Wave Parameters Research Articles

Experimental study on the morphodynamic evolution of sandbar-lagoon system with emergent vegetation

A mobile-bed sandbar-lagoon model was employed in a series of flume experiments to investigate the influence of vegetation with different densities over the sandbar on wave attenuation and bed profile evolution. Nineteen flume tests were carried out for the same sandbar-lagoon model under different wave conditions. Extensive analyses were conducted on the profile evolution and the wave parameters along the profile of the sandbar-lagoon system. Based on the weighted vegetation density by the canopy width, a new empirical relationship was established between wave attenuation and vegetation density, water depth and sandbar freeboard. It was found that wave attenuation increases with the sandbar freeboard and the weighted vegetation density, and decreases with incident wave height. The collision (s-shaped scarp) and overwash (upward concave scarp) types of fore-dune morphological evolution were observed in the experiments. The maximum erosion thickness of dune follows a quadratic polynomial relationship with vegetation density, indicating that too sparse vegetation cover may lead to more erosion. It follows that an optimal vegetation density may lead to the least wave reflection due to the quadratic polynomial relationship. However, when the maximum erosion thickness of fore-dune is small, the quadratic polynomial relationship become linear. Furthermore, the experimental results indicate that wave height, water depth, sandbar freeboard and vegetation density are all important contributing factors to the morphodynamic evolution of sandbar-lagoon system with emergent vegetation. These relationships promote the development of wave-vegetation-sediment mechanics and provide a scientific guide to carry out coastal ecological restoration projects especially in the sandbar-lagoon system.

REGULARITIES OF THE FIELD FOCUS OF THE THROUGH-TYPE ELECTROMAGNETIC ACOUSTIC TRANSDUCER OF TRANSVERSE WAVES

The article presents the results of experimental and theoretical research of the influence of the characteristics of a through-type electromagnetic-acoustic transducer and testing object on the focusing parameters of transverse waves using COMSOL Multiphysics. It is shown that in the radial plane of the section, the formation of a converging spherical front is observed, in the axial plane – close to a flat front. The influence on the focusing factor and the diameter of the focal spot of the diameter of the object, the operating frequency and the quality factor of the excitation pulse is presented. The developed model of the formation of the focus zone of the through-type EMAT can be used in the analysis of the acoustic path of the mirror-shadow method of multiple shadow, depending on the characteristics of the object and control parameters.

A Deep Learning–Based Approach for Empirical Modeling of Single-Point Wave Spectra in Open Oceans

Abstract Directional wave spectra are of importance for numerous practical applications such as seafaring and ocean engineering. The wave spectral densities at a certain point in the open ocean are significantly correlated to the local wind field and historical remote wind field. This feature can be used to predict the wave spectrum at that point using the wind field. In this study, a convolutional neural network (CNN) model was established to estimate wave spectra at a target point using the wind field from the ERA5 dataset. A geospatial range where the wind could impact the target point was selected, and then the historical wind field data within the range were analyzed to extract the nonlinear quantitative relationships between wind fields and wave spectra. For the spectral densities at a given direction, the wind data along the direction where waves come from were used as the input of the CNN. The model was trained to minimize the mean square error between the CNN-predicted and ERA5 reanalysis spectral density. The data structure of the wind input is reorganized into a polar grid centered on the target point to make the model applicable to different open-ocean locations worldwide. The results show that the model can predict well the wave spectrum shapes and integral wave parameters. The model allows for the prediction of single-point wave spectra in the open ocean with low computational cost and can be helpful for the study of spectral wave climate. Significance Statement The directional wave spectra (DWS) describe the distribution of wave energy among different frequencies and directions. They are useful for many marine practical applications. Usually, DWS are modeled using numerical wave models (NWMs) based on wave action balance differential equations. Although contemporary NWMs perform well after years of development, their computational costs are relatively high. The fast-developed artificial intelligence (AI) might provide an alternative solution to this task. In this study, convolutional neural networks are used to model the DWS at some selected points in the open ocean. By “learning” from NWM data, AI can effectively simulate single-point DWS in open oceans with low computational cost, which can serve as a faster data-driven surrogate model in related applications.

