scholarly journals Projections of Directional Spectra Help to Unravel the Future Behavior of Wind Waves

2021 ◽  
Vol 8 ◽  
Author(s):  
Hector Lobeto ◽  
Melisa Menendez ◽  
Iñigo J. Losada
Keyword(s):  
Wind Waves ◽  
Wave Climate ◽  
Future Behavior ◽  
Novel Approach ◽  
High Emission ◽  
Mean Wave Period ◽  
Northern Atlantic ◽  
High Emission Scenario ◽  
Projected Changes ◽  
Significant Underestimation

Based on a novel approach, present-day and future spectral wind-wave conditions in a high-emission scenario from a seven-member wave climate projection ensemble are compared. The spectral analysis at the selected locations aids in understanding the propagation of swell projected changes from the generation areas across the ocean basins. For example, a projected increase in the energy from Southern Ocean swells can be observed in all ocean basins and both hemispheres, which is especially relevant in the west coast of North America due to the penetration of these swells beyond 30°N. Similarly, a consistent decrease in the energy of large northern Atlantic swells is noted close to the equator. This work provides evidence that assessments based on only integrated wave parameters (e.g., significant wave height and mean wave period) can mask information about the sign, magnitude, and robustness of the actual wave climate changes due to the offset of positive and negative variations within the spectrum, leading to a significant underestimation of the change associated with certain wave systems.

Projected changes in wind wave directional spectra and their impact on coastal processes

2021 ◽  
Author(s):  
Hector Lobeto ◽  
Melisa Menendez ◽  
Iñigo J. Losada ◽  
Ottavio Mazzaretto
Keyword(s):  
Wave Energy ◽  
Wind Wave ◽  
Wave Climate ◽  
Wave Period ◽  
Standard Approach ◽  
Coastal Processes ◽  
Full Spectrum ◽  
Wave Parameters ◽  
Future Behavior ◽  
Projected Changes

<p>The assessment of the projected changes in wave climate due to climate change has been subject of study during the last two decades (Morim et al., 2018), largely due to the severe impacts these changes may have on coastal processes such as flooding and erosion. The wind wave climate is fully described by the sea surface elevation spectrum, which represents the distribution of energy resulting from the contributions of several superimposed waves with different periods and directions. Nevertheless, to this day the standard approach to address the future behavior of wind waves is based on the use of integrated wave parameters (e.g. significant wave height, mean wave period, mean wave direction) as a representation of the full spectrum. In this study, we analyze the changes in wave energy from directional spectra discretized in 24 directions and 32 frequencies in a number of locations distributed across all ocean basins, shedding light on the added value that an assessment based on the full spectrum offers with respect to the standard approach. In addition, the ESTELA method (Pérez et al., 2014) is applied to ease the understanding of the changes obtained in wave energy at the locations of study.</p><p>The spectral approach helps to assess the projected change in the energy of each wave system that reach a specific location. Results demonstrate that the use of integrated wave parameters can mask important information about the sign, magnitude and uncertainty of the actual projected changes in mean wave climate due to the offset of the expected variations in the different wave systems that integrate the spectrum. It is especially relevant at locations where an increase in the wave period or wave energy is hidden by the application of the standard approach, as these parameters are proven to play a key role in coastal processes. In addition, we reach relevant conclusions about the future behavior of swell systems. For instance, a robust increase in the energy carried by swells generated below 40°S can be observed in every ocean basin and both hemispheres, even beyond 30°N. Similarly, a decrease in the energy carried by northern swells can be observed close to the equator.</p>

scholarly journals Future behavior of wind wave extremes due to climate change

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hector Lobeto ◽  
Melisa Menendez ◽  
Iñigo J. Losada
Keyword(s):  
Climate Change ◽  
Wave Climate ◽  
Climate Change Scenarios ◽  
Return Periods ◽  
Extreme Wave ◽  
Future Behavior ◽  
Climate Simulations ◽  
Wave Conditions ◽  
Ne Pacific ◽  
Change In Mean

