Tidal Prediction Research Articles

Preliminary calibration results for Jason-3 and Sentinel-3 altimeters in the Wanshan Islands

We present preliminary calibration results for Jason-3 and Sentinel-3A altimeters that we set up in the Wanshan Islands in Guandong Province, China. Two campaigns were carried out in 2018, from March 8 to April 16 and from November 3 to December 11, 2018. Three GPS reference stations and tide gauges were established on the islands of Zhiwan, Dangan, and Wailingding during the campaigns. The in-situ sea surface height (SSH) of the altimeter footprint was determined using the tide gauge. The tidal and geoid connection between the tide gauge locations and the altimeter footprints were computed with the NAO.99Jb tidal prediction system and the EGM 2008 geoid, respectively. The data of the tide gauges were defined using the GPS buoy and GPS reference stations during the campaigns. The results show that the waveform of the altimeters was slightly contaminated by the small islands. The bias associated with Jason-3 and Sentinel-3A amounted to approximately +20.7±49.7 mm and +30.1±39.4 mm, respectively, which agreed well with the results from other in-situ calibration fields. This indicates that the Wanshan area was very suitable as an in-situ calibration/validation field. The wet zenith delay (WZD) determined from the Microwave Radiometer (MWR) and the GPS measurements diff ered from each other for the Jason-3 and Sentinel-3A by -6.6±7.4 mm and 0±6.8 mm, respectively.

Enhanced tide model: Improving tidal predictions with integration of wind data

Publicly available tidal predictions for coastlines are predominantly based on astronomical predictions. In shallow water basins, however, water levels can deviate from these predictions by a factor of two or more due to wind-induced fluctuations from non-regional storms. To model and correct these wind-induced tidal deviations, a two-stage empirical model was created: the Enhanced Tidal Model (ETM). For any given NOAA tide gauge location, this model first measured the wind-induced deviation based on a compiled dataset, and then adjusted the astronomical predictions into the future to create a 144-hour forecast. The ETM, when incorporating wind data, had only 76% of the error of NOAA astronomical tidal predictions (e.g. if NOAA had 1.0 ft. of error, ETM had only 0.76 ft. error from the observed water level). Certain ETM locations had approximately half (49%) as much prediction error as NOAA. With the improvement in tidal accuracy prediction, the ETM has the ability to significantly aid in navigation along with coastal flood prediction. We envision the ETM as a resource for industry and the public to make informed decisions that impact their livelihood.

Prediction Model of Red Tides in Fujian Sea Area Based on BP Neural Network

This paper presented a new model of the red tide in Fujian Province by BP neural network (BPNN) based on five sets of marine condition data between 2015 to 2019. Data cleansing and normalization were applied before the training. The 12-fold cross-validation reduced the shortage of data. As a result, this model could get a related correct prediction of red tide in this particular area.

Tidal velocities on the Mid-Atlantic Bight continental shelf using high-frequency radar

Surface current velocity from high-frequency radar data are used to study tidal currents in the Mid-Atlantic Bight, which represent an average 32% of the total kinetic energy of the surface circulation. Average annual and seasonal tidal current characteristics and the associated variance of the semi-major axis are computed. The M2 constituent dominates the tide, representing a maximum of 72.26% and an average of 51.63% of the total studied tidal signal. Its semi-major axis reaches a maximum of 10 cm s???1 around mid-shelf and its phase sweeps from north to south. Local maxima of the same order of magnitude are found near the mouths of estuaries (Long Island Sound, Hudson River, Delaware Bay, Chesapeake Bay) and an absolute maximum of 50 cm s???1 is found in Nantucket Shoals. These regions of localized elevated tidal amplitude are associated with high interannual and intra-annual variability due to seasonal stratification, internal waves, and sand waves. Seasonal tidal changes are large in some of these regions; thus, should not be neglected in making tidal predictions. Lastly, the authors position this paper as an updated alternative to the Moody tidal atlas as the source for tidal current values in the Mid-Atlantic Bight.

