scholarly journals Global ship accidents and ocean swell-related sea states

2017 ◽  
Vol 17 (11) ◽  
pp. 2041-2051 ◽  
Author(s):  
Zhiwei Zhang ◽  
Xiao-Ming Li
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Environmental Issues ◽  
Wave Model ◽  
Economic Losses ◽  
Wave Direction ◽  
Sea State ◽  
Mean Wave Period ◽  
Numerical Wave ◽  
Wind Sea

Abstract. With the increased frequency of shipping activities, navigation safety has become a major concern, especially when economic losses, human casualties and environmental issues are considered. As a contributing factor, the sea state plays a significant role in shipping safety. However, the types of dangerous sea states that trigger serious shipping accidents are not well understood. To address this issue, we analyzed the sea state characteristics during ship accidents that occurred in poor weather or heavy seas based on a 10-year ship accident dataset. Sea state parameters of a numerical wave model, i.e., significant wave height, mean wave period and mean wave direction, were analyzed for the selected ship accident cases. The results indicated that complex sea states with the co-occurrence of wind sea and swell conditions represent threats to sailing vessels, especially when these conditions include similar wave periods and oblique wave directions.

scholarly journals Global ship accidents and ocean swell-related sea states

2017 ◽  
Author(s):  
Zhiwei Zhang ◽  
Xiao-Ming Li
Keyword(s):  
Environmental Issues ◽  
Wave Model ◽  
Economic Losses ◽  
Model Data ◽  
Wave Direction ◽  
Sea State ◽  
Mean Wave Period ◽  
The Mean ◽  
Numerical Wave ◽  
Wind Sea

Abstract. With the increased frequency of shipping activities, navigation safety has become a major concern, especially when economic losses, human casualties and environmental issues are considered. As a contributing factor, sea state conditions play a significant role in shipping safety. However, the types of dangerous sea states that trigger serious shipping accidents are not well understood. To address this issue, we analyzed the sea state characteristics during ship accidents that occurred in poor weather or heavy seas based on a ten-year ship accident dataset. The sea state parameters, including the significant wave height, the mean wave period and the mean wave direction, obtained from numerical wave model data were analyzed for selected ship accidents. The results indicated that complex sea states with the co-occurrence of wind sea and swell conditions represent threats to sailing vessels, especially when these conditions include close wave periods and oblique wave directions.

scholarly journals Sea State Determination from Ship-Based Geodetic GPS

2014 ◽  
Vol 31 (11) ◽  
pp. 2556-2564 ◽  
Author(s):  
James Foster ◽  
Ning Li ◽  
Kwok Fai Cheung
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Ocean Waves ◽  
Sea Surface ◽  
Wave Direction ◽  
Sea State ◽  
Dominant Wave ◽  
Model Predictions ◽  
Economic Vitality ◽  
Buoy Data

AbstractOcean waves have a profound impact on navigation, offshore operations, recreation, safety, and the economic vitality of a nation’s maritime and coastal communities. This study demonstrates that ships equipped with geodetic GPS and a radar gauge can provide accurate estimates of sea state. The Research Vessel (R/V) Kilo Moana recorded 1-Hz data for the entire period of a 10-day cruise around the Hawaiian Islands. Solving for precise kinematic positions for the ship and combining these solutions with the ranges from the ship to the sea surface provided by the radar gauge, it was possible to retrieve 1-Hz estimates of the sea surface elevation along the cruise track. Converting these into estimates of significant wave height, strong agreement was found with wave buoy measurements and hindcast wave data. Comparison with buoy data indicates the estimates have errors on the order of 0.22 m, or less than 11% of the wave height. Using wave model predictions of the dominant directions, the data were processed further to correct for the Doppler shift and to estimate the dominant wave period. Although relatively noisy in locations where the predicted wave directions are expected to be poor, in general these estimates also show a good agreement with the wave buoy observations and hindcast wave estimates. A segment of the cruise that formed a circuit allowed for testing the consistency of the ship-based estimates and for determining a dominant wave direction, which was found to agree closely with model predictions.

