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The geometry of the Long Island Sound (LIS) renders the wave field fetch-limited and leads to marked differences between western and eastern areas. The mechanisms that contribute to the formation and dissipation of waves in the LIS are not well understood. We evaluated the ability of the wave module of a wave-coupled hydrodynamic model to simulate different wind–wave scenarios. We were unable to capture wave statistics correctly using existing meteorological model results for wind forcing due to the low resolution of the models and their inability to resolve the LIS coastline sufficiently. To solve this problem, we modified the wind fields using in situ wind observations from buoys. We optimized both the Komen and Jansen parameterizations for the LIS to better present the peak winds during storms. Waves in the LIS develop more quickly than simple theory predicts due to quadruplet nonlinear wave–wave interaction effects. Removing quadruplet nonlinear wave–wave interaction increases the time to full saturation by 50%. The spatial distribution of wave energy density input reveals the complex interaction between wind and waves in the LIS, with the area of greatest exposure receiving higher wave energy density. The interaction of nonlinear wave–wave interaction and whitecapping dissipation defines the shape of the directional spectrum along the LIS. Dissipation due to whitecapping and shoaling are the main parameters modulating a fully developed wave field. [ABSTRACT FROM AUTHOR]

For weakly nonlinear waves in one space dimension, the nonlinear Schrödinger Equation is widely accepted as a canonical model for the evolution of wave groups described by modulation instability and its soliton and breather solutions. When there is forcing such as that due to wind blowing over the water surface, this can be supplemented with a linear growth term representing linear instability leading to the forced nonlinear Schrödinger Equation. For water waves in two horizontal space dimensions, this is replaced by a forced Benney–Roskes system. This is a two-dimensional nonlinear Schrödinger Equation with a nonlocal nonlinear term. In deep water, this becomes a local nonlinear term, and it reduces to a two-dimensional nonlinear Schrödinger Equation. In this paper, we numerically explore the evolution of wave groups in the forced Benney–Roskes system using four cases of initial conditions. In the one-dimensional unforced nonlinear Schrödinger equa tion, the first case would lead to a Peregrine breather and the second case to a line soliton; the third case is a long-wave perturbation, and the fourth case is designed to stimulate modulation instability. In deep water and for finite depth, when there is modulation instability in the one-dimensional nonlinear Schdrödinger Equation, the two-dimensional simulations show a similar pattern. However, in shallow water where there is no one-dimensional modulation instability, the extra horizontal dimension is significant in producing wave growth through modulation instability. [ABSTRACT FROM AUTHOR]

Surface effects on deep-water gravity waves are investigated theoretically by the application of a Robin boundary condition with a complex Robin parameter, R=Rr+iRi. The Robin condition combines the shear stress and the horizontal velocity at the ocean surface. We show that this condition describes wave damping related to surface phenomena like elastic films or thin viscous fluid layers. It may also model wave generation by oscillating surface stresses depending on the signs and magnitudes of Rr and Ri.

The geometry of the Long Island Sound (LIS) renders the wave field fetch-limited and leads to marked differences between western and eastern areas. The mechanisms that contribute to the formation and dissipation of waves in the LIS are not well understood. We evaluated the ability of the wave module of a wave-coupled hydrodynamic model to simulate different wind–wave scenarios. We were unable to capture wave statistics correctly using existing meteorological model results for wind forcing due to the low resolution of the models and their inability to resolve the LIS coastline sufficiently. To solve this problem, we modified the wind fields using in situ wind observations from buoys. We optimized both the Komen and Jansen parameterizations for the LIS to better present the peak winds during storms. Waves in the LIS develop more quickly than simple theory predicts due to quadruplet nonlinear wave–wave interaction effects. Removing quadruplet nonlinear wave–wave interaction increases the time to full saturation by 50%. The spatial distribution of wave energy density input reveals the complex interaction between wind and waves in the LIS, with the area of greatest exposure receiving higher wave energy density. The interaction of nonlinear wave–wave interaction and whitecapping dissipation defines the shape of the directional spectrum along the LIS. Dissipation due to whitecapping and shoaling are the main parameters modulating a fully developed wave field.

