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Stricter controls on destructive human activities in recent years have improved the protection and management of sandy coasts in China. Marine-driven geomorphic changes have become the predominant process influencing future beach evolution. However, in the complex geomorphic conditions of mixed artificial and natural coastlines, the mechanisms and contributions of various marine-driven factors to beach changes remain unclear. Using methods of field observations and numerical simulations by FVCOM model, this study reveals the sedimentary dynamic mechanism of straight sandy beach in the southern Shandong Peninsula (Wanpingkou beach, WPK beach). From 2005 to 2016, the northern section of WPK Beach eroded at a rate of approximately 2-3 m/year, the middle section at about 0.5-1.5 m/year, and the southern section accrued at an average rate of about 1-2 m/year, demonstrating an overall pattern of "northern erosion and southern accretion." During winter, the average grain size of beach sediments is about 0.5 mm with minimal variations, indicating an onshore transport trend; in summer, the average grain size is about 0.7 mm with larger variations, indicating an offshore transport trend. Offshore sediment transport correlates mainly with seasonal changes in wind direction, while alongshore sediment transport is influenced by tidal currents, wind-induced currents, and wave-induced currents. Wave-induced currents are the primary force in alongshore sediment transport with a velocity of 0.1-0.3 m/s toward southwest. Followed by tidal currents with a velocity of 0.05-0.1 m/s, and wind-induced currents with a velocity of 0-0.1 m/s, which have a relatively minor impact. Therefore, seasonal changes in beach morphology are primarily controlled by waves, while interannual variations is mainly influenced by a combination of wave-induced currents and tidal currents. With increasing efforts in beach maintenance and coastal ecological restoration in recent years, understanding the sedimentary dynamics of beaches remains of vital theoretical and practical value. [ABSTRACT FROM AUTHOR]

A wave–current coupled numerical model with 3D radiation stress formalism is used to study baroclinic effects, specifically stratification and baroclinic pressure gradient force (BcPGF), on wind-wave-driven flows, separated as vertically sheared flows and vertically homogeneous flows. Numerical experiments are conducted under ideal offshore winds of 8 m s−1. Results show that stratification enhances the two-layer structure of the wave-driven sheared flow, while BcPGF has minimal impact. Stratification and BcPGF have limited influence on the direction of the wave-driven depth-averaged circulation, but they can enhance the total circulation by promoting the upper one. In the upper layer where form drag dominates, the competition between the vertical form drag divergence (FDD) and turbulent stress divergence (TSD) plays a critical role in shaping the wave-driven flow. Stratification reduces vertical eddy viscosity Km, suppressing the growth of TSD associated with the vertical shear of velocity, which facilitates the FDD driving the upper outflow. Likewise, stratification can enhance the effect of FDD curl on the upper horizontal circulation by limiting the growth of TSD curl related to the vertical shear of vorticity. Additionally, low Km reinforces geostrophic effect and therefore enhances the lateral circulation. Baroclinic torque contributes to reducing the vertical variation of vorticity and the growth of TSD curl, indirectly improving the effectiveness of FDD curl in driving the upper circulation. Stratification undergoes fortnightly adjustments due to the spring–neap cycle, leading to the synchronized variation in the strength of wave-driven flow, particularly its vertically sheared component. During neap tides with weak tidal forcing and well-developed stratification, wave-driven sheared flow, horizontal circulation, and lateral circulation are stronger. Significance Statement: The aim of this study is to enhance our comprehension of the impact of baroclinic processes on wind-wave-driven flows in wind-dominated regimes. During summer, wave-driven flows exhibit noticeable vertical shearing, which differ from those observed in winter. This is particularly important because during summer, river runoffs generate strong stratification and introduce large quantities of terrigenous materials into coastal oceans. Consequently, wave-driven flows may play a crucial role in bay-shelf exchange, which has been given in few studies. Our findings highlight the influence of baroclinic processes on turbulent stress divergence, which can enhance wave-driven flows, both the vertically sheared and the vertically homogeneous components, especially during neap tides. [ABSTRACT FROM AUTHOR]