THE ANALYSIS FORMULATION OF THE LOWEST ASTRONOMICAL TIDE (LAT) BASED ON THE TIME OBSERVATION (THE CASE STUDY OF BENOA WATERS)

According to the definition of International Hydrographic Organization (IHO) M-13 2005, the LowestAstronomical Tide (LAT) is Internationally used as chart datum, which is used as instruction for measuring thevalidation of high water surface in the Hydro-oceanography survey. It is predicted by tide prediction for 18.61years. This research is observed minimized in one year. In determining of LAT, it will be analyzed by the tideConstanta and prediction analysis.The analysis of tide Constanta will be calculated by the Rayleigh numberingmethod (the smallest quadrat), start on tide data observation for one month, two months, three months, fourmonths, six months until twelve months data of tide observation. Afterward, from that analysis results of t ideConstanta, it can be predicted the tide for 18.61 years. From this result, the prediction will be found thedifference of the LAT value of tide data less than in one year with tide data in one year. Then, from thedifference of LAT values can be analyzed at a significant level by using the statistical approach. From the resultof the LAT calculation by using data observation of tide in one year will be got the LAT position that is 43.3 cm.If comparing with LAT value which uses a variety of data less than in one year, it will result in the level ofsignificant differences. In this case, LAT value thas is calculated by data less than in one year cannot beequated with LAT which is used by observation of tide data in one year.Keywords: LAT, Tide Component, and interval of tide observation.

Wind-Induced Currents in the Gulf of California from Extreme Events and Their Impact on Tidal Energy Devices

Tidal renewable energy is a promising alternative energy resource, and marginal seas are known as excellent sites for tidal energy exploitation. In-stream and tidal energy devices are less exposed to extreme weather events than wind energy. Nevertheless, during tropical storms, the currents may intensify to levels that threaten the integrity of the devices. This paper presents Hurricane Odile and its impact on the currents in the Gulf of California (GC) as a worst case scenario. A methodology to analyze the impact and its potential effects on tidal energy converters installed within the region are presented. The analysis is based on predictions obtained with a 3D shallow water model forced by tides and the meteorological conditions generated by Odile. A tidal model with no wind forcing was used for validation of the tidal model predictions. After validation, the two models were used to analyze the maximum anomaly in surface currents and sea surface height caused by the passage of Odile, and to analyze at which depth the devices could be deemed safe from any impact of the hurricane. Some anomalies extended throughout the water column, even in the deep regions of the GC. This paper highlights the importance of including the meteorological forcing in evaluations of tidal range or in-stream renewable energy resources and introduces new measures of device exposure to the current anomalies.

Presentation of a Wavelet‑Based Harmonic Model for Tidal Level Forecasting at Sabah and Sarawak

The world’s tides are a result of the combined forces of celestial forces and centrifugal force exerted by the Earth‑Moon and the Sun acting on the water body, earth tides and the atmospheric tides. Harmonic analysis is the most popular and widely accepted method used for the processing and expression of tidal behavior as well as its characteristics. Despite its strengths, harmonic analysis has a few drawbacks when short data are involved for long term‑prediction. However, to enhance the accuracy of the popular methodology of harmonic analysis (HA), this study presents a wavelet‑based harmonic model for tidal analysis and prediction. Six months of water level heights at four tide gauge stations in Sabah and Sarawak of Malaysia were employed. The results obtained agrees with the original data when a comparison was made. The root mean square error (RMSE) and Pearson correlation coefficient (r) are the statistical index tools applied to test the functioning of the model. The residual error is the deviation between the original data and the predicted data which was also computed in this study. The new wavelet‑based harmonic model improves the accuracy of prediction. Moreover, the model is efficient and feasible for tidal analysis and prediction.

Fringing Red Sea Corals Survival: Is It Tide or Local Wind?

In this paper, we obtain tidal constituents and discuss observations of tidal and wind variations and its impact on water surface elevation at Zaki’s Reef; a fringing coral reef located in the Red Sea-Gulf of Suez. This manuscript focuses on investigating if tidal forces are playing a key role to keep the area’s unique coral reefs alive and well. Determining the reasons why coral species and community of organisms found here survive despite all stressors is critical, and such information may hold the key to the preservation of reefs elsewhere. Phase and amplitude for 35 tidal constituents were deducted from observations of water surface elevation at the study site (first of its kind). The main tidal constituents based on their amplitudes are: M2, N2, S2, K1, NU2, K2, 2Ns, L2, and MU2. The first five tidal constituents of the aforementioned list are enough to reproduce accurate predictions of tides at this location (R2 variance = 87.54% and RMS = 0.167). The Tidal Form number (0.07) at Zaki’s Reef indicates a fully semidiurnal dominated tidal regime. Moreover, the Sa and Ssa constituents obtained from nearby stations made no improvements on tidal prediction results. Spectral analysis results of the white noise (residuals) from observed water surface elevation are dominated by daily frequency, suggesting that local wind plays a key role in circulation at study site. Local wind generated southerly long-shore and year-round offshore wind stress with a mean of -0.36 & 0.35 , respectively. The persistent longshore and offshore currents help transport oil patches/spills, from the two nearby ports, away from the reef. Yet, offshore wind stress, pushing water away from the shore, may cause more exposure of the reef to extreme atmospheric conditions. We hypothesize that the repeated reef exposure to the combined effect of tides and offshore wind stress over many years may have played a key role in selecting and then enhancing corals ability, through training, to become more adaptable to those harsh conditions. Training of corals over the years, may have led to the dominance of only six species, out of 35 coral species known to exist in the gulf. Those heat-adopted dominant species can be used to stimulate and revive impacted coral sites elsewhere.