Error estimation of buoy, altimeter, and model significant wave height from triple collocation technique

2021 ◽  
Author(s):  
Guillaume Dodet ◽  
Jean-Raymond Bidlot ◽  
Mickaël Accensi ◽  
Mathias Alday ◽  
Saleh Abdalla ◽  
...  
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Sea State ◽  
Significant Wave ◽  
In Situ Data ◽  
Collocation Technique ◽  
Coastal Risk ◽  
Marine Engineering

<p>Ocean wave information is of major importance for a number of applications including climate studies, safety at sea, marine engineering (offshore and coastal), and coastal risk management. Depending on the scales and regions of interest, several data sources may be considered (e.g. in situ data, VOS observations, altimeter records, numerical wave model), each one with its pros and cons. In order to optimize the use of multiple source wave information (e.g. through assimilation scheme in NWP), the error characteristics of each measurement system need to be investigated and inter-compared. In this study, we use triple collocation technique to estimate the random error variances of significant wave height from in situ, altimeter and model data. The buoy dataset is a selection of ~100 in-situ measuring stations provided by the CMEMS In-Situ Thematic Assembly Center. The altimeter dataset is composed of the ESA Sea State CCI V1.1 L2P product. The model dataset is the result of WW3 Ifremer hindcast run forced with ERA5 winds using the recently updated T475 parameterization. In comparisons to previous studies using similar techniques, the large triple collocation dataset (~450 000 matchups in total) generated for this study provides some new insights on the error variability within in situ stations, satellite missions and upon sea state conditions.Moreover, the results of the triple collocation technique help developing improved calibration of the altimeter missions included in the ESA Sea State CCI V1.1 dataset.</p>

scholarly journals A study of the 1 and 2 January 2010 sea-storm in the Ligurian Sea

2011 ◽  
Vol 6 (1) ◽  
pp. 109-115 ◽  
Author(s):  
F. Pasi ◽  
A. Orlandi ◽  
L. F. Onorato ◽  
S. Gallino
Keyword(s):  
Wave Height ◽  
Western Europe ◽  
Weather Prediction ◽  
Wave Model ◽  
Western Mediterranean ◽  
Westerly Wind ◽  
Sea State ◽  
Pressure System ◽  
Ligurian Sea ◽  
Wind Sea

Abstract. During the last days of 2009 and the first days of 2010, a wide and deep low pressure system over Western Europe generated a very extended and strong southerly pressure gradient on the whole Western Mediterranean Sea with a resulting very rough to high sea state. Over the Ligurian Sea (North Western Mediterranean) the resulting sea state was a combination of a very tuned (in both frequency and direction) swell coming from the south-west, with nearly oceanic peak wave period, and a broader north-westerly wind sea with shorter period. This kind of sea state, not extreme in terms of significant wave height, caused unusual widespread damages to Ligurian coastal structures. In this study, authors investigated the structure of such a combined sea state by analysing numerical weather prediction outputs coming from atmospheric and wave models and comparing them with data coming from ondametric buoys and meteorological stations located in the Ligurian Sea area. As a result, it was found that the forecasting model chain almost correctly predicted the wave height in a first phase, when the sea state was only due to the first south-westerly swell peak, while significantly underestimated the combined sea state, when also the second north-westerly wind sea developed and interacted with the first one. By analysing the structure of directional wave spectra forecasted by the operational wave model and measured by the buoys, authors have attempted to find out the reasons for model deficiencies in forecasting the time evolution of significant parameters characterising the sea state.

scholarly journals The importance of wind forcing in fjord wave modelling

2019 ◽  
Vol 70 (1) ◽  
pp. 57-75 ◽  
Author(s):  
Konstantinos Christakos ◽  
Birgitte R. Furevik ◽  
Ole Johan Aarnes ◽  
Øyvind Breivik ◽  
Laura Tuomi ◽  
...  
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Ocean Waves ◽  
Wind Forcing ◽  
Significant Wave ◽  
Surface Ocean ◽  
Open Sea ◽  
Mean Wave Period ◽  
Wind Input

AbstractAccurate predictions of surface ocean waves in coastal areas are important for a number of marine activities. In complex coastlines with islands and fjords, the quality of wind forcing significantly affects the results. We investigate the role of wind forcing on wave conditions in a fjord system partly exposed to open sea. For this reason, we implemented the wave model SWAN at the west coast of Norway using four different wind forcing. Wind and wave estimates were compared with observations from five measurement sites. The best results in terms of significant wave height are found at the sites exposed to offshore conditions using a wind input that is biased slightly high compared with the buoy observations. Positively biased wind input, on the other hand, leads to significant overestimation of significant wave height in more sheltered locations. The model also shows a poorer performance for mean wave period in these locations. Statistical results are supported by two case studies which also illustrate the effect of high spatial resolution in wind forcing. Detailed wind forcing is necessary in order to obtain a realistic wind field in complex fjord terrain, but wind channelling and lee effects may have unpredictable effects on the wave simulations. Pure wave propagation (no wind forcing) is not able to reproduce the highest significant wave height in any of the locations.

