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This paper focuses on the Panama Canal expansion and its impact on American port infrastructure for the attention of academic researchers in maritime transportation and supply chain management (SCM). First, it provides a comprehensive background based on a review of pertinent practitioner as well as academic publications. This is followed by a summarization of the impact of this expansion on the infrastructure of the major East and Gulf Coast (EGC) ports, since these stand to be the most affected. Then it presents a categorization scheme for these EGC ports that capture their likelihood of attracting the expected increase in cargo traffic engendered by the expansion; this is preliminarily supported by the latest data on growth in container traffic. The policy implications of this categorization are then discussed and the paper ends by identifying key SCM research problems exposed by the above. [ABSTRACT FROM AUTHOR]

Critical infrastructures are essential for the society and economy. In recent years, climate change has been identified as an urgent and growing threat to critical infrastructures, and many studies have been conducted to assess the vulnerability of critical infrastructures to climate change. However, despite these research efforts, the vulnerability of critical infrastructures is often vaguely defined and inconsistently studied in the literature. This paper proposes a framework to analyze critical infrastructure's vulnerability to climate change based on the traditional vulnerability/sustainability framework and hazard-of-place model of vulnerability. The vulnerability assessment of emergency services to sea level rise and storm surge in Collier County, Florida, is taken as an example to validate the proposed framework. Flood simulation, comparisons of storm surge models, spatial analysis, and network-based service area analysis are conducted to assess the vulnerability of fire stations in the case study area. The vulnerability assessment identifies the predominant hazard risk and the exposed infrastructures, analyzes the sensitivity of serviceability, and evaluates the effectiveness of potential adaptive capacity. The results show that the fire stations in the case study area are more vulnerable to the potential landfall and changes in hurricane and tropical cyclone patterns compared to the flooding caused directly by sea level rise. It indicates that the lack of consideration of potential landfall and changes in storms could greatly underestimate the vulnerability to climate change, especially in coastal areas with limited historical tidal data. The analysis also illustrates the current floodplain management that focuses primarily on the 100-year flood may not be a sufficient standard for all regions given the potential changes in frequency and magnitude of climate-related hazards. Finally, it confirms that disaster risk management strategies could also contribute to climate change adaptation. The weak linkages between existing climate change adaptation and disaster risk management need to be strengthened. The proposed concept and framework could be generalized and expanded to other critical infrastructures, regions, and climate-related hazards. [ABSTRACT FROM AUTHOR]

Wave energy is one of the most concentrated ocean renewable energy resources. Although wave energy has been studied extensively for more than four decades, there is no large commercial installation for wave energy production or a consensus framework on how to exploit this resource. Wave energy is a complex resource that directly depends on two meteorological parameters, which produced significant fluctuations of wave energy in both temporal and spatial criteria. This paper presents a new concept called Energy Event, to analyze meteorological data generated by WaveWatch III over 36 years in the U.S. to characterize and assess wave energy behavior using the peak-over-threshold methodology. This methodology used extreme statistics, segmented the wave energy with different thresholds, and assessed wave energy production on a temporal and spatial framework. Three areas were studied in this paper, including the Gulf of Mexico, the East and West U.S. Coasts. The results indicated that wave energy behaved as a two-state energy system with each state having independent characteristics. The main difference among the three studied areas was the constant baseline of wave power density, with the West Coast having the highest constant baseline and the Gulf of Mexico having the lowest baseline. [ABSTRACT FROM AUTHOR]

In this paper we present a novel methodology, referenced as ORFEO (Ordinal classifier and Regressor Fusion for Estimating an Ordinal categorical target), to enhance the performance in ordinal classification problems for which the latent variable is observable. ORFEO is an artificial neural network model incorporating two outputs, one for ordinal classification, using the cumulative link model, and one for regression, using a linear model. Both outputs are simultaneously optimised considering a loss function that linearly combines both classification and regression losses. The main motivation behind developing the proposed approach is to enhance the performance of a standard ordinal classifier. This improvement is facilitated by considering the regression output, which allows the model to differentiate between patterns within the same category. The ORFEO model is applied to two problems in the field of marine and ocean engineering: short-term prediction of both significant wave height and flux of energy. Both problems are addressed considering four different coastal zones of the United States of America, using 13 datasets formed by buoys measurements and reanalysis data. A comprehensive comparison against 20 methodologies, including regression and nominal/ordinal classification approaches is performed, by using diverse nominal and ordinal performance metrics. Ranks achieved indicate that ORFEO outperforms all the compared methodologies in terms of all the performance measures, demonstrating the efficacy and robustness of the proposal. Finally, a statistical analysis is conducted, concluding that there are statistically significant differences across ordinal and nominal performance metrics in favour of the proposed ORFEO model. [ABSTRACT FROM AUTHOR]

Tropical cyclones (TCs) induce substantial upper‐ocean mixing and upwelling, leading to sea surface cooling. In this study, we explore changes in TC‐induced cold wakes along the United States (U.S.) Southeast and Gulf Coasts during 1982–2020. Our study shows a significant increase in TC‐induced sea surface temperature (SST) cooling of about 0.20°C near the U.S. Southeast Coast over this period. However, for the U.S. Gulf Coast, trends in TC‐induced SST cooling are insignificant. Analysis of the large‐scale oceanic environments indicate that the increasing TC‐induced cold wakes near the Southeast coast have been predominantly caused by the cooling of subsurface waters in that region. This upper‐ocean change is attributed to the enhancement of surface pressure gradient across land‐sea boundary and the associated increase in alongshore winds over there. Further analysis with climate models reveals the important role of anthropogenic forcings in driving these changes in the atmospheric circulation response along the U.S. Southeast Coast. Plain Language Summary: Tropical cyclones (TCs) can induce strong mixing in the upper ocean and upwelling of cold, nutrient‐rich water from subsurface to the surface. This process can induce significant sea surface cooling and enhance primary productivity. Utilizing satellite observations, we found evidence that the sea surface cooling associated with TCs has been increasing significantly in the near‐shore regions of United States (U.S.) Southeast Coast. However, corresponding trends in the U.S. Gulf Coast are not significant. Here we show that the enhanced TC‐induced SST cooling along the U.S. Southeast Coast has occurred in response to changes in the atmospheric circulation associated with global warming. These findings shed light on the potential changes in the interactions between TCs and the upper ocean conditions under a non‐stationary climate. Key Points: The tropical cyclone induced sea surface temperature cooling has significantly increased near the U.S. Southeast Coast in recent decadesThe increasing trend in TC‐induced cold wake is primarily attributed to subsurface cooling driven by the change in atmospheric circulationClimate models suggest greenhouse gases are likely responsible for the atmospheric circulation changes [ABSTRACT FROM AUTHOR]

