Retrieval of wave period from altimetry: Deep learning accounting for random wave field dynamics

2021 ◽  
Vol 265 ◽  
pp. 112629
Author(s):  
Jiuke Wang ◽  
Lotfi Aouf ◽  
Sergei Badulin
Keyword(s):  
Deep Learning ◽  
Wave Field ◽  
Wave Period ◽  
Random Wave ◽  
Random Wave Field

scholarly journals Soliton spectra of random water waves in shallow basins

2018 ◽  
Vol 13 (4) ◽  
pp. 40 ◽  
Author(s):  
J.-P. Giovanangeli ◽  
C. Kharif ◽  
Y.A. Stepanyants
Keyword(s):  
Shallow Water ◽  
Wave Field ◽  
Water Waves ◽  
Wind Waves ◽  
Inverse Scattering Method ◽  
Random Wave ◽  
Scattering Method ◽  
Wave Fields ◽  
Fourier Spectra ◽  
Random Wave Field

Interpretation of random wave field on a shallow water in terms of Fourier spectra is not adequate, when wave amplitudes are not infinitesimally small. A nonlinearity of wave fields leads to the harmonic interactions and random variation of Fourier spectra. As has been shown by Osborne and his co-authors, a more adequate analysis can be performed in terms of nonlinear modes representing cnoidal waves; a spectrum of such modes remains unchanged even in the process of nonlinear mode interactions. Here we show that there is an alternative and more simple analysis of random wave fields on shallow water, which can be presented in terms of interacting Korteweg–de Vries solitons. The data processing of random wave field is developed on the basis of inverse scattering method. The soliton component obscured in a random wave field is determined and a corresponding distribution function of number of solitons on their amplitudes is constructed. The approach developed is illustrated by means of artificially generated quasi-random wave field and applied to the real data interpretation of wind waves generated in the laboratory wind tank.

Observations of freak waves in random wave field in 2D experimental wave flume

2013 ◽  
Vol 27 (5) ◽  
pp. 659-670 ◽  
Author(s):  
Jin-xuan Li ◽  
Peng-fei Li ◽  
Shu-xue Liu
Keyword(s):  
Wave Field ◽  
Random Wave ◽  
Freak Waves ◽  
Wave Flume ◽  
Random Wave Field

Modeling the presence of wave groups in a random wave field

1978 ◽  
Vol 83 (C8) ◽  
pp. 4117 ◽  
Author(s):  
E. Mollo-Christensen ◽  
A. Ramamonjiarisoa
Keyword(s):  
Wave Field ◽  
Random Wave ◽  
Wave Groups ◽  
Random Wave Field

Statistics of Random Wave Field

1975 ◽  
Vol 101 (4) ◽  
pp. 435-449
Author(s):  
Keikhosrow Pajouhi ◽  
Chi C. Tung
Keyword(s):  
Wave Field ◽  
Random Wave ◽  
Random Wave Field

scholarly journals Spontaneous inertia-gravity-wave generation by surface-intensified turbulence

2012 ◽  
Vol 699 ◽  
pp. 153-173 ◽  
Author(s):  
E. Danioux ◽  
J. Vanneste ◽  
P. Klein ◽  
H. Sasaki
Keyword(s):  
Wave Field ◽  
Large Scale ◽  
Spatial Scales ◽  
Baroclinic Instability ◽  
Small Scale ◽  
Random Wave ◽  
Spontaneous Generation ◽  
Thin Filaments ◽  
Random Wave Field ◽  
Omega Equation

AbstractThe spontaneous generation of inertia-gravity waves (IGWs) by surface-intensified, nearly balanced motion is examined using a high-resolution simulation of the primitive equations in an idealized oceanic configuration. At large scale and mesoscale, the dynamics, which is driven by baroclinic instability near the surface, is balanced and qualitatively well described by the surface quasi-geostrophic model. This however predicts an increase of the Rossby number with decreasing spatial scales and, hence, a breakdown of balance at small scale; the generation of IGWs is a consequence of this breakdown. The wave field is analysed away from the surface, at depths where the associated vertical velocities are of the same order as those associated with the balanced motion. Quasi-geostrophic relations, the omega equation in particular, prove sufficient to separate the IGWs from the balanced contribution to the motion. A spectral analysis indicates that the wave energy is localized around dispersion relation for free IGWs, and decays only slowly as the frequency and horizontal wavenumber increase. The IGW generation is highly intermittent in time and space: localized wavepackets are emitted when thin filaments in the surface density are formed by straining, leading to large vertical vorticity and correspondingly large Rossby numbers. At depth, the IGW field is the result of a number of generation events; away from the generation sites it takes the form of a relatively homogeneous, apparently random wave field. The energy of the IGW field generated spontaneously is estimated and found to be several orders of magnitude smaller than the typical IGW energy in the ocean.

