Tidal Information Research Articles

Improved tide level prediction model combined GA-BP neural networks and GNSS SNR data

High-precision tidal forecasting plays a crucial role in providing reliable tidal information to coastal communities, ship operators, fishermen, and government agencies. Existing tidal prediction models, such as backpropagation neural networks (BPNN) and genetic algorithm-optimized BPNN (GA-BPNN), frequently difficulty in in achieving high precision because they rely solely on past tidal variations for real-time predictions. Signal-to-Noise Ratio (SNR) data have emerged as a valuable indicator closely related to real-time sea level changes due to the widespread adoption of Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) technology. In this paper, we propose a nowcasting tide level prediction method by adding SNR data to BPNN, i.e., Improved BPNN and Improved GA-BPNN, which predicts the next momentary tide level value by using the previous 15 tidal values and real-time SNR as input factors to BPNN. The results of 100-day, 200-day and 1-year tide prediction based on Astoria and Friday Harbor tide gauge stations show that the improved model prediction accuracies are better than the traditional model. Meanwhile, among the two improved models, Improved GA-BPNN has the higher prediction accuracy and can adapt to different time lengths of tide level prediction.

Nudging visitors into pro-environmental behaviour: Assessing the use of a tidal information pillar for effective dynamic zoning

In the past few years, more human-wildlife conflicts have occurred as a result of increased human visitations, particularly in areas where space is scarce and functions need to co-exist. Nature organisations are increasingly challenged to improve nature protection on the one hand, while offering visitors high quality nature experiences on the other hand. To encourage both go hand in hand, nudging has recently received more attention. Nudging is a tool to subtly change human behaviour without imposing strict rules. It is, however, hardly applied in nature areas. Currently, experiments are taking place in the Dutch part of the Wadden Sea with alternating signage (nudging message based on real-time data of the area) aided by a tidal information pillar to encourage dynamic zoning. At low tide the signage indicates: freely accessible, at high tide the advice: ‘do not enter’. The purpose is to address visitors' sense of responsibility, nudge pro-environmental behaviour and reduce human-wildlife conflicts by limiting access. This article assesses the effectiveness of the alternating nudging signage, and especially the effectiveness of the signage ‘high tide – do not enter’. The results show that the signage on the pillar is most effective when visitors stop at the pillar and read the advice. Among these visitors, about half turn around. Among the visitors who do not encounter the signage and the pillar, the majority goes on to access the area. With this study, we aim to contribute to the knowledge on nudging as a tool to promote pro-environmental behaviour in nature areas.

Assessing Tidal Models in the Ryukyu Islands Region Using the ENOPF Method

Abstract Satellite remote sensing can monitor sea level changes at temporal and spatial scales, plays an important role in the study of tides, and is widely used in numerical tidal models. However, these tidal models are usually computationally expensive. The equidistant nodes orthogonal polynomial fitting (ENOPF) method may overcome that drawback. This study evaluates the accuracy of the ENOPF method in fitting the major tidal constituents in the region near the Ryukyu Islands, where the water depth on either side of the islands varies significantly. The results show that the ENOPF method can accurately fit the major tidal constituents in the presence of complex topography. Furthermore, this approach can also be used to generate reasonable cotidal charts and provide valuable tidal information for hydrodynamic model simulations in the East China Sea. For the high-resolution hydrodynamic model of the East China Sea in particular, reasonable open boundary conditions can be provided by the ENOPF method.

Feasibility of tide simulation using nesting module of FVCOM—a case study of Xiangshan Bay

The nesting module of FVCOM is widely utilized in numerical simulations for both nearshore and offshore. However, the details of the nesting module on computation accuracy and efficiency have not been quantitatively assessed. In this study, we take Xiangshan Bay as a case study area and design two groups of experiments to examine this issue on tide simulation. The results indicate that nesting module effectively incorporates all tidal information from the open ocean through the boundary. The nesting module experiment successfully simulates the tides almost exactly similar to the original tides, while achieving an efficiency improvement of approximately 48% by avoiding computations outside the high-resolution area.