Sea level rise (SLR) is expected, even without greenhouse gas emissions. As SLR is inevitable, adapting to its impacts has received increasing attention, and local governments are the key actors in this emerging agenda. This study indicates that adaptation planning for SLR should be integrated into two local major planning mechanisms in the United States: the local comprehensive plans and hazard mitigation plans. By evaluating 36 plans from 15 US coastal cities that are considered at high risk and vulnerable to rising sea levels, the results demonstrate that SLR is widely identified, but the overall quality of the plans to address it requires significant improvement. A detailed table of selected plans' characteristics is also provided as a lens on how localities tackle this challenging issue. The paper concludes with planning suggestions for coastal communities to better adapt to SLR. [ABSTRACT FROM AUTHOR]

Abstract 1 1 The author is grateful for funding from the Bates Faculty Development Fund, which supported the original data collection on maritime boundaries and to three anonymous reviewers whose attention has certainly improved the paper. The United States has the largest Exclusive Economic Zone in the world by virtue of its long coastlines and multiple dependencies in the Caribbean and the Pacific Oceans. As a result it shares 27 maritime boundaries with 20 different states and dependencies. This paper analyzes how the United States settled 10 contested maritime boundaries between 1977 and until 1997, but has since then left 17 unresolved maritime boundaries. It advances the argument that in this area of relatively low salience for the United States' foreign policy, political and economic transaction costs are key variables in explaining the pattern of settlement. [ABSTRACT FROM AUTHOR]

van Gaalen, J.F.; Tebbens, S.F., and Barton, C.C., 2016. Longshore sediment transport directions and rates from northern Maine to Tampa Bay, Florida: Literature compilation and interpretation. This paper examines site-specific and regional longshore sediment transport directions and rates along the U.S. seaward coast from the northern Maine border to the mouth of Tampa Bay, Florida. From previous studies, it is known that along the coast, there are nodal zones, i.e. locations of divergence or convergence in longshore current, as well as variations in current direction and sediment transport rate. Available published field-based studies of sediment transport directions and rates were compiled to create a map of the direction and rate of longshore transport. A detailed compilation of local and regional published studies is provided in tables and in a sequence of eight regional maps. Compiled studies of longshore transport reveal a dominant southward direction. On the regional scale, 12 nodal zones are identified. At the local scale, the number of nodal zones increases by approximately an order of magnitude. This work builds upon the Master's thesis of van Gaalen (2004). [ABSTRACT FROM AUTHOR]

In ‘Writing Coastlines: Either and both’ J. R. Carpenter articulates the double meaning implied by the term 'writing coastlines'. The act of writing translates aural, physical, mental and digital processes into marks, actions, utterances and speech-acts. The intelligibility of that that is written is intertwined with both the context of its production and its consumption. Coastlines are shifting terrains where land and water meet, always neither land nor water and always both. Writing coastlines are edges, ledges and legible lines caught in the double bind of simultaneously writing and erasing. These in-between places are liminal spaces, both points of departure and sites of exchange. One coastline implies another, implores a far shore. The coastlines of the United Kingdom and Atlantic Canada are separated by 3,400 km of ocean. For centuries, fishers, sailors, explorers, migrants, emigrants, merchants, messengers, messages, packets, ships, submarine cables, aeroplanes, satellite signals and wireless radio waves have attempted to bridge this distance. Generations of transatlantic migrations have engendered networks of communications. As narratives of place and displacement travel across, beyond and through these networks, they become informed by the networks' structures and inflected with the syntax and grammar of the networks' code languages. This paper takes an overtly interdisciplinary approach to interrogating this in-between space with a series of questions: When does leaving end and arriving begin? When does the emigrant become the immigrant? What happens between call and response? What narratives resonate in the spaces between places separated by time, distance and ocean yet inextricably linked by generations of immigration? How may writing coastlines serve as contexts for stories of place and displacement that resonate between sites, confusing and confounding boundaries between physical and digital, code and narrative, past and future, land and sea, home and away? [ABSTRACT FROM PUBLISHER]

In late October 2012, Hurricane Sandy tracked along the eastern U.S. coastline and made landfall over New Jersey after turning sharply northwest and becoming posttropical while interacting with a complex upper-level low pressure system that had brought cold air into the Appalachian region. The cold air, intensified by the extreme low pressure tracking just north of the region, combined with deep moisture and topographically enhanced ascent to produce an unusual and high-impact early season northwest flow snow (NWFS) that has no analog in recent history. This paper investigates the importance of the synoptic-scale pattern, forcing mechanisms, moisture characteristics (content, depth, and likely sources), and low-level winds, as well as the evolution of some of these features compared to more typical NWFS events in the southern Appalachian Mountains. Several other aspects of the Sandy snowfall event are investigated, including low-level stability and mountain wave formation as manifested in vertical profiles and radar observations. The importance to operational forecasters of recognizing and understanding these factors and differences from more common NWFS events is also discussed. [ABSTRACT FROM AUTHOR]

Over the past decade, offshore wind installations have expanded dramatically in Europe and China, increasing renewable energy presence in these markets. However, the United States lags in offshore wind development despite significant coastline and wind resource availability. Each coast of the United States possesses unique opportunities and challenges to installation due to variations in bathymethry and weather patterns. This paper reviews the planning and installation challenges of offshore wind turbines in the United States by incorporating lessons learned from offshore wind plants already in place in other countries. The goal of this paper is to provide a review of offshore wind turbine installation methods by highlighting challenges unique to this form of renewable energy in the United States. [ABSTRACT FROM AUTHOR]

Compound flooding is a type of flood event caused by multiple flood drivers. The associated risk has usually been assessed using statistics-based analyses or hydrodynamics-based numerical models. This study proposes a compound flood (CF) risk assessment (CFRA) framework for coastal regions in the contiguous United States (CONUS). In this framework, a large-scale river model is coupled with a global ocean reanalysis dataset to (a) evaluate the CF exposure related to the coastal backwater effects on river basins, and (b) generate spatially distributed data for analyzing the CF hazard using a bivariate statistical model of river discharge and storm surge. The two kinds of risk are also combined to achieve a holistic understanding of the continental-scale CF risk. The estimated CF risk shows remarkable inter- and intra-basin variabilities along the CONUS coast with more variabilities in the CF hazard over the US west and Gulf coastal basins. Different risk assessment methods present significantly different patterns in a few key regions such as the San Francisco Bay area, the lower Mississippi River, and Puget Sound. Our results highlight the need to weigh different CF risk measures and avoid using single statistics-based or hydrodynamics-based CFRAs. Uncertainty sources in these CFRAs include the use of gauge observations, which cannot account for the flow physics or resolve the spatial variability of risks, and underestimations of the flood extremes and the dependence of CF drivers in large-scale models, highlighting the importance of understanding the CF risks for developing a more robust CFRA. [ABSTRACT FROM AUTHOR]