When wind blows over the ocean, short wind-waves (of wavelength smaller than 10 m) are generated, rapidly reaching an equilibrium with the overlying turbulence (at heights lower than 10 m). Understanding this equilibrium is key to many applications since it determines (i) air–sea fluxes of heat, momentum and gas, essential for numerical models; (ii) energy loss from wind to waves, which regulates how swell is generated and how energy is transferred to the ocean mixed layer and; (iii) the ocean surface roughness, visible from remote sensing measurements. Here we review phenomenological models describing this equilibrium: these models couple a turbulence kinetic energy and wave action budget through several wave-growth processes, including airflow separation events induced by breaking waves. Even though the models aim at reproducing measurements of air–sea fluxes and wave growth, some of the observed variability is still unexplained. Hence, after reviewing several state-of-the-art phenomenological models, we discuss recent numerical experiments in order to provide hints about future improvements. We suggest three main directions, which should be addressed both through dedicated experiments and theory: (i) a better quantification of the variability wind-wave growth and of the role played by the modulation of short and breaking wind-waves by long wind-waves; (ii) an improved understanding of the imprint of wind-waves on turbulent coherent structures and; (iii) a quantification of the interscale interactions for a realistic wind-wave sea, where wind-and-wave coupling processes coexist at multiple time and space scales. [ABSTRACT FROM AUTHOR]

For weakly nonlinear waves in one space dimension, the nonlinear Schrödinger Equation is widely accepted as a canonical model for the evolution of wave groups described by modulation instability and its soliton and breather solutions. When there is forcing such as that due to wind blowing over the water surface, this can be supplemented with a linear growth term representing linear instability leading to the forced nonlinear Schrödinger Equation. For water waves in two horizontal space dimensions, this is replaced by a forced Benney–Roskes system. This is a two-dimensional nonlinear Schrödinger Equation with a nonlocal nonlinear term. In deep water, this becomes a local nonlinear term, and it reduces to a two-dimensional nonlinear Schrödinger Equation. In this paper, we numerically explore the evolution of wave groups in the forced Benney–Roskes system using four cases of initial conditions. In the one-dimensional unforced nonlinear Schrödinger equa tion, the first case would lead to a Peregrine breather and the second case to a line soliton; the third case is a long-wave perturbation, and the fourth case is designed to stimulate modulation instability. In deep water and for finite depth, when there is modulation instability in the one-dimensional nonlinear Schdrödinger Equation, the two-dimensional simulations show a similar pattern. However, in shallow water where there is no one-dimensional modulation instability, the extra horizontal dimension is significant in producing wave growth through modulation instability.

A number of datasets from wave tank and field measurements have been assembled from published data. For fixed wind speed, the peak frequency has F ∝ x − 1 / 3 and the significant wave height has H ∝ x 1 / 2 . It has been confirmed following earlier work that wind speed should not be used to non-dimensionalise wave parameters, such as the frequency or the significant wave height because the wind-speed dependence is stronger than expected for the assembled data sets. New parameters have recently been proposed that use fetch, x, and the number of waves to create non-dimensional wave height and wave period, H ~ and T ~ . The applicability of these quantities to the assembled datasets has also been investigated. A new non-dimensional relationship has been found empirically that relates the wave steepness, ak to the dimensionless fetch, ν, of the waves, (a k) 2 ν = 130 (or H 2 k 3 x = 260), which has the property of being wind-speed invariant. The estimated wind-speed dependence varied with fetch, although the ratio between the wind-speed exponents for H and F remained constant at − 1 / 3 for all fetches. [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron (EMIC) waves can act as a loss process for both ring current ions and radiation belt electrons, and the spatial and temporal characteristics of these waves are important for quantifying their effects on energetic particles. Here we utilize observations from multiple spacecraft to constrain the azimuthal and radial dimensions as well as the duration of an EMIC wave event occurring on the nightside of the inner magnetosphere on 7 July 2013. These combined observations reveal waves limited to a narrow radial extent but persisting ~10+ hr and spanning ~12 hr in local time. The solar wind conditions, geomagnetic activity, and plasma environment are also examined to better understand the conditions under which persistent nightside EMIC waves can occur. Relativistic electron phase space density profiles during this event reveal local minima concurrent with the wave activity, consistent with EMIC‐driven scattering and loss of radiation belt electrons. Plain Language Summary: Various oscillating electric and magnetic fields, or waves, can interact with high‐energy particles in near‐Earth space and cause a change in the particles' energy and/or direction of motion. Where and when these waves occur can have a significant impact on how they interact with particles. Here we combine measurements from multiple spacecraft around the Earth to study one specific wave mode. While these waves are often thought to be localized and of short durations, we observe an event on 7 July 2013 where waves persist for over 10 hr and span the entire nightside of the Earth. We explore the dynamics of the Earth's magnetic field, in response to activity on the Sun, to better understand what causes these widespread, long‐lasting waves. Changes in the energetic particle environment around the Earth are also presented to examine the effects of these waves. Events like these have the potential to cause significant effects in the particle populations around the Earth. Key Points: Sustained, azimuthally extended EMIC waves are observed spanning the nightside of the inner magnetosphere on 7 July 2013Wave structure lies at the inner edge of the plasma sheet overlaping the outer plasmasphere and plumes following enhanced Kp activityLocal minima in phase space density are observed concurrent with wave activity, consistent with EMIC‐driven MeV electron scattering [ABSTRACT FROM AUTHOR]

