ◽  
Marine Radar ◽  
Satellite Radar ◽  
Remote Sensing Techniques

Heavy sea states and severe weather conditions have caused the loss of more than 200 super carriers within the last 20 years. In many cases single ‘rogue waves’ of abnormal height as well as groups of extreme waves have been reported by crew members of such vessels. The European Project MAXWAVE dealt with both theoretical aspects of extreme waves as well as new techniques to observe these waves using different remote sensing techniques. The final goal was to improve the understanding of the physical processes responsible for the generation of extreme waves and to identify geophysical conditions in which such waves are most likely to occur. This paper gives a summary of the results of the MAXWAVE projects with emphasis on the analysis of the marine and satellite radar data sets. Two dimensional sea surface elevation fields are derived from marine radar data and complex Spaceborne Synthetic Aperture Radar (SAR) images. Several ship and offshore platform accidents are analysed and new warning criteria are discussed.

Systematically Varied Rogue Wave Sequences for the Experimental Investigation of Extreme Structure Behavior

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Günther F. Clauss ◽  
Christian E. Schmittner ◽  
Janou Hennig
Keyword(s):  
Wave Height ◽  
Rogue Wave ◽  
Wave Train ◽  
Weather Conditions ◽  
Offshore Structures ◽  
Severe Weather ◽  
Wave Profile ◽  
Bending Moments ◽  
Extreme Wave ◽  
Improved Design

For an improved design of ships and offshore structures with regard to their behavior under severe weather conditions, wave height and steepness as well as the shape of the wave profile have to be considered. In this paper, the extreme new year wave as documented in numerous publications is varied with respect to wave height and period. These varied wave sequences are realized and measured in a model tank and applied to the investigation of motions and bending moments of a floating production storage and offloading ship. The results are compared to the responses in the original wave train. An investigation of the riskiness of extreme wave sequences in comparison with existing rules concludes this paper.

scholarly journals Cross-Comparison and Methodological Improvement in GPS Tomography

2019 ◽  
Vol 12 (1) ◽  
pp. 30 ◽  
Author(s):  
Hugues Brenot ◽  
Witold Rohm ◽  
Michal Kačmařík ◽  
Gregor Möller ◽  
André Sá ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Weather Prediction ◽  
Critical Role ◽  
Weather Conditions ◽  
Severe Weather ◽  
Research Station ◽  
Observational Technique ◽  
Independent Observations ◽  
Methodological Improvement ◽  
The Impact

GPS tomography has been investigated since 2000 as an attractive tool for retrieving the 3D field of water vapour and wet refractivity. However, this observational technique still remains a challenging task that requires improvement of its methodology. This was the purpose of this study, and for this, GPS data from the Australian Continuously Operating Research Station (CORS) network during a severe weather event were used. Sensitivity tests and statistical cross-comparisons of tomography retrievals with independent observations from radiosonde and radio-occultation profiles showed improved results using the presented methodology. The initial conditions, which were associated with different time-convergence of tomography inversion, play a critical role in GPS tomography. The best strategy can reduce the normalised root mean square (RMS) of the tomography solution by more than 3 with respect to radiosonde estimates. Data stacking and pseudo-slant observations can also significantly improve tomography retrievals with respect to non-stacked solutions. A normalised RMS improvement up to 17% in the 0–8 km layer was found by using 30 min data stacking, and RMS values were divided by 5 for all the layers by using pseudo-observations. This result was due to a better geometrical distribution of mid- and low-tropospheric parts (a 30% coverage improvement). Our study of the impact of the uncertainty of GPS observations shows that there is an interest in evaluating tomography retrievals in comparison to independent external measurements and in estimating simultaneously the quality of weather forecasts. Finally, a comparison of multi-model tomography with numerical weather prediction shows the relevant use of tomography retrievals to improving the understanding of such severe weather conditions.