A decision support system for autonomous ship trajectory planning

This study presents an approach to enhance human–machine collaboration in autonomous ship trajectory planning. A decision support system is developed, considering crucial environmental factors such as ocean currents, wind, and tidal information, alongside the integration of narrow channel geometry, squat effect, and Under-keel-clearance (UKC). The Dynamic Consequence Analysis (DCA) risk assessment method is utilized to establish dynamic safety domains, incorporating ship maneuvering characteristics and potential failure scenarios. The Multi-objective Particle Swarm Optimization (MOPSO) algorithm is then employed to generate alternative trajectories, optimizing five objective functions: minimizing safety domain violation, consecutive speed changes, path length, deviation from the initial plan, and deviation from the initial estimated time of arrival. Furthermore, two Multi-criteria Decision Making (MCDM) methods, Multi-Objective Optimization by Ratio Analysis (MOORA) with user preferences, and the Entropy Weight Method (EWM) with automatic weight allocation, are employed to rank alternative solutions from the Pareto front. Finally, a clustering method is employed on the Pareto front solutions. The outcomes that serve as representatives for these clusters are then merged with the highest-rated alternative solutions from MCDM methods. This combined set forms the basis for the final decision-making process carried out by the operator. While dynamic obstacles are not considered in this study, evaluation across three scenarios demonstrates the effectiveness of the proposed decision support system for trajectory planning.

Pelatihan Pembuatan Pemodelan Dan Simulasi Banjir Di Kawasan Pesisir Kota Semarang Menggunakan ArcScene 10.4

<p><em>In the field of regional and urban planning, several media can be used to convey information about the problems of an area. The most commonly used medium is using maps. The analysis carried out to present information in the form of maps varies according to needs. To represent and present flood and tidal information in the coastal area of Semarang City, 3D modeling training was conducted using ArcScene 10.4 software, which is part of ArcGIS software. This modeling is carried out by utilizing DEM (Digital Elevation Model) data and data on the addition of water discharge in coastal areas which will then be processed and simulated in the 3-dimensional form that can be watched in video form. It is hoped that this community service in the form of training can provide further knowledge and understanding regarding mapping activities so that it can be applied in student learning and research activities. So second-semester students of the Urban and Regional Planning Department, Faculty of Engineering, Universitas Semarang have a basic understanding of planning and a more sensitive to urban issues and how to do the right analysis according to the goals and needs of urban planning.</em></p>

Extraction of ocean tidal information based on global equal-area grid and satellite altimeter data

ABSTRACT Harmonic analysis of satellite altimetry data based on a global regular grid is affected by the grid spatial tessellation and placement of the grids. With the increase of latitude, the traditional lat/lon grid deforms greatly, resulting in uneven distribution of satellite altimeter data with latitude, which affects the extraction of tidal information. Alternatively, Hexagonal grids have been proved to be advantageous due to their isotropic, uniform neighbourhood, equal-area and more. Considering the merits above, the purpose of this paper is to use the global equal-area hexagonal grid to conduct a harmonic analysis of satellite altimeter data. First, the Icosahedron Snyder Equal Area projection method is used to construct a global equal-area hexagonal grid, Then the time series data of 19.8 years of Jason series satellite altimeter data are obtained. Finally, the harmonic constants of eight constituents (the M2, S2, N2, K2, K1, O1, P1, Q1) are extracted by harmonic analysis. By analysing the results, we conclude that the harmonic constants extracted from the global equal-area hexagonal grid have considerable accuracy and are consistent with the tidal characteristics of the eight components. Meanwhile, the accuracy of harmonic constants extracted from equal-area hexagonal grids is better than that of lat/lon grids.

Extraction of ocean tidal information based on global equal-area grid and satellite altimeter data

Extraction of ocean tidal information based on global equal-area grid and satellite altimeter data

Construction of Tidal Information Database on the Southern Coast of Korea and Prediction of the Tide

The construction of the tidal information database study was conducted through numerical simulations for the southern coast of Korea. Because Korea has a complex coastline, the grid size of the numerical model was set to 0.1min(approx. 200m) to improve the accuracy of tidal prediction. The NAO.99jb, one of the ocean tide models, was employed in the study to increase the accuracy of the database. The numerical model applied to the database construction was calibrated and validated using observation data from the Korea hydrographic and oceanographic agency. To construct a high-resolution tidal information database, we conducted harmonic analysis for each computational grid point using numerical simulation results. In order to evaluate the tide and tidal current prediction performance of the tidal information database, numerical simulation results were used and compared. The results show that the predictive performance of the harmonic constant database is sufficient, so it can be used where rapid tidal prediction is required.

