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Water level dynamics in continental‐scale rivers is an important factor for surface water studies and flood hazard management. However, most continental‐scale river models have not focused on the reproduction of water level because the storage and movement of surface waters are regulated by smaller‐scale topography than their grid resolutions. Here we analyzed the water level dynamics simulated by a state‐of‐the‐art global river model, CaMa‐Flood, with subgrid representation of floodplain topography. As a case study, hydrodynamics simulation in the Amazon River was accomplished, and the simulated water surface elevations along the main stem were compared against Envisat altimetry. The seasonal cycles of the simulated water surface elevations are in agreement with the altimetry (correlation coefficient >0.69, annual amplitude error <1.6 m). The accuracy of absolute water surface elevations was also good (averaged RMSE of 1.83 m), and the associated errors were within the range of the model uncertainty due to channel cross‐section parameters. Then the ocean tide variation at river mouth was incorporated for simulating the tidal effect in the inland Amazon basin, which requires realistic representation of absolute water surface elevations. By applying power spectra analysis to the simulated water level variations, the 15 day cycle due to spring and neap tides was detected at Obidos, located 800 km upstream from the river mouth. The reproduction of the ocean tide propagation to the inland region suggests that CaMa‐Flood includes the main physical processes needed to accurately simulate the water level dynamics in continental‐scale rivers. Key Points Accuracy of water surface elevation simulated by a continental‐scale river Simulation accuracy adequate for direct comparison against satellite altimeter Representation of ocean tide variation propagating to the inland Amazon basin

Arctic marine ecosystems are changing rapidly, largely due to the observed accelerated warming that is associated with ongoing climate change. Environmental DNA (eDNA) combined with metabarcoding has great potential for large-scale biomonitoring of Arctic marine communities. However, important limitations remain, such as understanding the complexity and drivers of spatio-temporal variation in eDNA distribution. In this study, we investigated the effect of tidal dynamics on aquatic metazoan (vertebrates and invertebrates) on eDNA metabarcoding results from nearshore estuarine and marine Arctic ports of Churchill (Manitoba) and Milne Inlet (Nunavut), respectively. We collected and sequenced 54 water samples per port at low, middle and high tide across three days, as well as two depths (surface, bottom), using four universal primer pairs (two primers in the COI gene and two in the 18S rRNA gene). We observed a significant transition in the estuarine community structure from low to high tide, whereas the marine community structure was more stable across tides. The eDNA community structure differed between the surface and bottom waters in both the estuarine and marine ecosystems. However, the biodiversity pattern within the water column was significantly different between estuarine and marine ecosystems. Finally, we observed short-term temporal variation of the communities in both systems. Altogether, our results highlight the short-term temporal dynamic nature of eDNA derived from coastal communities. This variability should be accounted for in eDNA sampling design to ensure robust characterization of coastal communities and long-term time series, particularly for estuarine environments where the effects of tide and depth are more important.

PurposeThe paper aims to propose a new mathematical model for allocation and scheduling of vessels at multiple marine container terminals of the same port, considering the access channel depth variations by time of day.Design/methodology/approachThis paper proposes a new mathematical model for allocation and scheduling of vessels at multiple marine container terminals of the same port, considering the access channel depth variations by time of day. The access channel serves as a gate for vessels entering or leaving the port. During low-depth tidal periods the vessels with deep drafts have to wait until the depth of the access channel reaches the required depth.FindingsA number of numerical experiments are performed using the operational data collected from Port of Bandar Abbas (Iran). Results demonstrate that the suggested methodology is able to improve the existing port operations and significantly decrease delayed vessel departures.Originality/valueThe contribution of this study to the state of the art is a novel mathematical model for allocation and scheduling of vessels at multiple terminals of the same port, taking into consideration channel depth variations by time of day. To the best of the authors’ knowledge, this is the first continuous berth scheduling linear model that addresses the tidal effects on berth scheduling (both in terms of vessel arrival and departure at/from the berth) at multiple marine container terminals.

