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J. Mar. Sci. Eng., Volume 5, Issue 3 (September 2017) – 20 articles

Cover Story (view full-size image): During the last decades, the large focus on renewable energy sources has led to development of different types of technologies for harvesting of energy. This includes wave energy converters. Despite comprehensive research, this sector is still not in a commercial state. Mooring of floating wave energy converters is an important topic in this research since it highly influences the overall cost of the devices. In addition, several wave energy converter failures have been observed due to insufficient mooring systems. This rises an apparent need for focus on cost and reliability and for definition of an applicable tool and standardized method for design and analysis of mooring systems.View the paper here.
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2591 KiB  
Article
Cost and Materials Required to Retrofit US Seaports in Response to Sea Level Rise: A Thought Exercise for Climate Response
by Austin Becker, Ariel Hippe and Elizabeth L. Mclean
J. Mar. Sci. Eng. 2017, 5(3), 44; https://doi.org/10.3390/jmse5030044 - 14 Sep 2017
Cited by 15 | Viewed by 11083
Abstract
Climate changes projected for 2100 and beyond could result in a worldwide race for adaptation resources on a scale never seen before. This paper describes a model for estimating the cost and materials of elevating coastal seaport infrastructure in the United States to [...] Read more.
Climate changes projected for 2100 and beyond could result in a worldwide race for adaptation resources on a scale never seen before. This paper describes a model for estimating the cost and materials of elevating coastal seaport infrastructure in the United States to prevent damage from sea level rise associated with climate change. This study pilots the use of a generic port model (GenPort) as a basis from which to estimate regional materials and monetary demands, resulting in projections that would be infeasible to calculate on an individual port-by-port basis. We estimate the combined cost of adding two meters of additional fill material to elevate the working surface and then reconstructing the generic port. We use the resulting unit area cost to develop an estimate to elevate and retrofit 100 major United States commercial coastal ports. A total of $57 billion to $78 billion (2012 US dollars) and 704 million cubic meters of fill would be required to elevate the 100 ports by two meters and to reconstruct associated infrastructure. This estimation method and the results serve as a thought exercise to provoke considerations of the cumulative monetary and material demands of widespread adaptations of seaport infrastructure. The model can be adapted for use in multiple infrastructure sectors and coastal managers can use the outlined considerations as a basis for individual port adaptation strategy assessments. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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18490 KiB  
Article
Impact of North Atlantic Teleconnection Patterns on Northern European Sea Level
by Léon Chafik, Jan Even Øie Nilsen and Sönke Dangendorf
J. Mar. Sci. Eng. 2017, 5(3), 43; https://doi.org/10.3390/jmse5030043 - 06 Sep 2017
Cited by 31 | Viewed by 9172
Abstract
Northern European sea levels show a non-stationary link to the North Atlantic Oscillation (NAO). The location of the centers of the NAO dipole, however, can be affected through the interplay with the East Atlantic (EAP) and the Scandinavian (SCAN) teleconnection patterns. Our results [...] Read more.
Northern European sea levels show a non-stationary link to the North Atlantic Oscillation (NAO). The location of the centers of the NAO dipole, however, can be affected through the interplay with the East Atlantic (EAP) and the Scandinavian (SCAN) teleconnection patterns. Our results indicate the importance of accounting for the binary combination of the NAO with the EAP/SCAN for better understanding the non-stationary drivers inducing sea level variations along the European coasts. By combining altimetry and tide gauges, we find that anomalously high monthly sea levels along the Norwegian (North Sea) coast are predominantly governed by same positive phase NAO+/EAP+ (NAO+/SCAN+) type of atmospheric circulation, while the Newlyn and Brest tide gauges respond markedly to the opposite phase NAO−/EAP+ combination. Despite these regional differences, we find that coherent European sea level changes project onto a pattern resembling NAO+/SCAN+, which is signified by pressure anomalies over Scandinavia and southern Europe forcing winds to trace the continental slope, resulting in a pile-up of water along the European coasts through Ekman transport. We conclude that taking into consideration the interaction between these atmospheric circulation regimes is valuable and may help to understand the time-varying relationship between the NAO and European mean sea level. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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Article
Choosing a Future Shoreline for the San Francisco Bay: Strategic Coastal Adaptation Insights from Cost Estimation
by Daniella Hirschfeld and Kristina E. Hill
J. Mar. Sci. Eng. 2017, 5(3), 42; https://doi.org/10.3390/jmse5030042 - 04 Sep 2017
Cited by 10 | Viewed by 7869
Abstract
In metropolitan regions made up of multiple independent jurisdictions, adaptation to increased coastal flooding due to sea level rise requires coordinated strategic planning of the physical and organizational approaches to be adopted. Here, we explore a flexible method for estimating physical adaptation costs [...] Read more.