Realistic weather conditions and removal of time-varying sea-surface effects: Application on ocean-bottom-cable data

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. V297-V315
Author(s):  
Elsa Cecconello ◽  
Walter Söllner
Keyword(s):  
Weather Conditions ◽  
Surface Effects ◽  
Sea Surface ◽  
Ocean Bottom ◽  
Time Varying ◽  
Theoretical Derivation ◽  
Data Set ◽  
Wave Heights ◽  
Sea Surface Effects ◽  
The Impact

In marine seismic acquisition, seismic reflections at the sea surface, such as sea-surface ghosts and multiples, affect the accuracy of the retrieved subsurface reflections and reduce the usable frequency bandwidth. These sea-surface effects tend to increase with the increasing roughness of the weather conditions. Consequently, processing techniques that neglect the roughness and time variation of the sea surface induce errors in the data that could compromise the validity of the final images and interpretations. We study the impact of time-varying rough sea surfaces using a modeling method derived from the Rayleigh reciprocity theorem for time-varying surfaces, and we analyze errors in the source-deghosting operation. We show that the source-deghosting limitations are weather dependent for data including sea-surface multiples: For calm sea states (wave heights below 1.25 m), the error made by the source-deghosting process is negligible; however, for rough seas (wave heights above 1.5 m), it becomes significant and blurs the deghosted image at the sea-surface multiple signals. To accurately remove all sea-surface effects from the seismic data, we simultaneously apply source-deghosting and multiple-removal operations to the same up-going wavefield. This procedure is shown to be weather independent based on our theoretical derivation and the synthetic results. Finally, this is tested on a 2D OBC data set. Comparing the proposed inversion to up-down deconvolution, we observe similar features in both wavefields: Source ghosts and sea-surface multiples seem to have been correctly removed from the data, and the inverted result indicates a slightly better resolution for deeper reflections.

Mid-Atlantic AERAs Conduct Third Annual Regional Hazardous Weather Conference

1997 ◽  
Vol 78 (3) ◽  
pp. 499-506
Author(s):  
D. R. Smith ◽  
M. A. Rosenthal ◽  
J. P. Mulvany ◽  
W. Sanford ◽  
W. R. Krayer ◽  
...  
Keyword(s):  
New York ◽  
Public Awareness ◽  
Weather Conditions ◽  
Severe Weather ◽  
Private Industry ◽  
Regional Workshop ◽  
The Media ◽  
Education Resource ◽  
The Impact ◽  
Hazardous Weather

For the third consecutive year mid-Atlantic Atmospheric Education Resource Agents (AERAs) conducted a regional workshop for educators on hazardous weather. This workshop attracted teachers from New York to Georgia for sessions by Project ATMOSPHERE AERAs, meteorologists from the National Weather Service, universities, the media, and private industry, who addressed a variety of topics pertaining to the impact of severe weather. As has been the case with the previous workshops, this event represents a partnership of individuals from schools, government agencies, and the private sector that enhances science education and increases public awareness of hazardous weather conditions.

scholarly journals Cross-validation of GPS tomography models and methodological improvements using CORS network

2018 ◽  
Author(s):  
Hugues Brenot ◽  
Witold Rohm ◽  
Michal Kačmařík ◽  
Gregor Möller ◽  
André Sá ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Deep Convection ◽  
Weather Prediction ◽  
Weather Conditions ◽  
Severe Weather ◽  
Vapour Density ◽  
Independent Observations ◽  
Using Data ◽  
The Impact

