Searching for Factors that Limit Observed Extreme Maximum Wave Height Distributions in the North Sea

2015 ◽  
pp. 93-105
Author(s):  
Gerrit Burgers ◽  
Frits Koek ◽  
Hans de Vries ◽  
Martin Stam
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Maximum Wave Height ◽  
The North ◽  
The North Sea

Searching for Factors that Limit Observed Extreme Maximum Wave Height Distributions in the North Sea

2008 ◽  
pp. 127-138 ◽  
Author(s):  
Gerrit Burgers ◽  
Frits Koek ◽  
Hans de Vries ◽  
Martin Stam
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Maximum Wave Height ◽  
The North ◽  
The North Sea

Towards a vulnerability assessment of the UK and northern European coasts: the role of regional climate variability

2005 ◽  
Vol 363 (1831) ◽  
pp. 1329-1358 ◽  
Author(s):  
M.N Tsimplis ◽  
D.K Woolf ◽  
T.J Osborn ◽  
S Wakelin ◽  
J Wolf ◽  
...  
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
North Sea ◽  
Positive Response ◽  
Sea Level Change ◽  
Empirical Relationships ◽  
Level Change ◽  
The North ◽  
The North Sea ◽  
The Uk

Within the framework of a Tyndall Centre research project, sea level and wave changes around the UK and in the North Sea have been analysed. This paper integrates the results of this project. Many aspects of the contribution of the North Atlantic Oscillation (NAO) to sea level and wave height have been resolved. The NAO is a major forcing parameter for sea-level variability. Strong positive response to increasing NAO was observed in the shallow parts of the North Sea, while slightly negative response was found in the southwest part of the UK. The cause of the strong positive response is mainly the increased westerly winds. The NAO increase during the last decades has affected both the mean sea level and the extreme sea levels in the North Sea. The derived spatial distribution of the NAO-related variability of sea level allows the development of scenarios for future sea level and wave height in the region. Because the response of sea level to the NAO is found to be variable in time across all frequency bands, there is some inherent uncertainty in the use of the empirical relationships to develop scenarios of future sea level. Nevertheless, as it remains uncertain whether the multi-decadal NAO variability is related to climate change, the use of the empirical relationships in developing scenarios is justified. The resulting scenarios demonstrate: (i) that the use of regional estimates of sea level increase the projected range of sea-level change by 50% and (ii) that the contribution of the NAO to winter sea-level variability increases the range of uncertainty by a further 10–20 cm. On the assumption that the general circulation models have some skill in simulating the future NAO change, then the NAO contribution to sea-level change around the UK is expected to be very small (<4 cm) by 2080. Wave heights are also sensitive to the NAO changes, especially in the western coasts of the UK. Under the same scenarios for future NAO changes, the projected significant wave-height changes in the northeast Atlantic will exceed 0.4 m. In addition, wave-direction changes of around 20° per unit NAO index have been documented for one location. Such changes raise the possibility of consequential alteration of coastal erosion.

Wave height variations in the North Sea and on the Norwegian Continental Shelf, 1881–1999

2003 ◽  
Vol 23 (3-4) ◽  
pp. 251-263 ◽  
Author(s):  
Frode Vikebø ◽  
Tore Furevik ◽  
Gunnar Furnes ◽  
Nils Gunnar Kvamstø ◽  
Magnar Reistad
Keyword(s):  
Continental Shelf ◽  
Wave Height ◽  
North Sea ◽  
The North ◽  
The North Sea ◽  
Norwegian Continental Shelf

Relative Motion During Single Blade Installation: Measurements From the North Sea

2020 ◽  
Author(s):  
Aljoscha Sander ◽  
Andreas F. Haselsteiner ◽  
Kader Barat ◽  
Michael Janssen ◽  
Stephan Oelker ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Sea ◽  
Relative Motion ◽  
Significant Wave Height ◽  
Offshore Wind ◽  
Wave Excitation ◽  
Significant Wave ◽  
The North ◽  
The North Sea

