Tidal Corrections Research Articles

VMD–WT-Based Method for Extracting On-the-Fly GNSS Tide Level and Its Realization

In this paper, a method for extracting the on-the-fly (OTF) GNSS tide level was designed by combining variational modal decomposition (VMD) and a wavelet thresholding (WT) method to improve the extraction accuracy of the OTF GNSS tide level. First, the energy difference ratio method was used to determine the number of layers for the VMD. Subsequently, the VMD performed a second decomposition of the IMF1 obtained from the first VMD to achieve an efficient separation of signal and noise. The normalized cross-correlation coefficient (NCC) was applied to determine the number of layers for the WT method. Finally, experimental results showed that the VMD–WT method outperformed the other seven filtering methods in three metrics: maximum error, the root-mean-square error (RMSE), and error distribution. Therefore, the VMD–WT method was able to extract extremely accurate on-the-fly GNSS tide level and additionally obtain more accurate bathymetry data after tidal correction of the bathymetry data.

Gravitational Bremsstrahlung with Tidal Effects in the Post-Minkowskian Expansion.

We compute the mass and current quadrupole tidal corrections to the four-momentum and energy flux radiated during the scattering of two spinless bodies, at leading order in G and at all orders in the velocities, using the effective field theory worldline approach. In particular, we derive the conserved stress-energy tensor linearly coupled to gravity generated by the two bodies, including tidal fields, and the waveform in direct space. The integral is solved using scattering amplitude techniques. We show that our expressions are consistent with existing results up to the next-to-next-to-leading order in the post-Newtonian expansion.

Analysis of coastal altimetry in the Mexican Caribbean

A reprocessing of sea-level anomalies (SLA) resulting from X-TRACK coastal altimetry was carried out for the ENVISAT (2002–2010) and TOPEX/POSEIDON-Jason (1992–2019) satellite missions in the coastal area of the Mexican Caribbean. This consisted of applying a tidal correction to coastal altimetry sea level observations. Harmonic analysis of five coastal tide gauge records was performed to estimate the most important tidal components of the area, resulting on M2, N2, O1, S2, K1, MF, and MM. The tidal signal was reconstructed with the seven tidal components using the TPXO9 model. The SLA signals corrected with the seven tidal components were validated with in situ data from coastal tide gauges. The validation showed that the TPXO9 tidal barotropic model (1/30° grid) used to reconstruct the tidal signal with the seven representative tidal components performed better than the FES2012 global model (1/16° grid) that uses 33 tidal components. The reprocessed SLAs showed clear seasonality with significant signals at 4, 6, and 12 months, with the annual signal being the dominant one. In the Mexican Caribbean coastal zone, oceanographic processes with different scales (from coastal to mesoscale) converge, showing their complexity in the different SLA signals observed. The aim of this work is to contribute to the analysis of coastal altimetry data and understanding the sea level variations in the Mexican Caribbean. This work is the first step in the implementation of methodologies that take advantage of coastal satellite altimetry in the Caribbean Sea.

Black-hole perturbation theory with post-Newtonian theory: Towards hybrid waveforms for neutron-star binaries

We consider the motion of nonspinning, compact objects orbiting around a Kerr black hole with tidal couplings. The tide-induced quadrupole moment modifies both the orbital energy and outgoing fluxes, so that over the inspiral timescale there is an accumulative shift in the orbital and gravitational wave phase. Previous studies on compact object tidal effects have been carried out in the Post-Newtonian (PN) and Effective-One-Body (EOB) formalisms. In this work, within the black hole perturbation framework, we propose to characterize the tidal influence in the expansion of mass ratios, while higher-order PN corrections are naturally included. For the equatorial and circular orbit, we derive the leading order, frequency dependent tidal phase shift which agrees with the Post-Newtonian result at low frequencies but deviates at high frequencies. We also find that such phase shift has weak dependence ($\le 10\%$) on the spin of the primary black hole. Combining this black hole perturbation waveform with the Post-Newtonian waveform, we propose a frequency-domain, hybrid waveform that shows comparable accuracy as the EOB waveform in characterizing the tidal effects, as calibrated by numerical relativity simulations. Further improvement is expected as the next-leading order in mass ratio and the higher-PN tidal corrections are included. This hybrid approach is also applicable for generating binary black hole waveforms.