River floods and human activities would impact land‐to‐sea sediment transport, which is essential for understanding the evolution of the global sediment cycle in the Anthropocene era. This study focused on investigating how river floods and a dike constructed in 2005 along a river channel influence sediment transport from the Ou River Estuary to the East China Sea. A validated three‐dimensional sediment transport model based on the Finite Volume Community Ocean Model was utilized for this study. The presence of the dike obstructs alongshore currents and fish migrations, leading to negative effects on marine ecology. Therefore, selective dismantling and ecological restoration measures are deemed necessary. Three scenarios were considered in this study: no‐dike, dike‐constructed, and dike‐partially‐removed conditions, along with various types of river floods. The findings indicate that the monthly sediment flux to the sea decreased by 7.7% from 8.11 × 106 to 7.49 × 106 t following dike construction, while the proportion of cross‐shore sediment flux to the total flux increased from 37% to 59%. The dike consistently has a greater impact than river floods in their interactions. However, partially removing the dike reduces its influence and restores sediment transport to pre‐dike levels, the effectiveness of which is more pronounced with more frequent floods, larger volumes, and rising sea levels. This study provides valuable insights into the interplay between river floods and dikes on sediment transport, thereby enhancing our understanding of the repercussions of human interventions on sediment dynamics. Plain Language Summary: Global warming is expected to cause an increase in sea levels and a rise in the frequency and volume of river floods, which will change the delivery of riverine sediment to the ocean. Human construction of dikes for various purposes has also changed modern estuarine sediment transport patterns. These alterations are significant as they affect the natural sediment cycling of the Earth, influencing marine geology and marine ecosystems. Through a case study of the Ou River Estuary in southeastern China, numerical sensitivity tests have shown that dikes constructed along river channels disrupt natural flow patterns, resulting in decreased sediment transport to the sea and redirection toward deeper oceanic areas. The presence of dikes is crucial in their interaction with river floods on sediment transport. However, removing sections of dikes can help restore sediment transport to conditions without dikes. The increasing frequency, larger volumes, and faster discharge rates of river floods, as well as dam‐controlled river floods and rising sea levels, may all play a role in restoring natural sediment transport dynamics. This study examines how floods and dikes collectively impact sediment transport in estuaries with drainage areas larger than the estuary area. Key Points: A dike redirects sediment transport from the alongshore to the cross‐shore from the Ou River to the East China SeaMetrics are proposed to quantify the interaction between various river flood conditions and dike configurations on sediment transportFrequency, pattern, and duration of river floods, as well as partial dike removal and sea‐level rise, impact the interaction [ABSTRACT FROM AUTHOR]

A comprehensive field survey was conducted, and a numerical model based on the Princeton Ocean Model was established to investigate the vertical structure of current induced by surface waves and identify its effect on sand loss from a beach. Previous studies have examined wave‐induced longshore transport, whereas this study focused on cross‐shore transport caused by waves. The introduction of vertically dependent radiation stress revealed that wave‐induced vertical gyres existed with onshore and offshore flows in the upper and lower layers, respectively, besides the well‐known wave‐induced longshore flow. It was found that the vertical gyres were caused by the onshore wave force (a gradient of radiation stress) in the upper layer and the offshore wave force usually existed in the lower layer, as well as the horizontal imbalance of local wave force. The locations of wave‐induced vertical gyres were found to correspond to the location of sediment erosion, and thus the lower part of the vertical gyres drove the offshore transport of eroded sediment. Moreover, the vertical gyres were located in areas with a highly variable topographic gradient (e.g., at a bar), and their driven offshore currents (undertow/return flow) extended far beyond the surf zone. The topographic slope had a profound effect on the vertical structure. Numerical experiments showed that an extended breakwater from the eastern headland of the bay could prevent sediment from being eroded. Furthermore, the shear front at the rim of a horizontal gyre could retain suspended sediment in the center of the gyre. Plain Language Summary: Rather than examining longshore flow, which has been extensively investigated, this study focused on cross‐shore flow due to waves. It was found that in addition to the longshore flow (vertically mean), a wave‐induced offshore flow component extended a long‐distance offshore. Moreover, the vertical and horizontal gyres (eddies) generated by waves greatly contributed to sand loss from a beach. Specifically, a vertical gyre eroded sediment and drove its offshore transport in the lower layer of water. Furthermore, it was determined that the vertical and horizontal gyres were both affected by highly variable topographic slopes, and that the fast‐rotating rim of a horizontal gyre ensured that suspended sediment was retained in the center of the gyre. The results suggest that a breakwater extending from the eastern headland could prevent the erosion of sediment in the bay, as simulations showed that the pattern of wave‐induced currents was mainly influenced by the length of barriers (headlands) and the bottom slope. Key Points: In addition to vertically mean longshore flow, there was a prevalent wave‐induced offshore component of flowWave‐induced vertical gyres were found to erode sediment and drive its offshore transportNumerical experiments showed that a breakwater at the eastern headland of the bay could prevent the erosion of sediment [ABSTRACT FROM AUTHOR]

