Estimation of extreme wave height and sea state

Ocean Waves ◽  
1998 ◽  
pp. 149-174 ◽  
Keyword(s):  
Wave Height ◽  
Extreme Wave ◽  
Sea State

Wave climate extremes from the Sea State CCI satellite data

2021 ◽  
Author(s):  
Marta Ramirez ◽  
Melisa Menendez ◽  
Guillaume Dodet
Keyword(s):  
Wave Height ◽  
Satellite Data ◽  
Significant Wave Height ◽  
Regional Analysis ◽  
Wave Climate ◽  
Extratropical Cyclones ◽  
Extreme Waves ◽  
Extreme Wave ◽  
Sea State ◽  
Significant Wave

<p>The knowledge of ocean extreme wave climate is of significant importance for a number of coastal and marine activities (e.g. coastal protection, marine spatial planning, offshore engineering). This study uses the recently released Sea State CCI v1 altimeter product to analyze extreme wave climate conditions at global scale. The dataset comprises 28-years inter-calibrated and denoised significant wave height data from 10 altimeter missions.</p><p>First, a regional analysis of the available satellite information of extreme waves associated with both, tropical and extratropical cyclones, is carried out. As tropical cyclones, we analyze two intense events which affected the Florida Peninsula and Caribbean Islands: Wilma (in October 2005) and Irma (in August 2017) hurricanes. As extratropical cyclones, we focused on the extreme waves during the 2013-2014 winter season along the Atlantic European coasts. The extreme waves associated with these events are identified in the satellite dataset and are compared with in situ and high-resolution simulated data. The analysis of the satellite data during the storm tracks and its comparison against other data sources indicate that satellite data can provide added value for the analysis of extreme wave conditions that caused important coastal damages.</p><p>After assessing the quality of extreme wave data measured by altimeters from this regional analysis, we explore a method to characterize wave height return values (e.g. 50yr return period significant wave height) from the multi-mission satellite data. The method is validated through comparisons with return values estimated from long-term wave buoy records. The extreme analysis is based on monthly maxima of satellite significant wave height computed over marine areas of varying extensions and centered on a target location (e.g. the wave buoy location for comparison and validation of the method).  The extension of the areas is defined from a seasonal study of the spatial correlation and the error metrics of the satellite data against the selected coastal location. We found a threshold of 0.85 correlation as the isoline to select the satellite data subsample (i.er. larger areas to select satellite maxima are found during winter seasons). Finally, a non-stationary extreme model based on GEV distribution is applied to obtain quantiles of low probability. Outcomes from satellite data are validated against extreme estimates from buoy records.</p>

scholarly journals Estimation of Significant Wave Heights from ASCAT Scatterometer Data via Deep Learning Network

2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
He Wang ◽  
Jingsong Yang ◽  
Jianhua Zhu ◽  
Lin Ren ◽  
Yahao Liu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Wave Height ◽  
Significant Wave Height ◽  
Incidence Angle ◽  
Ocean Waves ◽  
Global Scale ◽  
Learning Technology ◽  
Sea State ◽  
Significant Wave ◽  
Wave Heights

Sea state estimation from wide-swath and frequent-revisit scatterometers, which are providing ocean winds in the routine, is an attractive challenge. In this study, state-of-the-art deep learning technology is successfully adopted to develop an algorithm for deriving significant wave height from Advanced Scatterometer (ASCAT) aboard MetOp-A. By collocating three years (2016–2018) of ASCAT measurements and WaveWatch III sea state hindcasts at a global scale, huge amount data points (>8 million) were employed to train the multi-hidden-layer deep learning model, which has been established to map the inputs of thirteen sea state related ASCAT observables into the wave heights. The ASCAT significant wave height estimates were validated against hindcast dataset independent on training, showing good consistency in terms of root mean square error of 0.5 m under moderate sea condition (1.0–5.0 m). Additionally, reasonable agreement is also found between ASCAT derived wave heights and buoy observations from National Data Buoy Center for the proposed algorithm. Results are further discussed with respect to sea state maturity, radar incidence angle along with the limitations of the model. Our work demonstrates the capability of scatterometers for monitoring sea state, thus would advance the use of scatterometers, which were originally designed for winds, in studies of ocean waves.