Abstract. Using data from the Continuously Operating Reference Stations (CORS), recorded in March 2010 during severe weather in the Victoria State, in southern Australia, sensitivity and statistical results of GPS tomography retrievals (water vapour density and wet refractivity) from 5 models have been tested and verified – considering independent observations from radiosonde and radio occultation profiles. The impact of initial conditions, associated with different time-convergence of tomography inversion, can reduce the normalised RMS of the tomography solution with respect to radiosonde estimates by a multiple (up to more than 3). Thereby it is illustrated that the quality of the apriori data in combination with iterative processing is critical, independently of the choice of the tomography model. However, the use of data stacking and pseudo-slant observations can significantly improve the quality of the retrievals, due to a better geometrical distribution and a better coverage of mid- and low-tropospheric parts. Besides, the impact of the uncertainty of GPS observations has been investigated, showing the interest of using several sets of data input to evaluate tomography retrievals in comparison to independent external measurements, and to estimate simultaneously the quality of NWP outputs. Finally, a comparison of our multi-model tomography with numerical weather prediction from ACCESS-A model shows the relevant use of tomography retrieval to improve the understanding of such severe weather conditions, especially about the initiation of the deep convection.

HEAVYLIFTING OPERATIONS FOR THE ASSEMBLY OF THE ARCH OF BRIDGE REPLACEMENT

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Juan J. Marti ◽  
Alvaro Saenz ◽  
Javier Martínez ◽  
Jose L. Salamanca ◽  
Salvador Salamanca
Keyword(s):  
Weather Conditions ◽  
Severe Weather ◽  
Final Position ◽  
Construction Methods ◽  
The Impact

One of the main requirements for the Walterdale Bridge Replacement in Edmonton was to minimize the impact on the river during the construction. This was a big challenge, as the use of ordinary construction methods such as falseworks and cranes was almost impossible. Furthermore, the river was not navigable. Consequently, all water equipment used, such us barges, had to be modularized, land transported and assembled directly on site, limiting the capacity. Then, it was decided to split the construction of the arch in different stages, performing several special heavylifting activities. Firstly, a partial arch (the central part), weighing 1,000 metric ton was manufactured on a riverbank. After that, it was skidded and loaded-out onto two modular barges, which moved the segment to the area between the abutments. By means of two towers specifically assembled, which included four strand jacks, the arch was then partially lifted and connected to additional sections of the arch, creating a new 1,800 T and 146-m long arch. Following this, the new arch was also lifted to its final position, in a similar way. This paper describes all the special heavylifting operations and the equipment used to assemble the arch of the bridge, facing with severe weather conditions, such as temperatures down to-20ºC and a river partially frozen.

Modeling scattering effects from time-varying sea surface based on acoustic reciprocity

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. T49-T68 ◽  
Author(s):  
Elsa Cecconello ◽  
Endrias G. Asgedom ◽  
Okwudili C. Orji ◽  
Morten W. Pedersen ◽  
Walter Söllner
Keyword(s):  
Weather Conditions ◽  
Sea Surface ◽  
Time Varying ◽  
Flat Mirror ◽  
Sea Surface Effects ◽  
Marine Seismic ◽  
Rough Sea Surface ◽  
Frequency Domain Approach ◽  
The Impact ◽  
Rough Sea

In marine seismic processing, the sea surface is often considered a flat mirror; hence, the effects of different weather conditions during the acquisition are largely ignored. However, studies have shown that rough sea-surface ghosts can severely damage the 4D signal, if not handled properly in data processing. To account for realistic sea-surface effects in processing, the impact of time-varying rough sea surfaces needs to be studied. We derive a method for modeling source and receiver ghosts from the time-varying rough sea surface and their interaction with subsurface reflections. This method is based on acoustic reciprocity and leads to integral equations of nonstationary wavefields. These modeling equations can also serve as a basis for investigating source and receiver deghosting methods for time-varying rough sea surfaces. Our developed modeling algorithm is validated against a frequency-domain approach for a “frozen” rough sea surface. For a moving simple sea surface, the Doppler shift produced by our method is in very good agreement with the analytical solution. Using a Pierson-Moskowitz spectrum, we derive a time-varying rough sea surface and model the receiver ghost, the source ghost, and the source-receiver ghost for the subsurface primary reflections of a heterogeneous geologic model. The results highlight that the source and receiver ghost interactions with a time-varying sea surface differently affect the subsurface reflections, and these effects can significantly impact the seismic repeatability of 4D studies.

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