In metropolitan regions made up of multiple independent jurisdictions, adaptation to increased coastal flooding due to sea level rise requires coordinated strategic planning of the physical and organizational approaches to be adopted. Here, we explore a flexible method for estimating physical adaptation costs along the San Francisco Bay shoreline. Our goal is to identify uncertainties that can hinder cooperation and decision-making. We categorized shoreline data, estimated the height of exceedance for sea level rise scenarios, and developed a set of unit costs for raising current infrastructure to meet future water levels. Using these cost estimates, we explored critical strategic planning questions, including shoreline positions, design heights, and infrastructure types. For shoreline position, we found that while the shortest line is in fact the least costly, building the future shoreline at today’s transition from saltwater to freshwater vegetation is similar in cost but allows for the added possibility of conserving saltwater wetlands. Regulations requiring a specific infrastructure design height above the water level had a large impact on physical construction costs, increasing them by as much as 200%. Finally, our results show that the costs of raising existing walls may represent 70% to 90% of the total regional costs, suggesting that a shift to earthen terraces and levees will reduce adaptation costs significantly. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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2590 KiB  
Article
Effects of Salinity on Surface Lifetime of Large Individual Bubbles
by Magdalena D. Anguelova and Pablo Huq
J. Mar. Sci. Eng. 2017, 5(3), 41; https://doi.org/10.3390/jmse5030041 - 01 Sep 2017
Cited by 9 | Viewed by 4850
Abstract
The influence of salinity on the characteristics of individual bubbles (2–4 mm in diameter) in fresh and saline water (up to 40 practical salinity units) was investigated. Bubbles were produced by forcing air through capillary tubes. Aqueous solutions in distilled and filtered tap [...] Read more.
The influence of salinity on the characteristics of individual bubbles (2–4 mm in diameter) in fresh and saline water (up to 40 practical salinity units) was investigated. Bubbles were produced by forcing air through capillary tubes. Aqueous solutions in distilled and filtered tap waters with minimized presence of organic additives were used. Salinity, surface tension, and water temperature were monitored. Parameters measured were the bubble surface lifetime, diameter, and rise velocity. The surface lifetime varies widely (in the range of 0.4–35 s) depending on the salinity concentration and the purity of the solutions. Variations with salinity of size and rise velocity of large individual bubbles are discussed. Interpretation of the results in terms of anti-foaming (negative adsorption), as well as the Marangoni and the Gibbs effects, is helpful in understanding the results. Full article
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Article
Applying Principles of Uncertainty within Coastal Hazard Assessments to Better Support Coastal Adaptation
by Scott A. Stephens, Robert G. Bell and Judy Lawrence
J. Mar. Sci. Eng. 2017, 5(3), 40; https://doi.org/10.3390/jmse5030040 - 29 Aug 2017
Cited by 38 | Viewed by 8893
Abstract
Coastal hazards result from erosion of the shore, or flooding of low-elevation land when storm surges combine with high tides and/or large waves. Future sea-level rise will greatly increase the frequency and depth of coastal flooding and will exacerbate erosion and raise groundwater [...] Read more.
Coastal hazards result from erosion of the shore, or flooding of low-elevation land when storm surges combine with high tides and/or large waves. Future sea-level rise will greatly increase the frequency and depth of coastal flooding and will exacerbate erosion and raise groundwater levels, forcing vulnerable communities to adapt. Communities, local councils and infrastructure operators will need to decide when and how to adapt. The process of decision making using adaptive pathways approaches, is now being applied internationally to plan for adaptation over time by anticipating tipping points in the future when planning objectives are no longer being met. This process requires risk and uncertainty considerations to be transparent in the scenarios used in adaptive planning. We outline a framework for uncertainty identification and management within coastal hazard assessments. The framework provides a logical flow from the land use situation, to the related level of uncertainty as determined by the situation, to which hazard scenarios to model, to the complexity level of hazard modeling required, and to the possible decision type. Traditionally, coastal flood hazard maps show inundated areas only. We present enhanced maps of flooding depth and frequency which clearly show the degree of hazard exposure, where that exposure occurs, and how the exposure changes with sea-level rise, to better inform adaptive planning processes. The new uncertainty framework and mapping techniques can better inform identification of trigger points for adaptation pathways planning and their expected time range, compared to traditional coastal flooding hazard assessments. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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Article
An Analysis of Ship-Source Marine Pollution in Nigeria Seaports
by D. E. Onwuegbuchunam, T. E. Ebe, L. I. Okoroji and A. E. Essien
J. Mar. Sci. Eng. 2017, 5(3), 39; https://doi.org/10.3390/jmse5030039 - 23 Aug 2017
Cited by 17 | Viewed by 8924
Abstract
Existing studies indicate that marine pollution control in the ports of developing economies is marred by a lack of administrative control and inadequate provision of waste reception facilities. In Nigeria ports, ship generated waste control services and provision of waste reception facilities are [...] Read more.