Background: This systematic and meta-analytic review aimed to investigate the effects of physical exercise on the working memory of older adults, and to identify the moderators of these effects. Methods: We searched six electronic databases for randomized controlled trials on the effects of physical exercise on working memory that were published before or on May 15, 2020. The PEDro scale was used to evaluate the methodological quality of the included studies. Stata 14.0 software was used to perform the meta-analysis, subgroup analysis, and publication bias testing. Results: A total of 28 studies and 2156 participants were included. The methodological quality of the included studies was fair to excellent, and there was no publication bias. Overall, we found that physical exercise had a significant effect on working memory in older adults (standardized mean difference = 0.30, p < 0.0001). The effects of physical exercise on working memory were moderated by exercise frequency, intensity, type, duration, cognitive status, and control subgroup (active/passive), but not by intervention period or age of participant. Conclusion: Physical exercise can effectively improve the working memory of older adults. The recommended physical exercise is multi-component exercise or mind–body exercise of moderate intensity for 45–60 min 3 times a week, for more than 6 months. [ABSTRACT FROM AUTHOR]

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In 3 consecutive years from 2016 to 2018, extreme ocean warming events, or marine heatwaves (MHWs), occurred during boreal summers in the East China Sea (ECS) and South Yellow Sea (SYS), which is unprecedented in the past four decades based on the satellite record. In this study, we used a high‐resolution hydrodynamic model based on Finite Volume Community Ocean Model (FVCOM) to simulate the evolution of these warming events. An upper ocean temperature budget (0–20 m) analysis based on the model results shows that the shortwave radiation and the ocean advection anomalies jointly contributed to the anomalous warming in the three successive summers (June–August) in the SYS and the north part of the ECS. In addition, the reduction of surface wind speeds during the 2016 and 2017 summers further weakened the vertical mixing, thereby enhancing the anomalous warming in the north part of the ECS adjacent to the SYS. During the three summers, the increases of shortwave radiation were closely related to the East Asian Summer Monsoon (EASM) variability, which reduced the cloud cover in the ECS and SYS, whereas the advection anomalies were mostly associated with regional wind anomalies. In summer 2018, upper ocean heat was transported into the central trough of the SYS, accumulated in an anticyclonic eddy generated by the anomalous wind stress curls. Therefore, despite the primary driver of the MHWs is the EASM variation, regional processes are critical to driving the spatial pattern of the MHW intensity in the ECS and SYS. Plain Language Summary: Marine heatwaves, known as periods of extreme warming at the sea surface, can last for days to months and cause damages to the marine environment and marine life. In the East China Sea and the South Yellow Sea, the frequent occurrences of harmful algae blooms are often associated with marine heatwaves. Satellite data reveal that marine heatwaves occurred in the East China Sea and the South Yellow Sea during the three boreal summers from 2016 to 2018, which is unprecedented in the past four decades. Using a numerical model of the ocean, we examined the marine heatwaves during these three successive summers. We show that the increased solar radiation, ocean current anomalies, and reduced vertical mixing were three critical factors for the warming events in the three summers. This study helps the fisheries and aquaculture industries in the East China Sea and the South Yellow Sea to better manage the environmental risks under a warming climate by predictions of marine heatwaves. Key Points: Marine heatwaves in the ECS and SYS during 2016–2018 summers were caused by shortwave radiation, current, and vertical mixing anomaliesShortwave radiation increases in summers were due to reductions of the cloud cover, closely related to the East Asian Summer Monsoon variabilityAn anticyclonic eddy in SYS in summer 2018, driven by regional wind anomalies, played a significant role in trapping anomalous heat [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Xiao, K.; Li, H.; Song, D.; Chen, Y.; Wilson, A.M.; Shananan, M.; Li, G., and Huang, Y., 2019. Field measurements for investigating the dynamics of the tidal prism during a spring-neap tidal cycle in Jiaozhou Bay, China. Journal of Coastal Research, 35(2), 335–347. Coconut Creek (Florida), ISSN 0749-0208. The tidal prism is a crucial environmental index for evaluating the water self-purification capacity in semi-enclosed bay systems, but quantitative studies linking spring-neap tidal variations are few. In this paper, field measurements of the tidal level and tidal flux were conducted in Jiaozhou Bay (JZB) to estimate the hydrodynamic and tidal prism variations during a spring-neap tidal cycle. JZB is located on the south coast of Shandong Peninsula, China, with a narrow inlet of 3.1 km width, which was accessible for continuous shipboard Acoustic Doppler Current Profiler measurements over 15 days. Unfortunately, due to the violent sea induced by typhoon "Chan-hom," the measurements were suspended for 2 days. However, the fluxes during the temporary suspension were reproduced using the significant linear relationship between the inlet fluxes and the changes in tidal level (r2 = 0.94, P < 0.001), without considering the storm surge. The relationship between tidal range and tidal prism was also linearly correlative (r2 = 0.69, P < 0.001), indicating that the tidal prism was primarily controlled by the tidal range in JZB. These linear relationships are well verified by historical data in JZB. Compared with previous studies in JZB, the tidal prism has decreased 26% from 1928 to 2008. The decreased intertidal areas, caused by large-scale land reclamations, were likely responsible for the decrease in the tidal prism, which in turn weakened the self-purification capability and triggered the chronic pollutant enrichment. However, the tidal prism increased 4% from 2008 to 2015 as the restoration of water area through protective policies formulated by government. These findings will contribute to designing maintenance strategies for reducing human activity impacts on the health of JZB in the future. [ABSTRACT FROM AUTHOR]

