Wind and Wave Climate in Open Sea and Coastal Waters

2017 ◽  
Author(s):  
Elzbieta M. Bitner-Gregersen
Keyword(s):  
Wave Height ◽  
Coastal Waters ◽  
Significant Wave Height ◽  
Weather Conditions ◽  
Wave Climate ◽  
Peak Period ◽  
Significant Wave ◽  
The North ◽  
Open Sea ◽  
Adverse Weather

Wind and wave climate is much region and location dependent, affected by local properties of ocean environment. For safety of world-wide sailing ships knowledge about wind and wave climate is important, not only for open sea, but also in coastal areas. Wind and waves impact ship design, marine operations and they challenge ability of ships to maintain manoeuvrability in sea states. Their description differs in open sea and coastal waters, and recently it has got an attention due to the issue of the 2013 Interim Guidelines by IMO where adverse weather conditions to be used in assessment of ship manoeuvrability have been proposed. The present study shows differences between open sea and coastal water wind and wave climate using hindcast data in the analysis. The description of open sea metocean conditions is limited to the North Atlantic while European waters are used as representative for coastal regions. Correlations between wind speed and significant wave height as well as significant wave height and spectral peak period are established and compare with the ones suggested by the 2013 Interim Guidelines. Challenges in providing metocean description for assessment of ship manoeuvrability and uncertainties related to it are discussed.

Comparison of Bivariate Models of the Distribution of Significant Wave Height and Peak Wave Period

2007 ◽  
Author(s):  
Catarina S. Soares ◽  
C. Guedes Soares
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Bivariate Normal Distribution ◽  
Wave Period ◽  
Peak Period ◽  
Data Set ◽  
Significant Wave ◽  
The North ◽  
Bivariate Models ◽  
The North Sea

This paper presents the results of a comparison of the fit of three bivariate models to a set of 14 years of significant wave height and peak wave period data from the North Sea. One of the methods defines the joint distribution from a marginal distribution of significant wave height and a set of distributions of peak period conditional on significant wave height. Other method applies the Plackett model to the data and the third one applies the Box-Cox transformation to the data in order to make it approximately normal and then fits a bivariate normal distribution to the transformed data set. It is shown that all methods provide a good fit but each one have its own strengths and weaknesses, being the choice dependent on the data available and applications in mind.

scholarly journals Wave directional measurement in Patos Lagoon, RS, Brazil

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Natália Lemke ◽  
◽  
Lauro Julio Calliari ◽  
José Antônio Scotti Fontoura ◽  
Déborah Fonseca Aguiar
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Climate ◽  
Coastal Protection ◽  
Peak Period ◽  
Patos Lagoon ◽  
Significant Wave ◽  
Wave Parameters ◽  
Wave Heights ◽  
Significant Wave Heights

ABSTRACT The wave climate characterization in coastal environments is essentially important to oceanography and coastal engineering professionals regarding coastal protection works. Thus, this study aims to determine the most frequent wave parameters (significant wave height, peak period and peak direction) in Patos Lagoon during the period of operation of a directional waverider buoy (from 01/27/2015 to 06/30/2015). The equipment was moored at approximately 14 km from the São Lourenço do Sul coast at the geographic coordinates of 31º29’06” S and 51º55’07” W, with local depth of six meters, registering significant wave height, peak period and peak direction time series. During the analyzed period, the greatest wave frequencies corresponded to short periods (between 2 and 3.5 seconds) and small values of significant wave heights (up to 0.6 meters), with east peak wave directions. The largest wave occurrences corresponded to east peak wave directions (33.3%); peak wave periods between 2.5 and 3 seconds (25.6%) and between 3 and 3.5 seconds (22.1%); and to significant wave heights of up to 0.3 meters (41.2%) and from 0.3 to 0.6 meters (38%). This research yielded unprecedented findings to Patos Lagoon by describing in detail the most occurring wave parameters during the analyzed period, establishing a consistent basis for several other studies that might still be conducted by the scientific community.