The interactions between the North American, Pacific, and Gorda plates at the Mendocino Triple Junction (MTJ) create one of the most seismically active regions in North America. The earthquakes rupture all three plate boundaries but also include considerable intraplate seismicity reflecting the strong internal deformation of the Gorda plate. Understanding the stress levels that drive these ruptures and estimating the locking state of the subduction interface are especially important topics for regional earthquake hazard assessment. However owing to the lack of offshore seismic and geodetic instruments, the rupture process of only a few large earthquakes near the MTJ have been studied in detail and the locking state of the subduction interface is not well constrained. In this paper, first, we use the second moments inversion method to study the rupture process of the January 28, 2015 M w 5.7 earthquake on the Mendocino transform fault that was unusually well recorded by both onshore and offshore strong motion instruments. We estimate the rupture dimension to be approximately 6 km by 3 km corresponding to a stress drop of ∼4 MPa for a crack model. Next we investigate the frictional state of the subduction interface by simulating the afterslip that would be expected there as a result of the stress changes from the 2015 earthquake and a 2010 M w 6.5 intraplate earthquake within the subducted Gorda plate. We simulate afterslip scenarios for a range of depths of the downdip end of the locked zone defined as the transition to velocity strengthening friction and calculate the corresponding surface deformation expected at onshore GPS monuments. We can rule out a very shallow downdip limit owing to the lack of a detectable signal at onshore GPS stations following the 2010 earthquake. Our simulations indicate that the locking depth on the slab surface is at least 14 km, which suggests that the next M8 earthquake rupture will likely reach the coastline and strong shaking should be expected there. [ABSTRACT FROM AUTHOR]

The system of oceanic flows constituting the Atlantic Meridional Overturning Circulation (AMOC) moves heat and other properties to the subpolar North Atlantic, controlling regional climate, weather, sea levels, and ecosystems. Climate models suggest a potential AMOC slowdown towards the end of this century due to anthropogenic forcing, accelerating coastal sea level rise along the western boundary and dramatically increasing flood risk. While direct observations of the AMOC are still too short to infer long-term trends, we show here that the AMOC-induced changes in gyre-scale heat content, superimposed on the global mean sea level rise, are already influencing the frequency of floods along the United States southeastern seaboard. We find that ocean heat convergence, being the primary driver for interannual sea level changes in the subtropical North Atlantic, has led to an exceptional gyre-scale warming and associated dynamic sea level rise since 2010, accounting for 30-50% of flood days in 2015-2020. AMOC-induced heat advection controls ocean temperature in the subtropical North Atlantic, drives year-to-year changes of basin-wide and coastal sea level, and accounts for 30-50% of flood days along the South Atlantic Bight and Gulf of Mexico coasts in 2015-2020. [ABSTRACT FROM AUTHOR]

Multiple species of the genus Dinophysis produce diarrhetic shellfish toxins (okadaic acid and Dinophysis toxins, OA/DTXs analogs) and/or pectenotoxins (PTXs). Only since 2008 have DSP events (illnesses and/or shellfish harvesting closures) become recognized as a threat to human health in the United States. This study characterized 20 strains representing five species of Dinophysis spp. isolated from three US coastal regions that have experienced DSP events: the Northeast/Mid‐Atlantic, the Gulf of Mexico, and the Pacific Northwest. Using a combination of morphometric and DNA‐based evidence, seven Northeast/Mid‐Atlantic isolates and four Pacific Northwest isolates were classified as D. acuminata, a total of four isolates from two coasts were classified as D. norvegica, two isolates from the Pacific Northwest coast were identified as D. fortii, and three isolates from the Gulf of Mexico were identified as D. ovum and D. caudata. Toxin profiles of D. acuminata and D. norvegica varied by their geographical origin within the United States. Cross‐regional comparison of toxin profiles was not possible with the other three species; however, within each region, distinct species‐conserved profiles for isolates of D. fortii, D. ovum, and D. caudata were observed. Historical and recent data from various State and Tribal monitoring programs were compiled and compared, including maximum recorded cell abundances of Dinophysis spp., maximum concentrations of OA/DTXs recorded in commercial shellfish species, and durations of harvesting closures, to provide perspective regarding potential for DSP impacts to regional public health and shellfish industry. [ABSTRACT FROM AUTHOR]

Measurements of significant wave height from satellite altimeter missions are finding increasing application in investigations of wave climate, sea state variability and trends, in particular as the means to mitigate the general sparsity of in situ measurements. However, many questions remain over the suitability of altimeter data for the representation of extreme sea states and applications in the coastal zone. In this paper, the limitations of altimeter data to estimate coastal Hs extremes (<10 km from shore) are investigated using the European Space Agency Sea State Climate Change Initiative L2P altimeter data v1.1 product recently released. This Sea State CCI product provides near complete global coverage and a continuous record of 28 years. It is used here together with in situ data from moored wave buoys at six sites around the coast of the United States. The limitations of estimating extreme values based on satellite data are quantified and linked to several factors including the impact of data corruption nearshore, the influence of coastline morphology and local wave climate dynamics, and the spatio-temporal sampling achieved by altimeters. The factors combine to lead to considerable underestimation of estimated Hs 10-yr return levels. Sensitivity to these factors is evaluated at specific sites, leading to recommendations about the use of satellite data to estimate extremes and their temporal evolution in coastal environments. [ABSTRACT FROM AUTHOR]

Living shorelines provide a nature-based strategy for coastal restoration with ample opportunity for community engagement and collaboration with interdisciplinary stakeholders. While their implementation has increased over the past few decades, restoration via this technique is limited by several factors including a lack of data sharing among projects and geographical regions, a shortage of long-term monitoring to demonstrate efficacy at meeting project goals, and a need for greater interdisciplinary communication moving forward. In this study, we reviewed recent literature from a range of living shorelines studies throughout the United States and conducted interviews with nature-based coastal restoration practitioners primarily from the U.S. west coast. The insight from these stakeholder interviews allowed us to identify major knowledge gaps about living shorelines and establish priorities for future research and funding, including: (1) funding demonstration projects in their early research stages, (2) supporting projects and trainings for engineers utilizing nature-based infrastructure, (3) conducting long-term monitoring of both ecological and structural properties, (4) communicating findings, importance, and project visualizations to stakeholders within and between communities, and (5) advancing the causes of environmental justice and equity. By reviewing recent literature and engaging with living shoreline practitioners to gather their experiences and suggestions, we have increased understanding of how living shoreline restoration can be more effectively planned, constructed, and monitored at scale, in varied locations and using a range of techniques. [ABSTRACT FROM AUTHOR]

Rising coastal flood risk and recent disasters are driving interest in the construction of gated storm surge barriers worldwide, with current studies recommending barriers for at least 11 estuaries in the United States alone. Surge barriers partially block estuary‐ocean exchange with infrastructure across an estuary or its inlet and include gated areas that are closed only during flood events. They can alter the stratification and salt intrusion, change sedimentary systems, and curtail animal migration and ecosystem connectivity, with impacts growing larger with increasing gate closures. Existing barriers are being used with increasing frequency due to sea level rise. New barrier proposals typically come with maximum closure frequency recommendations, yet the future adherence to them is uncertain. Given that the broader environmental effects and coupled‐human dynamics of surge barriers are not well‐understood, we present an interdisciplinary research agenda for this increasingly prevalent modification to our coastal zone. Key Points: Gated storm surge barriers represent a fundamental change to our coastlines and potentially to ocean‐estuary exchangesThey are increasingly being built for coastal protection and closure frequency of existing barriers is increasing with sea level riseFunding of interdisciplinary basic and applied science research is critical to inform billion‐dollar decisions on coastal engineering [ABSTRACT FROM AUTHOR]

