Tidal Model Research Articles

ArcTiCA: Arctic tidal constituents atlas

Tides in the Arctic Ocean affect ocean circulation and mixing, and sea ice dynamics and thermodynamics. However, there is a limited network of available in situ tidal coefficient data for understanding tidal variability in the Arctic Ocean; e.g., the global TICON-3 database contains only 111 sites above 60°N and 21 above 70°N. At the same time, the presence of sea ice and latitude limits of satellite altimetry complicate altimetry-based retrievals of Arctic tidal coefficients. This leads to a reliance on ocean tide models whose accuracy depend on having sufficient in situ data for validation and assimilation. Here, we present a comprehensive new dataset of tidal constituents in the Arctic region, combining analyses of in situ measurements from tide gauges, ocean bottom pressure sensors and GNSS interferometric reflectometry. The new dataset contains 914 measurement sites above 60°N and 399 above 70°N, with each site being quality-assessed and expert guidance provided to help maximise the usage of the dataset. We also compare the dataset to recent tide models.

Detection of Tidally Excited Oscillations in Kepler Heartbeat Stars

Heartbeat stars (HBSs) with tidally excited oscillations (TEOs) are ideal laboratories for studying the effect of equilibrium and dynamical tides. However, studies of TEOs in Kepler HBSs are rare due to the need for better modeling of the equilibrium tide in light curves. We revisit the HBSs in our previous work and study the TEOs in these HBSs based on the derived orbital parameters that could express the equilibrium tide. We also compile a set of analytic procedures to examine the harmonic and anharmonic TEOs in their Fourier spectra. The TEOs of 21 HBSs have been newly analyzed and presented. Twelve of these HBSs show prominent TEOs (signal-to-noise ratio of the harmonics S/N ≥ 10). The relation between the orbital eccentricities and the harmonic number of the TEOs shows a positive correlation. The relation between the orbital periods and the harmonic number also shows a positive correlation. Furthermore, the distribution of HBSs with TEOs in the Hertzsprung–Russell diagram shows that TEOs are more visible in hot stars with surface effective temperatures T ≳ 6500 K. These samples may also be valuable targets for future studies of the effect of tidal action in eccentric orbits.

Tidal disruption event associated with the quasi-periodic eruptions from GSN 069: Possible disruption of a common envelope

Context. X-ray quasi-periodic eruptions (QPEs) from the galactic nucleus have been found in several galaxies. Among them, GSN 069 is the only one with a tidal disruption event (TDE), which was recently found to have brightened again 9 years after the main outburst. Aims. However, the origin of this TDE is still unclear. This Letter explores a particular model for the TDE. Methods. By comparing the fallback time with observations, we found the TDE could not be caused by the disruption of the envelope of a single star in the tidal stripping model. Thus, we suggest that it is a disruption of a common envelope (CE). Results. By calculating the fallback rate of such a model, we reproduced the second peak in the observed TDE light curve. If this model is correct, this TDE will be the closest observation to a direct observation of CE, which has never been directly observed.

'To loosen up and talk': Patients´ and facilitators´ experiences of discovery group sessions from the Tidal Model as an introduction before engaging in a person-centred group intervention.

Treatment groups in Mental Health Service is cost-effective, increases patients´ self-understanding and stimulate change Research shows that people with mental illness have different barriers to attend group sessions which often originates from a lack of trust in other people, but it is known that the possibility to build gradual trust among the participants encourages attendance. This study is based on the experience from outpatients and illuminates how discovery groups from the Tidal Model can be used as introductory sessions to build gradual trust among people with mental illness before engaging in a person-centred group intervention. The study fills a research gap in methods to create a safe and trusting environment in treatment groups for people with mental illness working with recovery-oriented person-centred interventions. This study emphasizes the importance of meeting concerns about social interactions in persons with mental illness when joining treatment groups. It presents a recovery-oriented method which meets this requirement and is easy to implement in practice. INTRODUCTION: Recovery-oriented interventions delivered individually or in groups are more and more common within mental health nursing. However, persons with mental illness may be cautious about engaging in groups. Therefore, it is important to provide a trusting basis in the group to allow for the best opportunities to promote engagement, attendance and impact of treatment. The aim was to explore how discovery group sessions were experienced as introductory sessions from the perspectives of participants and facilitators before engaging in a person-centred group intervention. A qualitative interview study was conducted, involving four group facilitators and 16 participants with mental illness from five completed groups. Data were analysed with Ricoeur's theory of interpretation. The findings showed that the two discovery group sessions were experienced as useful and meaningful to all and created a safe atmosphere and a trusted relationship among group participants and facilitators. Feeling safe and sharing experiences and emotions contribute to the relational climate in a group. Addressing concerns about social interactions in persons with mental illness is important in group treatment. This study proved that engaging patients in designing or adapting interventions for mental health services is important to improve quality.