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 Assessment of the Storm Avoidance Effect on the Wave Climate along the Main North Atlantic Routes

2015 ◽  
Vol 69 (1) ◽  
pp. 127-144 ◽  
Author(s):  
Roberto Vettor ◽  
C. Guedes Soares
Keyword(s):  
Wave Height ◽  
North Atlantic ◽  
Significant Wave Height ◽  
Numerical Models ◽  
Wave Climate ◽  
Scatter Diagram ◽  
Significant Wave ◽  
The North ◽  
The Mean ◽  
The North Atlantic

The wave climate along the main transoceanic routes of the North Atlantic sub basin is determined using three different databases: two derived by numerical models in the HIPOCAS and ERA40 databases and one from Voluntary Observing Ships. For each route the distribution of the mean significant wave height along the path is computed as well as the specific scatter diagram. In addition an assessment of the relative wave heading probability is provided. The results highlight a bias in the visual observations especially in the summer and, more in general, for low sea states. The correction of this bias allows better understanding of rough weather avoidance by ships and to determine a storm avoidance correction.

Semi-Empirical Crest Distributions of Long-Crest Nonlinear Waves of Three-Hour Duration

2017 ◽  
Author(s):  
Zhenjia (Jerry) Huang ◽  
Qiuchen Guo
Keyword(s):  
Nonlinear Wave ◽  
Wave Height ◽  
Model Test ◽  
Significant Wave Height ◽  
Spectral Peak ◽  
Wave Crest ◽  
Empirical Formulas ◽  
Peak Period ◽  
Significant Wave ◽  
Semi Empirical

In wave basin model test of an offshore structure, waves that represent the given sea states have to be generated, qualified and accepted for the model test. For seakeeping and stationkeeping model tests, we normally accept waves in wave calibration tests if the significant wave height, spectral peak period and spectrum match the specified target values. However, for model tests where the responses depend highly on the local wave motions (wave elevation and kinematics) such as wave impact, green water impact on deck and air gap tests, additional qualification checks may be required. For instance, we may need to check wave crest probability distributions to avoid unrealistic wave crest in the test. To date, acceptance criteria of wave crest distribution calibration tests of large and steep waves of three-hour duration (full scale) have not been established. The purpose of the work presented in the paper is to provide a semi-empirical nonlinear wave crest distribution of three-hour duration for practical use, i.e. as an acceptance criterion for wave calibration tests. The semi-empirical formulas proposed in this paper were developed through regression analysis of a large number of fully nonlinear wave crest distributions. Wave time series from potential flow simulations, computational fluid dynamics (CFD) simulations and model test results were used to establish the probability distribution. The wave simulations were performed for three-hour duration assuming that they were long-crested. The sea states are assumed to be represented by JONSWAP spectrum, where a wide range of significant wave height, peak period, spectral peak parameter, and water depth were considered. Coefficients of the proposed semi-empirical formulas, comparisons among crest distributions from wave calibration tests, numerical simulations and the semi-empirical formulas are presented in this paper.

Development of Operational Limit Diagrams for Offshore Lifting Procedures

2015 ◽  
Author(s):  
Leonardo Roncetti ◽  
Fabrício Nogueira Corrêa ◽  
Carl Horst Albrecht ◽  
Breno Pinheiro Jacob
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Technological Development ◽  
Automatic Generation ◽  
Dynamic Responses ◽  
Offshore Platforms ◽  
Peak Period ◽  
Significant Wave ◽  
Wave Heights ◽  
Offshore Crane

Lifting operations with offshore cranes are fundamental for proper functioning of a platform. Despite the great technological development, offshore cranes load charts only consider the significant wave height as parameter of environmental load, neglecting wave period, which may lead to unsafe or overestimated lifting operations. This paper aims to develop a method to design offshore crane operational limit diagrams for lifting of personnel and usual loads, in function of significant wave height and wave peak period, using time domain dynamic analysis, for a crane installed on a floating unit. The lifting of personnel with crane to transfer between a floating unit and a support vessel is a very used option in offshore operations, and this is in many cases, the only alternative beyond the helicopter. Due to recent fatal accidents with lifting operations in offshore platforms, it is essential the study about this subject, contributing to the increase of safety. The sea states for analysis were chosen covering usual significant wave heights and peak periods limits for lifting operations. The methodology used the SITUA / Prosim software to obtain the dynamic responses of the personnel transfer basket lifting and container loads on a typical FPSO. Through program developed by the author, it was implemented the automatic generation of diagrams as a function of operational limits. It is concluded that using this methodology, it is possible to achieve greater efficiency in the design and execution of personnel and routine load lifting, increasing safety and a wider weather window available.