This study analyzes the wind-generated wave climate conditions in the Red Sea. A 64-year (1959–2022) wave hindcast is developed using the spectral wave model WAVEWATCH III forced with ERA5 wind fields. The study addresses the climatologies of the significant wave height (H s), mean period (T m), and wave power (P) parameters, as well as the wind-sea and swell distributions throughout the basin. Special interest has been paid on assessing the extreme climate conditions. Additionally, the climate variability at seasonal and inter-annual scales, and the long-term trends are analyzed. The relationship between the Red Sea wave climate and the large-scale teleconnection climate patterns is investigated. The model is calibrated for wind-wave growth and validated against buoy and altimeter measurements revealing higher performance than previous datasets. The root mean square errors of H s and T m are reduced by 25% and 37%, respectively. Results show that wind-seas dominate in the northern and southernmost Red Sea regions. We also detect that the 100-year return period of H s reaches ∼5 m in the central basin. Furthermore, regional annual and seasonal variations of the wave climate show strong correlations with the circulation patterns described by the North Atlantic Oscillation at the northern Red Sea and both the Dipole Mode Index and El-Niño Southern Oscillation at the southern Red Sea. Finally, contrasting behaviours of negative and positive trends occur at the southern and northern regions, respectively, for H s , and P with a contrary behavior for T m. Trends under both mean and extreme conditions are mild, reaching 3 cm/decade, 0.016 s/decade, and 0.3 kW/m/decade for H s , T m, and P , respectively, in the northern basin in winter. • A 64-year high-resolution wave dataset is developed in the Red Sea using ERA5 wind fields. • Seasonal and inter-annual wave climate variabilities are analyzed and long-term trends in H s , T m , and P are addressed. • The 100-year return level of H s exhibits values >4 m in most of the basin, reaching maximum values of 5 m in the central area. • Wave directionality varies seasonally between the northern and southern areas and the convergence area disappears in summer. • Long-term trends are mild under mean and extreme conditions with higher values found in the northern basin in winter. [ABSTRACT FROM AUTHOR]