S2SHORES: A PYTHON LIBRARY FOR ESTIMATING COASTAL BATHYMETRY

Understanding coastal zone dynamics covering large spatial and dense temporal scales is paramount to understand and mitigate emerging coastal issues relating to climatological changes. However, the uncertainties on the coastal zone risks are still too large to predict effectively impacts on an overall increasing coastal population. Prediction, by deploying numerical models for waves, tide, and currents in the coastal zone, requires accurate and up-to-date bottom boundary conditions (bathymetry) to simulate coastal hydrodynamics accurately, let alone predict morphological change. There are three main approaches for estimating coastal bathymetry using satellite sensors: 1) linking water depth to a spectral response (colour), 2) underwater photogrammetry and 3) linking wave kinematics to a water depth. Here, we present S2Shores (Satellite to Shores), a python library that detects and extracts local wave parameters (geometry and kinematics) to derive coastal bathymetry.

THE IMPLICATIONS OF TRANSITIONAL CLIMATE REGIONS ON COASTAL RISK

The latest report of the IPCC-AR6 warned that coastal regions are one of the most vulnerable areas in the current climate emergency. In response, the knowledge concerning projected climatic-impact drivers (total water level, average and extreme waves) is rapidly progressing to reduce future coastal flooding and erosion risks. Climate change also shifts atmospheric circulation and affects the climate regions and their surrounding areas. This study aims to identify transitional wave climate regions and proposes a map of these critical areas. A spatial-temporal and multivariate analysis, based on Machine Learning approaches, was used to classify the wave parameters into climates for the end of the century (2081-2099) under the RCP8.5 scenario.

WAVE TRANSFORMATION OVER PALM BEACH REEF

Ocean wave parameters are influenced by shallowing water depth and varying bottom topography. Modelling and in-situ studies have found that as waves propagate over a reef, interaction in the form of friction with the shallower reef can alter wave height, wave period, wavelength, and wave direction. Submerged structures such as coral and rock-based reefs provide an uncertain amount of shoreline protection. Quantifying wave transformation over submerged structures will inform and aid in the design of future coastal protections.

UNRAVELING MULTIMODAL NEARSHORE WIND-WAVE FIELDS ON THE DUTCH SHOREFACE

Changing (wind) climate might influence the magnitude, direction, and frequency of wave systems (Lobeto et al., 2021). However, in coastal engineering applications, generalized wave parameters are commonly used in climate change assessments with the risk of, for example, misrepresenting the nearshore transformation of wind-driven wave climates (Hegermiller et al., 2017). In consequence, these uncertainties in the nearshore (wind) climate will affect, amongst others, ship navigation, the implementation of marine renewable energy farms, the feasibility of coastal infrastructure and defences, or the efficiency of sandy coastal maintenance, and thus the decision-making of long-term, multidecadal coastal strategies (Rijksoverheid, 2013), especially when they are designed accounting for the Building with Nature concept (de Vriend et al., 2015). This study analyses the importance and application of considering multiple coexisting wave trains on the Dutch shoreface.