SHORELINE MAPPING OF TELUK NIPAH USING DIGITAL SHORELINE ANALYSIS SYSTEM (DSAS) IN ARCGIS WITH TIDAL CORRECTION

Shoreline characterization using remote sensing technologies is a useful tool to determine the historical shoreline changes of a specific coast. Tidal variation is one of the important factors that should be considered in the shoreline mapping exercise. However, the tidal correction has often been neglected due to the need to access the historical tidal data series for the study site. As a result, the accuracy of the shoreline mapping without tidal correction is ambiguous. Hence, this study aims to establish the historical shoreline mapping of Pantai Teluk Nipah, Pangkor Island, Malaysia, with a tidal correction, using ArcGIS software. For 30 years of the study period, Landsat satellite imageries were processed via ArcGIS to quantify the shoreline change rate. Based on the previous shoreline mapping study without the tidal correction, transect 23 of Pantai Teluk Nipah has undergone severe erosion where the erosion rate is up to –6.83 m per year. With consideration of tidal correction, the shoreline erosion rate at the same transect has reduced to –3.87 m per year, which is consistent with the current beach condition at Pantai Teluk Nipah.
 Keywords: coastal, shoreline extraction, remote sensing, tidal effect, erosion, coastal retreat, tidal correction

Determination of Long-Term (1993–2019) Sea Level Rise Trends Around the Korean Peninsula Using Ocean Tide-Corrected, Multi-Mission Satellite Altimetry Data

It is vital to improve estimations of long-term trends in global and regional sea level rise to help mitigate and adapt to climate change. Satellite altimetry data have been widely used for this purpose; however, data collected in regions with strong tidalmotions often suffer from significant aliasing effects unless they are sufficiently corrected using accurate ocean tide models.Long-term trends estimated from altimetry data are often also considerably affected by regional circulation changes, and by artificial effects arising from inconsistencies between different satellite missions. Here, we focused on two regions with high (>5 mm⋅yr–1) rates of long-term linear trend in sea level rise (LTSLR) around the Korean Peninsula (KP). We addressed the impacts of tidal correction and mission inconsistency in satellite altimetry data, and discussed the potential impacts of circulation changes on LTSLR. Because the LTSLR estimation is affected by the aliasing effects of altimetry data when the tidal motions are not corrected sufficiently, yet the correction depends on the performance of ocean tide models, we employed eight ocean tide models to correct altimetry data for comparison and validated the results against observations from 13 tide gauge (TG) stations around the KP. We also estimated LTSLR from 1993 to 2019 using annual mean sea level anomalies (SLAs) from two satellite (two-sat) and all 21 satellite (all-sat) missions, with corrections for ocean tides. The TPXO9 model showed the most reasonable spatial LTSLR rate pattern (∼3 mm⋅yr–1), with the smallest difference from TG observations. It performed best near the west coast where the tidal range was the largest and when using two-sat data, because of inconsistencies in all-sat altimetry data. In contrast, off the east coast, where the impact of tidal correction is negligible, the high (∼7 mm⋅yr–1) LTSLR rates were robust regardless of ocean tide models and altimetry missions, potentially driven by long-term changes in regional circulation. Our results highlight the importance of tidal correction and mission inconsistency for improving LTSLR estimations around the KP. They also have significant implications for determining regional sea level rise under changing circulation patterns, within and beyond the region.

Neural ventilatory drive decline as a predominant mechanism of obstructive sleep apnoea events

BackgroundIn the classic model of obstructive sleep apnoea (OSA), respiratory events occur with sleep-related dilator muscle hypotonia, precipitating increased neural ventilatory ‘drive’. By contrast, a drive-dependent model has been proposed,...