Existing studies indicate that marine pollution control in the ports of developing economies is marred by a lack of administrative control and inadequate provision of waste reception facilities. In Nigeria ports, ship generated waste control services and provision of waste reception facilities are outsourced to private companies with no requirement for an activity audit. Apart from the port authority, other government agencies are also involved in pollution monitoring and control. Hence, functions are duplicated and effective regulation is arguably weakened by conflicts of interest. A scientific based integrated model is therefore proposed to address the managerial problem posed in the control of marine pollution in Nigerian ports. In this paper, we conduct a physico-chemical and microbiological analysis of samples of ships’ wastewater to determine the status of marine pollution in the port environment. The samples were collected from randomly selected ships at berths in seaport locations. The outputs from the analysis are then integrated as inputs into an administrative framework model. The integrated model developed is proposed as an alternative administrative tool for monitoring and controlling pollution in seaports. The policy implications of the developed model are discussed. Full article
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Article
Effect of Bottom Friction, Wind Drag Coefficient, and Meteorological Forcing in Hindcast of Hurricane Rita Storm Surge Using SWAN + ADCIRC Model
by Muhammad K. Akbar, Simbarashe Kanjanda and Abram Musinguzi
J. Mar. Sci. Eng. 2017, 5(3), 38; https://doi.org/10.3390/jmse5030038 - 21 Aug 2017
Cited by 27 | Viewed by 6447
Abstract
An evaluation of the effect of bottom friction, wind drag coefficient, and meteorological forcing is conducted using a tightly coupled wave and circulation model, SWAN + ADCIRC (i.e., Simulating WAves Nearshore + ADvanced CIRCulation), to hindcast the storm surge of Hurricane Rita (2005). [...] Read more.
An evaluation of the effect of bottom friction, wind drag coefficient, and meteorological forcing is conducted using a tightly coupled wave and circulation model, SWAN + ADCIRC (i.e., Simulating WAves Nearshore + ADvanced CIRCulation), to hindcast the storm surge of Hurricane Rita (2005). Wind drag coefficient formulations of Powell, Zijlema, and Peng & Li are used to calculate wind stresses. Bottom friction and wind drag coefficients are systematically increased and decreased to quantify their impacts on the hindcast. Different meteorological forcing options are applied to study the effect of wind fields on storm surge development and propagation. Simulated water levels are compared with observed data collected from about 150 locations. It is evident that a lower bottom friction causes higher and faster surge propagation, and earlier arrival of inundation peak at locations far from the land fall. Drag coefficients of Powell, with or without a cap of 0.002, and Zijlema produce similar results, while that of Peng & Li slightly overpredicted the surge. Wind fields may cause overprediction or underprediction of the surge, depending on the choice of the wind model. A good agreement is found between Zijlema’s findings and this study; that simultaneously decreasing or increasing both bottom friction and wind drag essentially provides the same hindcast results. Full article
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Article
Anti-Collision Assessment and Prediction Considering Material Corrosion on an Offshore Protective Device
by Ang Qiu, Xiangxi Han, Hongyu Qin, Wei Lin and Youhong Tang
J. Mar. Sci. Eng. 2017, 5(3), 37; https://doi.org/10.3390/jmse5030037 - 15 Aug 2017
Cited by 3 | Viewed by 4173
Abstract
Corrosion deterioration of steel can heavily degrade the performance of marine and offshore structures. A typical steel protective device, which has worked for a dozen years in a river estuary, is selected as the research object. Its current corrosion response is measured on [...] Read more.