Hurricanes have caused major healthcare system disruptions. No systematic assessment of hurricane risk to United States hospital‐based healthcare delivery has been performed. Here, we show that 25 of 78 metropolitan statistical areas (MSAs) on the United States Atlantic and Gulf Coasts have half or more of their hospitals at risk of flooding from relatively weak hurricanes. 0.82 m of sea level rise expected within this century from climate change increases the odds of hospital flooding 22%. Furthermore, in 18 MSAs at least half of the roads within 1.6 km of hospitals were at risk of flooding from a category 2 storm. These findings identify previously undescribed risks to hospital‐based care delivery in Atlantic and Gulf Coast communities. They suggest that lower intensity hurricanes can have outsized impacts on healthcare access, particularly in places where per capita bed availability is low. Plain Language Summary: Hurricanes often incapacitate hospitals, a critical component of healthcare delivery. Climate change is contributing to more intense hurricanes and sea level rise that increase flood risk. Flooding can curtail operations of and limit access to hospitals. We analyzed how hurricane landfalls affect flooding risks to hospitals that serve highly populated cities on the Atlantic and Gulf Coasts of the United States. We find that even relatively weak hurricanes can flood most of the hospitals in urban coastal areas and that sea level rise expected within this century due to climate change significantly increases flooding risk. Key Points: A total 25 of 78 metropolitan statistical areas (MSAs) on the U.S. Atlantic and Gulf Coasts have half or more of their hospitals at risk of flooding from relatively weak hurricanes0.82 m of sea level rise expected within this century from climate change increases the odds of hospital flooding 22%In 18 MSAs, at least half of the roads within 1.6 km of hospitals were at risk of flooding from a category 2 cyclone [ABSTRACT FROM AUTHOR]

Current estimates of U.S. property at risk of coastal hazards and sea level rise (SLR) are staggering—evaluated at over a trillion U.S. dollars. Despite being enormous in the aggregate, potential losses due to SLR depend on mitigation, adaptation, and exposure and are highly uneven in their distribution across coastal cities. We provide the first analysis of how changes in exposure (how and when) have unfolded over more than a century of coastal urban development in the United States. We do so by leveraging new historical settlement layers from the Historical Settlement Data Compilation for the U.S. (HISDAC-US) to examine building patterns within and between the SLR zones of the conterminous United States since the early twentieth century. Our analysis reveals that SLR zones developed faster and continue to have higher structure density than non-coastal, urban, and inland areas. These patterns are particularly prominent in locations affected by hurricanes. However, density levels in historically less-developed coastal areas are now quickly converging on early settled SLR zones, many of which have reached building saturation. These "saturation effects" suggest that adaptation polices targeting existing buildings and developed areas are likely to grow in importance relative to the protection of previously undeveloped land. [ABSTRACT FROM AUTHOR]

Abundance indices from fishery-independent surveys are preferred in stock assessments for their robust scientific designs that minimize uncertainty and bias. When sampling does not adhere to the design, researchers employ techniques such as imputation or standardization to improve accuracy and reduce bias. We examined 2 methods for adjusting for incomplete sampling within the Coastal Trawl Survey (CTS) of the Southeast Area Monitoring and Assessment Program--South Atlantic for 3 species commonly encountered in survey sampling, the Atlantic croaker (Micropogonias undulatus), bluefish (Pomatomus saltatrix), and white shrimp (Litopenaeus setiferus): design-based imputation of missing data and standardization through the delta-generalized-linear-model approach. Additionally, we determined the effect of modifying the seasonal component of the survey design through retrospective simulation. For all 3 species, standardization improved precision in annual abundance estimates relative to values estimated with the design-based method. When a stratum missed in sampling overlapped with an area or time of high variability for a species (e.g., 2019), standardization did not improve precision over the design-based method. Results from examination of the effects of dropping entire seasons, because of funding or logistical challenges, indicate that rotating which season is dropped was the best approach to balancing characteristics of each species. Overall, we recommend the standardization approach for accounting for missing data within the CTS time series. [ABSTRACT FROM AUTHOR]

Specimens of the spotted moray (Gymnothorax moringa) were obtained from fishery-dependent and fishery-independent sources off the Atlantic coast of the southeastern United States from May 2005 through April 2007. A total of 491 individuals, ranging in total length (TL) from 556 to 1267 mm, were collected; age estimates ranged from 4 to 23 years, with a mean of 12.3 years. Females attained greater ages and had a significantly greater mean age than males. Length at age of males was greater than that of females at all ages but was significantly greater only at ages 9, 10, 12, and 17. In size classes with lengths greater than 900 mm TL, males were significantly heavier than females. The overall male-to-female sex ratio of 1:1.09 did not significantly differ from 1:1. All specimens were examined histologically, and none were immature. Spawning females were collected from late April through February, and estimates of spawning periodicity (24-31 d) indicate that a female could spawn up to 12 times during a spawning season. Males were in spawning condition throughout the year, with the exception of March, when all individuals were in regressing condition. Two individuals had both testicular and ovarian tissue; however, histological evidence indicates that this species is likely gonochoristic. [ABSTRACT FROM AUTHOR]

A recent paper published in Geomorphology by Gabet et al. (2014) presents the results of a numerical model supporting the hypothesis that burrowing mammals build Mima mounds - small, densely packed hillocks found primarily in the western United States. The model is based on field observations and produces realistic-looking mounds with spatial distributions similar to real moundfields. Alternative explanations have been proposed for these Mima mounds, including formation by seismic shaking and vegetation-controlled erosion and deposition. In this short communication, we present observations from moundfields in the coastal states of the western U.S. that are incompatible with these alternative theories. [ABSTRACT FROM AUTHOR]

Sea level rise and intense hurricane events make the East and Gulf Coasts of the United States increasingly vulnerable to flooding, which necessitates the development of computational models for accurate water level simulation in these areas to safeguard the coastal wellbeing. With this regard, a model framework for water level simulation over coastal transition zone during hurricane events is built in this study. The model takes advantage of the National Water Model's strength in simulating rainfall–runoff process, and D‐Flow Flexible Mesh's ability to support unstructured grid in hydrodynamic processes simulation with storm surges/tides information from the Advanced CIRCulation model. We apply the model on the Delaware Estuary to simulate extreme water level and to investigate the contribution of different physical components to it during Hurricane Isabel (2003). The model shows satisfactory performance with an average Willmott skill of 0.965. Model results suggest that storm surge is the most dominating component of extreme water level with an average contribution of 78.16%, second by the astronomical tide with 19.52%. While the contribution of rivers is mainly restricted to the upper part of the estuary upstream of Schuylkill River, local wind‐induced water level is more pronounced with values larger than 0.2 m over most part of the estuary. [ABSTRACT FROM AUTHOR]