Dark Matter Effects on the Compact Star Properties

The neutron star properties are generally determined by the equation of state of β-equilibrated dense matter. In this work, we consider the interaction of fermionic dark matter (DM) particles with nucleons via Higgs exchange and investigate the effect on the neutron star properties with the relativistic mean-field model equation of state coupled with DM. We deduce that DM significantly affects the neutron star properties, such as considerably reducing the maximum mass of the star, which depends on the percentage of the DM considered inside the neutron star. The tidal Love numbers both for electric and magnetic cases and surficial Love numbers are also studied for DM admixed NS. We observed that the magnitude of tidal and surficial Love numbers increases with a greater DM percentage. Further, we present post-Newtonian tidal corrections to gravitational waves decreased by increasing the DM percentage. The DM effect on the GW signal is significant during the late inspiral and merger stages of binary evolution for GW frequencies >500 Hz.

Spatio-Temporal Changes and Driving Force Analysis of Wetlands in Jiaozhou Bay

Tian, Y.; Li, J.; Wang, S.; Ai, B.; Cai, H., and Wen, Z., 2022. Spatio-temporal changes and driving force analysis of wetlands in Jiaozhou Bay. Journal of Coastal Research, 38(2), 328–344. Coconut Creek (Florida), ISSN 0749-0208. Jiaozhou Bay is the largest bay-type coastal wetland with high biodiversity in Shandong Peninsula. In recent years, the wetland of Jiaozhou Bay has been reduced dramatically due to urban expansion. It is significant to study the characteristics and causes of the wetland changes in the past 40 years for the rational exploitation and sustainable development of coastal wetland resources. The types, spatial distribution, and area information of the wetland from 1983 to 2019 are obtained by artificial visual interpretation and supervised classification using ten Landsat remote sensing images, assisted by Google images. The research analyzes the conversion of land use types and the change rule of landscape pattern in the wetland, as well as the driving forces of the wetland evolution and the uncertainty factors affecting the analysis results. The results indicate that the wetland area shows an overall decreasing trend from 1983 to 2019, 77% of which are converted into nonwetland. The wetland area increases initially, followed by a decrease from 1990 to 2000, but then continues to decrease slowly from 2000 to 2019. There are many types of land use changes from coastal tidal flats to other land use types such as construction land or pond, and the landscape pattern has been gradually fragmented. The continuous increase in temperature is the main natural cause for the degradation of the wetland. Population factor is the most important driving force for the change of the wetland. The main uncertain factors affecting the analysis results are the capture time of remote sensing image, tidal level correction, wetland classification system, and method. The results provide a basis for the decision-making of wetland protection. The quantitative data will provide a reference for the construction of a multiyear wetland dataset in Jiaozhou Bay.

Monitoring Coastline Changes of the Malay Islands Based on Google Earth Engine and Dense Time-Series Remote Sensing Images

The use of remote sensing to monitor coastlines with wide distributions and dynamic changes is significant for coastal environmental monitoring and resource management. However, most current remote sensing information extraction of coastlines is based on the instantaneous waterline, which is obtained by single-period imagery. The lack of a unified standard is not conducive to the dynamic change monitoring of a changeable coastline. The tidal range observation correction method can be used to correct coastline observation to a unified climax line, but it is difficult to apply on a large scale because of the distribution of observation sites. Therefore, we proposed a coastline extraction method based on the remote sensing big data platform Google Earth Engine and dense time-series remote sensing images. Through the instantaneous coastline probability calculation system, the coastline information could be extracted without the tidal range observation data to achieve a unified tide level standard. We took the Malay Islands as the experimental area and analyzed the consistency between the extraction results and the existing high-precision coastline thematic products of the same period to achieve authenticity verification. Our results showed that the coastline data deviated 10 m in proportion to a reach of 40% and deviated 50 m within a reach of 89%. The overall accuracy was kept within 100 m. In addition, we extracted 96 additional islands that have not been included in public data. The obtained multi-phase coastlines showed the spatial distribution of the changing hot regions of the Malay Islands’ coastline, which greatly supported our analysis of the reasons for the expansion and retreat of the coastline in this region. These research results showed that the big data platform and intensive time-series method have considerable potential in large-scale monitoring of coastline dynamic change and island reef change monitoring.