Corrosion deterioration of steel can heavily degrade the performance of marine and offshore structures. A typical steel protective device, which has worked for a dozen years in a river estuary, is selected as the research object. Its current corrosion response is measured on site and its further corrosive response is predicted based on measurement data and the structure’s current state. Nonlinear finite element method is utilized to analyze the degradation of the protective device’s anti-collision performance. Meanwhile the rubber buffer effect has been investigated for its anti-collision on the protective device. A prediction method is proposed that can accurately forecast degradation of the anti-collision performance of a protective device as time progresses. Full article
(This article belongs to the Special Issue Marine Structures)
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Article
Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway
by Matthew J. R. Simpson, Oda R. Ravndal, Hilde Sande, Jan Even Ø. Nilsen, Halfdan P. Kierulf, Olav Vestøl and Holger Steffen
J. Mar. Sci. Eng. 2017, 5(3), 36; https://doi.org/10.3390/jmse5030036 - 14 Aug 2017
Cited by 18 | Viewed by 8725
Abstract
Changes to mean sea level and/or sea level extremes (e.g., storm surges) will lead to changes in coastal impacts. These changes represent a changing exposure or risk to our society. Here, we present 21st century sea-level projections for Norway largely based on the [...] Read more.
Changes to mean sea level and/or sea level extremes (e.g., storm surges) will lead to changes in coastal impacts. These changes represent a changing exposure or risk to our society. Here, we present 21st century sea-level projections for Norway largely based on the Fifth Assessment Report from the Intergovernmental Panel for Climate Change (IPCC AR5). An important component of past and present sea-level change in Norway is glacial isostatic adjustment. We therefore pay special attention to vertical land motion, which is constrained using new geodetic observations with improved spatial coverage and accuracies, and modelling work. Projected ensemble mean 21st century relative sea-level changes for Norway are, depending on location, from −0.10 to 0.30 m for emission scenario RCP2.6; 0.00 to 0.35 m for RCP 4.5; and 0.15 to 0.55 m for RCP8.5. For all RCPs, the projected ensemble mean indicates that the vast majority of the Norwegian coast will experience a rise in sea level. Norway’s official return heights for extreme sea levels are estimated using the average conditional exceedance rate (ACER) method. We adapt an approach for calculating sea level allowances for use with the ACER method. All the allowances calculated give values above the projected ensemble mean Relative Sea Level (RSL) rise, i.e., to preserve the likelihood of flooding from extreme sea levels, a height increase above the most likely RSL rise should be used in planning. We also show that the likelihood of exceeding present-day return heights will dramatically increase with sea-level rise. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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9782 KiB  
Article
CaMEL and ADCIRC Storm Surge Models—A Comparative Study
by Muhammad K. Akbar, Richard A. Luettich, Jason G. Fleming and Shahrouz K. Aliabadi
J. Mar. Sci. Eng. 2017, 5(3), 35; https://doi.org/10.3390/jmse5030035 - 09 Aug 2017
Cited by 5 | Viewed by 5205
Abstract
The Computation and Modeling Engineering Laboratory (CaMEL), an implicit solver-based storm surge model, has been extended for use on high performance computing platforms. An MPI (Message Passing Interface) based parallel version of CaMEL has been developed from the previously existing serial version. CaMEL [...] Read more.
The Computation and Modeling Engineering Laboratory (CaMEL), an implicit solver-based storm surge model, has been extended for use on high performance computing platforms. An MPI (Message Passing Interface) based parallel version of CaMEL has been developed from the previously existing serial version. CaMEL uses hybrid finite element and finite volume techniques to solve shallow water conservation equations in either a Cartesian or a spherical coordinate system and includes hurricane-induced wind stress and pressure, bottom friction, the Coriolis effect, and tidal forcing. Both semi-implicit and fully-implicit time stepping formulations are available. Once the parallel implementation is properly validated, CaMEL is evaluated against ADCIRC, an established storm surge model, using a hindcast of storm surge due to Hurricane Katrina. Observed high water marks are used to verify that both models have comparable accuracy. The effects of time step on the stability and accuracy of the models are investigated and indicate that the semi- and fully-implicit solvers in CaMEL allow the use of larger timesteps than ADCIRC’s explicit and semi-implicit solvers. However, ADCIRC outperforms CaMEL in parallel scalability and execution wall clock times. Wall times of CaMEL improve significantly when the largest stable time step sizes are used in respective models, although ADCIRC still is faster. Full article
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3558 KiB  
Article
Integrating Long Tide Gauge Records with Projection Modelling Outputs. A Case Study: New York
by Phil J. Watson
J. Mar. Sci. Eng. 2017, 5(3), 34; https://doi.org/10.3390/jmse5030034 - 05 Aug 2017
Cited by 1 | Viewed by 4173
Abstract
Sea level rise is one of the key artefacts of a warming climate which is predicted to have profound impacts for coastal communities over the course of the 21st century and beyond. The IPCC provide regular updates (5–7 years) on the global status [...] Read more.