Sea State Estimation Based on Ship Motions Measurements and Data Fusion

2013 ◽  
Author(s):  
Céline Drouet ◽  
Nicolas Cellier ◽  
Jérémie Raymond ◽  
Denis Martigny
Keyword(s):  
Data Fusion ◽  
State Estimation ◽  
Wave Height ◽  
Significant Wave Height ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Ship Motions ◽  
Sea State ◽  
Significant Wave ◽  
X Band

In-service monitoring can help to increase safety of ships especially regarding the fatigue assessment. For this purpose, it is compulsory to know the environmental conditions encountered: wind, but also the full directional wave spectrum. During the EU TULCS project, a full scale measurements campaign has been conducted onboard the CMA-CGM 13200 TEU container ship Rigoletto. She has been instrumented to measure deformation of the ship as well as the sea state encountered during its trip. This paper will focus on the sea state estimation. Three systems have been installed to estimate the sea state encountered by the Rigoletto: An X-band radar from Ocean Waves with WAMOS® system and two altimetric wave radars from RADAC®. Nevertheless, the measured significant wave height can be disturbed by several external elements like bow waves, sprays, sea surface ripples, etc… Furthermore, ship motions are also measured and can provide another estimation of the significant wave height using a specific algorithm developed by DCNS Research for the TULCS project. As all those estimations are inherently different, it is necessary to make a fusion of those data to provide a single estimation (“best estimate”) of the significant wave height. This paper will present the data fusion process developed for TULCS and show some first validation results.

scholarly journals Assessment of reliability of extreme wave height prediction models

2017 ◽  
Vol 17 (3) ◽  
pp. 409-421 ◽  
Author(s):  
Satish Samayam ◽  
Valentina Laface ◽  
Sannasiraj Sannasi Annamalaisamy ◽  
Felice Arena ◽  
Sundar Vallam ◽  
...  
Keyword(s):  
North America ◽  
Mediterranean Sea ◽  
Wave Height ◽  
Prediction Models ◽  
North Pacific Ocean ◽  
Coastal Hazards ◽  
Extreme Wave ◽  
Indian Water ◽  
Wave Hindcast ◽  
Buoy Data

Abstract. Extreme waves influence coastal engineering activities and have an immense geophysical implication. Therefore, their study, observation and extreme wave prediction are decisive for planning of mitigation measures against natural coastal hazards, ship routing, design of coastal and offshore structures. In this study, the estimates of design wave heights associated with return period of 30 and 100 years are dealt with in detail. The design wave height is estimated based on four different models to obtain a general and reliable model. Different locations are considered to perform the analysis: four sites in Indian waters (two each in Bay of Bengal and the Arabian Sea), one in the Mediterranean Sea and two in North America (one each in North Pacific Ocean and the Gulf of Maine). For the Indian water domain, European Centre for Medium-Range Weather Forecasts (ECMWF) global atmospheric reanalysis ERA-Interim wave hindcast data covering a period of 36 years have been utilized for this purpose. For the locations in Mediterranean Sea and North America, both ERA-Interim wave hindcast and buoy data are considered. The reasons for the variation in return value estimates of the ERA-Interim data and the buoy data using different estimation models are assessed in detail.

scholarly journals Operability Guidelines For Product Tanker In Heavy Weather In The Adriatic Sea

