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Houser C, Carswell A, Chittle B, Johnson G, Caschera A, Smith A. 2024. Relative energy and perceived impact of vessel-generated waves in fetch-limited environments. Lake Reserv Manag. 40:285–302 Vessel-generated waves (or wakes) are perceived as an important stressor in both marine and freshwater systems, and they are an increasingly important focus of coastal management. Recent studies suggest that wakes account for a significant portion of the total wave energy in fetch-limited environments and in turn have the potential to resuspend sediment, erode shorelines, degrade water quality, damage infrastructure, and disrupt aquatic ecosystems, in addition to being considered a safety hazard and a nuisance. To assess the relative contribution of wakes to the total wave energy, monitoring was completed at 32 sites across 7 fetch-limited lakes in Ontario, Canada between 2020 and 2023. The percent wake energy was inversely related to the average fetch length, with deviations to the relationship dependent on whether the site was open, an embayment or along a narrow section of the lake. A survey of property owners and residents suggests that the perceived impact of wakes also varies with the fetch length. Shoreline erosion and degraded water quality were identified as primary impacts of wakes in lakes with the smallest average fetch, but very few respondents provided direct evidence of boat wake impacts. Most respondents described vessel operation, experience of the vessel operator and conflict over different boating uses as the primary issues associated with wakes. While boat wakes may contribute a significant portion of the wave energy in fetch-limited lakes, further research is required to determine when and where they may represent a physical and ecological stressor rather than being just a nuisance. [ABSTRACT FROM AUTHOR]

Sea surface wind, waves, and currents are the three basic parameters that describe the dynamic process of sea surface, and they are coupled with each other. To more accurately describe large-scale ocean motion and extract the ocean dynamic parameters, we adopt the spaceborne Doppler measurement to estimate the radial Doppler velocity generated by the sea surface motion. Due to the presence of wind and waves, the Doppler spectrum will be formed, shifted and broadened. Pulse-pair phase interference is used to obtain the Doppler spectrum from the sea surface echo. We simulate the Doppler spectrum with different look geometry and ocean states in a spaceborne condition. In this paper, the Doppler centroid variations are estimated after reducing the platform Doppler velocity under different observation conditions. With the increase in wind speed, the measured Doppler shift increases, and the simulated Doppler centroid accuracy is estimated. In addition, the measurement error along the trace direction is at the maximum, and the error in the cross-track is the smallest. At moderate wind-wave conditions, the Doppler velocity offset can be less than 0.1 m/s. [ABSTRACT FROM AUTHOR]

In the laboratory experiment, 1:25 scaled models are constructed to investigate the effect of different swell and wind-sea proportions on the wave transformation. The source of the wave spectrum is related to the wave conditions in the Gulf of Guinea. Swell from the westerlies and local wind-sea forms the bimodal spectral waves in the region. To better understand the transformation of bimodal spectral waves, a series of wave conditions are measured by the wave gauges in a wave flume. Based on the wave spectrum at the Bight of Benin, the wave transformation along the slopes and variations of different swell proportions are analyzed. The result of the wave height variations shows that the slope and swell proportion play a significant role in the maximum wave height, and the wave height has an upward trend with a large swell proportion. The analysis of wave nonlinearity is conducted, showing that the large swell proportion in the wave spectrum leads to a more significant nonlinearity before wave breaking. Combining the variations of wave height and wave nonlinearity, the influence of bimodal spectral waves on nearshore wave prediction, shoreline change, marine operations, and structure design is discussed. [ABSTRACT FROM AUTHOR]

The global wave model WAVEWATCH III®; works well in open water. To simulate the propagation and attenuation of waves through ice-covered water, existing simulations have considered the influence of sea ice by adding the sea ice concentration in the wind wave module; however, they simply suppose that the wind cannot penetrate the ice layer and ignore the possibility of wind forcing waves below the ice cover. To improve the simulation performance of wind wave modules in the marginal ice zone (MIZ), this study proposes a parameterization scheme by directly including the sea ice thickness. Instead of scaling the wind input with the fraction of open water, this new scheme allows partial wind input in ice-covered areas based on the ice thickness. Compared with observations in the Barents Sea in 2016, the new scheme appears to improve the modeled waves in the high-frequency band. Sensitivity experiments with and without wind wave modules show that wind waves can play an important role in areas with low sea ice concentration in the MIZ. [ABSTRACT FROM AUTHOR]

Sea surface wind, waves, and currents are the three basic parameters that describe the dynamic process of sea surface, and they are coupled with each other. To more accurately describe large-scale ocean motion and extract the ocean dynamic parameters, we adopt the spaceborne Doppler measurement to estimate the radial Doppler velocity generated by the sea surface motion. Due to the presence of wind and waves, the Doppler spectrum will be formed, shifted and broadened. Pulse-pair phase interference is used to obtain the Doppler spectrum from the sea surface echo. We simulate the Doppler spectrum with different look geometry and ocean states in a spaceborne condition. In this paper, the Doppler centroid variations are estimated after reducing the platform Doppler velocity under different observation conditions. With the increase in wind speed, the measured Doppler shift increases, and the simulated Doppler centroid accuracy is estimated. In addition, the measurement error along the trace direction is at the maximum, and the error in the cross-track is the smallest. At moderate wind-wave conditions, the Doppler velocity offset can be less than 0.1 m/s.