The Cluster Virtual Observatory for ULF Waves

AbstractSince its launch in 2000, the Cluster fleet visited a vast domain of the circum‐terrestrial environment, from the upstream solar wind and the distant tail, down to the plasmasphere, scanning in detail all magnetospheric regions during over two solar cycles. This led to an unprecedentedly rich data collection of multi‐point measurements which will be used for years to come to decipher the mechanisms of Solar‐Terrestrial interactions. The large volume of data gathered by Cluster requires special strategies to make efficient use of it. To address this issue we constructed a browsable database containing parameters of the detected Ultra low frequency waves and of the spacecraft formation geometry. The primary data used to derive the parameters are the magnetic field, the electric field and the electron density. The data is resampled to a cadence of 1 s and processed using a sliding analysis window of 2,048 s with a step of 256 s over 24 hr intervals. This results in time‐frequency arrays for each parameter covering the 0.5 mHz to 0.5 Hz frequency range. The database is accessible at http://plasma.spacescience.ro/cluster.html. In total there are 47 wave parameters in the database, among them being the ellipticity, the degree of polarization, the (unsigned) wave vector direction, and the Poynting vector. Plots for the planarity, elongation, and degeneration of the Cluster tetrahedron are also available. At the moment, the database covers measurements made between 01 January 2001 and 31 December 2020 with more data being added in time. Here we present this database, discuss the methods used to derive the parameters and give practical examples.

WAVE TRANSFORMATION OVER PALM BEACH REEF

Ocean wave parameters are influenced by shallowing water depth and varying bottom topography. Modelling and in-situ studies have found that as waves propagate over a reef, interaction in the form of friction with the shallower reef can alter wave height, wave spectra, wavelength, and wave direction. Quantifying wave transformation over submerged structures will inform and aid in the design of future coastal protection. The natural reef at Palm Beach on the Gold Coast, Queensland, Australia is a rock-based reef that extends seaward, surrounded by sand bottom. The seaward reef edge is 10 to 16 metres deep while the shore edge is 5 to 9 metres deep, hence the reef shallows towards the shore. The reef is generally exposed to a dominant south easterly swell but Point Danger to the south offers some protection. Waverider buoys were deployed at four strategic locations at the Palm Beach reef and used to determine how the reef influences wave characteristics as waves travel over the reef. Wave transformation occurs, with the presence of Palm Beach reef having an observable influence on wave height and wave direction. Windward to leeward of the reef significant wave height was reduced by up to 12.7 per cent, wave direction changed by up to 13.9 degrees depending on how the measurement station was aligned with propagation over the reef, peak wave period was not changed significantly.

A Method for Estimating Global Subgrid‐Scale Orographic Gravity‐Wave Temperature Perturbations in Chemistry‐Climate Models

AbstractMany chemical processes depend non‐linearly on temperature. Gravity‐wave‐induced temperature perturbations have been shown to affect atmospheric chemistry, but accounting for this process in chemistry‐climate models has been a challenge because many gravity waves have scales smaller than the typical model resolution. Here, we present a method to account for subgrid‐scale orographic gravity‐wave‐induced temperature perturbations on the global scale for the Whole Atmosphere Community Climate Model. Temperature perturbation amplitudes consistent with the model's subgrid‐scale gravity wave parameterization are derived and then used as a sinusoidal temperature perturbation in the model's chemistry solver. Because of limitations in the parameterization, we explore scaling of between 0.6 and 1 based on comparisons to altitude‐dependent distributions of satellite and reanalysis data, where we discuss uncertainties. We probe the impact on the chemistry from the grid‐point to global scales, and show that the parameterization is able to represent mountain wave events as reported by previous literature. The gravity waves for example, lead to increased surface area densities of stratospheric aerosols. This increases chlorine activation, with impacts on the associated chemical composition. We obtain large local changes in some chemical species (e.g., active chlorine, NOx, N2O5) which are likely to be important for comparisons to airborne or satellite observations, but the changes to ozone loss are more modest. This approach enables the chemistry‐climate modeling community to account for subgrid‐scale gravity wave temperature perturbations interactively, consistent with the internal parameterizations and are expected to yield more realistic interactions and better representation of the chemistry.