Abstract During single blade installation in offshore wind farms, relative motion between nacelle and blade root due to wind and wave excitation pose a significant challenge. Wave excitation can be modelled considerably well by employing state-of-the-art simulation tools and can, therefore, be included in installation planning. Other phenomena, such as flow-induced vibrations are hard to capture and hence challenging to account for when defining installation procedures and limitations. Here, we present measurements conducted during the installation of an offshore wind farm consisting of multi-megawatt turbines installed on monopile foundations in the North Sea. A custom-built sensor capturing linear & angular acceleration and GPS-data was deployed atop the nacelle. Both partially and fully assembled turbines displayed complex oscillation orbits, swiftly changing amplitude and direction. Mean nacelle deflection correlated strongly with significant wave height as well as mean wind speed. As wind speed and significant wave height showed a strong correlation as well, it is difficult to discern which load drives the observed relative motions. While wind loads are significantly smaller than wave loads on partially assembled turbines under installation conditions, additional momentum induced by vortex shedding may prove sufficient to cause the observed effects.

scholarly journals Wave Climate Change in the North Sea and Baltic Sea

2019 ◽  
Vol 7 (6) ◽  
pp. 166 ◽  
Author(s):  
Antonio Bonaduce ◽  
Joanna Staneva ◽  
Arno Behrens ◽  
Jean-Raymond Bidlot ◽  
Renate Anna Irma Wilcke
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Wave Height ◽  
North Sea ◽  
Significant Wave Height ◽  
Wave Climate ◽  
Significant Wave ◽  
The North ◽  
The North Sea

Wave climate change by the end of the 21st century (2075–2100) was investigated using a regional wave climate projection under the RCP 8.5 scenario. The performance of the historical run (1980–2005) in representing the present wave climate was assessed when compared with in situ (e.g., GTS) and remote sensing (i.e., Jason-1) observations and wave hindcasts (e.g., ERA5-hindcast). Compared with significant wave height observations in different subdomains, errors on the order of 20–30% were observed. A Principal Component (PC) analysis showed that the temporal leading modes obtained from in situ data were well correlated (0.9) with those from the historical run. Despite systematic differences (10%), the general features of the present wave climate were captured by the historical run. In the future climate projection, with respect to the historical run, similar wave climate change patterns were observed when considering both the mean and severe wave conditions, which were generally larger during summer. The range of variation in the projected extremes (±10%) was consistent with those observed in previous studies both at the global and regional spatial scales. The most interesting feature was the projected increase in extreme wind speed, surface Stokes drift speed and significant wave height in the Northeast Atlantic. On the other hand, a decrease was observed in the North Sea and the southern part of the Baltic Sea basin, while increased extreme values occurred in the Gulf of Bothnia during winter.

scholarly journals MISALIGNMENT AND LAG TIME OF WIND AND WAVE OCCURRENCE BASED ON 10 YEARS MEASUREMENTS IN THE NORTH SEA NEAR THE GERMAN COAST

2018 ◽  
pp. 13
Author(s):  
Arndt Hildebrandt ◽  
Remo Cossu
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Sea ◽  
Offshore Wind ◽  
Wave Loads ◽  
Wind Speeds ◽  
The North ◽  
The North Sea ◽  
The Impact ◽  
The Waves

There are several intentions to analyze the correlation of wind and wave data, especially in the North Sea. Fatigue damage is intensified by wind and wave loads acting from different directions, due to the misaligned aerodynamic damping of the rotor regarding the wave loads from lateral directions. Furthermore, construction time and costs are mainly driven by the operational times of the working vessels, which strongly depend on the wind and wave occurrence and correlation. Turbulent wind can rapidly change its direction and intensity, while the inert water waves react slowly in relation to the wind profile. Tuerk (2008) investigates the impact of wind and turbulence on offshore wind turbines by analyzing data of four years. The study shows that the wave height is increasing with higher wind speeds but when the wind speed drops the reaction of the waves is postponed. The dependence of the wave height on the wind speed is varying because of the atmospheric stability and different wind directions. Fischer et al. (2011) estimated absolute values of misalignment between wind and waves located in the Dutch North Sea. The study presents decreasing misalignment for increasing wind speeds, ranging up to 90 degrees for wind speeds below 12 m/s and up to 30 degrees for wind speeds above 20 m/s. Bredmose et al. (2013) present a method of offshore wind and wave simulation by using metocean data. The study describes characteristics of the wind and wave climate for the North and Baltic Sea as well as the directional distribution of wind and waves. Güner et al. (2013) cover the development of a statistical wave model for the Karaburun coastal zone located at the southwest coast of the Black Sea with the help of wind and wave measurements and showed that the height of the waves is directly correlating with the duration of the wind for the last four hours.