Harmonic Analysis of Non-Phase-Locked Tides with Red Noise Using the red_tide Package

Abstract A novel tidal analysis package (red_tide) has been developed to characterize low-amplitude non-phase-locked tidal energy and dominant tidal peaks in noisy, irregularly sampled, or gap-prone time series. We recover tidal information by expanding conventional harmonic analysis to include prior information and assumptions about the statistics of a process, such as the assumption of a spectrally colored background, treated as nontidal noise. This is implemented using Bayesian maximum posterior estimation and assuming Gaussian prior distributions. We utilize a hierarchy of test cases, including synthetic data and observations, to evaluate this method and its relevance to analysis of data with a tidal component and an energetic nontidal background. Analysis of synthetic test cases shows that the methodology provides robust tidal estimates. When the background energy spectrum is nearly spectrally white, red_tide results replicate results from ordinary least squares (OLS) commonly used in other tidal packages. When background spectra are red (a spectral slope of −2 or steeper), red_tide’s estimates represent a measurable improvement over OLS. The approach highlights the presence of tidal variability and low-amplitude constituents in observations by allowing arbitrarily configurable fitted frequencies and prior statistics that constrain solutions. These techniques have been implemented in MATLAB in order to analyze tidal data with non-phase-locked components and an energetic background that pose challenges to the commonly used OLS approach.

Cosmic Tidal Reconstruction with Halo Fields

Abstract The gravitational coupling between large-scale perturbations and small-scale perturbations leads to anisotropic distortions of the small-scale matter distribution. The measured local small-scale power spectrum can thus be used to infer the large-scale matter distribution. In this paper, we present a new tidal reconstruction algorithm for reconstructing large-scale modes using the full three-dimensional tidal shear information. We apply it to simulated dark matter halo fields and find the reconstructed large-scale density field correlates well with the original matter density field on large scales, improving upon the previous tidal reconstruction method, which only uses two transverse shear fields. This has profound implications for recovering lost 21 cm radial modes due to foreground subtraction and constraining primordial non-Gaussianity using the multitracer method with future cosmological surveys.

Tidal water exchange drives fish and crustacean abundances in salt marshes

Coastal salt marshes provide important habitat for fishes and crustaceans, including species of commercial value that feed or take refuge in the marsh. Yet population abundances vary considerably between sites, often without clear explanation. We hypothesised that faunal abundance and mean size would be positively related to 2 physical properties that govern marsh accessibility to water-dependent species, as has been found on the southeastern coast of the USA: (1) the volume of water exchanged by tidal flooding, which gives access to the marsh, and (2) edge amount, the length of the water-vegetation borderline per unit area where species can take refuge and feed. Digital terrain models and tidal information were used to select 5 marshes in Wales, UK, that differed in edge amount and water exchange (52°N, 4°W). Fishes and crustaceans were sampled using baited traps, fyke nets and seine nets. In total, 15 species were caught, including commercially valuable brown shrimp, European eel and sea bass. We found water exchange volume, but not edge amount, boosted fish and crustacean abundances. Crab and sea bass sizes were both negatively affected by water exchange, while shrimp and fish sizes were unaffected. Our findings show how the mechanisms that drive fish and crustacean abundances and sizes vary between geographical regions. Feasibly, fisheries associations with marsh hydrogeomorphology might operate differently as well.

First results of undersea muography with the Tokyo-Bay Seafloor Hyper-Kilometric Submarine Deep Detector

Tidal measurements are of great significance since they may provide us with essential data to apply towards protection of coastal communities and sea traffic. Currently, tide gauge stations and laser altimetry are commonly used for these measurements. On the other hand, muography sensors can be located underneath the seafloor inside an undersea tunnel where electric and telecommunication infrastructures are more readily available. In this work, the world’s first under-seafloor particle detector array called the Tokyo-bay Seafloor Hyper-Kilometric Submarine Deep Detector (TS-HKMSDD) was deployed underneath the Tokyo-Bay seafloor for conducting submarine muography. The resultant 80-day consecutive time-sequential muographic data were converted to the tidal levels based on the parameters determined from the first-day astronomical tide height (ATH) data. The standard deviation between ATH and muographic results for the rest of a 79-day measurement period was 12.85 cm. We anticipate that if the length of the TS-HKMSDD is extended from 100 m to a full-scale as large as 9.6 km to provide continuous tidal information along the tunnel, this muography application will become an established standard, demonstrating its effectiveness as practical tide monitor for this heavy traffic waterway in Tokyo and in other important sea traffic areas worldwide.

