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  1. Lagoon systems are more heavily impacted by hurricanes, whereas the relevant stormsurge modeling studies have been paid little attention to lagoon systems and the storm-induced exchange in lagoon systems is even less understood. To address this gap, a three-dimensional unstructured grid-based model was configured for the Maryland Coastal Bays, a typical lagoon system with two unique inlets (Ocean City Inlet (OCI) and Chincoteague Inlet (CI)), to investigate how Hurricane Sandy impacted inlet dynamics. A nesting model framework was applied to provide the necessary remote forcing from a large model domain and maintain the intricate shoreline and bathymetry of an inner model domain. Results indicated that the flux patterns varied in response to the change in wind direction and rising/falling high water levels from the coastal ocean, rather than a single flow pattern during the passage of Sandy. FromOctober 29 05:00 to 17:00 UTC, mild (> 10 m/s) and strong (> 15m/s) northerly winds accompanied by the rising high water level from the coastal ocean promoted a mean inflow pattern at the OCI and amean outflow pattern at the CI. Strong southwesterly winds (> 15 m/s) dominated in the bays from October 30 03:00 to 15:00 UTC. Under strong southwesterly winds and falling high water levels from the coastal ocean, flux was transported landward at the CI and seaward at the OCI. Sensitivity experiments on various storm temporal scales showed that a net inflow pattern occurred in the bays, and the net exchange amounts became smaller in response to longer storm durations. Residual effect of relatively high river flow from Sandy could still influence the salinity at the OCI, whereas the CI salinity was not affected by river flow owing to a long distance between the CI and river locations. 
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  2. Two sessions were organized during the 2018 Fall AGU Meeting entitled, (1) Coastal Response to Extreme Events: Fidelity of Model Predictions of Surge, Inundation, and Morphodynamics and (2) Improved Observational and Modeling Skills to Understand the Hurricane and Winter Storm Induced Surge and Meteotsunami. The focus of these sessions was on examining the impact of natural disasters on estuarine and coastal regions worldwide, including the islands and mainland in the northwestern Atlantic and the northwestern Pacific. The key research interests are the investigations on the regional dynamics of storm surges, coastal inundations, waves, tides, currents, sea surface temperatures, storm inundations and coastal morphology using both numerical models and observations during tropical and extratropical cyclones. This Special Issue (SI) ‘Estuarine and coastal natural hazards’ in Estuarine Coastal and Shelf Science is an outcome of the talks presented at these two sessions. Five themes are considered (effects of storms of wave dynamics; tide and storm surge simulations; wave-current interaction during typhoons; wave effects on storm surges and hydrodynamics; hydrodynamic and morphodynamic responses to typhoons), arguably reflecting areas of greatest interest to researchers and policy makers. This synopsis of the articles published in the SI allows us to obtain a better understanding of the dynamics of natural hazards (e.g., storm surges, extreme waves, and storm induced inundation) from various physical aspects. The discussion in the SI explores future dimensions to comprehend numerical models with fully coupled windwave- current-morphology interactions at high spatial resolutions in the nearshore and surf zone during extreme wind events. In addition, it would be worthwhile to design numerical models incorporating climate change projections (sea level rise and global warming temperatures) for storm surges and coastal inundations to allow more precisely informed coastal zone management plans. 
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  3. Low elevation coastal zones (LECZ) are extensive throughout the southeastern United States. LECZ communities are threatened by inundation from sea level rise, storm surge, wetland degradation, land subsidence, and hydrological flooding. Communication among scientists, stakeholders, policy makers and minority and poor residents must improve. We must predict processes spanning the ecological, physical, social, and health sciences. Communities need to address linkages of (1) human and socioeconomic vulnerabilities; (2) public health and safety; (3) economic concerns; (4) land loss; (5) wetland threats; and (6) coastal inundation. Essential capabilities must include a network to assemble and distribute data and model code to assess risk and its causes, support adaptive management, and improve the resiliency of communities. Better communication of information and understanding among residents and officials is essential. Here we review recent background literature on these matters and offer recommendations for integrating natural and social sciences. We advocate for a cyber-network of scientists, modelers, engineers, educators, and stakeholders from academia, federal state and local agencies, non-governmental organizations, residents, and the private sector. Our vision is to enhance future resilience of LECZ communities by offering approaches to mitigate hazards to human health, safety and welfare and reduce impacts to coastal residents and industries. 
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  4. Abstract