2014 ◽  
Vol 21 (1) ◽  
pp. 95-106
Author(s):  
Luka Mudronja ◽  
Marko Katalinić ◽  
Rino Bošnjak ◽  
Pero Vidan ◽  
Joško Parunov
Keyword(s):  
Wave Height ◽  
Adriatic Sea ◽  
Wave Spectrum ◽  
Extreme Weather ◽  
The South ◽  
Sea State ◽  
M Wave ◽  
The North ◽  
Limiting Values ◽  
Deck Wetness

AbstractThis paper presents operability guidelines for seafarers on a product tanker which navigates in the Adriatic Sea during heavy weather. Tanker route starts from the Otranto strait in the south to the island Krk in the north of Adriatic Sea. Heavy weather is caused by south wind called jugo (blowing from E-SE to SS-E, sirocco family). Operability guidelines are given based on an operability criteria platform for presenting ship seakeeping characteristics. Operability criteria considered in this paper are propeller emergence, deck wetness and bow acceleration of a product tanker. Limiting values of mentioned criteria determine sustainable speed. Heavy weather is described by extreme sea state of 7.5 m wave height. Wave spectrum used in this paper is Tabain spectrum which is developed specifically for Adriatic Sea. Seafarer's approach of decisions making in extreme weather is also shown and servers as a guideline for further research of the authors.

Extreme Wave Condition at Doggerbank

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Espen Engebretsen ◽  
Sverre K. Haver ◽  
Dag Myrhaug
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Offshore Wind ◽  
Extreme Condition ◽  
Exceedance Probability ◽  
Extreme Wave ◽  
Sea State ◽  
Wave Condition ◽  
The North ◽  
Wave Conditions

In design of offshore wind turbines, extreme wave conditions are of interest. Usually, the design wave condition is taken as the sea state corresponding to an annual exceedance probability of 2 × 10−2, i.e., a return period of 50 years. A possible location for a future wind farm, consisting of bottom fixed wind turbines, is the Doggerbank area. The water depth in this area varies from about 60 m in the north to about 20 m in the south. The hindcast database NORA10 provides sea state characteristics from 1957 to present over a domain covering Doggerbank. Regarding the deeper areas just north of Doggerbank, this hindcast model is found to be of good quality. Larger uncertainties are associated with the hindcast results as we approach shallower water further south. The purpose of the present study is to compare sea state evolution over Doggerbank as reflected by NORA10 with the results of the commonly used shallow water hindcast model SWAN. The adequacy of the default parameters of SWAN for reflecting changes in wave conditions over a sloping bottom is investigated by comparison with model test results. Extreme wave conditions for two locations 102.5 km apart in a north–south direction are established using NORA10. This is done using both, an all sea states approach and a peak over threshold (POT) approach. Assuming the extremes for the northern position to represent good estimates, the wave evolution southward is analyzed using SWAN. The extreme condition obtained from NORA10 in the northern position is used as input to SWAN and the results from the two hindcast models are compared in the southern position. SWAN seems to suggest a somewhat faster decay over Doggerbank compared to NORA10.

scholarly journals STATISTICAL PROPERTIES OF THE MAXIMUM RUN OF IRREGULAR SEA WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 48 ◽  
Author(s):  
Akira Kimura
Keyword(s):  
Probability Distribution ◽  
Wave Height ◽  
Probability Distributions ◽  
Confidence Regions ◽  
Statistical Properties ◽  
Irregular Waves ◽  
Sea Waves ◽  
Sea State ◽  
Irregular Wave ◽  
Distribution Of The Maximum

The probability distribution of the maximum run of irregular wave height is introduced theoretically. Probability distributions for the 2nd maximum, 3rd maximum and further maximum runs are also introduced. Their statistical properties, including the means and their confidence regions, are applied to the verification of experiments with irregular waves in the realization of a "severe sea state" in the test.