Highlights • A high resolution hindcast model SWAN was calibrated and validated for the Algerian Basin. • Janssen (1991) formulation with C ds1 = 1 for whitecapping in the W-Med Sea has a better performance. • Komen et al. (1984) formulation for wind growth in the W-Med Sea presents a better accuracy. • The calibrated SWAN performs better using Komen formula compared to the new ST6. Abstract This study aims to present an evaluation and implementation of a high-resolution SWAN wind wave hindcast model forced by the CFSR wind fields in the west Mediterranean basin, taking into account the recent developments in wave modelling as the new source terms package ST6. For this purpose, the SWAN model was calibrated based on one-year wave observations of Azeffoune buoy (Algerian coast) and validated against eleven wave buoys measurements through the West Mediterranean basin. For the calibration process, we focused on the whitecapping dissipation coefficient C ds and on the exponential wind wave growth and whitecapping dissipation source terms. The statistical error analysis of the calibration results led to conclude that the SWAN model calibration corrected the underestimation of the significant wave height hindcasts in the default mode and improved its accuracy in the West Mediterranean basin. The exponential wind wave growth of Komen et al (1984) and the whitecapping dissipation source terms of Janssen (1991) with C ds = 1.0 have been thus recommended for the western Mediterranean basin. The comparison of the simulation results obtained using this calibrated parameters against eleven measurement buoys showed a high performance of the calibrated SWAN model with an average scatter index of 30% for the significant wave heights and 19% for the mean wave period. This calibrated SWAN model will constitute a practical wave hindcast model with high spatial resolution (˜3 km) and high accuracy in the Algerian basin, which will allow us to proceed to a finer mesh size using the SWAN nested grid system in this area. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve our understanding of physical air‐sea interaction, it is essential to better describe the short‐scale ocean wave response to wind forcing. This is particularly true for waves which are small enough to evade observation by traditional buoy and point‐based gauge measurements but large enough to appreciably alter the transfer of momentum between atmosphere and ocean. Such waves are restored to equilibrium both by the Earth's gravity and air‐sea surface tension, hence the classification as “gravity‐capillary.” Radar remote sensing techniques depend greatly upon these waves in order to extract useful physical parameters from afar. Despite this importance, field observations of gravity‐capillary wave characteristics are uncommon and results vary from study to study. Furthermore, leading‐edge model wave number spectra generally do not match each other in shape or important spectral parameters. Here we present an extended analysis of short wave data collected via a polarimetric camera aboard Research Platform Floating Instrument Platform in the Santa Barbara Channel. Our wave number saturation spectra show the emergence of a peak in the gravity‐capillary subrange at low wind forcing magnitude ( u*~0.045 m/s), consistent with critical wave growth in air side stability theory and previously only observed in the laboratory. Finally, the effects of microbreaking on wave spectral characteristics are discussed. [ABSTRACT FROM AUTHOR]

Simulation of the interfacial wave growth in a plane channel is performed by a phase field lattice Boltzmann method (LBM) in this work. The numerical results are validated against linear theory analysis. The influence of viscosity ratio and liquid layer height on the wave initiation is studied Results show that the wave grows slower with increasing viscosity ratio. On the other hand, the wave growth rate has more complex relationships with the liquid layer height. It is also found that there is a critical liquid layer height that prompts the strongest wave growth. Besides the linear characteristics during the early stage, nonlinear interfacial changes such as forming of ligament and droplets are also captured in this work. [ABSTRACT FROM AUTHOR]

The accuracy of wave models in semi-enclosed-basins and orography-controlled wind conditions, especially during fetch-limited storm events, is known to be limited. Wind wave forecasting in the NW Mediterranean Sea is particularly demanding due to the characteristic sharp gradients of the wind and wave conditions. In this work we focus on the commonly observed underestimation of wave parameters even when the wind field is “correct” or overestimated. This is a small step to analyse such a discrepancy, where wind overestimation has been commonly used to get the “right” wave predictions for the “wrong” reason. Here we selected a suitable combination of nested meteorological and wave models to focus on the physics (in parameterized terms) of meso-scale wave generation in restricted domains. First, to better capture the typical sharp gradients in wind and wave fields under those conditions, the spatial resolution of the atmospheric model was progressively increased during a characteristic storm event from 18 km to 4 km; the corresponding frequency of the wind input was increased from 6 to 1 h. Second, the calculated rate of wave growth in the numerical model (i.e. the balance between the input term and the whitecapping dissipation) was analysed and tuned to match the observed local rate of wave growth. The rate of non-dimensional growth in the region of study, which was calculated using measurements along the fetch, turned out to be faster than simulated with the initial model settings and faster than reported in previous studies. Adjusting the wave growth rate in the model to the observations improved the estimated wave height by about 18% and the wave period by about 4%. Decreasing the grid size of the numerical models from 12 km to 4 km improved the timing of the wave peaks but not the maximum values of the storm. Increasing the frequency of the wind input (from 6 to 3 h) improved the estimation of the maximum wave height values (peaks) of the storm by about 13%. Summarizing, the results of this work showed that using high resolution and physically adjusted parameterizations in complex regions with strong wind and wave gradients such as the study area, it is possible to significantly reduce the under-estimation of wave parameters and to locally improve wave growth forecasting. [ABSTRACT FROM AUTHOR]