Bayesian inference of multimessenger astrophysical data: Methods and applications to gravitational waves

We present ${\tt bajes}$, a parallel and lightweight framework for Bayesian inference of multimessenger transients. ${\tt bajes}$ is a Python modular package with minimal dependencies on external libraries adaptable to the majority of the Bayesian models and to various sampling methods. We describe the general workflow and the parameter estimation pipeline for compact-binary-coalescence gravitational-wave transients. The latter is validated against injections of binary black hole and binary neutron star waveforms, including confidence interval tests that demonstrates the inference is well-calibrated. Binary neutron star postmerger injections are also studied using a network of five detectors made of LIGO, Virgo, KAGRA and Einstein Telescope. Postmerger signals will be detectable for sources at ${\lesssim}80\,$Mpc, with Einstein Telescope contributing over 90\% of the total signal-to-noise ratio. As a full scale application, we re-analyze the GWTC-1 black hole transients using the effective-one-body ${\tt TEOBResumS}$ approximant, and reproduce selected results with other approximants. ${\tt bajes}$ inferences are consistent with previous results; the direct comparison of ${\tt bajes}$ and ${\tt bilby}$ analyses of GW150914 shows a maximum Jensen-Shannon divergence of $5.2{\times}10^{-4}$. GW170817 is re-analyzed using ${\tt TaylorF2}$ with 5.5PN point-mass and 7.5PN tides, ${\tt TEOBResumSPA}$, and ${\tt IMRPhenomPv2\_NRTidal}$ with different cutoff-frequencies of $1024\,$Hz and $2048\,$Hz. We find that the former choice minimizes systematics on the reduced tidal parameter, while a larger amount of tidal information is gained with the latter choice. ${\tt bajes}$ can perform these analyses in about 1~day using 128 CPUs.

Establishing a framework of a watershed-wide screening tool to support the development of watershed-based flood protection plans for low-lying coastal communities

Flood risk analysis is the instrument by which floodplain and stormwater utility managers create strategic adaptation plans to reduce the likelihood of flood damages in their communities, but there is a need to develop a screening tool to analyze watersheds and identify areas that should be targeted and prioritized for mitigation measures. The authors developed a screening tool that combines readily available data on topography, groundwater, surface water, tidal information for coastal communities, soils, land use, and precipitation data. Using the outputs of the screening tool for various design storms, a means to identify and prioritize improvements to be funded with scarce capital funds was developed, which combines the likelihood of flooding from the screening tool with a consequence of flooding assessment based on land use and parcel size. This framework appears to be viable across cities that may be inundated with water due to sea-level rise, rainfall, runoff upstream, and other natural events. The framework was applied to two communities using the 1-day 100-year storm event: one in southeast Broward County with an existing capital plan and one inland community with no capital plan.

Probing modified gravitational-wave propagation through tidal measurements of binary neutron star mergers

Gravitational-wave sources can serve as standard sirens to probe cosmology by measuring their luminosity distance and redshift. Such standard sirens are also useful to probe theories beyond general relativity with a modified gravitational-wave propagation. Many of previous studies on the latter assume multi-messenger observations so that the luminosity distance can be measured with gravitational waves while the redshift is obtained by identifying sources' host galaxies from electromagnetic counterparts. Given that gravitational-wave events of binary neutron star coalescences with associated electromagnetic counterpart detections are expected to be rather rare, it is important to examine the possibility of using standard sirens with gravitational-wave observations alone to probe gravity. In this paper, we achieve this by extracting the redshift from the tidal measurement of binary neutron stars that was originally proposed within the context of gravitational-wave cosmology (another approach is to correlate "dark sirens" with galaxy catalogs that we do not consider here). We consider not only observations with ground-based detectors (e.g. Einstein Telescope) but also multi-band observations between ground-based and space-based (e.g. DECIGO) interferometers. We find that such multi-band observations with the tidal information can constrain a parametric non-Einsteinian deviation in the luminosity distance (due to the modified friction in the gravitational wave evolution) more stringently than the case with electromagnetic counterparts by a factor of a few. We also map the above-projected constraints on the parametric deviation to those on specific theories and phenomenological models beyond general relativity to put the former into context.