Sea level rise is one of the key artefacts of a warming climate which is predicted to have profound impacts for coastal communities over the course of the 21st century and beyond. The IPCC provide regular updates (5–7 years) on the global status of the science and projections of climate change to assist guide policy, adaptation and mitigation endeavours. Increasingly sophisticated climate modelling tools are being used to underpin these processes with demand for improved resolution of modelling output products (such as predicted sea level rise) at a more localized scale. With a decade of common coverage between observational data and CMIP5 projection model outputs (2007–2016), this analysis provides an additional method by which to test the veracity of model outputs to replicate in-situ measurements using the case study site of New York. Results indicate that the mean relative velocity of the model projection products is of the order of 2.5–2.8 mm/year higher than the tide gauge results in 2016. In the event this phenomena is more spatially represented, there is a significant role for long tide gauge records to assist in evaluating climate model products to improve scientific rigour. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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3328 KiB  
Article
Sea Level Forecasts Aggregated from Established Operational Systems
by Andy Taylor and Gary B. Brassington
J. Mar. Sci. Eng. 2017, 5(3), 33; https://doi.org/10.3390/jmse5030033 - 01 Aug 2017
Cited by 9 | Viewed by 4851
Abstract
A system for providing routine seven-day forecasts of sea level observable at tide gauge locations is described and evaluated. Forecast time series are aggregated from well-established operational systems of the Australian Bureau of Meteorology; although following some adjustments these systems are only quasi-complimentary. [...] Read more.
A system for providing routine seven-day forecasts of sea level observable at tide gauge locations is described and evaluated. Forecast time series are aggregated from well-established operational systems of the Australian Bureau of Meteorology; although following some adjustments these systems are only quasi-complimentary. Target applications are routine coastal decision processes under non-extreme conditions. The configuration aims to be relatively robust to operational realities such as version upgrades, data gaps and metadata ambiguities. Forecast skill is evaluated against hourly tide gauge observations. Characteristics of the bias correction term are demonstrated to be primarily static in time, with time varying signals showing regional coherence. This simple approach to exploiting existing complex systems can offer valuable levels of skill at a range of Australian locations. The prospect of interpolation between observation sites and exploitation of lagged-ensemble uncertainty estimates could be meaningfully pursued. Skill characteristics define a benchmark against which new operational sea level forecasting systems can be measured. More generally, an aggregation approach may prove to be optimal for routine sea level forecast services given the physically inhomogeneous processes involved and ability to incorporate ongoing improvements and extensions of source systems. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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252 KiB  
Review
UK Macro-Algae Biofuels: A Strategic Management Review and Future Research Agenda
by Per Gegg and Victoria Wells
J. Mar. Sci. Eng. 2017, 5(3), 32; https://doi.org/10.3390/jmse5030032 - 31 Jul 2017
Cited by 18 | Viewed by 6154
Abstract
Macro-algae is increasingly gaining attention as a potential feedstock for biofuels and as a potential alternative fuel for aviation. Technological aspects are showing promise, and being examined more widely. This paper uses a strategic management perspective to complete an initial macro-environmental scan of [...] Read more.