Large radiational S2 tides in the East China Sea

S2 ocean tide, as one of the most important semi-diurnal constituents, is composed of astronomical S2 tide originated from gravitational forcing and radiational S2 tide derived from solar radiation. Although there are lots of researches which have explored the features of radiational S2 tides in the globe, less known and less discussed, are the radiational S2 tides in the East China Sea due to lack of water level observations. In present study, radiational S2 tides in the East China Sea are estimated and discussed via the combination of 39 coastal tide gauges and EOT20 tidal model derived from multi-satellite altimeter records. We find that radiational S2 tides obtained from tide gauges and satellite-derived EOT20 model are roughly consistent in the East China Sea: (1) The largest radiational S2 amplitude can be as high as 14 cm. (2) Radiational and astronomical S2 tidal amplitudes are large in the coastal zones but small in the open sea. (3) Radiational S2 amplitudes are ∼12% of astronomical S2 amplitudes while phase differences between radiational and astronomical S2 tides are ∼114°. The inconsistency between coastal tide gauges and EOT20 model in coastal zones should be induced by the temporal evolution of tides and the inaccuracy of satellite altimeter observations in this region. Furthermore, the methods used in the East China Sea can be easily applied to other sea areas, except diurnal resonant sea areas where the smooth nature of semi-diurnal admittances may be corrupted by nonlinear interactions between anomalously large diurnal tides.

Study on the spatiotemporal variation of the Yangtze estuarine tidal species

Owing to the nonlinear influence of river discharge, estuarine tides are nonstationary and more complicated than oceanic tides. This study investigated the spatiotemporal variation pattern of the Yangtze estuarine tides by considering tidal species separated using the Variational Mode Decomposition (VMD) model. The separated tidal species were compared with tidal species reconstructed using the NS_TIDE model. The results showed that the subtidal (D0) amplitude increased landward because of the enhanced influence of river discharge and river-tide interactions; diurnal (D1) and semi-diurnal (D2) tidal amplitudes consistently decayed landward because of frictional dissipation and nonlinear energy transfer to other tidal constituents; while quarter-diurnal (D4) and six-diurnal (D6) tidal amplitudes initially increased and then decreased in the landward direction because of the transformation of the dominant role of river discharge from nonlinear energy transfer to frictional dissipation. The spatiotemporal variations in different tidal species can illustrate other tidal processes, such as seasonal differences in tidal duration asymmetry. Although the VMD model neglects the separation of each tidal constituent, it can provide reasonable information, even when NS_TIDE may provide implausible results during the flood season because of the highly nonstationary conditions.

Analysis of Wave Characteristic in Fuel Terminal Serui

The Serui Fuel Terminal is a vital state-owned facility distributing fuel oil throughout Yapen Island, Papua Province. However, this facility has a problem: waves or overtopping, which can even cause damage to existing facilities. This research aims to determine the hydrodynamic process and wave characteristics through theoretical analysis and numerical modeling using Mike21 with Hydrodynamic (HD) and Spectral Wave (SW) Modules. Bathymetry, current and tidal data collected in the field and wave data collected from ECMWF, calibration is carried out by comparing modeling output (currents & tides) with the results of observations and wave propagation and transformation study theoretically and compared with the results of wave modeling, so the accuracy of the modeling results can be reviewed. The validation results of tidal modeling with a MAPE (Mean Absolute Percentage Error) value of 0.3%, current modeling with a MAPE value of 30%, and waves from each orthogonal with an average MAPE of 15%. Generally, wave height on the shoreline is 0.3-0.4 m (calm waves), and the cause of the overtopping that occurs is due to the geometry and type of existing coastal buildings with smooth sloping sides and impermeable, which makes the wave height double with a run-up height 0.6-0.8 m