Liu, H.; Deng, J., and Wu, J., 2023. Benthic turbulence affected by various wave conditions in the surf zone. Journal of Coastal Research, 39(6), 1082–1093. Charlotte (North Carolina), ISSN 0749-0208. To understand turbulence and associated sediment transport in the surf zone, it is of crucial importance to explore the effect of wind waves consisting of non-breaking (low) and breaking (moderate) waves. A bottom-mounted instrumental tripod was deployed on a dissipative beach in the surf zone in the south China coast to examine the relative importance of wave-induced turbulence and bed-induced turbulence in the different hydrodynamic conditions. The data were collected in 0.5–3 m water depth from 20–29 July 2016. During the survey, a tropical storm attacked the nearby coast from 26–27 July. The Synchrosqueezed Wavelet Transform method was used to decompose the wave and turbulent data. The results show that the bed-generated turbulence dominated with weak wind waves during neap tide. The Reynolds shear stresses and turbulent kinetic energy was almost vertically uniform in this period. On the contrary, the degree of turbulence anisotropy became weak and various turbulence properties or scaling (e.g., Reynolds shear stresses, turbulent kinetic energy, dissipation rate, Froude-scaled turbulence) enhanced significantly with moderate waves during spring tide and storm period. The turbulent properties increased in magnitude away from the bed beneath waves breaking. The observations suggest that breaking waves are the dominant source of turbulence under strong onshore winds, which are significant and may dominate over bottom boundary layer process in the surf zone. [ABSTRACT FROM AUTHOR]

Suspended sediment fronts (SSFs) significantly affect water quality, ecology, and geomorphological evolution of estuarine and coastal waters. Based on 10‐year suspended sediment concentration data derived from satellite images, the multiscale spatio‐temporal variability of SSFs in the Bohai Sea was studied. Frontal probability (FP) was used to quantify the intensity of frontal activity. The 10‐year averaged FP was higher near the coast and decreased with increasing offshore distance. The arc‐shaped distributions of FP near the Yellow River Estuary revealed two tidal shear frontal zones. In the eastern Bohai Sea, 13 finger‐shaped high‐FP areas reflected the spatial pattern and fine structures of tidal sand ridges. The complex topography and strong tidal dynamics provided the essential conditions for frontogenesis. The seasonality of frontal activity was dominantly regulated by the change in wind waves associated with monsoons and stratification. The direct or indirect effects of sediment discharges from the Yellow River and Liaohe River on seasonal and annual variations of frontal activity only existed within close proximity to the estuaries. Frontal activity generally showed an interannual weakening trend, especially in the Laizhou Bay (−0.27%/yr), while an opposite trend was identified in the Liaodong Bay (0.10%/yr). This phenomenon was related to the interannual variations of wind speeds. Meanwhile, wind speed anomalies caused by El Niño‐Southern Oscillation events could explain the significant interannual fluctuations in frontal activity such that, frontal activity was significantly enhanced (suppressed) when El Niño (La Niña) events occurred, especially during 2015–2016 (2017–2018). Plain Language Summary: Suspended sediment fronts, one of the most common phenomena in estuarine and coastal waters, are defined as narrow zones with large spatial changes in suspended sediment concentration over relatively short distances. The Frontogenesis and frontal variability of the Bohai Sea, east coast of mainland China have unique patterns because of its complex hydro‐sedimentary environment, but no relevant studies have been systematically conducted yet. In this study, the intensity of frontal activity in the Bohai Sea was quantified by using satellite observation data spanning 10 years. Our analyses revealed that strong frontal activity mainly occurred in areas with dramatic changes in topography and shoreline and distinct tidal features. The seasonal and year‐to‐year variations of frontal activity were closely related to wind waves, stratification, riverine sediment input, and El Niño‐Southern Oscillation events. Nevertheless, their influence mechanisms varied in different regions. The new findings are of significance to further investigate the sedimentary patterns and the ecological effects of sub‐mesoscale processes in the Bohai Sea, and can also shed light on frontal variability of semi‐enclosed shallow seas worldwide. Key Points: Geostationary Ocean Color Imager remote sensing data were used to quantify suspended sediment front variations in the Bohai SeaSpatial patterns and seasonal‐to‐interannual variability of frontal activity were revealedEffects of dynamic factors on the spatio‐temporal variations of frontal activity were analyzed [ABSTRACT FROM AUTHOR]