Macro-algae is increasingly gaining attention as a potential feedstock for biofuels and as a potential alternative fuel for aviation. Technological aspects are showing promise, and being examined more widely. This paper uses a strategic management perspective to complete an initial macro-environmental scan of the potential opportunities and threats to a seaweed biofuels industry. This is in response to calls to look beyond technological aspects, and highlights the importance of social acceptance. It is clear that very little is known about the potential economic, social, environmental and political/legal issues that might arise in the development of this industry. While we can look at the development of other, more established renewable technologies and seaweed industries away from the UK to highlight potential issues this does not give us a clear picture. Further research is needed to ensure that a proactive approach is used to research and inform stakeholders who will affect the further technological development and commercialization of the industry. Full article
(This article belongs to the Special Issue Algal Biofuels)
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Article
South Florida’s Encroachment of the Sea and Environmental Transformation over the 21st Century
by Joseph Park, Erik Stabenau, Jed Redwine and Kevin Kotun
J. Mar. Sci. Eng. 2017, 5(3), 31; https://doi.org/10.3390/jmse5030031 - 28 Jul 2017
Cited by 8 | Viewed by 7130
Abstract
South Florida encompasses a dynamic confluence of urban and natural ecosystems strongly connected to ocean and freshwater hydrologic forcings. Low land elevation, flat topography and highly transmissive aquifers place both communities at the nexus of environmental and ecological transformation driven by rising sea [...] Read more.
South Florida encompasses a dynamic confluence of urban and natural ecosystems strongly connected to ocean and freshwater hydrologic forcings. Low land elevation, flat topography and highly transmissive aquifers place both communities at the nexus of environmental and ecological transformation driven by rising sea level. Based on a local sea level rise projection, we examine regional inundation impacts and employ hydrographic records in Florida Bay and the southern Everglades to assess water level exceedance dynamics and landscape-relevant tipping points. Intrinsic mode functions of water levels across the coastal interface are used to gauge the relative influence and time-varying transformation potential of estuarine and freshwater marshes into a marine-dominated environment with the introduction of a Marsh-to-Ocean transformation index (MOI). Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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Article
Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats: In a Marine Renewable Energy Perspective
by Francisco Francisco, Nicole Carpman, Irina Dolguntseva and Jan Sundberg
J. Mar. Sci. Eng. 2017, 5(3), 30; https://doi.org/10.3390/jmse5030030 - 21 Jul 2017
Cited by 5 | Viewed by 5954
Abstract
With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn [...] Read more.
With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn Island in Stockholm Archipelago. The objectives of the survey were to assess whether the sonar systems were able to observe and measure the depth of what can be cavitating flow (in a form of convected cloud cavitation) produced by one specific type of ferryboats frequently operating in that route, as well as investigate if the cavitating flow within the wake would propagate deep enough to disturb the water column underneath the surface. A multibeam and a dual-beam sonar systems were used as measurement instruments. The hypothesis was that strong and deep wake can disturb the optimal operation of a hydrokinetic energy converter, therefore causing damages to its rotors and hydrofoils. The results showed that both sonar system could detect cavitating flows including its strength, part of the geometrical shape and propagation depth. Moreover, the boat with a propeller thruster produced cavitating flow with an intense core reaching 4 m of depth while lasting approximately 90 s. The ferry with waterjet thruster produced a less intense cavitating flow; the core reached depths of approximately 6 m, and lasted about 90 s. From this study, it was concluded that multibeam and dual-beam sonar systems with operating frequencies higher than 200 kHz were able to detect cavitating flows in real conditions, as long as they are properly deployed and the data properly analyzed. Full article
(This article belongs to the Section Ocean Engineering)
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Article
Observed Sea-Level Changes along the Norwegian Coast
by Kristian Breili, Matthew J. R. Simpson and Jan Even Øie Nilsen
J. Mar. Sci. Eng. 2017, 5(3), 29; https://doi.org/10.3390/jmse5030029 - 17 Jul 2017
Cited by 14 | Viewed by 7729
Abstract
Norway’s national sea level observing system consists of an extensive array of tide gauges, permanent GNSS stations, and lines of repeated levelling. Here, we make use of this observation system to calculate relative sea-level rates and rates corrected for glacial isostatic adjustment (GIA) [...] Read more.