Large-time evolution of statistical moments of wind–wave fields

2013 ◽  
Vol 726 ◽  
pp. 517-546 ◽  
Author(s):  
Sergei Y. Annenkov ◽  
Victor I. Shrira
Keyword(s):  
Wave Field ◽  
Large Time ◽  
Random Wave ◽  
Wave Spectra ◽  
Large Time Asymptotics ◽  
Wave Fields ◽  
Weakly Nonlinear ◽  
Time Asymptotics ◽  
Random Wave Field ◽  
Skewness And Kurtosis

AbstractWe study the long-term evolution of weakly nonlinear random gravity water wave fields developing with and without wind forcing. The focus of the work is on deriving, from first principles, the evolution of the departure of the field statistics from Gaussianity. Higher-order statistical moments of elevation (skewness and kurtosis) are used as a measure of this departure. Non-Gaussianity of a weakly nonlinear random wave field has two components. The first is due to nonlinear wave–wave interactions. We refer to this component as ‘dynamic’, since it is linked to wave field evolution. The other component is due to bound harmonics. It is non-zero for every wave field with finite amplitude, contributes both to skewness and kurtosis of gravity water waves and can be determined entirely from the instantaneous spectrum of surface elevation. The key result of the work, supported both by direct numerical simulation (DNS) and by the analysis of simulated and experimental (JONSWAP) spectra, is that in generic situations of a broadband random wave field the dynamic contribution to kurtosis is small in absolute value, and negligibly small compared with the bound harmonics component. Therefore, the latter dominates, and both skewness and kurtosis can be obtained directly from the instantaneous wave spectra. Thus, the departure of evolving wave fields from Gaussianity can be obtained from evolving wave spectra, complementing the capability of forecasting spectra and capitalizing on the existing methodology. We find that both skewness and kurtosis are significant for typical oceanic waves; the non-zero positive kurtosis implies a tangible increase of freak wave probability. For random wave fields generated by steady or slowly varying wind and for swell the derived large-time asymptotics of skewness and kurtosis predict power law decay of the moments. The exponents of these laws are determined by the degree of homogeneity of the interaction coefficients. For all self-similar regimes the kurtosis decays twice as fast as the skewness. These formulae complement the known large-time asymptotics for spectral evolution prescribed by the Hasselmann equation. The results are verified by the DNS of random wave fields based on the Zakharov equation. The predicted asymptotic behaviour is shown to be very robust: it holds both for steady and gusty winds.

Closure to “Statistics of Random Wave Field”

1977 ◽  
Vol 103 (2) ◽  
pp. 289-290
Author(s):  
Keikhosrow Pajouhi ◽  
Chi C. Tung
Keyword(s):  
Wave Field ◽  
Random Wave ◽  
Random Wave Field

scholarly journals Nonlinear random wave field in shallow water: variable Korteweg-de Vries framework

2011 ◽  
Vol 11 (2) ◽  
pp. 323-330 ◽  
Author(s):  
A. Sergeeva ◽  
E. Pelinovsky ◽  
T. Talipova
Keyword(s):  
Shallow Water ◽  
Wave Field ◽  
Large Amplitude ◽  
Rogue Waves ◽  
High Amplitude ◽  
Random Wave ◽  
Flat Bottom ◽  
Wave State ◽  
De Vries ◽  
Random Wave Field

Abstract. The transformation of a random wave field in shallow water of variable depth is analyzed within the framework of the variable-coefficient Korteweg-de Vries equation. The characteristic wave height varies with depth according to Green's law, and this follows rigorously from the theoretical model. The skewness and kurtosis are computed, and it is shown that they increase when the depth decreases, and simultaneously the wave state deviates from the Gaussian. The probability of large-amplitude (rogue) waves increases within the transition zone. The characteristics of this process depend on the wave steepness, which is characterized in terms of the Ursell parameter. The results obtained show that the number of rogue waves may deviate significantly from the value expected for a flat bottom of a given depth. If the random wave field is represented as a soliton gas, the probabilities of soliton amplitudes increase to a high-amplitude range and the number of large-amplitude (rogue) solitons increases when the water shallows.

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