Vulnerability of coastal regions to extreme events motivates an operational coupled inland‐coastal modeling strategy focusing on the coastal transition zone (CTZ), an area between the coast and upland river. To tackle this challenge, we propose a top‐down framework for investigating the contribution of different processes to the hydrodynamics of CTZs with various geometrical shapes, different physical properties, and under several forcing conditions. We further propose a novel method, called tidal vanishing point (TVP), for delineating the extent of CTZs through the upland. We demonstrate the applicability of our framework over the United States East and Gulf coasts. We categorize CTZs in the region into three classes, namely, without estuary (direct river–coast connection), triangular‐, and trapezoidal‐shaped estuary. The results show that although semidiurnal tidal constituents are dominant in most cases, diurnal tidal constituents become more prevalent in the river segment as the discharge increases. Also, decreasing the bed roughness value promotes more significant changes in the results than increasing it by the same value. Additionally, the estuary promotes tidal energy attenuation and consequently decreases the reach of tidal signals through the upland. The proposed framework is generic and extensible to any coastal region. [ABSTRACT FROM AUTHOR]

The exposure of populations to sea-level rise (SLR) is a leading indicator assessing the impact of future climate change on coastal regions. SLR exposes coastal populations to a spectrum of impacts with broad spatial and temporal heterogeneity, but exposure assessments often narrowly define the spatial zone of flooding. Here we show how choice of zone results in differential exposure estimates across space and time. Further, we apply a spatio-temporal flood-modeling approach that integrates across these spatial zones to assess the annual probability of population exposure. We apply our model to the coastal United States to demonstrate a more robust assessment of population exposure to flooding from SLR in any given year. Our results suggest that more explicit decisions regarding spatial zone (and associated temporal implication) will improve adaptation planning and policies by indicating the relative chance and magnitude of coastal populations to be affected by future SLR. The exposure of populations to sea-level rise is a leading indicator assessing the impact of future climate change on coastal regions. The authors identify three spatial zones of flooding such as mean higher water, the 100 year floodplain and the low-elevation coastal zone and show population exposure can differ between those zones. [ABSTRACT FROM AUTHOR]

Archaeology is in a period of change, a point of inflection in which the discipline strives to reject its colonial roots. Embracing the "ontological turn," archaeologists are applying diverse worldviews within their interpretations, yet these worldviews continue to reintroduce colonial ideals as they emerge out of Western philosophical schools. Using Native American philosophy, a recent addition to the academy, several key themes are identified and applied to the study of Late Archaic shell rings found along the Southeast United States coastlines. Through these themes, these sites are interpreted as places where Native Americans established communication with non-human forces and eventually socialized the newly formed coastline. The use of Native American philosophy is provided as a counter-balance to the use of Western philosophy as a means of further decolonizing archaeology [ABSTRACT FROM AUTHOR]

This study reports a new and significantly enhanced analysis of US flood hazard at 30 m spatial resolution. Specific improvements include updated hydrography data, new methods to determine channel depth, more rigorous flood frequency analysis, output downscaling to property tract level, and inclusion of the impact of local interventions in the flooding system. For the first time, we consider pluvial, fluvial, and coastal flood hazards within the same framework and provide projections for both current (rather than historic average) conditions and for future time periods centered on 2035 and 2050 under the RCP4.5 emissions pathway. Validation against high‐quality local models and the entire catalog of FEMA 1% annual probability flood maps yielded Critical Success Index values in the range 0.69–0.82. Significant improvements over a previous pluvial/fluvial model version are shown for high‐frequency events and coastal zones, along with minor improvements in areas where model performance was already good. The result is the first comprehensive and consistent national‐scale analysis of flood hazard for the conterminous US for both current and future conditions. Even though we consider a stabilization emissions scenario and a near‐future time horizon, we project clear patterns of changing flood hazard (3σ changes in 100 years inundated area of −3.8 to +16% at 1° scale), that are significant when considered as a proportion of the land area where human use is possible or in terms of the currently protected land area where the standard of flood defense protection may become compromised by this time. Plain Language Summary: We develop a method to estimate past, present, and future flood risk for all properties in the conterminous United States whether affected by river, coastal or rainfall flooding. The analysis accounts for variability within environmental factors including changes in sea level rise, hurricane intensity and landfall locations, precipitation patterns, and river discharge. We show that even for a conservative climate change trajectory we can expect locally significant changes in the land area at risk from floods by 2050, and by this time defenses protecting 2,200 km2 of land may be compromised. The complete dataset has been made available via a website (https://floodfactor.com/) created by the First Street Foundation in order to increase public awareness of the threat posed by flooding to safety and livelihoods. Key Points: First complete high‐resolution flood hazard analysis of conterminous US flood risk from all major sources (fluvial, pluvial, and coastal)In validation tests the model achieved Critical Success Index scores of 0.69–0.82, similar to many local custom‐built 2D modelsBy 2050, flood hazard increases for the Eastern seaboard and Western states, but decreases or changes little for the center and South‐West [ABSTRACT FROM AUTHOR]

Despite their limited area relative to the global ocean, coastal zones—the regions where land meets the sea—play a disproportionately important role in generating ecosystem services. However, coastal ecosystems are under increasing pressure from human populations. In particular, urban stormwater is an increasingly important threat to the integrity of coastal systems. Urban catchments exhibit altered flow regimes that impact ecosystem processes and coastal foodwebs. In addition, urban stormwater contains complex and unpredictable mixtures of chemicals that result in a multitude of lethal and sublethal impacts on species in coastal systems. Along the western coast of the United States, we estimate that hundreds of billions of kilograms of suspended solids flow off land surfaces and enter the Northern California Current each year. However, 70% of this pollution could be addressed by treating only 1.35% of the land area. Determining how to prioritize treatment of stormwater in this region requires a clear articulation of objectives—spatial distribution of appropriate management actions is dependent on the life histories of species, and management schemes optimized for one species may not achieve desired objectives for other species. In particular, we highlight that the scale of stormwater interventions must match the ecological scale relevant to species targeted by management. In many cases, management and policy will require mechanisms in order to ensure that local actions scale-up to efficiently and effectively achieve management objectives. In the face of rapid urbanization of coastal zones, failure to consider the match of management and ecological scales will result in the continued decline of coastal ecosystems and the species they support. This article is part of the theme issue 'Integrative research perspectives on marine conservation'. [ABSTRACT FROM AUTHOR]