南通港潮汐优化模型和算法研究

南通港潮汐优化模型和算法研究

Enhanced predictions of tides in the Persian Gulf through data assimilatio

Enhanced predictions of tides in the Persian Gulf through data assimilatio

Development of Tidal Prediction Functions Considering Ocean Meteorological Factors

The accurate calculation of tide levels is important in the design, construction, and management of structures associated with the sea or water areas. However, conventional tidal predictions only consider astronomical factors. Therefore, it is difficult to predict based on storm surges, oceanic weather and other factors. Herein, we presented a predictive function to accurately determine tide levels by considering marine factors. For the eastern coastal area, past forecasts and survey data were collected from three tide stations at the Korea Hydrographic and Oceanographic Administration. In addition, data of maritime factors such as wind speed, wave height, and wave period were collected from domestic buoy stations at the Korea Meteorological Administration. Logistic regression analysis was conducted to predict the occurrence of abnormal tides, and a new tidal prediction function was proposed through multiple regression analyses. The Bayesian Information Criterion (BIC) method was used to select variables, and accuracy verification through k-division cross-validation and Normalized-Root Mean Square Error (N-RMSE) was performed. For the latter, the values ranged from 3.37% to 12.03%. If continuous meteorological data are accumulated and marine meteorological data are acquired near the tidal observation point, tidal levels can be predicted more accurately. Keywords: Abnormal Tidal, Multiple Linear Regression, Logistic Regression, Tidal Prediction

On Robust Multi-Year Tidal Prediction Using T_TIDE

A minimum 19 year tidal prediction dataset covering nodal (satellite) modulation effects is required to determine the Lowest Astronomical Tide (LAT) and Highest Astronomical Tide (HAT) datums. In this study, we explore the ability of a widely used conventional standard harmonic prediction program, T_TIDE ‘t_predic.m’ from Pawlowicz et al. (2002), to produce accurate continuous multi-year predictions. Comparisons are made with the more recent tidal prediction program, UTide ‘ut_reconstr.m’ from Codiga (2011). Tidal height records for two different regimes are employed: for diurnal tides data are employed from Cape Roberts in Antarctica, while for semi-diurnal tides data are used from Incheon, Gyeonggi Bay, Korea. Results demonstrate an issue arises in continuous multi-year tidal predictions made via T_TIDE, due to the program’s single calculation (fixed) of nodal modulation corrections (NMC). We explain a modified NMC update method that successfully solves this problem, rendering the program of use for accurate continuous multi-year tidal predictions.

Meteorological Tidal Predictions in the Mekong Estuary Using an Evolved ANN Time Series

Retraction NoticeThe Marine Technology Society Journal was contacted in April 2022 pointing to major concerns, including forged affiliations, related to this publication. The claimant noted the unethical practice of these two authors has been reported in relation to 60+ articles published in more than one dozen other journals. Recently, these authors plausibly changed their forenames/first names to repeat similar misconducts. In the paper 'Meteorological Tidal Predictions in the Mekong Estuary Using an Evolved ANN Time Series' (doi: 10.4031/mtsj.53.6.3), the affiliation of the author CYJ Chen to NAAM Research Group, King Abdulaziz University Saudi Arabia, is false. This university did not employ CYJ Chen between 2018 and 2021.