Abstract: A model for the downward transfer of wind momentum is derived for growing waves. It is shown that waves, which grow due to an uneven pressure distribution on the water surface or a wave-coherent surface shear stress have horizontal velocities out of phase with the surface elevation. Further, if the waves grow in the x-direction, while the motion is perhaps time-periodic at any fixed point, the Reynolds stresses associated with the organized motion are positive. This is in agreement with several field and laboratory measurements which were previously unexplained, and the new theory successfully links measured wave growth rates and measured sub-surface Reynolds stresses. Wave coherent air pressure (and/or surface shear stress) is shown to change the speed of wave propagation as well as inducing growth or decay. From air pressure variations that are in phase with the surface elevation, the influence on the waves is simply a phase speed increase. For pressure variations out of phase with surface elevation, both growth (or decay) and phase speed changes occur. The theory is initially developed for long waves, after which the velocity potential and dispersion relation for linear waves in arbitrary depth are given. The model enables a sounder model for the transfer to storm surges or currents of momentum from breaking waves in that it does not rely entirely on ad-hoc turbulent diffusion. Future models of atmosphere-ocean exchanges should also acknowledge that momentum is transferred partly by the organized wave motion, while other species, like heat and gasses, may rely totally on turbulent diffusion. The fact that growing wind waves do in fact not generally obey the dispersion relation for free waves may need to be considered in future wind wave development models. [Copyright &y& Elsevier]

Wavelet analysis is considered a state-of-the-art technique in signal processing; it transforms the signal into a scale-time representation (scalogram) with high resolution, preserving the temporal characteristics of the signal. In the present study, an overview of Fourier analysis, short-time Fourier analysis, and wavelet analysis are given, and the differences between them are addressed. To demonstrate the importance of wavelet analysis in the field of coastal engineering and other related fields, a summary of the recent literature concerning its applications is given first, and then wavelet analysis is used to analyze the complex phenomenon of wave growth due to a sudden change in the wind conditions. This study shows that the temporal characteristics of the time series of wind speed and significant wave height can be explored qualitatively by using the complex Morlet wavelet analysis. The results reveal that the waves are responding immediately to the sudden change in wind conditions. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the key results from a ten-year data set for Lake IJssel and Lake Sloten in The Netherlands, containing information on wind, storm surges and waves, supplemented with SWAN 40.51 wave model results. The wind speeds U 10, effective fetches x and water depths d for the data set ranged from 0–24 m s− 1, 0.8–25 km and 1.2–6 m respectively. For locations with non-sloping bottoms, the range in non-dimensional fetch x⁎ (= g x U 10 − 2) was about 25–80,000, while the range in dimensionless depth d⁎ (= g d U 10 − 2) was about 0.03–1.7. Land–water wind speed differences were much smaller than the roughness differences would suggest. Part of this seems due to thermal stability effects, which even play a role during near-gale force winds. For storm surges, a spectral response analysis showed that Lake IJssel has several resonant peaks at time scales of order 1 h. As for the waves, wave steepnesses and dimensionless wave heights H⁎ (= g H m0 U 10 − 2) agreed reasonably well with parametric growth curves, although there is no single curve to which the present data fit best for all cases. For strongly depth-limited waves, the extreme values of d⁎ (0.03) and H m0 / d (0.44) at the 1.7 m deep Lake Sloten were very close to the extremes found in Lake George, Australia. For the 5 m deep Lake IJssel, values of H m0 / d were higher than the depth-limited asymptotes of parametric wave growth curves. The wave model test cases of this study demonstrated that SWAN underestimates H m0 for depth-limited waves and that spectral details (enhanced peak, secondary humps) were not well reproduced from H m0 / d =0.2–0.3 on. SWAN also underestimated the quick wave response (within 0.3–1 h) to sudden wind increases. For the remaining cases, the new [Van der Westhuysen, A.J., Zijlema, M., and Battjes, J.A., 2007. Nonlinear saturation-based whitecapping dissipation in SWAN for deep and shallow water, Coast. Eng., 54, 151–170] SWAN physics yielded better results than the standard physics of Komen, G.J., Hasselmann, S., Hasselmann, K., 1984. On the existence of a fully developed wind-sea spectrum. J. Phys. Oceanogr. 14, 1271–1285, except for persistent overestimations that were found for short fetches. The present data set contains many interesting cases for detailed model validation and for further studies into the evolution of wind waves in shallow lakes. [Copyright &y& Elsevier]