scholarly journals Reliability of Extreme Significant Wave Height Estimation from Satellite Altimetry and In Situ Measurements in the Coastal Zone

2020 ◽  
Vol 8 (12) ◽  
pp. 1039
Author(s):  
Ben Timmermans ◽  
Andrew G. P. Shaw ◽  
Christine Gommenginger
Keyword(s):  
Coastal Zone ◽  
Wave Height ◽  
Satellite Data ◽  
Significant Wave Height ◽  
Wave Climate ◽  
In Situ Measurements ◽  
Altimeter Data ◽  
Sea State ◽  
Significant Wave

Measurements of significant wave height from satellite altimeter missions are finding increasing application in investigations of wave climate, sea state variability and trends, in particular as the means to mitigate the general sparsity of in situ measurements. However, many questions remain over the suitability of altimeter data for the representation of extreme sea states and applications in the coastal zone. In this paper, the limitations of altimeter data to estimate coastal Hs extremes (<10 km from shore) are investigated using the European Space Agency Sea State Climate Change Initiative L2P altimeter data v1.1 product recently released. This Sea State CCI product provides near complete global coverage and a continuous record of 28 years. It is used here together with in situ data from moored wave buoys at six sites around the coast of the United States. The limitations of estimating extreme values based on satellite data are quantified and linked to several factors including the impact of data corruption nearshore, the influence of coastline morphology and local wave climate dynamics, and the spatio-temporal sampling achieved by altimeters. The factors combine to lead to considerable underestimation of estimated Hs 10-yr return levels. Sensitivity to these factors is evaluated at specific sites, leading to recommendations about the use of satellite data to estimate extremes and their temporal evolution in coastal environments.

Spectral Modeling of Sea States With Multiple Wave Systems

1992 ◽  
Vol 114 (4) ◽  
pp. 278-284 ◽  
Author(s):  
C. Guedes Soares ◽  
M. C. Nolasco
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Theoretical Models ◽  
Wave System ◽  
Spectral Parameters ◽  
Peak Period ◽  
Multiple Wave ◽  
Significant Wave ◽  
General Acceptance ◽  
Spectral Models

The spectral models of individual wave systems have one peak and are described by theoretical models that have gained general acceptance. This work deals with sea states with more than one wave system, leading to spectral models with two or more peaks. Use is made of spectra derived from measurements off the Portuguese Coast and data is provided as to their probability of occurrence as well as about the dependence of the spectral parameters on the significant wave height and peak period. It is shown that wind-dominated and swell-dominated two-peaked spectra tend to occur in different areas of the scatter diagram. The spectral parameters of the two-peaked spectra show little correlation with significant wave height and peak period.

Comparison Between a Fatigue Model for Voyage Planning and Measurements of a Container Vessel

2009 ◽  
Author(s):  
Wengang Mao ◽  
Jonas W. Ringsberg ◽  
Igor Rychlik ◽  
Gaute Storhaug
Keyword(s):  
Fatigue Damage ◽  
Wave Height ◽  
Significant Wave Height ◽  
Route Planning ◽  
Estimation Model ◽  
Ongoing Research ◽  
Significant Wave ◽  
The North ◽  
Fatigue Damage Accumulation ◽  
Fatigue Model

This paper presents results from an ongoing research project which aims at developing a numerical tool for route planning of container ships. The objective with the tool is to be able to schedule a route that causes minimum fatigue damage to a vessel before it leaves port. Therefore a new simple fatigue estimation model, only using encountered significant wave height, is proposed for predicting fatigue accumulation of a vessel during a voyage. The formulation of the model is developed based on narrow-band approximation. The significant response height hs, is shown to have a linear relationship with its encountered significant wave height Hs. The zero up-crossing response frequency fz, is represented as the corresponding encountered wave frequency and is expressed as a function of Hs. The capacity and accuracy of the model is illustrated by application on one container vessel’s fatigue damage accumulation, for different voyages, operating in the North Atlantic during 2008. For this vessel, all the necessary data needed in the fatigue model, and for verification of it, was obtained by measurements. The results from the proposed fatigue model are compared with the well-known and accurate rain-flow estimation. The conclusion is that the estimations made using the current fatigue model agree well with the rain-flow method for almost all of the voyages.

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