Norway’s national sea level observing system consists of an extensive array of tide gauges, permanent GNSS stations, and lines of repeated levelling. Here, we make use of this observation system to calculate relative sea-level rates and rates corrected for glacial isostatic adjustment (GIA) along the Norwegian coast for three different periods, i.e., 1960 to 2010, 1984 to 2014, and 1993 to 2016. For all periods, the relative sea-level rates show considerable spatial variations that are largely due to differences in vertical land motion due to GIA. The variation is reduced by applying corrections for vertical land motion and associated gravitational effects on sea level. For 1960 to 2010 and 1984 to 2014, the coastal average GIA-corrected rates for Norway are 2.0 ± 0.6 mm/year and 2.2 ± 0.6 mm/year, respectively. This is close to the rate of global sea-level rise for the same periods. For the most recent period, 1993 to 2016, the GIA-corrected coastal average is 3.5 ± 0.6 mm/year and 3.2 ± 0.6 mm/year with and without inverse barometer (IB) corrections, respectively, which is significantly higher than for the two earlier periods. For 1993 to 2016, the coastal average IB-corrected rates show broad agreement with two independent sets of altimetry. This suggests that there is no systematic error in the vertical land motion corrections applied to the tide-gauge data. At the same time, altimetry does not capture the spatial variation identified in the tide-gauge records. This could be an effect of using altimetry observations off the coast instead of directly at each tide gauge. Finally, we note that, owing to natural variability in the climate system, our estimates are highly sensitive to the selected study period. For example, using a 30-year moving window, we find that the estimated rates may change by up to 1 mm/year when shifting the start epoch by only one year. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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Article
Spatial and Temporal Clustering Analysis of Extreme Wave Events around the UK Coastline
by Victor Malagon Santos, Ivan D. Haigh and Thomas Wahl
J. Mar. Sci. Eng. 2017, 5(3), 28; https://doi.org/10.3390/jmse5030028 - 14 Jul 2017
Cited by 25 | Viewed by 7907
Abstract
Densely populated coastal regions are vulnerable to extreme wave events, which can cause loss of life and considerable damage to coastal infrastructure and ecological assets. Here, an event-based analysis approach, across multiple sites, has been used to assess the spatial footprint and temporal [...] Read more.
Densely populated coastal regions are vulnerable to extreme wave events, which can cause loss of life and considerable damage to coastal infrastructure and ecological assets. Here, an event-based analysis approach, across multiple sites, has been used to assess the spatial footprint and temporal clustering of extreme storm-wave events around the coast of the United Kingdom (UK). The correlated spatial and temporal characteristics of wave events are often ignored even though they amplify flood consequences. Waves that exceeded the 1 in 1-year return level were analysed from 18 different buoy records and declustered into distinct storm events. In total, 92 extreme wave events are identified for the period from 2002 (when buoys began to record) to mid-2016. The tracks of the storms of these events were also captured. Six main spatial footprints were identified in terms of extreme wave events occurrence along stretches of coastline. The majority of events were observed between November and March, with large inter-annual differences in the number of events per season associated with the West Europe Pressure Anomaly (WEPA). The 2013/14 storm season was an outlier regarding the number of wave events, their temporal clustering and return levels. The presented spatial and temporal analysis framework for extreme wave events can be applied to any coastal region with sufficient observational data and highlights the importance of developing statistical tools to accurately predict such processes. Full article
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
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Article
Numerical Modeling of Marine Circulation, Pollution Assessment and Optimal Ship Routes
by Vladimir Zalesny, Valeriy Agoshkov, Robert Aps, Victor Shutyaev, Anton Zayachkovskiy, Floris Goerlandt and Pentti Kujala
J. Mar. Sci. Eng. 2017, 5(3), 27; https://doi.org/10.3390/jmse5030027 - 12 Jul 2017
Cited by 11 | Viewed by 4133
Abstract
Methods and technology have been developed to solve a wide range of problems in the dynamics of sea currents and to assess their “impact” on objects in the marine environment. Technology can be used for monitoring and forecasting sea currents, for solving the [...] Read more.
Methods and technology have been developed to solve a wide range of problems in the dynamics of sea currents and to assess their “impact” on objects in the marine environment. Technology can be used for monitoring and forecasting sea currents, for solving the problems of minimizing risks and analyzing marine disasters associated with the choice of the optimal course of the ship, and assessing the pollution of coastal zones, etc. The technology includes a numerical model of marine circulation with improved resolution of coastal zones, a method for solving the inverse problem of contamination of the sea with a passive impurity, and a variational algorithm for constructing the optimal trajectory of the vessel. The methods and technology are illustrated by solving problems of Baltic Sea dynamics. The model of sea dynamics is governed by primitive equations that are solved on a grid with an improved resolution of the selected coastal zone—in this case, the Gulf of Finland. The equations of the model are formulated in a bipolar orthogonal coordinate system with an arbitrary arrangement of poles and the sigma coordinate in the vertical direction. An increase in the horizontal resolution of the allocated zone is achieved due to the displacement of the north pole in the vicinity of the city of St. Petersburg. A class of dangerous technogenic situations and natural phenomena (sea accidents, which can be investigated with the help of the proposed methodology), includes tanker accidents in the case of a possible collision with a stationary object (with “dynamic danger”) or a moving object (including another ship), accidents on oil-producing platforms and oil pipelines, and coastal pollution. Full article
(This article belongs to the Section Physical Oceanography)
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Article
Meteorological Aspects of the Eastern North American Pattern with Impacts on Long Island Sound Salinity
by Justin A. Schulte, Nickitas Georgas, Vincent Saba and Penelope Howell
J. Mar. Sci. Eng. 2017, 5(3), 26; https://doi.org/10.3390/jmse5030026 - 12 Jul 2017
Cited by 2 | Viewed by 10384
Abstract
The eastern North American sea level pressure dipole (ENA) pattern is a recently identified teleconnection pattern that has been shown to influence mid-Atlantic United States (U.S) streamflow variability. Because the pattern was only recently identified, its impacts on U.S. precipitation and estuaries on [...] Read more.