Reassessment of long-period constituents for tidal predictions along the German North Sea coast and its tidally influenced rivers

Abstract. The harmonic representation of inequalities (HRoI) is a procedure for tidal analysis and prediction that combines aspects of the non-harmonic and the harmonic method. With this technique, the deviations of heights and lunitidal intervals, especially of high and low waters, from their respective mean values are represented by superpositions of long-period tidal constituents. This article documents the preparation of a constituents list for the operational application of the harmonic representation of inequalities. Frequency analyses of observed heights and lunitidal intervals of high and low water from 111 tide gauges along the German North Sea coast and its tidally influenced rivers have been carried out using the generalized Lomb–Scargle periodogram. One comprehensive list of partial tides is realized by combining the separate frequency analyses and by applying subsequent improvements, e.g. through manual inspections of long time series data. The new set of 39 partial tides largely confirms the previously used set with 43 partial tides. Nine constituents are added and 13 partial tides, mostly in the close neighbourhood of strong spectral components, are removed. The effect of these changes has been studied by comparing predictions with observations from 98 tide gauges. Using the new set of constituents, the standard deviations of the residuals are reduced on average by 2.41 % (times) and 2.30 % (heights) for the year 2016. The new set of constituents will be used for tidal analyses and predictions starting with the German tide tables for the year 2020.

Evaluation of Delay Factors on Dry Bulk Cargo Operation in Malaysia: A Case Study of Kemaman Port

There are various types of delay factors that could affect the efficiency and effectiveness of the dry bulk cargo operation, especially in port. Hence, it raises the concerns of the stakeholders, as some of them can significantly affect their actual transport plans and cost them extra money to handle the cargo. Due to uncertainty of the most significant delay factor in some Malaysia's dry bulk ports, therefore, this study aims to evaluate the most significant delay factors that causing delays in dry bulk cargo operation by using the analytical hierarchy process (AHP) method. This study found that the factor of ‘Miscellaneous’ is the most significant factor that contributed to the most of delay creations in dry bulk cargo operation in Kemaman port. Meanwhile, sub-criterion of ‘Foul weather and tide prediction’ is selected as the most significant sub-cause of delay creation in similar port. This study contributes the practical technique and valuable findings to the port and its stakeholders, where it may alert the them to measure the factors that affect their operational performance and business. Also, it introduces the usage of practical and systematical analysis technique for assisting the seaport operator or interested parties in analyzing the potential contributors of a condition in the port settings.

The October 29, 2018 storm in Northern Italy – An exceptional event and its modeling

On October 29, 2018 a very severe storm affected Northern Italy, including the Adriatic Sea. The ensuing surge and wave conditions at and in front of Venice stand at the extreme tail of the respective historical return period distributions. The large set of available measured data, at the coast and at the offshore oceanographic tower, coupled with detailed numerical simulations, allows a keen analysis of the storm, its predictability and in particular of the ensuing enhanced coastal processes. These include the coastal set-up, the input information for tidal prediction in Venice, the documented passage of an atmospheric cold front and, using the local tidal data, the derived possibility of estimating the surface wind stress, the evidence of reflected waves from the coast and the associated seismometers signal 40 km inland. The highest crest and wave heights measured at the tower are beyond what is suggested by non-linear statistics. The relative out-of-scale magnitude of the three major storms since 1966 suggests the possibility that they belong to a self-standing family of events.

Validating an Operational Flood Forecast Model Using Citizen Science in Hampton Roads, VA, USA

Changes in the eustatic sea level have enhanced the impact of inundation events in the coastal zone, ranging in significance from tropical storm surges to pervasive nuisance flooding events. The increased frequency of these inundation events has stimulated the production of interactive web-map tracking tools to cope with changes in our changing coastal environment. Tidewatch Maps, developed by the Virginia Institute of Marine Science (VIMS), is an effective example of an emerging street-level inundation mapping tool. Leveraging the Semi-implicit Cross-scale Hydro-science Integrated System Model (SCHISM) as the engine, Tidewatch operationally disseminates 36-h inundation forecast maps with a 12-h update frequency. SCHISM’s storm tide forecasts provide surge guidance for the legacy VIMS Tidewatch Charts sensor-based tidal prediction platform, while simultaneously providing an interactive and operationally functional forecast mapping tool with hourly temporal resolution and a 5 m spatial resolution throughout the coastal plain of Virginia, USA. This manuscript delves into the hydrodynamic modeling and geospatial methods used at VIMS to automate the 36-h street-level flood forecasts currently available via Tidewatch Maps, and the paradigm-altering efforts involved in validating the spatial, vertical, and temporal accuracy of the model.