Ocean waves are crucial for driving various oceanic processes. In this study, the spatial and temporal distribution of significant wave height (SWH) in the North Pacific (NP) is analyzed using the 42-year ERA5 reanalysis dataset from European Centre for Medium-Range Weather Forecasts (ECMWF). The presence of an ENSO signal is confirmed in wave fields of the North Pacific. Furthermore, the spatial distributions of swells and wind waves are analyzed using the Empirical Orthogonal Function (EOF) method, revealing that waves can transport large-scale signals from the NP to lower latitudes through swells. In addition, our research reveals a relationship between ENSO and Stokes drift in the NP. Stokes drift contributes positively to the maintenance of stable sea surface temperatures (SSTs) by transporting more (less) water towards the equatorial Pacific during El Niño (La Niña year) years. It is further noted that during strong ENSO events, the strength of the Stokes drift anomaly intensifies accordingly, which implies a strong link between wave-induced transport and ENSO. [ABSTRACT FROM AUTHOR]

This paper investigates the wind wave deformations above two isolated shallow seamounts using a phase-resolved wave model simulation using the HAWASSI-AB software. The first seamount is located some 8 km from the south coast of Jawa, Indonesia, near Glagah, with its top area about 2 m from the water level, while the second is the Socotra Rock, in the East China Sea, which has a top 4.6 m under the sea surface. The simulations found that isolated shallow bathymetry may generate a crossing sea region endangering ships. In both domains, short-crested wave simulations of second order show strong refraction and diffraction effects when waves run towards and downstream of the top of the seamount. Waves near the summit embrace the seamount and form a focal area with larger waves downstream. After crossing the Socotra Rock, the interaction waves lead to a crossing sea in the deep water. On the other hand, having passed the Glagah, waves further downstream are partly absent over a substantial stretch of the coast. For both cases, the phase-resolved wave simulation results determine detailed wind wave conditions and wave spectra over the whole area, compensating for a lack of experimental data. [ABSTRACT FROM AUTHOR]

In the laboratory experiment, 1:25 scaled models are constructed to investigate the effect of different swell and wind-sea proportions on the wave transformation. The source of the wave spectrum is related to the wave conditions in the Gulf of Guinea. Swell from the westerlies and local wind-sea forms the bimodal spectral waves in the region. To better understand the transformation of bimodal spectral waves, a series of wave conditions are measured by the wave gauges in a wave flume. Based on the wave spectrum at the Bight of Benin, the wave transformation along the slopes and variations of different swell proportions are analyzed. The result of the wave height variations shows that the slope and swell proportion play a significant role in the maximum wave height, and the wave height has an upward trend with a large swell proportion. The analysis of wave nonlinearity is conducted, showing that the large swell proportion in the wave spectrum leads to a more significant nonlinearity before wave breaking. Combining the variations of wave height and wave nonlinearity, the influence of bimodal spectral waves on nearshore wave prediction, shoreline change, marine operations, and structure design is discussed.

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]

Reanalysis datasets provide temporally/spatially continuous data for sea level and wind wave climate studies but often lack the resolution to resolve the complex coastal physical processes. To address this issue, a high-resolution coupled circulation-wave model (ADCIRC + SWAN) is applied to dynamically downscale storm tides (tide + surge + wave setup) and waves in the western North Atlantic Ocean. The model is forced at its sea surface boundary with hourly surface pressure and wind fields, and its open boundary with water levels and direction-frequency wave spectrum from the ERA5 reanalysis dataset. The sensitivity of the model is evaluated for different combinations of internal tide energy conversion, quadratic friction coefficients, and wave physics packages. For the best model setup, the results show an RMSE range of 0.114 m–0.295 m for storm tide, 0.176 m–0.298 m for non-tidal residual, 0.143 m–0.39 m for significant wave height, and 0.42 s–1.04 s for mean wave period. Incorporating the direction-frequency wave spectrum as an open boundary condition improves the model's accuracy, reducing the RMSE for significant wave heights by up to 7% and for the mean wave period by up to 30% over a one-month simulation period. • Developed a high-resolution ADCIRC + SWAN model for simulating storm tide and wave. • Explored various wave physics packages and identified the best model setup. • Improved wave prediction accuracy by incorporating the direction-frequency (2D) wave spectrum as a boundary condition. [ABSTRACT FROM AUTHOR]

Ocean waves are crucial for driving various oceanic processes. In this study, the spatial and temporal distribution of significant wave height (SWH) in the North Pacific (NP) is analyzed using the 42-year ERA5 reanalysis dataset from European Centre for Medium-Range Weather Forecasts (ECMWF). The presence of an ENSO signal is confirmed in wave fields of the North Pacific. Furthermore, the spatial distributions of swells and wind waves are analyzed using the Empirical Orthogonal Function (EOF) method, revealing that waves can transport large-scale signals from the NP to lower latitudes through swells. In addition, our research reveals a relationship between ENSO and Stokes drift in the NP. Stokes drift contributes positively to the maintenance of stable sea surface temperatures (SSTs) by transporting more (less) water towards the equatorial Pacific during El Niño (La Niña year) years. It is further noted that during strong ENSO events, the strength of the Stokes drift anomaly intensifies accordingly, which implies a strong link between wave-induced transport and ENSO.

