On the space-time maximum oceanic waves and related sea-state parameters during the tropical storm Kong-rey (2018)

2021 ◽  
Author(s):  
Alvise Benetazzo ◽  
Francesco Barbariol ◽  
Filippo Bergamasco ◽  
Luciana Bertotti ◽  
Luigi Cavaleri ◽  
...  
Keyword(s):  
Wave Height ◽  
Wave Model ◽  
Space Time ◽  
Tropical Storm ◽  
Sea Surface ◽  
Surface Elevation ◽  
Extreme Value Statistics ◽  
Northwestern Pacific ◽  
Sea State ◽  
Temporal Domain

<div> <p><span>The characteristics of the space-time extreme value statistics of maximum oceanic waves under the tropical storm Kong-rey (2018) is investigated in the Northwestern Pacific Ocean (Yellow Sea and East China Sea). We base our composite analysis upon space-time 3D measurements of the sea surface elevation field and wave model frequency/direction spectra. We focus on the highest individual waves that may develop at short-term/range under the cyclonic winds and we consider the spatial distribution around the storm centre of two main variables of interest, namely the maximum sea surface elevation (crest height) and the maximum wave height. Their expectations are linked to characteristic parameters of the sea state, such as the significant wave height, the mean steepness, the directional spreading, the bandwidth, of which we extend the meaning in the temporal domain in order to include the 3D geometry of the wave field. Our results evidence the sea regions where the highest individual waves may be expected and highlights, via scale analysis, the main mechanisms responsible for the generation of space-time extreme conditions. </span></p> </div>

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.

scholarly journals Operational numerical wind-wave model for the Black Sea

2000 ◽  
Vol 1 (1) ◽  
pp. 65
Author(s):  
A. KORTCHEVA ◽  
G. KORTCHEV ◽  
J. M. LEFEVRE
Keyword(s):  
Shallow Water ◽  
Real Time ◽  
Wave Height ◽  
Black Sea ◽  
Water Wave ◽  
Wind Wave ◽  
Wave Model ◽  
The Black Sea ◽  
Sea State ◽  
Height Data

In this paper the discrete spectral shallow water wave model named VAGBUHL1 is presented. This model is used for real-time Black Sea state forecasting. The model was verified against satellite ERS-2 altimeter wave height data.

X-Band Radar as a Tool to Determine Spectral and Single Wave Properties

2006 ◽  
Author(s):  
Konstanze Reichert ◽  
Katrin Hessner ◽  
Jens Dannenberg ◽  
Ina Traenkmann
Keyword(s):  
Real Time ◽  
Ocean Waves ◽  
Sea Surface ◽  
Surface Elevation ◽  
Radar Signal ◽  
Sea State ◽  
Single Wave ◽  
Radar Images ◽  
X Band ◽  
Wave Properties

The Wave Monitoring System WaMoS II was developed for real time measurements of directional ocean waves spectra to monitor the sea state from fixed platforms in deep water or coastal areas as well as from moving vessels. The system is based on a standard marine X-Band radar used for navigation and ship traffic control. WaMoS II digitises the analogous radar signal and analyses the sea clutter information to obtain directional wave spectra from the sea surface in real time even under harsh weather conditions and during night. Spectral sea state parameters such as significant wave height, peak wave period and peak wave direction both for wind sea and swell are derived. Within the EU funded project ‘MaxWave’ and the German project ‘SinSee’ new algorithms were developed to determine sea surface elevation maps from radar images which are used to investigate the spatial and temporal evolution of single waves simultaneously. In this paper a short overview describes the calculation of surface elevation maps and the detection of individual waves. Considering two case studies, the results of spatial single wave detection and corresponding temporal single wave properties are compared and discussed. Individual wave parameters derived from radar images are compared to individual waves measured by a buoy. An application of the method to characterise extreme sea states is discussed.

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.

Harmony's ocean elevation measurements: potential and performance

2020 ◽  
Author(s):  
Andreas Theodosiou ◽  
Paco Lopez Dekker ◽  
Marcel Kleinherenbrink ◽  
Gert Mulder
Keyword(s):  
Sea Surface ◽  
Surface Elevation ◽  
Sea State ◽  
Temporal Decorrelation ◽  
First Results ◽  
Sea State Bias ◽  
Sea Surface Heights ◽  
And Performance ◽  
Cross Track ◽  
Along Track

<p>Harmony, an Earth Explorer 10 candidate mission, consists of two receive-only Synthetic Aperture Radar (SAR) satellites using Sentinel-1D as the illuminator. The mission will switch between close formation phases and StereoSAR phases, dedicated to relative surface elevation and relative surface motion respectively. Interferometric observations of the ocean have, in the past, been hindered by the quick temporal decorrelation of the sea surface; a result of the along-track baseline that often comes with the cross-track baseline necessary for interferometry. Specialised SAR systems aiming to observe the oceans need to account for the decorrelation of the surface. SWOT overcomes the issue by fixing the two SAR antennas to physically eliminate their along-track separation. Due to the squinted, bistatic nature of the formation, Harmony can act as an altimeter, observing relative sea-surface heights (SSH) over unprecedented wide swaths. Hence, the mission promises to have highly coherent observations of the sea surface, leading to accurate surface elevation measurements. The wide swath will enable the recovery of mesoscale features of the ocean surface in a single pass. We will present the first results of the performance analysis of the mission's observations of elevation over the oceans. The effect of errors, namely the residual Doppler, baseline errors and sea-state bias, on the observations will also be discussed.</p>

Remote Sensing of Sea Surface Wave by Using CW X-Band Microwave Doppler Radar at Sagami-Bay

2008 ◽  
Author(s):  
Chang-Kyu Rheem
Keyword(s):  
Surface Waves ◽  
Wave Height ◽  
Water Surface ◽  
Doppler Radar ◽  
Sea Surface ◽  
Surface Elevation ◽  
Sagami Bay ◽  
Water Surface Elevation ◽  
Water Particle ◽  
Sea Surface Waves

Sea surface waves had been observed remotely by using a continuous wave (CW) X-band microwave Doppler radar at the off Hitatsuka of Sagami-bay in Japan. A new algorithm was applied to retrieve sea surface elevation from radar output Doppler signals. The sea surface waves observed by the microwave Doppler radar had been compared with the waves measured by a supersonic wave height meter. There were good correlations in both the wave height and the wave period between the waves observed by the microwave Doppler radar and that measured by a supersonic wave height meter. The correlation of wave heights was better than that of wave periods. The microwave irradiation width on sea surface does a role of space filter. It seems that the filtering effect is a kind of aliasing, the energy of short wavelength waves moves to low wave number region. The algorithm to retrieve a sea surface elevation is described by the relation of the water surface elevation and the orbital velocity of water particle on water surface that generated by water surface waves. A linear superposition method has been used to retrieve sea surface elevation. No empirical parameters are used in the algorithm, because the water surface elevation can be obtained from the water particle velocity on water surface by using the mathematical relation of the water surface elevation and the orbital motion of water particle. Water particle motion on sea surface is affected by sea surface wind, currents, and sea surface waves. Water particle motion generated by sea surface waves can be separated by the difference of the fluctuation scale of each physical process.

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 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.

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