Remote Sensing Method for Extracting Topographic Information on Tidal Flats Using Spatial Distribution Features

A remote sensing method combining remote sensing and ground surveying is proposed to extract tidal flat topographic information via the spatial distribution characteristics of tidal flat surface features. Based on the eastern Chongming beach of the Yangtze Estuary and Landsat-5 satellite images, this study identifies the spatial distribution characteristics of tidal flat features using field-based RTK data and spectral data. The remote sensing method for extracting the geometric and physical characteristics of linear and surface geographical elements on tidal flats and the elevation assignment method are discussed. The effectiveness of this method is verified by the quality of the resultant tidal flat DEM. The results show that the use of spatial distribution features in remote sensing images can provide rich topographic information. The DEM results have an accuracy of 0.16 m, are in line with the basic topographic patterns of tidal flats, and can describe local microscale geomorphic features. This technique solves the problem of a single topographic information source in current remote sensing measurement methods and provides technical support for detecting dynamic changes in coastal zones by using remote sensing technology.

Study of Tidal Characteristics in The South and North Coastal of Sumenep Regency, Madura

Sumenep is one of Madura's regency, which has many islands with a wealth and diversity of natural resources, especially in its marine and coastal areas. With many islands owned, sea transportation in Sumenep is of great importance in the regency. One of the crucial aspects that must be considered related to this transportation is tidal information. This study aims to determine the tidal characteristics in the South and North Coast of Sumenep Regency using the Least Square method. The tide data used in February and September 2020 were obtained from the Geospatial Information Agency (BIG) with an observation interval of one hour. This time was chosen because it represents monsoons' occurrence in Indonesia in the annual season, namely the dry and rainy seasons. The results of this study indicate that the southern coastal area (Giligenting District) has a mixed tidal type, tends to be semi-diurnal with Formzahl numbers of 0.86 and 1.29 (0.25 3.0). The different tides are due to the sampling's location representing different geographical conditions, namely open waters (North Coast) and closed waters (Pesisir Selatan). The elevation parameters obtained still need supporting data such as waves, currents, and bathymetry used by policymakers for safety in using sea transportation.

A Framework for a Subwatershed-Scale Screening Tool to Support Development of Resiliency Solutions and Flood Protection Priority Areas in a Low-Lying Coastal Community

Flood risk analysis is the instrument for local officials to create a sound strategy and adaptation plans for the impacts of inundation due to heavy rains, climate change and sea level rise. Hence, cities with aging infrastructure are retrofitting their stormwater management systems to mitigate the impacts. However determining the most at risk areas and the options for corrections is more challenging. As a result, there is an urgent need to develop a screening tool to analyze watersheds and identify the most at-risk areas. High-quality, open source data and sophisticated spatial analysis techniques allow engineers to create innovative ways to conduct watershed wide inundation analysis. In this study, the investigators developed a screening tool to identify at-risk properties by combining readily available data on topography, groundwater, surface water, tidal information for coastal communities, soils, open space, and rainfall data. Once the screening tool is developed, the means to identify and prioritize improvements to be funded with scarce capital funds is the next step. A tool box of solutions was developed to address flood risk and vulnerability. Testing of the screening tool was conducted in Broward County, Florida and shows encouraging results. Comparison with FEMA Flood maps and repetitive loss mapping indicates that the process works in a coastal community. The framework appears to be viable across cities that may be inundated with water due to sea-level rise, rainfall, runoff upstream, and other natural events.

Numerical simulation study of oil diffusion at low tide near the port area of Ma’ao, Zhoushan

In this paper, the numerical hydrodynamic simulation has been carried out by using measured topographic data and related tidal information. The oil particle tracking module of MIKE21 is adopted to study the processes of drifting and turbulent diffusion of oil particles on the water surface, where four working conditions, namely, static wind, dominant wind direction, maximum wind direction and most unfavourable wind direction, are applied. Results show that Xiushan Island will be the apparent ‘victim’ in the cases of oil spill in all wind directions. Meanwhile, due to the existence of Changbai Island and Xiushan Island, the diffusion process of oil particles is obviously retarded to impact the protected marine areas.