This paper investigates the wind wave deformations above two isolated shallow seamounts using a phase-resolved wave model simulation using the HAWASSI-AB software. The first seamount is located some 8 km from the south coast of Jawa, Indonesia, near Glagah, with its top area about 2 m from the water level, while the second is the Socotra Rock, in the East China Sea, which has a top 4.6 m under the sea surface. The simulations found that isolated shallow bathymetry may generate a crossing sea region endangering ships. In both domains, short-crested wave simulations of second order show strong refraction and diffraction effects when waves run towards and downstream of the top of the seamount. Waves near the summit embrace the seamount and form a focal area with larger waves downstream. After crossing the Socotra Rock, the interaction waves lead to a crossing sea in the deep water. On the other hand, having passed the Glagah, waves further downstream are partly absent over a substantial stretch of the coast. For both cases, the phase-resolved wave simulation results determine detailed wind wave conditions and wave spectra over the whole area, compensating for a lack of experimental data.

This study used the ERA‐5 40‐year reanalysis data set from the European Centre for Medium‐Range Weather Forecasts to analyze the spatial characteristics of wind waves and swells in the Indian Ocean. Although swells from the Southern Ocean can propagate into the Bay of Bengal, the zonal surface Stokes drift has been shown to correlate well with wind waves. Investigation of the relationship between the Indian Ocean Dipole (IOD) and the surface Stokes drift revealed strong correlation in the tropical Indian Ocean. The surface Stokes drift plays a positive role in maintaining sea surface temperature stability by transporting more (less) abnormally cold water during periods of positive (negative) IOD events. The depth‐integrated wave transport is quantified by the spectra and bulk parameters, respectively. Although two methods provide estimates of the same order of magnitude, the transport value is larger when wave spectra are used. With this approach, the estimated wave transport is comparable to the Ekman transport and its zonal component is even greater for more than 80% of the sea areas in the Indian Ocean; thus, it would have substantial effect on sea surface temperature. This paper proposes a new idea for studying this climatic phenomenon by considering the large‐scale wave effect, which builds a bridge for energy transport between the eastern and western boundaries of the Indian Ocean. Plain Language Summary: The Indian Ocean is closed on three sides and open only to the Southern Ocean. Swells from the Southern Ocean can propagate to the northern Indian Ocean, but the spatial distribution of the surface Stokes drift (i.e., wave‐induced current) is related to that of wind waves. The Indian Ocean Dipole (IOD) describes an irregular variation in sea surface temperature in which western parts of the Indian Ocean become alternately abnormal warming and cooling comparing with southeastern parts. In the tropical Indian Ocean, the abnormal surface Stokes drift has strong correlation with the IOD. During IOD events, the depth‐integrated Stokes drift can transport abnormally cold water to the area where sea surface temperature decreases anomalously, promoting stability of the tropical sea surface temperature. In quantifying the magnitude of wave transport, we found that it was comparable to the Ekman transport and its zonal component was even larger in the Indian Ocean. Because Ekman transport is one of the main processes of water transport in the upper ocean, we suggest that wave transport cannot be ignored when interpreting corresponding physical processes in the upper Indian Ocean. Key Points: Although swells from the Southern Ocean propagate northward for a long distance, the zonal surface Stokes drift is related to the wind wavesStokes drift plays a positive role in maintaining the zonal stability of sea surface temperature at low latitudes in the Indian OceanWave transport is of the same order of magnitude as Ekman transport and its zonal component is greater for more than 80% of the sea areas [ABSTRACT FROM AUTHOR]

Reasonably understanding of the long-term wave characteristics is very crucial for the ocean engineering. A feedforward neural network is operated for interpolating ERA5 wave reanalysis in this study, which embodies a detailed record from 1950 onwards. The spatiotemporal variability of wave parameters in the Bohai Sea, especially the significant wave height (SWH), is presented in terms of combined wave, wind wave and swell by employing the 71 years (1950–2020) of interpolated ERA5 reanalysis. Annual mean SWH decreases at −0.12 cm/a estimated by Theil-Sen estimator and 95th percentile SWH reflecting serve sea states decreases at −0.20 cm/a. Inter-seasonal analysis shows SWH of wind wave has steeper decreasing trend with higher slopes than that of swell, especially in summer and winter, showing the major decrease may attribute to the weakening of monsoon. The inner Bohai Sea reveals a general decreasing trend while the intersection connecting with the Yellow Sea has the lower significance derived by Mann-Kendall test. Meanwhile, 95th percentile SWH decreases at a higher rate while with a lower significance in comparison with the mean state. The frequencies of mean wave directions in sub-sector are statistically calculated to find the seasonal prevailing directions. Generally, the dominant directions in summer and winter are south and north. A similar variation concerning to SWH, the trend of the mean wave period is provided, which also shows a decrease for decades. [ABSTRACT FROM AUTHOR]