Sea‐level dynamics, sediment availability, and marine energy are critical drivers of coastal wetland formation and persistence, but their roles as continental‐scale drivers remain unknown. We evaluated the timing and spatial variability of wetland formation from new and existing cores collected along the Atlantic and Gulf coasts of the United States. Most basal peat ages occurred after sea‐level rise slowed (after ~4,000 years before present), but predominance of sea‐level rise studies may skew age estimates toward older sites. Near‐coastal sites tended to be younger, indicating creation of wetlands through basin infilling and overwash events. Age distributions differed among regions, with younger wetlands in the northeast and southeast corresponding to European colonization and deforestation. Across all cores, wetland age correlated strongly with basal peat depth. Marsh age elucidates the complex interactions between sea‐level rise, sediment supply, and geomorphic setting in determining timing and location of marsh formation and future wetland persistence. Plain Language Summary: Marshes, a type of coastal wetland, form under stable, slow rates of sea‐level rise (SLR). Although many marshes along the East Coast of the United States formed after the most recent slowing of SLR (approximately 4,000–6,000 years ago), there is evidence that sediment erosion from colonial deforestation expanded marshes. This study uses sediment cores to determine when and where marshes formed to understand what drives modern marsh formation. We found that most marshes did form following SLR slowing after around 4,000 years ago. We also found evidence of marshes forming during European colonization in the northeastern and southeastern United States. Finally, we found recent formation of marshes closest to the coast, possibly driven by storm events and associated overwash. Through this study, we outline a novel way to easily determine marsh age and to better understand why marshes form through future research. Key Points: Marshes largely formed after SLR slowed (after 4,000 ybp). A second formation period occurred (~400 ybp), coinciding with land cover changeStudies that dated marshes to assess historic sea‐level rise had an older and less varied age distribution than other studiesCoastal marshes are younger nearer the coast and in regions where land use change may have delivered large amounts of sediment to the coast [ABSTRACT FROM AUTHOR]

The coastal ecosystems of temperate North America provide a variety of ecosystem services including high rates of carbon sequestration. Yet, little data exist for the carbon stocks of major tidal wetland types in the Pacific Northwest, United States. We quantified the total ecosystem carbon stocks (TECS) in seagrass, emergent marshes, and forested tidal wetlands, occurring along increasing elevation and decreasing salinity gradients. The TECS included the total aboveground carbon stocks and the entire soil profile (to as deep as 3 m). TECS significantly increased along the elevation and salinity gradients: 217 ± 60 Mg C/ha for seagrass (low elevation/high salinity), 417 ± 70 Mg C/ha for low marsh, 551 ± 47 Mg C/ha for high marsh, and 1,064 ± 38 Mg C/ha for tidal forest (high elevation/low salinity). Soil carbon stocks accounted for >98% of TECS in the seagrass and marsh communities and 78% in the tidal forest. Soils in the 0–100 cm portion of the profile accounted for only 48%–53% of the TECS in seagrasses and marshes and 34% of the TECS in tidal forests. Thus, the commonly applied limit defining TECS to a 100 cm depth would greatly underestimate both carbon stocks and potential greenhouse gas emissions from land‐use conversion. The large carbon stocks coupled with other ecosystem services suggest value in the conservation and restoration of temperate zone tidal wetlands through climate change mitigation strategies. However, the findings suggest that long‐term sea‐level rise effects such as tidal inundation and increased porewater salinity will likely decrease ecosystem carbon stocks in the absence of upslope wetland migration buffer zones. [ABSTRACT FROM AUTHOR]

One of the major concerns engendered by a warming climate are changing sea levels and their lasting effects on coastal populations, infrastructures, and natural habitats. Sea levels are now monitored by satellites, but long‐term records are only available at discrete locations along the coasts. Sea levels and sea‐level processes must be better understood at the local level to best inform real‐world adaptation decisions. We propose a statistical model that facilitates the characterization of known sea‐level processes, which jointly govern the observed sea level along the United States Atlantic Coast. Our model not only incorporates long‐term sea level rise and seasonal cycles but also accurately accounts for residual spatiotemporal processes. By combining a spatially varying coefficient modeling approach with spatiotemporal factor analysis methods in a Bayesian framework, the method represents the contribution of each of these processes and accounts for corresponding dependencies and uncertainties in a coherent way. Additionally, the model provides a consistent way to estimate these processes and sea level values at unmonitored locations along the coast. We show the outcome of the proposed model using thirty years of sea level data from 38 stations along the Atlantic (east) Coast of the United States. Among other results, our method estimates the rate of sea level rise to range from roughly 1 mm/year in the northern and southern regions of the Atlantic coast to 5.4 mm/year in the middle region. [ABSTRACT FROM AUTHOR]

Sea-level rise will radically redefine the coastline of the 21st century. For many coastal regions, projections of global sea-level rise by the year 2100 (e.g., 0.5–2 meters) are comparable in magnitude to today's extreme but short-lived increases in water level due to storms. Thus, the 21st century will see significant changes to coastal flooding regimes (where present-day, extreme-but-rare events become common), which poses a major risk to the safety and sustainability of coastal communities worldwide. So far, estimates of future coastal flooding frequency focus on endpoint scenarios, such as the increase in flooding by 2050 or 2100. Here, we investigate the continuous shift in coastal flooding regimes by quantifying continuous rates of increase in the occurrence of extreme water-level events due to sea-level rise. We find that the odds of exceeding critical water-level thresholds increases exponentially with sea-level rise, meaning that fixed amounts of sea-level rise of only ~1–10 cm in areas with a narrow range of present-day extreme water levels can double the odds of flooding. Combining these growth rates with established sea-level rise projections, we find that the odds of extreme flooding double approximately every 5 years into the future. Further, we find that the present-day 50-year extreme water level (i.e., 2% annual chance of exceedance, based on historical records) will be exceeded annually before 2050 for most (i.e., 70%) of the coastal regions in the United States. Looking even farther into the future, the present-day 50-year extreme water level will be exceeded almost every day during peak tide (i.e., daily mean higher high water) before the end of the 21st century for 90% of the U.S. coast. Our findings underscore the need for immediate planning and adaptation to mitigate the societal impacts of future flooding. [ABSTRACT FROM AUTHOR]

We develop an aggregated extreme sea level (ESL) indicator for the contiguous United States coastline, which is comprised of separate indicators for mean sea level (MSL) and storm surge climatology (SSC). We use water level data from tide gauges to estimate interannual to multi-decadal variability of MSL and SSC and identify coastline stretches where the observed changes are coherent. Both the MSL and SSC indicators show significant fluctuations. Indicators of the individual components are combined with multi-year tidal contributions into aggregated ESL indicators. The relative contribution of the different components varies considerably in time and space. Our results highlight the important role of interannual to multi-decadal variability in different sea level components in exacerbating, or reducing, the impacts of long-term MSL rise over time scales relevant for coastal planning and management. Regularly updating the proposed indicator will allow tracking changes in ESL posing a threat to many coastal communities, including the identification of periods where the likelihood of flooding is particularly large or small. [ABSTRACT FROM AUTHOR]