    Given that few drifter experiments combined with a wave‐current coupled model system had been conducted in the complex nearshore area, this work was motivated to reveal the nearshore dynamics by applying an observation‐modeling system to Lake Michigan. Analysis of 11 surface drifters, wind, and current observations along the lake's eastern coast indicates that their trajectories are synergistically controlled by winds and initial releasing sites. Additionally, strong winds significantly impact nearshore dynamics, and the highly sensitive nearshore and offshore drifters are stranded in distinct regions. Simulations indicate that the model reproduces drifter trajectories and endpoints reasonably and that particle fates are mainly dominated by winds, while effects from heat flux and waves are also important. Further analysis of wave effects on particle dynamics indicates that both the wave‐induced sea surface roughness and Stokes drift advection are crucial to the simulated particle trajectories during wind events. Finally, virtual experiments confirm that particle dynamics are evidently susceptible to winds and initial locations. Overall, both the inclusion of physics effects (e.g., adding winds, heat fluxes, and waves) and diminishing the model uncertainties (e.g., from various wind data sources, wind drag coefficient formulations, model grids, and vertical turbulent mixing parameterizations) are important methods to improve the particle simulations. The successful application of this nearshore observation‐modeling system to Lake Michigan can be beneficial to the understanding of nearshore‐offshore transports and larval and fisheries recruitment success in similar freshwater and estuarine environments.

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  5. Abstract

    The Great Lakes’ atmosphere predominantly signposts signatures of climate change in terms of an elongated summer, depletion of ice‐cover, and up‐surging lake surface temperature and air temperature, which demands an in‐depth comprehension of future lake circulation dynamics. After satisfactory validations for the lake meteorology and hydrodynamics during 2010–2019, historical and future predictions based on a downscaled climate model for the Great Lakes region under Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios are used to drive the Finite‐Volume Community Ocean Model applied to Lake Michigan during the ice‐free months of 2010–2069. Substantial rises in lake surface current speed during May–June and September–October are connected to the rising wind speed and air temperature in the lake domain. Under the RCP 4.5 scenario, the study expects a 6.5% per decade relative increase in surface current speed, with a rise of 1.3% in the coastal circulation (within 50‐m depth from the coast) until 2050. Surface circulation strength can reach the highest rise (13%) during 2030–2039 and a slight drop (−1%) during 2050–2069. During May–December, only a 0.3% variation is predicted in current magnitudes under RCP 4.5 and 8.5 scenarios. The projections anticipate the occurrence of a stronger, wider, and northward shifting lake gyre with changing lake meteorology. Further analysis indicates that the reduced thermal gradient over the lake surface tends to resist sharp modulations in winds and lake dynamics in the successive decades.

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  6. Abstract

    A comprehensive understanding of lake circulation is fundamental to inform better management of ecological issues and fishery resources in the Great Lakes. In this study, a high‐resolution, wave‐current coupled, three‐dimensional modeling system was applied to investigate the monthly and episodic dynamics of summer circulation in Lake Michigan. Model sensitivities to three wind sources and two grid resolutions against observed current velocities, water temperatures, and significant wave heights in the summer of 2014 were examined. Model performance was validated with additional satellite imageries and current measurements in the summer of 2015. Results indicated that the high‐resolution model driven by the observation‐based winds reproduced lake dynamics most reasonably. In July 2014, a pair of monthly averaged anticyclonic (i.e., clockwise) gyres in the surface layer were simulated in southern Lake Michigan. Analysis indicates that they originate from the wind‐driven, upwelling‐favorable, jet‐like Ekman currents along the west shore, which are connected by the density‐driven basin‐scale circulation. Although river inputs, strait exchanges, waves, grid resolutions, and bathymetric variations influence the monthly surface circulation, their effects are less important than the wind and density‐driven currents. Additional simulations support the predominant impacts of wind and density‐driven currents on lake surface circulation during a strong wind event. Further investigations suggest that lake circulation varies from surface to bottom layers, and this knowledge is significant to the related ecological issues and fishery resources management. The numerical model configured to Lake Michigan is beneficial to understanding dynamics in the Great Lakes system and other large water bodies.

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