In this review, the potential of an emerging field of interdisciplinary climate research, Coastal Boulder Deposits (CBDs) as natural archives for intense storms, is explored with particular reference to the Mediterranean region. First, the identification of the pertinent scientific articles was performed by the using Web of Science (WoS) engine. Thus, the selected studies have been analysed to feature CBDs produced and/or activated during the last half-century. Then, the meteorological events responsible for the literature-reported cases were analysed in some detail using the web archives of the Globo-Bolam-Moloch model cascade. The study of synoptical and local characteristics of the storms involved in the documented cases of boulder production/activation proved useful for assessing the suitability of selected sites as geomorphological storm proxies. It is argued that a close and fruitful collaboration involving several scientific disciplines is required to develop this climate research field. [ABSTRACT FROM AUTHOR]

Wind waves, which frequently occur on large surface water bodies such as lakes, may temporarily alter flow patterns in a subsurface zone and the corresponding water and nutrient interactions between surface waters and shallow groundwaters. To better understand these processes, soil flume experiments were carried out to investigate wind wave-driven water and chloride interactions across the lake–groundwater interface, and the Hydrus-2D model was used to analyze and evaluate the observed experimental results. Two interaction cases between the lake and groundwater systems were considered: groundwater discharging into a lake (the GDL case), and lake water recharging groundwater (the LRG case). For comparison, no-wave conditions for both the GDL and LRG cases were also analyzed. The results revealed that, similarly to no-wave conditions, water and chloride exchange fluxes between the lake and groundwater systems under wave conditions occurred mainly within narrow bands near the intersection of the water level in the lake and the interface in both the GDL and LRG cases, and then exponentially decreased along the interface. Most water and chloride that infiltrated into the subsurface zone through the upper part of the interface during a wave crest returned to the lake through the lower part during a wave trough in both the GDL and LRG cases, creating local recirculation zones in the subsurface near the interface. Such recirculation produced a more frequent exchange of water and solute across the interface compared with those under no-wave conditions. During a one-day period after wind waves started, the total exchange fluxes of water and chloride to the lake decreased by 36.2% and 71.9%, respectively, compared to the no-wave conditions in the GDL case. In the LRG case, the total exchange water fluxes to the subsurface increased by 89.7%, while the total exchange chloride fluxes increased only slightly (4.5%) compared to the no-wave conditions due to the difference in chloride concentrations between the upper and lower parts of the interface. The sensitivity analysis revealed that the hydraulic conductivity of the lakeshore zone and the characteristics of the waves were important factors influencing water and chloride exchange between the lake and groundwater systems. The simulated results helped us to better understand water and solute interactions in the lake–groundwater system during windy periods.

This paper describes an ocean-bottom laser seismograph, based on the modified laser meter of hydrosphere pressure variations, and designed to record vertical bottom displacements at the place of its location. Its measuring accuracy is about 1 nm, limited by the stability of the laser emission, which can be improved by using more advanced lasers. The purpose of this instrument is to measure the displacements of the seabed's upper layer in the low-frequency sonic and infrasonic ranges. Theoretically, it can operate in the frequency range from 0 (conditionally) to 1000 Hz; the upper limit is determined by the operating speed of the digital registration system. We demonstrated the capabilities of the ocean-bottom laser seismograph while registering vertical bottom displacements caused by sea wind waves and lower frequency processes—seiches, i.e., eigenoscillations of the bay in which the instrument was installed. Comparison of experimental data of the bottom laser seismograph with the data of the laser hydrosphere pressure variations meter and the velocimeter—installed in close proximity—shows good efficiency of the instrument. [ABSTRACT FROM AUTHOR]

Standard environmental condition is one of the main inputs in designing a vessel especially in assessment of stability condition. The performance based minimum stability requirements are determined by assessing vessels' dynamic failure modes. Winds as well as wind generated waves are the main factors that affect a specific vessel’s dynamics. Wind generated waves in rivers though are usually small in comparison with ocean waves may play a crucial role behind inland vessels accidents. The river condition of a crucial location in Bangladesh inland river routes is assessed where wind velocities have been taken for a specific duration from a reliable secondary source. A narrow fetch model that considers the wave generation in off-wind direction for estimating wind wave parameters has been used to consider the spiral shape of Bangladesh inland routes. The Bretschneider energy spectrum model for short term wave state is compared with the fetch limited model JONSWAP for the estimated wave condition. This study indicates the rationality of conforming the safety level of Bangladesh inland vessels equivalent to river-sea vessels as defined by other nationals and the classification societies. The wave parameters that are estimated in this study can be used to form a limited wave scatter table for predicting short term environmental conditions to assess the dynamic stability failure modes of the vessels.