Ocean Observations Required to Minimize Uncertainty in Global Tsunami Forecasts, Warnings, and Emergency Response

It is possible that no catastrophe has mobilized the global ocean science and coastal emergency management communities more than the 2004 Indian Ocean tsunami. Though the Pacific tsunami threat was recognized, and a warning system had been in place since 1965, there was no warning system in the Indian Ocean, and almost 230,000 people perished. More broadly, the event highlighted critical gaps in global tsunami science and observation systems. In 2004, real-time coastal and deep-ocean observation systems were almost nonexistent. Tsunami sources were inferred based on rough seismic parameters. Since then, tremendous strides have been made under the auspices of IOC/UNESCO toward better understanding tsunami mechanisms, deploying advanced real-time tsunami observation systems, and establishing tsunami warning and mitigation systems for the four main ocean basins at risk from tsunamis. Nevertheless, significant detection, measurement, and forecast uncertainties remain to meet emergency response and community needs. A new generation of ocean sensing capabilities presents an opportunity to address several of these uncertainties. Ocean bottom pressures can be measured over dense, multisensor grids linking stand-alone buoy systems with emerging capabilities like fiber-optic cables. The increasing number of coastal sea-level stations can better verify forecasts and account for local variability. In addition, GNSS sensors may be able to provide solid-earth data needed to define seismic tsunami sources more precisely in the short timescales required. When combined with advances in seismology, other emerging techniques, and state-of-the-art modeling and computational resources, these capabilities will enable more timely and accurate tsunami detection and measurement to meet identified user needs and save lives. Because of these advances in detection and measurement, the opportunity exists to greatly reduce and/or quantify uncertainties associated with forecasting tsunamis. Providing more timely and accurate information related to tsunami location, arrival time, height, inundation, and duration would improve public trust and confidence and fundamentally alter tsunami emergency response. Additionally, this capability could be integrated with related fields (e.g., storm surge, sea-level rise, tide predictions, and ocean forecasting) to develop and deploy one continuous, real-time, accurate depiction of the always moving boundary that separates ocean from coast, wet from dry, and, sometimes, life from death.

Improving the Definition and Algorithms of China’s Coastline Considering the Diversity of Tidal Characteristics

Two commonly used definitions of coastline are compared and analyzed in this article. To build a more perfect digital tide-coordinated coastline model in China, we should first solve the problems of the existing definition and unclear algorithms of China’s coastline. On the basis of defining the coastline in China as the intersection of coastal land and the mean high water spring (MHWS), it should be further revised, and defined either as an intersection of coastal land and the MHWS or as a mean higher high water level (MHHWL) considering the diversity of tidal characteristics in China Sea areas. Since MHWS is related to the extreme of the lunar phase and MHHWL is related to the extreme of the angle of the lunar declination elevation, the algorithms to obtain them are more complicated than that of mean high water (MHW) used in the United States. We should consider the specific law of tidal movement in different tide types of the predominantly semidiurnal or diurnal sea areas in China when studying the precise algorithms for MHWS and MHHWL. Several experiments show that the difference between the two types of calculations of coastal height, such as water level observations and tidal predictions, is within centimeter level. The research results of this article have a certain reference value for countries with similar coastline features as in China.

Long-Distance Path Planning for Unmanned Surface Vehicles in Complex Marine Environment

Many missions require unmanned surface vehicles to operate in complex environments over large distances. Marine environments are dynamic in nature and change over time as a result of tides, weather, and environmental restrictions. As a result, the available free traversal space for a marine vehicle in the given map can change over time. This requires the marine vehicle to dynamically generate and update the traversal map to represent the free space. This paper presents techniques for speeding up A* search on the nodes of visibility graphs. We use a quadtree representation of the marine environment to enable the algorithm to efficiently compute the nodes of the visibility graphs. We have developed an admissible heuristic that considers the large islands while estimating cost-to-go, and provide better estimates than a Euclidean distance-based heuristic. Due to the large size of the marine environment, the branching factor of the search tree can become large and reduce the efficiency of the path planner. We have developed an approach that focuses the search by only considering the child nodes lying in the local region around each node. Our experiments demonstrate that by focusing the search, we can reduce the computational time without significantly sacrificing the optimality of the computed path. We also present an extension to the algorithm for handling dynamic environments with time-varying free spaces. We incorporated the depth charts developed by the National Oceanic and Atmospheric Administration (NOAA), Silver Spring, MD, USA, along with the tide predictions to estimate the time-varying free space that can be used by the planner.