Einstein’s general relativity theory provides a successful understanding of the flow of time in the gravitational field. From Einstein’s equivalence principle, the influence of the Sun and Moon masses on clocks is given in the form of tidal potentials. Two clocks fixed on the surface of the Earth, compared to each other, can measure the tidal effects of the Sun and Moon. The measurement of tidal effects can provide a test for general relativity. Based on the standard general relativity method, we rigorously derive the formulas for clock comparison in the Barycentric Celestial Reference System and Geocentric Celestial Reference System, and demonstrate the tidal effects on clock comparison experiments. The unprecedented performance of atomic clocks makes it possible to measure the tidal effects on clock comparisons. We propose to test tidal effects with the laboratory clock comparisons and some international missions, and give the corresponding estimations. By comparing the state-of-the-art clocks over distances of 1000 km, the laboratory may test tidal effects with a level of 1%. Future space missions, such as the China space station and FOCOS mission, can also be used to test tidal effects, and the best accuracy may reach 0.3%.

Business districts are urban areas that have various functions for gathering people, such as work, consumption, leisure and entertainment. Due to the dynamic nature of business activities, there exists significant tidal effect on the boundary and functionality of business districts. Indeed, effectively analyzing the tidal patterns of business districts can benefit the economic and social development of a city. However, with the implicit and complex nature of business district evolution, it is non-trivial for existing works to support the fine-grained and timely analysis on the tidal effect of business districts. To this end, we propose a data-driven and multi-dimensional framework for dynamic business district analysis. Specifically, we use the large-scale human trajectory data in urban areas to dynamically detect and forecast the boundary changes of business districts in different time periods. Then, we detect and forecast the functional changes in business districts. Experimental results on real-world trajectory data clearly demonstrate the effectiveness of our framework on detecting and predicting the boundary and functionality change of business districts. Moreover, the analysis on practical business districts shows that our method can discover meaningful patterns and provide interesting insights into the dynamics of business districts. For example, the major functions of business districts will significantly change in different time periods in a day and the rate and magnitude of boundaries varies with the functional distribution of business districts.

Suzuki, T. and Cox, D.T., 2019. Statistical analysis of longshore currents on a barred beach. Journal of Coastal Research, 35(6), 1215–1224. Coconut Creek (Florida), ISSN 0749-0208. Longshore currents were observed using a horizontally mounted acoustic Doppler current profiler in the nearshore on a dissipative barred beach. The data were taken for 20 days from 13 May to 2 June 2016. Wave, current, water level, and wind data were continuously observed. From a statistical point of view, the exceedance probability/occurrence ratio of higher currents is important. Therefore, in this research, the hourly data were used to investigate the spatial and wave-energetic distributions of exceedance probability of the longshore currents. Moreover, the effect of tidal range on this exceedance probability is discussed. From the analysis, the exceedance probabilities of longshore currents were well predicted by the Weibull distribution, with parameters estimated using the normalized wave energy flux, relative surf-zone location, and normalized water depth. The exceedance probability of the longshore current was largely affected by water level (tidal elevation): during high tide it was the same or lower than that of the full data set. However, the exceedance probability was approximately two times larger during low tide than that using the full data set.

The problem of current urban groundwater pollution is very serious, which has influenced social development and people’s daily life. Around the land-sea interface, tide obviously changes nearshore the groundwater flow regime and makes the pollutant migration process become more complex. In the present study, the effect of tide-induced groundwater table fluctuations and on the pollutants migration in beach aquifers is investigated by constructing a two-dimensional sand trough physical experimental model. The model considered brackish-water density differences and the tide by controlling experimental medium properties and boundary conditions. The results showed that the groundwater table fluctuation cycle is the same as the tidal cycle and the fluctuation lag time increases linearly with the increase of the offshore distance. Tidal fluctuation flattens brackish-freshwater interface, widens the dispersion zone, and generates the upper saline and the freshwater belt. Time lag corresponding relationships between saline water and tidal fluctuation was observed. With the pollutant approaching the saline water area, the profile of the pollutant migration is gradually developed into a spindle shape until the strip shape, and the pollutant enters the saline water body along the curved edge of the upper part of the saline water. The transverse dispersion of pollutants is larger than the longitudinal dispersion in a tidal cycle and its outline presents a strip shape development. No mixing or exchange between the pollutants and the saline water body happened during the whole process. This study can provide scientific references for nearshore groundwater pollution prevention and control in the future.