Modeling of Barotropic Tide off the Southeastern Coast of the Kamchatka Peninsula in View of the Accuracy of Global Tidal Models in the Northwest Pacific Ocean

This study introduces the development and implementation of a regional numerical finite-volume model FESOM–C, specifically designed to accurately compute barotropic tidal dynamics in the Pacific waters adjacent to the southeastern region of the Kamchatka Peninsula. The dynamics of principal harmonics of the semidiurnal M2 and diurnal K1 tidal constituents are replicated, as well as the total tide, which encompasses 12 constituents. The computed results, obtained using a detailed unstructured grid, are interpreted through the Long-wave approach. The FESOM–C regional model revealed the variability of harmonic constants of tide and current characteristics within the shelf and canyon-cut continental slope, due to topographic scattering of tidal waves. The assessment includes the estimation of maximum currents and eddy structures associated with residual tidal circulation on the shelf and continental slope. To investigate the influence of varying open boundary conditions, sensitivity experiments have been conducted using data from two state-of-the-art global tidal models FES2014 and TPXO9. The findings reveal that the regional model’s solution exhibits only minimal dependency on this choice, and it aligns well with the limited available tidal data. Interestingly, the global models themselves demonstrate significant disparities in the tidal currents. Furthermore, we assess the accuracy of global tidal model solutions in a broader region encompassing the Sea of Okhotsk, as well as the Pacific waters along the Kuril Islands and the Kamchatka Peninsula. This assessment utilizes a verified database of tidal harmonic constants derived from the Soviet and British tide tables. While the average errors in tidal heights calculations remain minor and closely approximate officially declared values, certain areas within the region exhibit notable discrepancies in the outputs of the global models. These discrepancies are site-specific and vary depending on the particular model and tidal harmonic under consideration. This underscores the need for caution when applying results from global tidal models at the regional scale. Meanwhile, the importance of advancing regional tidal dynamics modeling remains evident.

Assessment of Tide Model Prediction and Discrepancy in Shallow Waters of Taiwan to Improve Data Fusion Methods

Assessment of Tide Model Prediction and Discrepancy in Shallow Waters of Taiwan to Improve Data Fusion Methods

Evaluation of Regional Tidal Model on the West Coast of North Sumatera Province

On the west coast of North Sumatra, the availability of tidal data has not been optimal, hence a tidal model is required to describe marine information. The regional tidal model (developed by Indonesia Geospatial Agency, hereafter called as BIG model) was built from multi-mission altimetry data that was assimilated with 138 tide stations (TS) data over the Indonesian ocean before 2018. The research aimed to evaluate the BIG model using TS data that was built after 2018, namely, TS.Barus, TS.Sirombu and TS.Batahan at 2019-2020. The research method is to calculate the Root Mean Square, Root Sum of Squares, Root Sum of Squares of the In-phase and Quadrature, and Discrepancy (D) of 8 harmonic constants (HC: M2, K1, S2, O1, P1, N2, K2, Q1). Also calculated the correlation between BIG model and prediction from TS data in January 2021. According to HC analysis, the smallest amplitude difference in K1 TS.Barus is - 0.0077m, while the largest is 0.0278m in M2 TS.Batahan.Q1 has the least RMS at 0.0039m, while M2 has the most at 0.035m.The Discrepancy (D) between the BIG model and TS data is 5.5609 percent, showing that the tidal model is reliable. The correlation value between BIG model and predicted observational data shows a strong positive relationship, indicated by an R value between 0.996 - 0.998.