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.

The previous studies have simulated the variability of the wave within the Indonesian seas which showed that the variability of wave follows the seasonal pattern. However, their analysis only consider the influence of local wind forcings. The bias and error of their simulated wave were also unclear. In the present study, we investigate the variability of wave within the Indonesian seas and its relation with the surface wind speed using the combination of reanalysis and remote sensing data with high accuracies. We split the analysis into swell and wind wave to obtain the influence of local and remote wind forcings. We show that at the inner seas (i.e., the South China Sea, Java Sea, Flores Sea, Banda Sea and Arafura Sea), the variability of significant wave height (SWH) is majorly influenced by the variability of the speed of monsoon wind. The maximum SWH during Northwest monsoon (NWM) season is located at the South China Sea while during Southeast monsoon (SEM) season is at Arafura Sea. This indicates that the wind wave (sea) is dominant at the inner seas. At the open seas (i.e., Pacific Ocean and Indian Ocean) the variability of SWH less corresponds to the the speed of monsoon wind. The remote wind forcings control the wave variability in the open ocean area. This indicates that swell is dominant at the open seas. In general, the magnitude of SWHswell is also more than SWHsea within the Indonesian seas. [ABSTRACT FROM AUTHOR]

Houser C, Smith A, Lilly J. 2021. Relative importance of recreational boat wakes on an inland lake. Lake Reserv Manage. 37:227–234. Wakes generated by recreational boats have the potential to erode the shoreline, damage infrastructure, or disrupt aquatic ecosystems. Therefore, boat wakes are an increasingly important focus of coastal management, particularly along vulnerable shorelines. This short communication quantifies the relative importance of recreational boat wake energy along the shoreline of an inland cottage lake in Northern Ontario, Canada. Measurements of recreational boat wakes at the end of one of the longest fetches for locally generated wind waves on the lake account for >61% of total wave energy. Based on this result, recreational wake energy likely is the primary source of wave activity along sections of the lake adjacent to the primary sailing lines but not aligned to the primary directions of wind wave energy. Recreational boat wakes may be a significant source of wave energy on other inland lakes. [ABSTRACT FROM AUTHOR]

In this paper, the formation of wind wave, swell and mixed wave in open seas were summarized, and the reason why mixed wave often appears in the form of bimodal spectrum in open sea area was discussed. The bimodal spectrum was represented by the summation of low frequency swell and high frequency wind wave. Combined with the motion response data of a pile driving vessel, the heave motion response of a pile driving vessel excited by the single low frequency swell, single high frequency wind wave, and mixed wave was investigated. The calculation results reveal that the low frequency swell which is not prominent in the bimodal spectrum mixed wave is the main source of exciting the pile driving vessel to move violently. It should be taken seriously when making decisions for offshore wind farm construction. [ABSTRACT FROM AUTHOR]

Standard environmental condition is one of the main inputs in designing a vessel especially in assessment of stability condition. The performance based minimum stability requirements are determined by assessing vessels' dynamic failure modes. Winds as well as wind generated waves are the main factors that affect a specific vessel's dynamics. Wind generated waves in rivers though are usually small in comparison with ocean waves may play a crucial role behind inland vessels accidents. The river condition of a crucial location in Bangladesh inland river routes is assessed where wind velocities have been taken for a specific duration from a reliable secondary source. A narrow fetch model that considers the wave generation in off-wind direction for estimating wind wave parameters has been used to consider the spiral shape of Bangladesh inland routes. The Bretschneider energy spectrum model for short term wave state is compared with the fetch limited model JONSWAP for the estimated wave condition. This study indicates the rationality of conforming the safety level of Bangladesh inland vessels equivalent to river-sea vessels as defined by other nationals and the classification societies. The wave parameters that are estimated in this study can be used to form a limited wave scatter table for predicting short term environmental conditions to assess the dynamic stability failure modes of the vessels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wave disturbance is the main factor leading to the low transparency in shallow lakes. • Artificial shoals can greatly alter hydrodynamic characteristics of shallow lakes. • Suitable terrain reshaping is a key basis for grass-type lake formation. This paper focuses on a typical shallow lake, Lake Changdanghu, which is subject to frequent hydrodynamic disturbances and suspended sediment deposition, resulting in reduced water clarity and the degradation of the grass-type ecosystem. Using a combination of long-term systematic observations and numerical simulations, the impact of terrain modification on the hydrodynamic characteristics of Lake Changdanghu and its resulting environmental improvements are systematically analyzed. The results indicate that there is a significant correlation between the wind wave intensity, suspended solids concentration of the water, and water clarity. The artificial shoal project effectively reduces the local wind wave intensity, increases the water area of the weak waves, and alters the flow structure and transport path of the lake. The wave reduction effect of the artificial shoal significantly improves the transparency of the local water, especially under high wind wave conditions, with a 60% increase in the sheltered area, significantly improving the physical habitat environment. Additionally, the flow resistance and guidance roles of the artificial shoal concentrate the impact of the poor water quality of the inflow in a local area, reducing its adverse effects on the main body of the lake. Our research demonstrates that for shallow lakes, the water transparency can be improved, the physical habitat conditions for aquatic vegetation can be enhanced, and grass-type ecosystems can be gradually restored through artificial intervention and vegetation recovery projects by reducing the wave energy, flow resistance, and guidance through the construction of artificial shoals. This approach achieves long-term maintenance of eutrophication control and water quality improvement in shallow lakes. [ABSTRACT FROM AUTHOR]