Bouguer Anomaly of Geothermal Reservoir at Tiris Area, Probolinggo, East Java, Indonesia

Research related to the geothermal system in the Tiris geothermal area (TGA) Probolinggo Regency has been conducted using the gravity method. This study aims to investigate the subsurface structure, with a target on estimating geothermal reservoir rocks from the study area. This study utilized the Gravity meter La Coste & Romberg type G-1503 on 116 acquisition points in an area of 2.16 km2, covering all geothermal manifestation points in TGA. The gravity measurement data obtained is then processed through gravity corrections, which include: conversion into milli-Gals (mGal) units, tidal correction, drift correction, latitude correction, free air correction, Bouguer correction, and terrain correction. These corrections to obtain a complete Bouguer anomaly (CBA) value. The study area shows the CBA value on a horizontal plane which ranges from 0.1 mGal to 4.2 mGal. The separation of the regional and residual Bouguer anomaly from the CBA on a horizontal plane employed the Moving Average method through spectrum analysis. The value of residual Bouguer anomaly ranges from -0.7 mGal to 2.7 mGal. The low anomalies are scattered in the northwest, and a small number are spread in the northeast and southeast, while the high anomalies are in the middle of the study area. The result of 3D inversion modeling finds that the study area's subsurface structure consists of four rock layers, namely lapilli tuff, tuffaceous breccia, volcanic breccia, and basalt. Volcanic breccia is approximated as geothermal reservoir rocks at a depth of 700 to 1000 meters below the acquisition point. In contrast, basalt is supposed to be intrusive igneous rock because it tends to break through the surface at a depth of 348 to 350 meters below the acquisition point. The presence of these intrusive rocks can be predicted through spectrum analysis result, which shows a regional anomaly source at a depth of 348 meters below the acquisition point. This intrusion rock is suspected to be a heat source rock in the geothermal system in the study area.

COASTLINE CHANGE ANALYSIS ON BALI ISLAND USING SENTINEL-1 SATELLITE IMAGERY

Bali is well-known as a popular tourism location for both local and foreign tourists. There are nine areas designated for tourism, eight of which are coastal. However, due to coastal erosion, the coastline of Bali is changing every year. The purpose of this study is to determine the changes that took place between 2015 and 2020 using Sentinel-1 satellite imagery. The study was conducted along the coastline of Bali Island at coordinates 08° 53' 35.5648" S, 114° 24' 41.8359" E and 08° 00' 46.7865" S, 115° 44' 17.5928" E. The coastlines were identified using the Otsu image thresholding method and linear tidal correction was performed. The coastline change analysis was made using the transect method. Ground truths were conducted in representative areas where major changes had occurred, either as a result of abrasion or accretion. According to the Sentinel-1 analysis, the coastline changes in Bali during the period 2015 – 2020 were mainly caused by abrasion, apart from at Buleleng, which were generally caused by accretion. Abrasion in Bali is dominantly affected by strong currents and high waves meanwhile accretion which having weak currents and low waves was more affected by human factor such as the construction in this study area.