Modelling of ocean currents and distribution of total suspended solids in Citarum River estuary

The Citarum River is an important river in West Java, which empties into the Java Sea carrying large suspended sediment concentrations. The purpose of this study is to examine the interaction of current patterns and distribution of total suspended solids (TSS) in the Northwest and Southeast Monsoons using hydrodynamic Modelling. The flow model and TSS used were 2-dimensional models with the OpenFlows FLOOD software. The ocean tide model results were validated using the Root Mean Square Error (RMSE) method with a value of 0.10. The current velocity in the West and East monsoons ranges from 0.07 - 0.35 m/s. Currents flow north and northeast during high-tide conditions and move south and southwest during low-tide conditions in both seasons. The movement of TSS was influenced by the current patterns. The highest concentration of TSS is in the Northwest Monsoon at low tide, which was in the range of 560–575 mg/L. The lowest TSS concentration was in the Southeast Monsoon during high tide conditions, ranging from 80 to 120 mg/L. The high concentration of TSS in the Northwest Monsoon was influenced by higher rainfall, with an average in January and only 23.2 mm/day while in the Southeast Monsoon it is only 7.8 mm/day.

Tidal current energy resources assessment in Zhoushan Archipelago, China

ABSTRACT Zhoushan Archipelago, the largest archipelago in China, harbors a significant tidal stream resource due to robust tidal currents coursing through numerous channels between its islands. Nevertheless, the tidal energy resource in the Zhoushan Archipelago has not been systematically characterized considering both topography and energy flow density. This study presents a modeling study aimed at characterizing the tidal energy resource in the whole Zhejiang coast, including Zhoushan Archipelago, employing a high-resolution tidal hydrodynamic model, i.e. MIKE 21. Through a comparison of the model output with observed data from two tidal stations and three current stations, the accuracy of the numerical model was confirmed. The study identified areas with robust currents and suitable water depths, both essential factors for the advancement of tidal current energy. The findings showed that many channels in Zhoushan Archipelago and Wenzhou Bay in Zhejiang experience the highest tidal power density, reaching nearly 5500 W/m2. Furthermore, the study estimated the theoretical tidal current energy production for the whole area, highlighting Loutou channel, Cezi channel, Taohuagang, and the channel between Xiushan island and Daishan island as regions with high potential.

Satellite Evidence for Strengthened M2 Internal Tides in the Past 30 Years

AbstractSatellite altimetry sea surface height measurements from 1993 to 2022 are used to show the strengthened mode‐1 M2 internal tides in the past 30 years. Two mode‐1 M2 internal tide models M9509 and M1019 are constructed using the data in 1995–2009 and 2010–2019, respectively. The results show that the global mean M2 internal tides strengthened by 6% in energy. However, the internal tide strengthening is spatially inhomogeneous. Significantly strengthened internal tides are observed in a number of regions including the Aleutian Ridge and the Madagascar‐Mascarene region. Weakened internal tides are observed in the central Pacific. On global average, M1019 leads M9509 by about 10° (20 min in time), suggesting that the propagation speed of M2 internal tides increased. M9509 and M1019 are evaluated using independent altimetry data. The results show that M9509 and M1019 perform better for the data in 1993–1994 and 2020–2022, respectively.

Tidal Flood Hazard Assessment in Pekalongan City, Central Java

Climate change has had a significant impact on regional climate in many countries, including Indonesia. The coastal sector is one of the most vulnerable to climate change. Pekalongan City is one of the most vulnerable coastal areas in Indonesia to the effects of climate change. Tidal flooding is a disaster that occurs in coastal areas due to rising sea levels, which average 6-10 mm per year on Java’s northern coast. Tidal flood hazard analysis was performed using indicators of sea-level rise, distance to the sea, distance to the river, slope, topography, land cover, and land subsidence. The results of the field validation were consistent with those of the tidal flood hazard analysis. Areas covered by the tidal flood hazard modeling include Pasirkratonkramat, Bandengan, Kandang Panjang, Panjang Baru, Panjang Wetan, Krapyak, and Degayu. Pekalongan City experienced an increase in hazard area of 6.18% of the total area of Pekalongan City based on the results of the CSIRO modeling RCP 4.5 scenario. In comparison, the other three models show a decrease of up to 3.13% in the total area of Pekalongan City. However, when viewed at the site scale (per urban village), Podosugih Village experienced the highest increase in hazard area, up to 20.5% of the total area for the CSIRO-modeled RCP 4.5. The highest decrease in the area occurred in Klego Village, at 8.94% of the area for the RCP 4.5 scenario of the MIROC model. Future changes in rainfall, sea level, and land subsidence will cause these changes.