SPATIAL ANALYSIS OF COASTAL CHANGE AND DISASTER MITIGATION ON MASAKAMBING ISLAND, SUMENEP REGENCY

Masakambing Island is one of the small islands in Sumenep Regency which has its own uniqueness and beauty. Small islands easily experience changes, one of which is changes in coastlines. The aim of this research is to determine the changes that occur along the coast and mitigation efforts by utilizing hydro-oceanographic parameters. Measurements of coastline changes were obtained from digitization results using the Normalized Different Water Index (NDWI) method with structural and non-structural mitigation efforts based on the parameter data taken. Wind parameters are dominated from the southeast and east with speeds ranging from 0.09 m/s - 22.75 m/s. The wave parameter values obtained were between 0.25 m – 0.83, while the current parameters ranged between 0.006 m/s – 0.642 m/s with the Formhazal number values showing 1.5 – 1.8. The wind was blowing cool and strong, as was the wave height in the slight category. The current flows southwest from the north of the island to the east. Single daily mixed Tide Type. The reduction in the area of Masakambing Island ranges from 0.063 km2 – 1.933 km2. Mitigation efforts that can be considered structurally include creating breakwaters and revetments, strengthening coastal buildings and planting vegetation. Non-structural mitigation that can be carried out includes creating standardization policies for disaster-resistant buildings, exploration and economic activity policies, public awareness as well as counseling and outreach regarding disaster mitigation.

Performance based assessment of a small-scale artificially nourished beach

In coastal engineering studies, coastal protection procedures can be provided by hard and soft methods. Soft methods applied using the right techniques and methods are not only long-lasting but also adapt to the natural structure of the coast. This study aims to present monitoring the development of a small-scale artificial nourished beach between the groins for 15 months and analyze its performance. For this purpose, field studies were carried out with land and sea observations taken once before nourishment and at 8 different times after nourishment. The seabed and profile variations observed at different sections were analyzed after processing field data. For determining the characteristics of the natural beach and borrow area before nourishment a sieve analysis was done for sediment samples taken from the shoreline, beach face, and 1-m depth on the nourished area. Sediment transportation of nourished material was observed by monitoring the amount of material remaining in 3 sub-regions (a nearshore region between the groins - A, a region representing the seaward end of the groins - B, and a region offshore of the groins - C) in the nourished region over time. The relationship between this behavior and waves was examined by considering the wave roses and time series of wave parameters produced as a result of wave simulations performed with the third-generation wave hindcast model SWAN. Lastly, as well as the variation of the mean layer thickness, the retreat of coastline, and mean beach width on the nourished area by the time were extracted for 8 different surveys. The results show that artificial beach nourishment materials were eroded in less than five months and the beach width returned to its initial position. The nourished material transported out groin-protected area moved eastward due to north-west dominated waves and the eastward longshore transport.

Changes of tropical gravity waves and the quasi‐biennial oscillation in storm‐resolving simulations of idealized global warming

Gravity waves generated by tropical deep convection contribute significantly to driving the downward propagation of the quasi‐biennial oscillation (QBO). However, it is currently uncertain how gravity waves and their interaction with the QBO, and thus the QBO itself, will respond to a warming climate. Previous work showed that this uncertainty is a consequence of the parametrization of gravity waves employed in conventional general circulation models. In this study, we therefore perform short explicit simulations of the QBO for different idealized climate states with the model ICON‐A in a deep convection‐permitting set‐up, which means that neither a parametrization of convection nor a parametrization of gravity waves is employed and that the QBO is entirely driven by explicitly resolved waves. Thereby, our simulations allow us to provide a very first direct estimate of how tropical gravity waves and the QBO may change in a warming climate. We found that the gravity wave momentum flux in the lower stratosphere that is relevant for the QBO increases substantially in the warmer climate states and shifts towards faster zonal phase speeds. As a consequence, the downward propagation of the QBO accelerates and the magnitude of the QBO jets in the upper QBO domain increases in the warmer climate states. Thus, our work builds an important first step towards a more comprehensive assessment of potential QBO changes using global storm‐resolving models.