Accuracy Evaluation of Altimeter-Derived Gravity Field Models in Offshore and Coastal Regions of China

Satellite radar altimetry has made unique contributions to global and coastal gravity field recovery. This paper starts with a general introduction followed by the progress of satellite radar altimetry technology. Then, the methods of marine gravity field recovery and dominating gravity models are described briefly. Finally, typical gravity models are compared with shipboard gravity measurements to evaluate their accuracies in offshore and coastal regions of China. The root mean squares of deviations between gravity models and shipboard gravity are all more than 7 mGal in offshore regions and within the range of 9.5–10.2 mGal in coastal regions. Further analysis in coastal regions indicates that the new gravity models with new satellite missions including Jason-2, SARAL/Altika, and Envisat data have relatively higher accuracy, especially SARAL/Altika data, significantly improving the coastal gravity field. Accuracies are low in areas with strong currents, showing that tide correction is very important for altimetry-derived marine gravity recovery as well as shipboard measurements in coastal gravity field determination. Moreover, as an external check, shipboard gravity data need more operations to improve their precision, such as higher instrument accuracy and finer data processing.

Regional Evaluation of Minor Tidal Constituents for Improved Estimation of Ocean Tides

Satellite altimetry observations have provided a significant contribution to the understanding of global sea surface processes, particularly allowing for advances in the accuracy of ocean tide estimations. Currently, almost three decades of satellite altimetry are available which can be used to improve the understanding of ocean tides by allowing for the estimation of an increased number of minor tidal constituents. As ocean tide models continue to improve, especially in the coastal region, these minor tides become increasingly important. Generally, admittance theory is used by most global ocean tide models to infer several minor tides from the major tides when creating the tidal correction for satellite altimetry. In this paper, regional studies are conducted to compare the use of admittance theory to direct estimations of minor tides from the EOT20 model to identify which minor tides should be directly estimated and which should be inferred. The results of these two approaches are compared to two global tide models (TiME and FES2014) and in situ tide gauge observations. The analysis showed that of the eight tidal constituents studied, half should be inferred (2N2, ϵ2, MSF and T2), while the remaining four tides (J1, L2, μ2 and ν2) should be directly estimated to optimise the ocean tidal correction. Furthermore, for certain minor tides, the other two tide models produced better results than the EOT model, suggesting that improvements can be made to the tidal correction made by EOT when incorporating tides from the two other tide models. Following on from this, a new approach of merging tidal constituents from different tide models to produce the ocean tidal correction for satellite altimetry that benefits from the strengths of the respective models is presented. This analysis showed that the tidal correction created based on the recommendations of the tide gauge analysis provided the highest reduction of sea-level variance. Additionally, the combination of the EOT20 model with the minor tides of the TiME and FES2014 model did not significantly increase the sea-level variance. As several additional minor tidal constituents are available from the TiME model, this opens the door for further investigations into including these minor tides and optimising the tidal correction for improved studies of the sea surface from satellite altimetry and in other applications, such as gravity field modelling.

Evaluation of global ocean tide models based on tidal gravity observations in China

Previous studies show that the calculated loading effects from global ocean tide models do not match actual measurements of gravity attraction and loading effects in Southeast Asia. In this paper, taking advantage of a unique network of gravity tidal stations all over the Chinese mainland, we compare the observed and modeled tidal loading effects on the basis of the most recent global ocean tide models. The results show that the average efficiencies of the ocean tidal loading correction for O1, K1, M2 are 77%, 73% and 59%, respectively. The loading correction efficiencies using recent ocean tidal models are better than the 40 years old Schwiderskis model at coastal stations, but relative worse at stations far from ocean.