Access to geophysical data poses a challenge in Oceanography and Marine Sciences. Ocean databases are an efficient solution to storing, standardizing, validating, and sharing marine and environmental data. However, ocean databases of regional seas and coastal systems are still rare. In this article, we describe a regional ocean database for Jiaozhou Bay, a coastal system affected by increasing anthropogenic activities, such as land reclamation, a cross‐bay bridge construction, and land‐based pollutant discharges. Understanding the impact of human activities on Jiaozhou Bay requires a comprehensive range of research on biogeochemical and physical changes, and on the current environmental state of the bay. The Jiaozhou Bay database described here aims to inform this key research and also to serve as a reference for the future development of regional ocean databases. It includes three kinds of variables: on‐site, satellite, and modeling data. The database structure is unified and incorporates file names, header information (including metadata), measured values and data‐quality flags, which facilitate data exchange and use. We propose a system of data‐quality flags, based on 13 checks that encompass quality control of the different kinds of variables (e.g., satellite 2D data and on‐site profile data). Three examples, one for each type of data, illustrate the use and value of the Jiaozhou Bay database in better understanding the oceanographic characteristics of this bay and the impact of intensive anthropogenic activities on its marine environment. [ABSTRACT FROM AUTHOR]

Since 2002, an artificial water and sediment regulation (AWSR) has been carried out, which largely reduced water and sediment discharged from the Yellow River into the Bohai Sea. Although the sediment transport in the Yellow River Mouth (YRM) has been observed and modeled intensively since AWSR, but preferentially for the non-storm conditions. In this study, a three-dimensional current-wave-sediment coupled model, DHI-MIKE numerical model, was used to examine the seasonal suspended-sediment transport in the YRM after the AWSR. Results show that the seasonal distribution of suspended-sediments in the YRM is dominated by wind and wave rather than river input. The major transport pathway of suspended-sediments is from the western Laizhou Bay to the Bohai Strait during the winter monsoon, especially in storm events. In addition, about 66% of the river sediments deposit within 30 km of the YRM, which is smaller than previous estimations. It suggests that the YRM has been eroded in recent decades. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that the Geostationary Ocean Colour Imager (GOCI) could retrieve sea surface currents accurately in low-moderate turbid coastal waters, based on maximum crosscorrelation (MCC) technique. However, its performance in highly turbid waters remains unclear. In this study, the MCC method is used to derive hourly sea surface currents in Hangzhou Bay (HZB) with highly turbid waters from the GOCI data, and its performance is examined by in situ measurements and model simulations. The results show that the GOCI-derived sea surface currents can catch tidal phase variations well, yet the performance of the derived velocity is not as good as the previous studies in low-moderate turbid waters. The reason may be due to the rapid deposition and resuspension processes of suspended particulate matter in high turbidity waters, which contaminate the MCC pattern tracking. The GOCI-derived deposition and resuspension rates can reach up to about 190 and 270 mg l-1 h-1 in HZB, respectively, which demonstrates that the potential of geostationary ocean colour imagery in deriving the suspended particle deposition and resuspension rates. [ABSTRACT FROM AUTHOR]