Climate change is leading to significant alterations to ecosystems all over the world and some of the resulting impacts on fish and fisheries are now becoming apparent. Estuaries, which are highly susceptible to climate change because they are relatively shallow and in close proximity to anthropogenic stressors, provide habitat to many fish species at a critical time in the life history, after transport and just prior to settlement in nurseries. Despite this, the long-term impacts of climate change on larval fish at this critical location/stage in the life history are not well documented. The larval fish assemblage of a coastal estuary was sampled once per week for twenty-six years at a fixed location in southern New Jersey, USA. We used ordination and regression analysis to evaluate the whole assemblage, individual species/family occurrence, and trends in total density and diversity over that time. The larval fish assemblage changed significantly in response to warming water temperatures. In addition, approximately one quarter of the species/families in the assemblage exhibited a statistically significant trend in individual occurrence over time. Of these, all five of the five northern-affiliated species decreased in occurrence while 18 of 21 southern-affiliated species increased in occurrence. Finally, total fish density and species diversity increased over the course of the study. The non-uniform response of the species/families in this larval assemblage is similar to what has been documented in other studies that evaluated the temporal trend of open ocean juvenile and adult fish assemblages. [ABSTRACT FROM AUTHOR]

Two commonly used definitions of coastline are compared and analyzed in this article. To build a more perfect digital tide-coordinated coastline model in China, we should first solve the problems of the existing definition and unclear algorithms of China's coastline. On the basis of defining the coastline in China as the intersection of coastal land and the mean high water spring (MHWS), it should be further revised, and defined either as an intersection of coastal land and the MHWS or as a mean higher high water level (MHHWL) considering the diversity of tidal characteristics in China Sea areas. Since MHWS is related to the extreme of the lunar phase and MHHWL is related to the extreme of the angle of the lunar declination elevation, the algorithms to obtain them are more complicated than that of mean high water (MHW) used in the United States. We should consider the specific law of tidal movement in different tide types of the predominantly semidiurnal or diurnal sea areas in China when studying the precise algorithms for MHWS and MHHWL. Several experiments show that the difference between the two types of calculations of coastal height, such as water level observations and tidal predictions, is within centimeter level. The research results of this article have a certain reference value for countries with similar coastline features as in China. [ABSTRACT FROM AUTHOR]

National Weather Service (NWS) forecasters across the west coast of the United States often deal with cool season hail showers that produce hazardous driving conditions. These small hail events, with diameters averaging 5.8 mm, occur with cold upper troughs that support weak instability favorable for low-topped convection and reflectivity values averaging 48 dBZ. The public generally assumes that heavy snow is common across west coast mountains, while heavy rain prevails near sea level. However, motorists can be caught offguard when wet, relatively warm low elevation roadways suddenly transition to icy hail-covered conditions. Thus, west coast small hail events represent an opportunity for the NWS to provide tailored messaging that can modify public perceptions and optimize outcomes. This research examines environments supportive of accumulating small hail over the western United States during the period 2008-2018, and supplements the environmental analysis with a summary of enhanced impact-based decision support techniques used to alert NWS partners and the general public. [ABSTRACT FROM AUTHOR]

Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches from the temperate zone to past the Arctic circle. Oceanographic conditions vary from quiet estuaries to exposed open coasts. Water temperatures range from over 20°C in the summer in the south to ice covered water in the north. Consequently, the marine flora is plentiful and diverse with over 500 species of seaweeds. Three species of floating kelps occur from the southern boundary to Kodiak Island and westward along the Aleutian Chain. Species of Fucus are dominant in the intertidal along most of the coastline. There is also an abundance of red algae in the intertidal and subtidal. There is only minimal subsistence and commercial utilization of the seaweed resource. The major commercial use of seaweeds is in the herring spawn-on-kelp fishery. "Black seaweed" (Pyropia sp.) is a special resource for Alaskan Native subsistence harvest. Recently, there has been increasing interest and activity in the commercial mariculture of kelps such as Saccharina latissima and Alaria marginata. [ABSTRACT FROM AUTHOR]

The rapid growth of offshore wind energy requires accurate modeling of the wind resource, which can be depleted by wind farm wakes. Turbulence dissipation rate (ϵ) governs the accuracy of model predictions of hub‐height wind speed and the development and erosion of wakes. Here we assess the variability of turbulence kinetic energy and ϵ using 13 months of observations from a profiling lidar deployed on a platform off the Massachusetts coast. Offshore, ϵ is 2 orders of magnitude smaller than onshore, with a subtle diurnal cycle. Wind direction influences the annual cycle of turbulence, with larger values in winter when the wind flows from the land, and smaller values in summer, when the wind flows from open ocean. Because of the weak turbulence, wind plant wakes will be stronger and persist farther downwind in summer. Key Points: Strength and peturbulence dissipation rate offshore is smaller than onshore, with a weak diurnal cycleDissipation rate is larger when flow is from the land, usually in wintertime at this siteLarge wind veer is often associated with low turbulence at the site [ABSTRACT FROM AUTHOR]

This article explores the deployment of Louisiana's highly touted $50 billion, fifty-year Master Plan for a Sustainable Coast, which is often characterized as saving Louisiana's Working Coast of disappearing marshlands that are home to several major industry sectors, along with migratory flyways, seafood estuaries, and two million residents. As a concept, the Working Coast attempts to signify the importance of Louisiana's coastal zone to the nation's economy in order to justify expensive restoration projects. By complicating the euphemism and the extractive logic it signifies, I hope to show that the state's current approach to slow the disappearance of its coastline in fact rationalizes the very practices sinking it. The Working Coast reifies the state's fragile marshlands through metrics that can only be realized through continued extraction. [ABSTRACT FROM AUTHOR]

Abstract: This study reports on the movements of swordfish tagged within the Pacific Leatherback Conservation Area (PLCA), an expansive region (>500,000 km2) off the U.S. West Coast that has been seasonally restricted to drift‐gillnet fishing since 2001 to reduce leatherback sea turtle (Dermochelys coricea) interactions. Thirteen swordfish were outfitted with satellite‐linked archival tags scheduled for short (2–20 days, n = 11) and longer‐term (150 days, n = 2) data collection. All tags were deployed on basking swordfish using traditional harpoon‐based methods during the fall of 2012–2013, near offshore seamounts (35.6°N/122.9°W to 37.4°N/123.5°W). Depth and temperature data from 11 swordfish (~90 to 150 kg) resulted in <251 days of movement information from the PLCA region. All tagged individuals exhibited surface‐oriented nocturnal movements, spending >99% of the night above the average thermocline depth (37.5 m), with an average night depth of 8.3 ± 1.6 m. Daytime depth distribution was greater and more variable (mean 107.1 ± 21.2 m), with fish primarily displaying three behavioral patterns: (i) basking activity, 16.7% of the day, (ii) a mixed‐layer distribution between 3 m and the thermocline (26.8% of the day), and (iii) prolonged dives below the thermocline, 56.5% of the day. For seven of the tracks, daytime basking rates increased when thermocline depth was <37 m. As fish moved offshore, there was less variability in vertical movements with a reduction in both basking activity and mixed layer occupancy, as well as an increase in average daytime depth. These data are discussed with respect to the potential development of alternative fishery options for the PLCA. [ABSTRACT FROM AUTHOR]