The statistics of wave height and crest elevation during the December 2012 storm in the North Sea

2014 ◽  
Vol 64 (9) ◽  
pp. 1305-1317 ◽  
Author(s):  
Richard Gibson ◽  
Marios Christou ◽  
Graham Feld
Keyword(s):  
Wave Height ◽  
North Sea ◽  
The North ◽  
The North Sea

Comparison of Umbilical Installation Analysis Using Two Irregular Wave Spectra

2010 ◽  
Author(s):  
Airindy Felisita ◽  
Ove Tobias Gudmestad ◽  
Lars Olav Martinsen
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Physical Environment ◽  
Wave Spectra ◽  
Irregular Wave ◽  
The North ◽  
Bending Radius ◽  
The North Sea ◽  
The Impact ◽  
Jonswap Spectrum

Umbilicals are widely used to provide monitoring and control functions for distant satellite wellheads in subsea developments. Detailed analysis is required to predict the behavior of the umbilical during the installation process. Finite Element Analysis is performed to determine the limiting operational sea-state for the installation operations. This paper presents work carried out with Acergy Norway AS, comparing two irregular wave spectra that are commonly used for installation analysis in the North Sea. The purpose of the study is to select the most suitable method for the installation analysis with respect to different types of installation operations. Selection is carried out based on several limiting criteria, including top tension, compression, minimum bending radius and the tension at the touchdown point. The JONSWAP spectrum and Torsethaugen spectrum are used to model the physical environment of the North Sea. Both of these spectra are especially designed for North Sea environment. The JONSWAP spectrum represents the fetch-limited (or coastal) wind generated seas, meanwhile the Torsethaugen spectrum represents the wave conditions in open ocean areas where the waves are dominated not only by local wind seas but are also exposed to swells (Torsethaugen and Haver, 2004). Two types of installation operations are selected for this work, which are the “buoyancy overboarding” for dynamic umbilical installation analysis and “normal lay” for static umbilical installation analysis. The analysis shows that the Torsethaugen spectrum generates higher tension forces compared to the JONSWAP spectrum. On the other hand, the JONSWAP spectrum generates higher compression and lower bending radius. However, the differences between the results using these two spectra are not large. This is due to the limited wave height and period applicable for installation operations. This work only covers wave height of Hs = 2.5–4.0 m and wave period of Tp = 6–14 s. The selection of these low conditions is based on typical sea states for installation operation (without consideration of survival conditions). Since there is only small variation on the results from the two spectra, both JONSWAP and Torstehaugen spectra are considered suitable for analysis of installation operations. It is further noted that although the Torstehaugen spectra will often provide a more realistic representation of the physical environment, forecast or measured weather data is rarely presented in this form, therefore the JONSWAP or other single peak spectra must be used for decision making offshore. This study has validated that for the range of condition studied, this is an acceptable approach. The conclusion from this study is only applicable for low sea-states and without considering effects from different direction of wind seas and swells components in the Torsethaugen spectrum. Therefore further work is required to fully asses the impact of directionality between the wave components and the impact of higher sea states which are applicable to survival conditions.

scholarly journals Evolution of marine storminess in the Belgian part of the North Sea

2012 ◽  
Vol 12 (2) ◽  
pp. 305-312 ◽  
Author(s):  
D. Van den Eynde ◽  
R. De Sutter ◽  
P. Haerens
Keyword(s):  
Wave Height ◽  
North Sea ◽  
Scientific Evidence ◽  
Clear Trend ◽  
Wind Speeds ◽  
The North ◽  
Mitigation And Adaptation ◽  
Extreme Wind ◽  
The North Sea ◽  
Extreme Wind Speeds

Abstract. Severe storms have affected European coast lines in the past but knowledge on changes in storminess for the last decades is still sparse. Climate change is assumed to be a main driving factor with the potential to induce changes on the intensity, duration and frequency of powerful marine storms, including a long-term influence on peak wind speeds, surges and waves. It is, therefore, important to investigate whether in the last decades changes in the magnitude of storms, their duration and frequency could be observed. Understanding trends in storminess in the last decades will help to better prepare coastal managers for future events, taking into account potential changes on storm occurrence and magnitude to improve planning of mitigation and adaptation strategies. The purpose of this study was to focus on the evolution of extreme wind conditions, wave height and storm surge levels in the North Sea Region, especially in the Belgian part of the North Sea (BPNS). Based on the analysis performed it is concluded that no clear trend can be observed for the occurrence of significant increasing extreme wind speeds over the BPNS. Furthermore, one can conclude that not enough scientific evidence is available to support scenarios with increased wave height or storminess.

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