Overcoming Challenges of Mechanical Lifting Capabilities on Offshore Installation by Utilizing Coiled Tubing Boat Spooling Technique

2021 ◽  
Author(s):  
Stefan Dinger ◽  
Andrei Casali ◽  
Frank Lind ◽  
Azwan Hadi Keong ◽  
Johnny Bårdsen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Real Time ◽  
Wave Height ◽  
Careful Study ◽  
Sea State ◽  
M Wave ◽  
Coiled Tubing ◽  
Wide Range ◽  
Downhole Measurements ◽  
Outside Diameter

Abstract Coiled tubing (CT) operations in the Norwegian continental shelf (NCS) often require a long and large-outside-diameter pipe due to big diameter completions, deep wells, and the need for high annular velocity during fluid circulation. However, getting the CT string onboard becomes a challenge when the crane lifting limit is 35 t, and using a standalone crane barge increases the cost of the operation. The alternative is spooling the CT from a vessel to the platform. Boat spooling is done by placing the CT string on a floating vessel with dynamic positioning while the standard CT injector head is secured at the edge of the platform to pull the pipe from the vessel to an empty CT reel on the platform. The boat is equipped with a CT guide; special tension clamps; and an emergency disconnect system, which consists of a standard CT shear-seal blowout preventer. The technique requires careful study of the platform structure for placement of the injector head support frame, metocean data of the field, and equipment placement on the vessel and platform. The boat spooling operation of a 7,700-m long, 58.7-t, 2.375-in.-outside-diameter CT string was successfully executed for a platform at 70-m height from mean sea level. The total operating time from hooking up the vessel to successfully spooling the string only took 12 hours. Historically for the region, the method has been attempted in sea state of up to 4-m wave height and 16 knots maximum wind speed. For this operation, the spooling was carried out during an average sea state of 2-m wave height and 15-knot wind speed. The continuous CT string allows a telemetry cable to be installed inside the pipe after the CT is spooled onto the platform reel, enabling real-time downhole measurements during the intervention. Such installation is not possible or presents high risk if the CT string is taken onboard by splicing two sections of pipe together with a spoolable connector or butt welding. From a cost perspective, the boat-spooling operation had up to 80% direct cost saving for the operator when compared to other methods of lifting a single CT string onboard, such as using a motion-compensated barge crane. The planning for the boat spooling included several essential contingency plans. Performing a CT boat spooling operation in a complex environment is possible and opens new opportunities to use longer and heavier CT strings, with lower mobilization costs. Such strings enable more advanced and efficient interventions, with the option of using real-time CT downhole measurements during the execution of a wide range of production startup work. This, in turn, is critical to support the drilling of more extended reach wells, which allow access to untapped reservoirs.

scholarly journals Quasistatic Nonlinear Analysis of a Drill Pipe in Subsea Xmas Tree Installation

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Haozhi Qin ◽  
Jian Liu ◽  
Wensheng Xiao ◽  
Bingxiang Wang
Keyword(s):  
Nonlinear Analysis ◽  
Wave Height ◽  
Drill Pipe ◽  
Beam Theory ◽  
Sea State ◽  
Variable Parameters ◽  
Towing Speed ◽  
Stress And Deformation ◽  
Method Accuracy ◽  
Euler Bernoulli Beam

To analyse the stress and deformation of a drill pipe during the lowering of a subsea Xmas tree, a mechanical analytical model and equation were established based on Euler-Bernoulli beam theory. The wave phase is selected as one of the variable parameters for analysis of the deformation and stress of the drill pipe. The research results indicate that the maximum response occurs at 0 radians in the scope of 0 to 2π, and the quasistatic nonlinear analysis is analysed at 0. In addition, Orcaflex software is applied for simulation, and the simulation results are compared with the results from proposed method, which demonstrate the model and the method accuracy. Factors that affect the installation process are discussed, such as current velocity, wave height, pipe size, and towing speed. The results show that all factors have remarkable effects on stress and deformation and that the wave height has a lesser effect on the deformation of the drill pipe. The viable towing speed is chosen by discussing the total stress of the drill pipe with various towing speeds and is notably useful for installation in the real sea state.

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