Observing glacier dynamics with low-cost, multi-GNSS positioning in Victoria Land, Antarctica

Abstract This study examines the performance of low-cost, low-power GNSS positioning systems for glacier monitoring in high-latitude environments. We compare the positioning performance of co-located low-cost u-blox ZED-F9P GNSS units (a few hundred USDs) and survey-grade Trimble R10 units (> $10,000 USD) under stationary (on land) and dynamic (on glacier) conditions near Terra Nova Bay, Antarctica. Low-cost and survey-grade systems yield almost identical error magnitudes under short (3 m), medium (34 km) and long (390 km) baseline kinematic-positioning scenarios. We further examined the efficacy of low-cost GNSS for glaciological applications by installing four u-blox and two Trimble receivers on Priestley Glacier to observe tide-modulated ice flexure. All receivers successfully detected subtle tidal oscillations with amplitudes < 3 cm, consistent with the predicted phasing from a tide model. These experiments offer a strong rationale for the widespread use of low-cost receivers to expand and densify GNSS monitoring networks, both in Antarctica and in glaciated regions worldwide.

Physics-informed neural networks as surrogate models of hydrodynamic simulators

In response to growing concerns surrounding the relationship between climate change and escalating flood risk, there is an increasing urgency to develop precise and rapid flood prediction models. Although high-resolution flood simulations have made notable advancements, they remain computationally expensive, underscoring the need for efficient machine learning surrogate models. As a result of sparse empirical observation and expensive data collection, there is a growing need for the models to perform effectively in ‘small-data’ contexts, a characteristic typical of many scientific problems. This research combines the latest developments in surrogate modelling and physics-informed machine learning to propose a novel Physics-Informed Neural Network-based surrogate model for hydrodynamic simulators governed by Shallow Water Equations. The proposed method incorporates physics-based prior information into the neural network structure by encoding the conservation of mass into the model without relying on calculating continuous derivatives in the loss function. The method is demonstrated for a high-resolution inland flood simulation model and a large-scale regional tidal model. The proposed method outperforms the existing state-of-the-art data-driven approaches by up to 25 %. This research demonstrates the benefits and robustness of physics-informed approaches in surrogate modelling for flood and hydroclimatic modelling problems.

Future sea level rise exacerbates compound floods induced by rainstorm and storm tide during super typhoon events: A case study from Zhuhai, China

Compound floods are becoming a growing threat in coastal cities against a background of global sea level rise (SLR), and may cause increasing impacts on societal safety and economy. How to quantify the impact of SLR and compound effects among various flood causes on compound flood have become important challenges. We propose a modeling framework which integrates atmospheric, storm tide and urban flood (IASTUF) models to characterize the various physical processes related to compound flood. Future SLR projections under various shared socioeconomic and respective concentration pathway emission scenarios are considered. Hengqin Island (Zhuhai City, China) frequently experiences typhoon conditions combined with rainstorm and storm surge events. Its population has increased more than sixfold during the past decade, stimulating urgent demands for assessments of the potential risks associated with future compound floods in the context of potential SLR. A compound flood event in northern Hengqin Island, caused by the super typhoon Mangkhut in 2018, is selected as a case study to verify the proposed modeling framework. Results show that the IASTUF modeling framework can capture well the combined processes of typhoon, rainstorm, storm tide and inland flooding and demonstrates good performance in quantifying compound flood magnitudes. Compared to the current scenario, the node flooding volume (from the drainage system) and the maximum inundation area (with inundation depths >1 m) in 2050 are projected to increase by 20–26 % and 41–85 %, respectively, and these increases rise to 46–84 % and 23–71 times by 2100. The inundation volumes and water depths due to compound events are larger than the sum of those caused by the corresponding single-cause events, indicating that concurrent rainstorm and storm surge induce positive compound effects on flood magnitude. These findings can provide guidance for the management and mitigation of future compound flood hazards driven by super typhoon events.