The eastern North American sea level pressure dipole (ENA) pattern is a recently identified teleconnection pattern that has been shown to influence mid-Atlantic United States (U.S) streamflow variability. Because the pattern was only recently identified, its impacts on U.S. precipitation and estuaries on daily to seasonal timescales is unknown. Thus, this paper presents the first seasonal investigation of ENA relationships with global atmospheric fields, U.S. precipitation, and mid-Atlantic estuarine salinity. We show that the ENA pattern explains up to 25–36% of precipitation variability across Texas and the western U.S. We also show that, for the Northeast U.S, the ENA pattern explains up to 65% of precipitation variability, contrasting with previous work showing how well-known climate indices can only explain a modest amount of precipitation variability. The strongest ENA-precipitation relationships are in the spring and fall. The relationships between the ENA pattern and precipitation across remote regions reflect the upper-atmospheric Rossby wave pattern associated with the ENA pattern that varies seasonally. The El-Nino/Southern Oscillation (ENSO) is related to the spring ENA pattern, indicating that extended outlooks of the ENA pattern may be possible. We also show that the ENA index is strongly correlated with salinity and vertical haline stratification across coastal portions of the mid-Atlantic Bight so that hypoxia forecasts based on the ENA index may be possible. Statistical connections between vertical salinity gradient and ENSO were identified at lags of up two years, further highlighting the potential for extended hypoxia outlooks. The strong connection between anomalies for precipitation and mid-Atlantic Bight salinity suggests that the ENA pattern may be useful at an interdisciplinary level for better understanding historical regional climate variability and future impacts of climate change on regional precipitation and the health of estuaries. Full article
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Article
Determining the Horizontal and Vertical Water Velocity Components of a Turbulent Water Column Using the Motion Response of an Autonomous Underwater Vehicle
by Supun A. T. Randeni P., Alexander L. Forrest, Remo Cossu, Zhi Q. Leong and Dev Ranmuthugala
J. Mar. Sci. Eng. 2017, 5(3), 25; https://doi.org/10.3390/jmse5030025 - 04 Jul 2017
Cited by 11 | Viewed by 5797
Abstract
This work introduces a new method to calculate the water velocity components of a turbulent water column in the x, y, and z directions using Autonomous Underwater Vehicle (AUV) motion response (referred to as the ‘WVAM method’). The water column velocities [...] Read more.
This work introduces a new method to calculate the water velocity components of a turbulent water column in the x, y, and z directions using Autonomous Underwater Vehicle (AUV) motion response (referred to as the ‘WVAM method’). The water column velocities were determined by calculating the difference between the motion responses of the vehicle in calm and turbulent water environments. The velocity components obtained using the WVAM method showed good agreement with measurements from an acoustic Doppler current profiler (ADCP) mounted to the AUV. The standard deviation between the two datasets were below 0.09 m s−1 for the velocity components in the x, y, and z directions, and were within the uncertainty margin of the ADCP measurements. With the WVAM method, it is possible to estimate the velocity components within close proximity to the AUV. This region encompasses the vehicle boundary layer and the ADCP blanking distance, which is not typically resolved. Estimating vertical and horizontal velocities around the boundary layer of the AUV is important for vehicle navigation and control system optimization, and to fill the blanking distance gap within a water column velocity profile, which is important for flow field characterization. The results show that it is possible to estimate the flow field in the vicinity of AUVs and other self-propelled vehicles. Full article
(This article belongs to the Section Ocean Engineering)
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