Statistical characteristics of sea surface waves derived from buoy measurements in the eastern Guangdong offshore water

The wave characteristics of the eastern Guangdong offshore water were quantified based on 1-year wave observations at a water depth of 60 m. This study statistically analyzed the observed wave characteristics and quantified the variations of the wave parameters and spectrum due to Super Typhoon Mangkhut. Results showed that the dominant and strong wave directions in the northeastern South China Sea were north-eastern and eastern, respectively. The average significant wave height was in the range of 0.7–2.4 m. During Super Typhoon Mangkhut, the maximum wave height and period were 11.3 m and 10–12 s, respectively, and peak spectral density mainly varied between 0.06 and 0.1 Hz. Results of this study can provide a basis for offshore engineering design and are of great significance for marine forecasting and disaster prevention and reduction.

3D Computational Fluid Dynamic Investigation on Wave Transmission behind Low-Crested Submerged Geo-Bag Breakwater

Wave transmission characteristics behind low-crested submerged breakwaters involve complex-hydrodynamic interaction of water waves on the structures. To properly comprehend the induced-nonlinear wave transformation, the problem necessitates a trustworthy prediction using a computational fluid dynamic (CFD) technique. The goal of this study is to develop a three-dimensional (3-D) computational model of the hydrodynamic performance of a narrow crest behind a submerged breakwater in order to gain a thorough understanding of the wave transmission coefficient, K_t. The simulation took into account a number of wave parameters such as wave steepness (H_i⁄L), relative submergence depth (H_i⁄h), and crest width (c_w⁄L) of the structure. A numerical wave flume model is included, which is based on the full Navier-Stokes solver and includes a shallow water model to account for nonlinearity in the incident wave field. In addition, laboratory measurements were also conducted using a geo-bag dike model as the main breakwater structure. The result shows that the reduction in transmission coefficient correlates highly with the wave steepness and the relative submergence and crest parameters. This can be attributed to most breaking waves over the submerged breakwater. The steeper the incident wave, the greater the reduction in the transmitted wave. And, the greater the principal dimensions of the breakwater, the greater the drop in transmission coefficient. For validation, the CFD results corroborate satisfactorily with measurements

Kajian Karakteristik Gelombang Laut di Wilayah Pantai Pulau Merah, Kabupaten Banyuwangi


 
 
 
 Sea wave parameter information is used in maritime-related activities such as sea transportation, offshore exploration, fisheries, port construction, shipping safety, coastal area development, and coastal mitigation. This study described the characteristics of the sea waves in Pulau Merah Beach, Banyuwangi Regency. Wind reanalysis data of 10 meters was processed using the Sverdrup Munk Bretschneider (SMB) method using the Easywave algorithm. The analyzed and processed the sea wave model's assimilation data from Marine Copernicus pointwise by WRPLOT. The results of wind and ocean wave data processing showed that the direction, height, and period of sea waves on Pulau Merah Beach are strongly influenced by the Monsoon Wind. The sea wave height in the Pulau Merah Beach region reaches its peak value during the East season, which is 1.5 meters. In contrast, the value of the period of sea waves in the Pulau Merah Beach area reached its peak value during the Transitional Season I period, which was 8.3 seconds.
 
 
 

A Novel Wave Energy Equivalence Based Lumping Block Method for Efficiently Predicting the Fatigue Damage of Mooring Lines

The lumping block equivalent method (LBEM) is widely used to reduce the computational effort in the fatigue damage assessment of offshore structures, and the wave parameters of the representative sea states (RSSs) resulting from LBEM are of vital importance for the accurate prediction of offshore structures’ fatigue damage. In this study, a novel wave energy equivalence (WEE)-based LBEM is proposed to determine the wave parameters of the RSS accurately. The novelty of the proposed method is that a compact relationship between the input wave energy component and mooring lines’ fatigue damage is derived, and the modified statistical relationships between the wave parameters and spectral moments are provided by incorporating the effects of the peak enhancement factor of the input wave spectrum, the number of original sea states (OSSs) and the equivalence bandwidth of the OSSs. Based on the compact relationship, the wave energy component of the RSS can be determined from the wave energy component of the OSSs for each wave frequency from the viewpoint of the fatigue damage equivalence criterion. The wave energy distribution of the RSS can be accurately characterized with the wave energy distribution of the OSSs, and the spectral moments of the RSS can be calculated by its energy distribution directly, without any approximation. Moreover, the wave parameters of the RSS can be determined from the modified statistical relationships easily. The effectiveness of the proposed WEE LBEM is numerically investigated with a moored semi-submersible platform. Results show that the proposed WEE LBEM is robust, efficient and accurate within engineering expectations, and it outperforms the conventional LBEMs both in accuracy and robustness.