In this study, our objective is to evaluate the long-term variability of global wave power and its underlying mechanisms, utilizing the longest wave reanalysis available (ERA5, 1940–2022). We introduce a novel validation of the global wave power of the ERA5 wave reanalysis against measurements from multi-platform satellite altimeters from 1985 to 2022. This validation shows good agreement over the period. Our analysis shows a consistent increase in global wave power throughout the study period. This rise in global wave power predominantly stems from the influences of global climate change and the intensification of Antarctic Oscillation (AAO) events. As low-pressure systems move southward in the Southern Hemisphere over this period, they generate an increase in wave power 2.6 times larger than the global average increase. This energetic wave power propagates towards the mid and low-latitude regions of the Pacific, Indian, and Atlantic Oceans. This conclusion is verified by an examination of wind wave and swell contributions to wave power. Specifically, the wind wave component (swell) is more (less) important in the Southern Ocean than in the low and mid-latitude regions. • A global assessment of the potential of ocean wave power • Utilization of the longest available wave reanalysis dataset to investigate global wave power variability. • First-time validation of global wave power against multi-platform satellite altimeter data. • Quantification of the contributions of significant wave height and energy period to global wave power. • Identification of major mechanisms responsible for modulating global wave power variability. [ABSTRACT FROM AUTHOR]

Wind waves are one of the most important phenomena that should be considered in coastal and offshore activities. They have many effects on coastal environments such as wave-induced erosion, sediment and pollution transport and even in the worst cases destruction the marine ecosystems. Therefore, knowing the wave characteristics is very important for environmental research. In this paper, the accuracy of CEM semi-empirical method in forecasting the wind-induced waves characteristics in the Strait of Hormuz (SOH) have been studied. Initially, the characteristics of the waves have been calculated by employing the CEM based on wind data from local synoptic stations. Then, the evaluating process have been done by comparing the forecasting values (wave heights and periods) of this method with same recorded value of wave buoys in the SOH. According to the performed study, the accuracy of semi-empirical method in forecasting wave characteristics were in close agreement with measurements values and the SMB method is suitable for determining the wave characteristics in this area. The results show that there is a good correlation coefficient between observations and forecasting data in the CEM and the CEM method has a very small bias error. So, this method is suitable for determination the wave characteristics in this area.

In this review, the potential of an emerging field of interdisciplinary climate research, Coastal Boulder Deposits (CBDs) as natural archives for intense storms, is explored with particular reference to the Mediterranean region. First, the identification of the pertinent scientific articles was performed by the using Web of Science (WoS) engine. Thus, the selected studies have been analysed to feature CBDs produced and/or activated during the last half-century. Then, the meteorological events responsible for the literature-reported cases were analysed in some detail using the web archives of the Globo-Bolam-Moloch model cascade. The study of synoptical and local characteristics of the storms involved in the documented cases of boulder production/activation proved useful for assessing the suitability of selected sites as geomorphological storm proxies. It is argued that a close and fruitful collaboration involving several scientific disciplines is required to develop this climate research field.

This paper describes an ocean-bottom laser seismograph, based on the modified laser meter of hydrosphere pressure variations, and designed to record vertical bottom displacements at the place of its location. Its measuring accuracy is about 1 nm, limited by the stability of the laser emission, which can be improved by using more advanced lasers. The purpose of this instrument is to measure the displacements of the seabed’s upper layer in the low-frequency sonic and infrasonic ranges. Theoretically, it can operate in the frequency range from 0 (conditionally) to 1000 Hz; the upper limit is determined by the operating speed of the digital registration system. We demonstrated the capabilities of the ocean-bottom laser seismograph while registering vertical bottom displacements caused by sea wind waves and lower frequency processes—seiches, i.e., eigenoscillations of the bay in which the instrument was installed. Comparison of experimental data of the bottom laser seismograph with the data of the laser hydrosphere pressure variations meter and the velocimeter—installed in close proximity—shows good efficiency of the instrument.