EOT20: a global ocean tide model from multi-mission satellite altimetry

Abstract. EOT20 is the latest in a series of empirical ocean tide (EOT) models derived using residual tidal analysis of multi-mission satellite altimetry at DGFI-TUM. The amplitudes and phases of 17 tidal constituents are provided on a global 0.125∘ grid based on empirical analysis of seven satellite altimetry missions and four extended missions. The EOT20 model shows significant improvements compared to the previous iteration of the global model (EOT11a) throughout the ocean, particularly in the coastal and shelf regions, due to the inclusion of more recent satellite altimetry data as well as more missions, the use of the updated FES2014 tidal model as a reference to estimated residual signals, the inclusion of the ALES retracker and improved coastal representation. In the validation of EOT20 using tide gauges and ocean bottom pressure data, these improvements in the model compared to EOT11a are highlighted with the root sum square (RSS) of the eight major tidal constituents improving by ∼ 1.4 cm for the entire global ocean with the major improvement in RSS (∼ 2.2 cm) occurring in the coastal region. Concerning the other global ocean tidal models, EOT20 shows an improvement of ∼ 0.2 cm in RSS compared to the closest model (FES2014) in the global ocean. Variance reduction analysis was conducted comparing the results of EOT20 with FES2014 and EOT11a using the Jason-2, Jason-3 and SARAL satellite altimetry missions. From this analysis, EOT20 showed a variance reduction for all three satellite altimetry missions with the biggest improvement in variance occurring in the coastal region. These significant improvements, particularly in the coastal region, provide encouragement for the use of the EOT20 model as a tidal correction for satellite altimetry in sea-level research. All ocean and load tide data from the model can be freely accessed at https://doi.org/10.17882/79489 (Hart-Davis et al., 2021). The tide gauges from the TICON dataset used in the validation of the tide model, are available at https://doi.org/10.1594/PANGAEA.896587 (Piccioni et al., 2018a).

Near-Coast Tide Model Validation Using GNSS Unmanned Surface Vehicle (USV), a Case Study in the Pertuis Charentais (France)

Nowadays, uncertainties related to the determination of ocean tides remain a major issue for the exploitation of altimetry data in coastal areas. Using Sea Surface Height (SSH) observations from a new GNSS-based system mounted on an Unmanned Surface Vehicle (USV), we develop a crossover methodology to assess tide models under altimetry tracks. To this purpose, we address the Pertuis Charentais area, a semi enclosed sea located in the centre of the Bay of Biscay (France), as a field and modelling case study. We have developed a barotropic model configuration, based on SCHISM platform, using tidal elevations of an up-to-date regional atlas as boundary conditions. To test the impact of boundary conditions, we propose a second configuration where we applied uniform empirical biases in phases and amplitudes on M3 and MN4 constituents. In addition, the survey was designed to highlight the contribution of third and fourth-diurnal waves that are strongly amplified on the shelf and is used to assess model performances under the pass 216 of Sentinel-3A. Our results show that the second configuration reduces the Root-Mean-Square Error (RMSE) of the survey crossover residuals by more than 60%, leading to half of the residuals below 2.5 cm. This improved solution also reduces by 20% the RMSE computed with data from tide gauges located in the inner part of the Pertuis Charentais. Therefore, our study reinforces the importance for coastal tide modelling of an accurate tidal forcing, especially for shallow water waves. We finally discuss the impact of the remaining M4 error on crossover residual heights. By introducing an empirical correction term based on M4 observations at tide gauges, we further reduce the RMSE of crossover residuals by 15–25%. With this innovative study, we demonstrate the interest of combining crossover validation methods and USV systems to spatially extend our understanding of coastal areas dynamics. This will be crucial in the scope of the future SWOT mission, for which the tide correction accuracy must be assessed over the large-extent areas covered by swaths observations.

A Tidal Flat Wetlands Delineation and Classification Method for High-Resolution Imagery

As an important part of coastal wetlands, tidal flat wetlands provide various significant ecological functions. Due to offshore pollution and unreasonable utilization, tidal flats have been increasingly threatened and degraded. Therefore, it is necessary to protect and restore this important wetland by monitoring its distribution. Considering the multiple sizes of research objects, remote sensing images with high resolutions have unique resolution advantages to support the extraction of tidal flat wetlands for subsequent monitoring. The purpose of this study is to propose and evaluate a tidal flat wetland delineation and classification method from high-resolution images. First, remote sensing features and geographical buffers are used to establish a decision tree for initial classification. Next, a natural shoreline prediction algorithm is designed to refine the range of the tidal flat wetland. Then, a range and standard deviation descriptor is constructed to extract the rock marine shore, a category of tidal flat wetlands. A geographical analysis method is considered to distinguish the other two categories of tidal flat wetlands. Finally, a tidal correction strategy is introduced to regulate the borderline of tidal flat wetlands to conform to the actual situation. The performance of each step was evaluated, and the results of the proposed method were compared with existing available methods. The results show that the overall accuracy of the proposed method mostly exceeded 92% (all higher than 88%). Due to the integration and the performance superiority compared to existing available methods, the proposed method is applicable in practice and has already been applied during the construction project of Hengqin Island in China.