Io’s polar volcanic thermal emission indicative of magma ocean and shallow tidal heating models

The distribution of Io’s volcanic activity probably reflects the position and magnitude of internal tidal heating, but full mapping of the moon has not been possible due to a lack of polar coverage. Here we use new observations of Io’s polar regions by the Juno spacecraft Jovian Infrared Auroral Mapper to complete near-infrared coverage, revealing the global distribution and magnitude of thermal emission from Io’s currently erupting volcanoes. We show that the distribution of volcanic heat flow from 266 active hot spots is consistent with the presence of a global magma ocean and/or shallow asthenospheric heating. We find that Io’s polar volcanoes are less energetic but approximately the same in number per unit area than those at lower latitudes. We also find that volcanic heat flow in the north polar cap is greater than that in the south. The low volcanic advection seen at Io’s poles is therefore at odds with measurements of background temperature, showing that Io’s poles are anomalously warm. We suggest that the differences in volcanic thermal emission from Io’s poles compared with those at lower latitudes are indicative of lithospheric dichotomies that inhibit volcanic advection towards Io’s poles, particularly in the south polar region.

Late Pleistocene Evolution of Tides and Tidal Dissipation

AbstractStudies of the Last Glacial Maximum (LGM; 26.5–19 ka) tides showed strong enhancements in open ocean tidal amplitudes and dissipation rates; however, changes prior to the LGM remain largely unexplored. Using two different ice sheet and sea level reconstructions, we explicitly simulate the evolution of the leading semi‐diurnal and diurnal tidal constituents (M2, S2, K1, and O1) over the last glacial cycle with a global tide model. Both sets of simulations show that global changes, dominated by the Atlantic, take place for the semi‐diurnal constituents, while changes for the diurnal constituents are mainly regional. Irrespective of the reconstruction, open ocean dissipation peaks during the sea level lowstands of MIS 2 (∼20 ka) and MIS 4 (∼60 ka), although dissipation values prior to MIS 2 are sensitive to differences in reconstructed ice sheet extent. Using the statistically significant relationship between global mean sea level and dissipation, we apply regression analysis to infer open ocean and shelf dissipation, respectively, over the last four glacial cycles back to 430 ka. Our analysis shows that open ocean tidal energy was probably increased for most of this period, peaking during glacial maxima, and returning to near‐present‐day values during interglacials. Due to tidal resonance during glacial phases, small changes in bathymetry could have caused large changes in tidal amplitudes and dissipation, emphasizing the need for accurate ice margin reconstructions. During glacial phases, once global mean sea level decreased by more than ∼100 m, the amount of open ocean tidal energy available for ocean mixing approximately doubled.

Reflection and Scattering of Low-Mode Internal Tides on the Continental Slope of the South China Sea

Abstract It is well known that strong low-mode internal tides generated in Luzon Strait propagate westward to impinge continental slopes in the northeastern South China Sea (SCS). The reflection and scattering of these internal tides including diurnal and semidiurnal components on the slopes are quantitatively investigated using two sets of mooring data and a linear internal tide model with realistic topography and stratification. Flux reflections computed from mooring data collected on the continental slopes are consistent with the linear model. Based on the results of the observations and simulations, a map of low-mode internal tide reflection and scattering coefficients along the continental margin in the northeastern SCS is revealed. On average, diurnal internal tides lose 38% of their energy to high modes (≥mode 4) that are assumed to dissipate on the slopes, transmit 28% onto the continental shelf, and reflect 31% back to the deep ocean. On the contrary, most of the semidiurnal energy (89%) transmits onto the continental shelf, and only 11% is scattered to high modes (7%) and reflected back to the deep ocean (4%). For diurnal internal tides, a large fraction of energy that is scattered to high modes and reflected back to the deep sea can be attributed to the critical–supercritical slopes, while the weak reflection for the semidiurnal energy is due to the subcritical slopes. These quantitative descriptions for evolutions of low-mode internal tides incident to the slopes provide an energy budget map on the continental slopes in the northeastern SCS.