This work reports an efficient bulk formulation of sea surface drag that incorporates effect of dynamic stability under varied atmospheric forcing. The proposed formulation exhibits a polynomial dependence of wind speed on air–sea temperature difference based on statistical analysis. Quality checked meteorological and oceanographic data from four shallow water buoys located off Korean seas having measurements at an interval of every 1 h were used for this study. The analyses of in situ records for this region suggest stability ranging from highly stable to very unstable conditions. Importance of this proposed formulation is better reflected during unstable condition where other popular bulk formulations fail. In addition, importance and impact of such a study on wind-wave growth using the state-of-art wave model was also investigated. Finally, we advocate a new drag formulation, which accounts for varied atmospheric stability and suggest that this should be considered as an essential pre-requisite for ocean modeling studies. [ABSTRACT FROM AUTHOR]

Abstract: Wave growth in slanting fetch (with wind blowing obliquely off a coast) is investigated with 7 years worth of routine wave measurements in Lake IJssel in The Netherlands and with the SWAN wave model. Two aspects are considered in particular for this case: the validity of the concept of effective fetch and the role of the non-linear four-wave interactions. For slanting and parallel fetch conditions, we found some significant deviations from the effective fetch assumption, leading to 20–35% mismatch in either the peak period T p or the significant wave height H m0 respectively. However, the effect of discrepancies between various widely accepted wave growth formulas turned out to be even more important. The wave directions during slanting fetch are significantly ‘steered’ by the coastline, especially in the first kilometre(s) off the coast. The role of the non-linear four-wave interactions is investigated by running the SWAN (version 40.41) wave model with three different quadruplet formulations. Exact quadruplet methods (Xnl) yielded relatively strong wave steering, despite the four-wave interactions being relatively weak. Application of Xnl did not lead to better overall agreement with measurements — improvements for the mean wave period T m01 were offset by some deterioration for the wave height H m0. [Copyright &y& Elsevier]

This study investigates the nonlinear wind-wave interaction that occurs during wave growth. Wavelet bicoherence is used in analyzing the detailed phase coupling and nonlinear interaction between wind speed and wave height considering both the sum and difference rules between different frequencies to give the full picture of nonlinear wind-wave interaction. The results show that the phase coupling and nonlinear wind-wave interaction in the case of considering the sum rule of the frequencies is different from the case of considering the difference rule of frequencies. This consequently emphasizes the importance of considering both rules in analyzing the phase coupling between wind speed and wave height during wave growth. [ABSTRACT FROM AUTHOR]

A theory is developed based on the premise that nonneural processes occur in the brain exemplified as spatial working memory, and is the seat of consciousness. Additionally, wave storage of spatial information, a Bose condensate to support the waves, and the location of wave storage are provided as illustrative, "existence proofs" that a coherent theory can be built along these lines in agreement with the data. The theory can be built argues on functional grounds that a nonneural spatial memory may serve a vital biological function. This article demonstrate how this same non-neural memory can bridge the explanatory gap to consciousness, in agreement with the facts. The article proposes a possible mechanism and location for the nonneural component. [ABSTRACT FROM AUTHOR]

Wavelet bicoherence is considered a state-of-the art technique in detecting the phase coupling and nonlinear interactions that occur in a signal or signals. It is used in this study to analyze the nonlinear wind-wave interactions for the simultaneously measured wind speed and wave height during 6 hours of wave generation in a mistral event. The results show that wavelet coherence can detect the linear coherence between wind and wave. On the other hand, the wavelet bicoherence has the ability to detect the phase coupling and nonlinear development between wind and wave during wave growth. This study shows that the phase coupling and nonlinear wind-wave interaction can occur over a certain range of frequencies and that this range is different from one record to another because of the nonstationary feature of the data set. [ABSTRACT FROM AUTHOR]