Mid-Holocene to present circum-Arabian sea level database: Investigating future coastal ocean inundation risk along the Arabian plate shorelines

The Arabian Peninsula has a unique setting to resolve how proximity to tectonically diverse plate margins, eustacy, and glacial isostatic adjustment (GIA) influences coastal sea level fluctuations. New 14C AMS and U series dating of coastal sediments from the western, southern, and eastern plate margins (Al-Wajh and Thuwal, Saudi Arabia; Bar Al-Hikman, Oman; Abu Dhabi, U.A.E) have been integrated with an archive of dated coastal sediments (n = 145, 31 locations). Each dated sample is recalibrated for its elevation based on a high-resolution coastal DEM dataset, tidal and tectonic correction, and reservoir correction, to develop a new-suite of relative sea level (RSL) plots, separated into six tectonically distinct zones. A mid-Holocene highstand has been identified in most of the zones (1, 2, 4, 6), however, with complex spatial and temporal variability. No data is available for zone 3, whereas no Holocene highstand was observed in zone 5. The results suggest that eustacy, varying rates of vertical tectonic change (max 1 mm/year) and glacial isostatic adjustment (max 0.5 mm/year) were the major drivers of sea level fluctuations since Mid-Holocene albeit in different proportions along the different sections of Arabian shorelines. Furthermore, the topography of a shoreline, tidal range, and presence/absence of a coastal barrier also significantly influences the coastal inundation. Based on our findings, eastern Arabia will in the near future experience the largest coastal flooding (largest 0–10 m elevation area, > 2 m tidal amplitude, no barriers), followed by western (1–2 m tidal amplitude, discontinuous coral reef barriers) and southern Arabia shorelines (>3 m tidal amplitude, no barriers) shorelines. The presented insights are critical in supporting communities along the coasts of the Arabian Peninsula, who will have to cope with flooding from rising oceans over the next few decades due to climate change.

FES2014 global ocean tide atlas: design and performance

Abstract. Since the mid-1990s, a series of FES (finite element solution) global ocean tidal atlases has been produced and released with the primary objective to provide altimetry missions with tidal de-aliasing correction at the best possible accuracy. We describe the underlying hydrodynamic and data assimilation design and accuracy assessments for the latest FES2014 release (finalized in early 2016), especially for the altimetry de-aliasing purposes. The FES2014 atlas shows extremely significant improvements compared to the standard FES2004 and (intermediary) FES2012 atlases, in all ocean compartments, especially in shelf and coastal seas, thanks to the unstructured grid flexible resolution, recent progress in the (prior to assimilation) hydrodynamic tidal solutions, and use of ensemble data assimilation technique. Compared to earlier releases, the available tidal constituent's spectrum has been significantly extended, the overall resolution has been augmented, and additional scientific byproducts such as loading and self-attraction, energy diagnostics, or lowest astronomical tides have been derived from the atlas and are available. Compared to the other available global ocean tidal atlases, FES2014 clearly shows improved de-aliasing performance in most of the global ocean areas and has consequently been integrated in satellite altimetry geophysical data records (GDRs) and gravimetric data processing and adopted in recently renewed ITRF standards (International Terrestrial Reference System, 2020). It also provides very accurate open-boundary tidal conditions for regional and coastal modelling.