A simple electroanalytical methodology for determination of zaleplon by adsorptive stripping voltammetry in oral fluids

A glassy carbon electrode (GCE), modified with reduced graphene oxide (ErGO) (ErGO/GCE) was prepared for the determination of zaleplon, a common hypnotic pharmaceutical in synthetics and oral fluids. The modified electrode was evaluated using cyclic voltammetry, Raman spectroscopy, and scanning electrochemical microscopy (SECM). The electroanalytical studies were developed by square wave adsorptive stripping voltammetry (SW-AdSV) and parameters such as pH, accumulation potential, deposition time, and current response were optimized to determine zaleplon in Britton Robinson buffer. The validation was made using saliva-certified reference materials (Fusayama/Meyer Artificial Saliva and Artificial Saliva for Pharmaceutical Research showing good accuracy and reproducibility. The ErGO/GCE system showed a linear response between 10 and 130 µg/L at pH 10.0. The limit of detection was 5.30 μg L−1. The methodology was applied in the determination of zaleplon in saliva samples, obtaining excellent results (RSD < 10%), allowing the sensitive detection of zaleplon.

Advancements in Buoy Wave Data Processing through the Application of the Sage-Husa Adaptive Kalman Filtering Algorithm.

In this paper, we propose a combined filtering method rooted in the application of the Sage-Husa Adaptive Kalman filtering, designed specifically to process wave sensor data. This methodology aims to boost the measurement precision and real-time performance of wave parameters. (1) This study delineates the basic principles of the Kalman filter. (2) We discuss in detail the methodology for analyzing wave parameters from the collected wave acceleration data, and deeply study the key issues that may arise during this process. (3) To evaluate the efficacy of the Kalman filter, we have designed a simulation comparison encompassing various filtering algorithms. The results show that the Sage-Husa Adaptive Kalman Composite filter demonstrates superior performance in processing wave sensor data. (4) Additionally, in Chapter 5, we designed a turntable experiment capable of simulating the sinusoidal motion of waves and carried out a detailed errors analysis associated with the Kalman filter, to facilitate a deep understanding of potential problems that may be encountered in practical application, and their solutions. (5) Finally, the results reveal that the Sage-Husa Adaptive Kalman Composite filter improved the accuracy of effective wave height by 48.72% and the precision of effective wave period by 23.33% compared to traditional bandpass filter results.

State estimation of lithium-ion batteries based on the initial rise time feature of ultrasonic signals

Lithium-ion batteries have become one of the most critical energy storage systems due to their long cycle life and high energy density. Ultrasonic testing technology has been applied to the battery state estimation for the assurance of durability, safety and performance, however, the accuracy and reliability still need to be improved. In this paper, a new signal feature of the ultrasonic signal is proposed for the state of charge (SOC) estimation of batteries. The signal-shear effect is observed during charge/discharge cycles and is explained by the ultrasonic resonance phenomenon, based on which a SOC estimation method is proposed by using damped sine waves as excitations. This signal feature is characterized by the initial rise time (IRT), which is calculated by an algorithm based on the temporal moment and the adaptive moving root mean square. The optimal frequency and damping ratio parameters of the damped sine waves are found by a parameter-sweep study. Based on the experiment results, the proposed IRT feature is highly correlated to the SOC status with satisfying accuracy, monotonicity and linearity. The IRT feature has the additional advantage to be calculated by only a single data acquisition channel, providing a more convenient mean of battery status estimation.