Neural tissue, a medium containing electro-chemical energy, can amplify small increments in cellular activity. The growing disturbance, measured as the fraction of active cells, manifests as propagating waves. In a layered geometry with a time delay in synaptic signals between the layers, the delay is instrumental in determining the amplified wavelengths. The growth of the waves is limited by the finite number of neural cells in a given region of the continuum. As wave growth saturates, the resulting activity patterns in space and time show a variety of forms, ranging from regular monochromatic waves to highly irregular mixtures of different spatial frequencies. The type of wave configuration is determined by a number of parameters, including alertness and synaptic conditioning as well as delay. For all cases studied, using numerical solution of the nonlinear Wilson–Cowan (1973) equations, there is an interval in delay in which the wave mixing occurs. As delay increases through this interval, during a series of consecutive waves propagating through a continuum region, the activity within that region changes from a single-frequency to a multiple-frequency pattern and back again. The diverse spatio-temporal patterns give a more concrete form to several metaphors advanced over the years to attempt an explanation of cognitive phenomena: Activity waves embody the “holographic memory” (Pribram, 1991); wave mixing provides a plausible cause of the competition called “neural Darwinism” (Edelman, 1988); finally the consecutive generation of growing neural waves can explain the discontinuousness of “psychological time” (Stroud, 1955). [ABSTRACT FROM AUTHOR]

Abstract: A new technique in the analysis of wind–wave interaction, wavelet bicoherence, will be applied in this article. Wavelet bicohence has the ability to detect phase coupling and nonlinear interactions of the quadratic order with time resolution. It is used in this study to analyze wind–wave interaction during wave growth in a Mistral event. A selected record of simultaneously measured wind and wave data during Mistral is divided into five segments and the computations of the wavelet bicoherence are conducted for the whole record and for all divided segments. The results show that the phase coupling occurs between wind speed and wave height over a certain range of frequencies and that the range is different from one segment to another due to the non-stationary feature of the time series. [Copyright &y& Elsevier]

Abstract: During wave growth non-linear wave–wave interactions cause transfer of some wave energy from lower to higher wave periods as the spectrum grows. Wavelet bicoherence, which is a new technique in the analysis of wind–wave and wave–wave interactions, is used to analyze non-linear wave–wave interactions. A selected record of wind wave that contains the maximum wave height observed during 6h of wave generation is divided into five segments and wavelet bicoherence is computed for the whole record, and for all divided segments. The study shows that the non-linear wave–wave interaction occurs at different bicoherence levels and these levels are different from one segment to another due to the non-stationarity feature of the examined data set. [Copyright &y& Elsevier]

In the present study, SWAN wave model is nested with Wavewatch 3 to reproduce waves off the central west coast of India using ERA-5 winds. The sensitivity of SWAN wave model was tested with different wave growth and bottom friction schemes to identify the most suitable scheme for this region. The model parameters have been validated with one year buoy measurements. Among all the four wave growth schemes (Komen, Janssen, Westhuysen and ST6) and three friction schemes (JONSWAP, Collin and Madsen) considered, SWAN with Komen or ST6 and JONSWAP setup performed better in predicting the waves, including the high waves during the southwest monsoon. Model performance has also been tested with high resolution WRF winds and the statistical results showed comparably the same performance as ERA5 winds. The model very well demonstrated the existence of single peaked spectra during the southwest monsoon and double/multi-peaked spectra due to strong local winds and the swells arriving from the Southern Ocean during fair/moderate weather season. Hence, Komen or ST6 wave growth with JONSWAP bottom friction is recommended for the prediction of waves off the central west coast of India using ERA5 winds. • SWAN wave model nested with WW3 has been used to simulate waves using ERA5 winds. • Wave growth and 3 friction schemes in SWAN are tested to identify the most suitable. • SWAN with Komen or ST6 and JONSWAP setup performed better in predicting the waves. • WRF winds showed comparably the same performance like ERA5 winds. • Model accurately reproduced wave spectral properties during different seasons. [ABSTRACT FROM AUTHOR]