Comparing Nearshore Wave Parameters in Amurang Bay location using MIKE-21 Spectral Wave Model

2019 ◽  
Vol 1 (2) ◽  
pp. 150-158
Author(s):  
Tommy Jansen
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Wave Model ◽  
Google Earth ◽  
Coastal Development ◽  
Wave Direction ◽  
Wet Season ◽  
Significant Wave ◽  
Wave Parameters ◽  
Mike 21

Wave parameters as an accurate prediction in ocean environment are important thing for good coastal development. Spectral wind wave model as a tools in MIKE 21 SW based on unstructured mesh is used in this study which the model simulates the growth, decay and transformation of wind generated waves and swell in offshore and coastal areas. The Amurang Bay as the province of North Sulawesi Indonesia was selected as the study area which the geography position around 1012’16.16” N-124027’04.33” E to 1015’43.80” N-124032’01.06”E. The bathymetry and tide data used in this research from Indonesian Coastline Environmental map of year 1995 with scale 1:50.000 from BIG (Badan Informasi Geospasial) with a satellite data from Google earth of year 2018 and LANTAMAL Manado, the wind and current data was obtained from BMKG Manado. Time simulations are taken from 25 November to 23 December 2016 as a wet season and 25 Mei to 23 June 2016 as a dry season.The model computed the wave parameters using the forecast wind input. The synoptic map of significant wave height (Hs), wave period, wave direction are obtained from the result of simulation. During the dry and wet season conditions the predicted wave parameters as the result of the simulation with tide and wind show to be higher than with tide and no wind simulation. The average condition of significant wave height is higher in outside of bay than inside of bay.

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.

Effect of Uni- and Bi-Directional Coupling of Ocean-Met Interaction on Significant Wave Height and Local Wind

2017 ◽  
Author(s):  
Adil Rasheed ◽  
Jakob Kristoffer Süld ◽  
Mandar Tabib
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Wave Model ◽  
Ocean Surface ◽  
Observation Data ◽  
Local Wind ◽  
Near Surface ◽  
Significant Wave ◽  
Bidirectional Coupling

Accurate prediction of near surface wind and wave height are important for many offshore activities like fishing, boating, surfing, installation and maintenance of marine structures. The current work investigates the use of different methodologies to make accurate predictions of significant wave height and local wind. The methodology consists of coupling an atmospheric code HARMONIE and a wave model WAM. Two different kinds of coupling methodologies: unidirectional and bidirectional coupling are tested. While in Unidirectional coupling only the effects of atmosphere on ocean surface are taken into account, in bidirectional coupling the effects of ocean surface on the atmosphere are also accounted for. The predicted values of wave height and local wind at 10m above the ocean surface using both the methodologies are compared against observation data. The results show that during windy conditions, a bidirectional coupling methodology has better prediction capability.

scholarly journals Nearshore Waves and Littoral Drift Along a Micro-Tidal Wave-Dominated Coast Having Comparable Wind-Sea and Swell Energy

2020 ◽  
Vol 8 (1) ◽  
pp. 55
Author(s):  
Jesbin George ◽  
V. Sanil Kumar ◽  
R. Gowthaman ◽  
Jai Singh
Keyword(s):  
Sediment Transport ◽  
Wave Model ◽  
Model Data ◽  
Wave Direction ◽  
Littoral Drift ◽  
Relative Contribution ◽  
Wave Parameters ◽  
Longshore Sediment Transport ◽  
Wind Sea ◽  
Small Change

The nearshore wave characteristics and variations in littoral drift (longshore sediment transport; LST) are estimated based on different approaches for four years along the Vengurla coast, with comparable wind-sea and swell energy assessed. The waverider buoy-measured data at 15 m water depth is utilized as the input wave parameters along with the reanalysis model data, and the numerical wave model Delft-3D is used for estimating the nearshore wave parameters. The relative contribution of wind-seas and swells on LST rates are specifically examined. The clear prevalence of west-southwest waves implies the prevalence of south to north longshore sediment transport with net transport varying from 0.19–0.37 × 105 m3/yr. LST is strongly dependent on the breaker angle and a small change in the wave direction substantially alters the LST, and hence reanalysis/model data with coarse resolutions produce large errors (~38%) in the LST estimate. The annual gross LST rate based on integral wave parameters is only 58% considering the wind-seas and swells separately, since the wind-sea energy is comparable to swell energy, and the direction of these two systems differs significantly.

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