In this review, we primarily address the present state of the arts and latest progresses in a few frontier issues mostly relevant to free surface/interface in ocean engineering. They include TC (tropical cyclone) induced extreme surface wave, sloshing of LNG (liquefied natural gas), cavitation/bubble dynamics and VIM (vortex-induced motion) and VIV (vortex-induced vibration). In addition to general description, we mainly focus on the recent advances and challenging aspects of above-mentioned topics. Inspired by the achievements in the previous 70 years, mankind starts a new round of ocean exploration activities. Then, we can find obvious trends: the realm of ocean engineering is expanding from sea surface to deep sea, from low and middle latitude to polar region and from fossil to renewable energy in near future. [ABSTRACT FROM AUTHOR]

An interesting physical phenomenon was recently observed when a fresh-water basin is covered by a thin ice film that has properties similar to the property of a rubber membrane. Surface waves can be generated under the action of wind on the air–water interface that contains an ice film. The modulation property of hydro-elastic waves (HEWs) in deep water covered by thin ice film blown by the wind with a uniform vertical profile is studied here in terms of the airflow velocity versus wavenumber. The modulation instability of HEWs is studied through the analysis of coefficients of the nonlinear Schrödinger (NLS) equation with the help of the Lighthill criterion. The NLS equation is derived using the multiple scale method in the presence of airflow. It is demonstrated that the potentially unstable hydro-elastic waves with negative energy appear for relatively small wind speeds, whereas the Kelvin–Helmholtz instability arises when the wind speed becomes fairly strong. Estimates of parameters of modulated waves for the typical conditions are given.

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The Kolmogorov spectrum of waves on water is a result of cascading energy via four-wave interactions. For this spectrum in the isotropic case, we introduce basic small perturbations and calculate the decrement of their damping depending on the frequency. We confirm the stability of the Kolmogorov spectrum. The calculation results are applicable for analyzing the stability of numerical methods for solving the kinetic equation. We show that using the discrete-interaction approximation strongly reduces the damping in certain cases. [ABSTRACT FROM AUTHOR]

In this paper, the numerical simulation of sediment erosion and siltation near the Yellow River estuary is carried out by using wave, tidal current and sediment coupling model. A fine triangular mesh is used in the pattern to improve the spatial resolution of numerical calculations. Comparing the measured water depth data with the simulation results, the result shows that the simulation results are in good agreement with the actual situation. In order to analyze the influence of waves on sediment erosion and siltation, the paper carried out wave influence experiments under four conditions: no wind, north wind, easterly wind and south wind. The experimental results show that the wave has a great influence on the erosion and siltation of the seabed in the study sea area. Under the northward wave condition, an erosion zone is distributed in the SE-NW direction, and the maximum erosion thickness is about 1.9 m. Under the eastward wave condition, the erosion zone is north-south. The maximum scouring thickness is about 1.7 m; the scouring and silting effect under the southward wave condition is relatively weak. [ABSTRACT FROM AUTHOR]

Highlights • The dominant velocity parameters for the equilibrium-range constant are investigated. • Three wind velocities correlate with the equilibrium-range constant. • Wind and phase velocities are needed for modelling the equilibrium-range constant. Abstract When improving wave models, it is important to determine the equilibrium-range constant for the wind-wave spectrum and find the dominant velocity parameter that well represents the equilibrium-range constant both at normal and extremely high wind speeds. Eight dominant velocity parameters were evaluated using laboratory experiments in two wind-wave tanks. One tank, installed at Kyoto University, is used for generating mechanically-generated large wind-waves. This tank has a maximum 10-m wind speed (U 10) of 67 m/s and is equipped with a programmable irregular wave generator for the loop-type wave-generation method, which was originally developed in our previous study. The other tank, installed at Kyusyu University, is used for generating pure large wind-waves, and has a total length of 54 m. The results show that at extremely high wind speeds the equilibrium-range constants for mechanically-generated large wind-waves agree with those of pure small wind-waves. In addition, comparison of the correlation coefficients of the eight dominant velocity parameters with the equilibrium-range constant reveals that three dominant velocity parameters of (u *2 C P)1/3, (U 10 2 C P)1/3, and U LS/2 (u *: friction velocity; C P : phase velocity; U LS/2 : wind velocity at half the height of wavelength over the ocean) well correlate with the equilibrium-range constant at both normal and extremely high wind speeds. [ABSTRACT FROM AUTHOR]

This paper presents an instrument based on an equal-arm Michelson interferometer and a frequency-stabilized helium-neon laser. It is designed to record hydrosphere pressure variations in the frequency range from 0 (conventionally) to 1000 Hz, with accuracy of 0.24 mPa at sea depths of up to 50 m. The operating range of the instrument can be increased by order of magnitude by improving the registration system speed, and accuracy can be enhanced by using larger diameter membranes and/or their smaller thickness. The paper demonstrates some experimental results obtained on the supersensitive detector of hydrosphere pressure variations, confirming its high performance in the infrasonic and sonic ranges.