Recent studies have linked interannual sea level variability and extreme events along the U.S. northeast coast (NEC) to the North Atlantic Oscillation (NAO), a natural internal climate mode that prevails in the North Atlantic Ocean. The correlation between the NAO index and coastal sea level north of Cape Hatteras was weak from the 1960s to the mid-1980s, but it has markedly increased since around 1987. The causes for the decadal shift remain unknown. Yet understanding the abrupt change is vital for decadal sea level prediction and is essential for risk management. Here we use a robust method, the Bayesian dynamic linear model (DLM), to explore the nonstationary NAO impact on NEC sea level. The results show that a spatial pattern change of NAO-related winds near the NEC is a major cause of the NAO–sea level relationship shift. A new index using regional sea level pressure is developed that is a significantly better predictor of NEC sea level than is the NAO and is strongly linked to the intensity of westerly winds near the NEC. These results point to the vital importance of monitoring regional changes of wind and sea level pressure patterns, rather than the NAO index alone, to achieve more accurate predictions of sea level change along the NEC. [ABSTRACT FROM AUTHOR]

Coastal risks are increasing from both development and climate change. Interest is growing in the protective role that coastal nature-based measures (or green infrastructure), such as reefs and wetlands, can play in adapting to these risks. However, a lack of quantitative information on their relative costs and benefits is one principal factor limiting their use more broadly. Here, we apply a quantitative risk assessment framework to assess coastal flood risk (from climate change and economic exposure growth) across the United States Gulf of Mexico coast to compare the cost effectiveness of different adaptation measures. These include nature-based (e.g. oyster reef restoration), structural or grey (e.g., seawalls) and policy measures (e.g. home elevation). We first find that coastal development will be a critical driver of risk, particularly for major disasters, but climate change will cause more recurrent losses through changes in storms and relative sea level rise. By 2030, flooding will cost $134–176.6 billion (for different economic growth scenarios), but as the effects of climate change, land subsidence and concentration of assets in the coastal zone increase, annualized risk will more than double by 2050 with respect to 2030. However, from the portfolio we studied, the set of cost-effective adaptation measures (with benefit to cost ratios above 1) could prevent up to $57–101 billion in losses, which represents 42.8–57.2% of the total risk. Nature-based adaptation options could avert more than $50 billion of these costs, and do so cost effectively with average benefit to cost ratios above 3.5. Wetland and oyster reef restoration are found to be particularly cost-effective. This study demonstrates that the cost effectiveness of nature-based, grey and policy measures can be compared quantitatively with one another, and that the cost effectiveness of adaptation becomes more attractive as climate change and coastal development intensifies in the future. It also shows that investments in nature-based adaptation could meet multiple objectives for environmental restoration, adaptation and flood risk reduction. [ABSTRACT FROM AUTHOR]

In association with the Department of Energy--funded Position of Offshore Wind Energy Resources (POWER) project, we present results from compositing a 3-year dataset of 80-m (above ground level) wind forecasts from the 3-km High-Resolution Rapid Refresh (HRRR) model over offshore regions for the contiguous United States. The HRRR numerical weather prediction system runs once an hour and features hourly data assimilation, providing a key advantage over previous model-based offshore wind datasets. On the basis of 1-hour forecasts from the HRRR model, we highlight the different climatological regimes of the nearshore environment, characterizing the mean 80-m wind speed as well as the frequency of exceeding 4, 12, and 25 m s-1 for east and west coast, Gulf of Mexico, and Great Lake locations. Preliminary verification against buoy measurements demonstrates good agreement with observations. This dataset can inform the placement of targeted measurement systems in support of improving resource assessments and wind forecasts to advance offshore wind energy goals both in New England and other coastal regions of the United States. [ABSTRACT FROM AUTHOR]

ABSTRACT: Previously unrecognized clusters of regularly spaced, low‐relief ridges were recently revealed by LiDAR data acquired in the Seacoast region of New Hampshire, USA. Based on their morphometry and geologic context, these features are interpreted as De Geer moraines that formed during regional deglaciation. While De Geer moraines are widely recognized as products of ice recession in glaciomarine settings, their formative processes remain debated. Here, we integrate geospatial mapping, morphometric analyses, stratigraphic investigations and ground‐penetrating radar (GPR) subsurface profiling to characterize De Geer moraines in New Hampshire and assess their origin. On average, the moraines are 1.2 km long, 28 m wide, 1.7 m tall and spaced 104 m apart. Trenches expose stratigraphic units consistent with subaqueous deposition along a tidewater glacier margin, including subglacial traction till indicative of proglacial pushing, and gravity‐driven flow deposits on an ice‐distal moraine slope. GPR profiles reveal variable till thicknesses beneath the ridges and stratified sediment in adjacent swales. Our findings suggest De Geer moraine formation was driven by annual oscillations of the retreating Laurentide Ice Sheet margin. In this interpretation, average moraine spacing would represent a retreat rate of ∼100 m a−1, which is in line with previous estimates of recession rates across New England. [ABSTRACT FROM AUTHOR]

It is well known that the majority of buoy measurements are located around the US coast and along some Europeans countries. The lack of long-term and densely spaced in situ measurements in the Southern Hemisphere in general, and the South Atlantic in particular, hinders several investigations due to the lack of detailed metocean information. Here, we present an effort to overcome this limitation, with a dense network of buoys along the Brazilian coast, equipped with several meteorological and oceanographic sensors. Out of ten currently operational buoys, three are employed to present the main characteristics of waves in the Southern part of the network. For the first time, sensor characteristics and settings are described, as well as the methods applied to the raw wave data. Statistics and distributions of wave parameters, swell propagating events, comparison with a numerical model and altimeters and a discussion about the occurrence of freak waves are presented. [ABSTRACT FROM AUTHOR]

Tropical cyclones that make landfall often spawn tornadoes. Previous studies have shown that these tornadoes are not uniformly distributed in the United States or in the tropical cyclone environment. They show that tornadoes tend to occur relatively close to the coastline and that they tend to cluster to the east-of-center in the tropical cyclone environment, particularly in the northeast and east-of-center quadrants. This study contributes to these studies by analyzing the spatial distributions of tropical cyclone tornadoes by intensity, path length, path width, and the damage potential index. The analyses confirm that most tornadoes occur relatively close to the coastline, but show that stronger tornadoes with larger paths are disproportionately common farther inland. They also confirm that the highest amount of activity is located within the northeast and east-of-center quadrants and show that the most potentially damaging tornadoes cluster in a sub region near the intersection of these two quadrants. [ABSTRACT FROM AUTHOR]