Based on the analysis of the quality level in a Pathfinder 4km daily nighttime Sea Surface Temperature product (PFSST) in the East China Seas (ECS) from 1985 to 2004, the proportion of high-quality data was lower than that in the global level. Additionally, the PFSST maps showed clearly the void and anomaly data impacted by atmospheric contamination. In order to solve the above problem, an optimal algorithm was established through introducing the structure function, setting up the daily first-guess sea surface temperature (SST) field and taking PFSST product of the highest quality as reference points. Comparisons were done between this optimally interpolated SST and the selected original PFSST and the simultaneous in situ measurements. It illustrated it was possible to exactly estimate the SST values in the ECS during the recent two decades. The mean bias error and the root mean square error between data sets optimally evaluated and in situ observed were lower than those between the previous global estimations and in situ measurnments. [ABSTRACT FROM AUTHOR]

When petroleum hydrocarbon pollutants enter the ocean, besides the migration under hydrodynamic constraints, their degradation due to environmental conditions also occurs. However, available observations are usually spatiotemporally disperse, which makes it difficult to study the degradation characteristics of pollutants. In this paper, a model of transport and degradation is used to estimate the degradation coefficient of petroleum hydrocarbon pollutants with the adjoint method. Firstly, the results of a comprehensive physical–chemical–biological test of the degradation of petroleum hydrocarbon pollutants in Laizhou Bay provide a reference for setting the degradation coefficient on the time scale. In ideal twin experiments, the mean absolute errors between observations and simulation results obtain an obvious reduction, and the given distributions can be inverted effectively, demonstrating the feasibility of the model. In a practical experiment, the actual distribution of petroleum hydrocarbon pollutants in Laizhou Bay is simulated, and the simulation results are in good agreement with the observed ones. Meanwhile, the spatial distribution of the degradation coefficient is inverted, making the simulation results closer to the actual observations. [ABSTRACT FROM AUTHOR]

The Ou River, a medium-sized river in the southeastern China, is examined to study the estuarine turbidity maximum (ETM) response to rapidly varied river discharge, i.e., peak river discharge (PRD). This study analyzes the difference in ETM and sediment transport mechanisms between low-discharge and PRD during neap and spring tides by using the Finite-Volume Community Ocean Model. The three-dimensional model is validated by in-situ measurements from 23 April to 22 May 2007. In the Ou River Estuary (ORE), ETM is generally induced by the convergence between river runoff and density-driven flow. The position of ETM for neap and spring tides is similar, but the suspended sediment concentration during spring tide is stronger than that during neap tide. The sediment source of ETM is mainly derived from the resuspension of the seabed. PRD, compared with low-discharge, can dilute the ETM, but cause more sediment to be resuspended from the seabed. The ETM is more seaward during PRD. After PRD, the larger the peak discharge, the longer the recovery time will be. Moreover, the river sediment supply helps shorten ETM recovery time. Mechanisms for this ETM during a PRD can contribute to studies of morphological evolution and pollutant flushing. [ABSTRACT FROM AUTHOR]

The Ou River, a medium-sized river in southeastern China, is selected to study the lateral flow response to rapidly varied river discharge, i.e., peak river discharge (PRD). A three-dimensional model based on the Finite-Volume Community Ocean Model is validated by in situ measurements from 15 June to 16 July 2005. PRD, which considers the extra buoyancy and longitudinal momentum in a short time, rebuilds the stratification and lateral flow. PRD, compared with low-discharge, generally makes stratification stronger and lateral flow weaker. PRD mainly rebuilds lateral flow by changing lateral advection, lateral Coriolis, and lateral-barotropic pressure gradient terms. After PRD, the salinity recovery time is longer than that of the flow because the impact on buoyancy lasts longer than that on longitudinal flow. Longitudinal flow is mostly affected by the momentum transferred during PRD; therefore, the recovery time is close to the flooding duration. However, the lateral flow is affected by the buoyancy, and its recovery time is generally longer than the flooding duration. The lateral flow recovery time depends on transect width, flow velocity and the variation caused by PRD. PRD occurs widely in global small-/medium-sized river estuaries, and the result of this work can be extended to other estuaries. [ABSTRACT FROM AUTHOR]