Three seabed-mounted TD/CTD chains and two upward-looking acoustic Doppler current profilers (ADCPs) in the southwest of Zhangzi Island are used and a simultaneous cruise observation in the northern North Yellow Sea (NYS) is conducted to study temperature variation in the bottom thermal front zone of the NYS Cold Water Mass (NYSCWM) during the summer of 2009. In the flood-ebb tidal cycles, the bottom temperature decreases (increases) during flood (ebb) tides, which are dominated by the tidal-current induced horizontal advection. The ebb tide-induced temperature increase is larger than the flood tide-induced temperature decrease due to seasonal warming. In the spring-neap tidal cycles, the temperature and the vertical temperature structure show notable fortnightly variation from 16 July to 25 August. The bottom temperature increases from neap to spring tides and decreases from spring to neap. The Richardson number demonstrates strengthened vertical mixing during spring tides but enhanced stratification during neap tides. The spring-neap variation in vertical shear caused by tidal current is the dominant factor that induces the fortnightly variation in vertical mixing and thus bottom temperature.

Aquifer parameters are useful for modeling sea water intrusion and other groundwater management issues in coastal areas. Oscillations in tide-induced groundwater levels contain important information of the properties of coastal aquifers and measurements of tidal effects can be employed to estimate the aquifer parameters. The solution to the transient groundwater flow model in a coastal confined aquifer with a sinusoidal fluctuation of the tide shows that the amplitude of groundwater levels is smaller than the tide, the tidal efficiency decreases exponentially with distance from the coast and the time lag increases linearly with distance from the coast. The aquifer property described by the ratio of storativity to transmissivity can be estimated if the amplitude (or tidal efficiency) and the time lag of groundwater levels are obtained based on filed measurements of tidal effects. Principle of these tidal methods is presented in this article, including those with one observation well and two observation wells. Hourly observations of the tide and groundwater levels at 14 observation wells in the coastal aquifer near Beihai, China are used to illustrate the application of these methods. The estimated ratio of storativity to transmissivity of the confined aquifer ranges from 1.66 × 10–⁷to 4.84 × 10–⁷ d/m². For a given transmissivity of 750 m²/d, the storativity of the aquifer is in the range 1.245 × 10–⁴to 3.63 × 10–⁴.

Interactions between exoplanetary atmospheres and internal properties have long been proposed to be drivers of the inflation mechanisms of gaseous planets and apparent atmospheric chemical disequilibrium conditions 1 . However, transmission spectra of exoplanets have been limited in their ability to observationally confirm these theories owing to the limited wavelength coverage of the Hubble Space Telescope (HST) and inferences of single molecules, mostly H 2 O (ref.  2 ). In this work, we present the panchromatic transmission spectrum of the approximately 750 K, low-density, Neptune-sized exoplanet WASP-107b using a combination of HST Wide Field Camera 3 (WFC3) and JWST Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). From this spectrum, we detect spectroscopic features resulting from H 2 O (21 σ ), CH 4 (5 σ ), CO (7 σ ), CO 2 (29 σ ), SO 2 (9 σ ) and NH 3 (6 σ ). The presence of these molecules enables constraints on the atmospheric metal enrichment (M/H is 10–18× solar 3 ), vertical mixing strength (log 10 K z z  = 8.4–9.0 cm 2  s −1 ) and internal temperature (>345 K). The high internal temperature is suggestive of tidally driven inflation 4 acting on a Neptune-like internal structure, which can naturally explain the large radius and low density of the planet. These findings suggest that eccentricity-driven tidal heating is a critical process governing atmospheric chemistry and interior-structure inferences for most of the cool (<1,000 K) super-Earth-to-Saturn-mass exoplanet population. Analysis of the panchromatic transmission spectrum of the warm, low-density, Neptune-sized exoplanet WASP-107b from instruments aboard the HST and JWST suggests that tidal interaction with its host star led to changes in its atmospheric chemistry.