AbstractExtreme waves will undergo changes in the future when exposed to different climate change scenarios. These changes are evaluated through the analysis of significant wave height (Hs) return values and are also compared with annual mean Hs projections. Hourly time series are analyzed through a seven-member ensemble of wave climate simulations and changes are estimated in Hs for return periods from 5 to 100 years by the end of the century under RCP4.5 and RCP8.5 scenarios. Despite the underlying uncertainty that characterizes extremes, we obtain robust changes in extreme Hs over more than approximately 25% of the ocean surface. The results obtained conclude that increases cover wider areas and are larger in magnitude than decreases for higher return periods. The Southern Ocean is the region where the most robust increase in extreme Hs is projected, showing local increases of over 2 m regardless the analyzed return period under RCP8.5 scenario. On the contrary, the tropical north Pacific shows the most robust decrease in extreme Hs, with local decreases of over 1.5 m. Relevant divergences are found in several ocean regions between the projected behavior of mean and extreme wave conditions. For example, an increase in Hs return values and a decrease in annual mean Hs is found in the SE Indian, NW Atlantic and NE Pacific. Therefore, an extrapolation of the expected change in mean wave conditions to extremes in regions presenting such divergences should be adopted with caution, since it may lead to misinterpretation when used for the design of marine structures or in the evaluation of coastal flooding and erosion.

Mediterranean climate change projections: an update from CMIP5 and CMIP6.

2021 ◽  
Author(s):  
Josep Cos ◽  
Francisco J Doblas-Reyes ◽  
Martin Jury
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Hot Spot ◽  
Weighting Scheme ◽  
Temperature And Precipitation ◽  
High Emission ◽  
The Mediterranean ◽  
Model Ensembles ◽  
Projected Changes ◽  
Model Weighting

<p>The Mediterranean has been identified as a climate change hot-spot due to increased warming trends and precipitation decline. Recently, CMIP6 was found to show a higher climate sensitivity than its predecessor CMIP5, potentially further exacerbating related impacts on the Mediterranean region.</p><p>To estimate the impacts of the ongoing climate change on the region, we compare projections of various CMIP5 and CMIP6 experiments and scenarios. In particular, we focus on summer and winter changes in temperature and precipitation for the 21st century under RCP2.6/SSP1-2.6, RCP4.5/SSP2-4.5 and RCP8.5/SSP5-8.5 as well as the high resolution HighResMIP experiments. Additionally, to give robust estimates of projected changes we apply a novel model weighting scheme, accounting for historical performance and inter-independence of the multi-member multi-model ensembles, using ERA5, JRA55 and WFDE5 as observational reference. </p><p>Our results indicate a significant and robust warming over the Mediterranean during the 21st century irrespective of the used ensemble and experiments. Nevertheless, the often attested amplified Mediterranean warming is only found for summer. The projected changes vary between the CMIP5 and CMIP6, with the latter projecting a stronger warming. For the high emission scenarios and without weighting, CMIP5 indicates a warming between 4 and 7.7ºC in summer and 2.7 and 5ºC in winter, while CMIP6 projects temperature increases between 5.6 and 9.2ºC in summer and 3.2 to 6.8ºC in winter until 2081-2100 in respect to 1985-2005. In contrast to temperature, precipitation changes show a higher level of uncertainty and spatial heterogeneity. However, for the high emission scenario, a robust decline in precipitation is projected for large parts of the Mediterranean during summer. First results applying the model weighting scheme indicate reductions in CMIP6 and increases in CMIP5 warming trends, thereby reducing differences between the two ensembles.</p>

Wave Climate Analysis for a Wave Energy Conversion Application in Brazil

2007 ◽  
Author(s):  
Eliab R. Beserra ◽  
Andre´ L. T. Mendes ◽  
Segen F. Estefen ◽  
Carlos E. Parente
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Wind Waves ◽  
Energy Resource ◽  
Wave Climate ◽  
Northern Coast ◽  
Wave Energy Conversion ◽  
Annual Fluctuation ◽  
Significant Wave ◽  
Climate Analysis

A variety of ocean wave energy conversion devices have been proposed worldwide considering different technology and energy extraction methods. In order to support full-scale prototype design and performance assessments of a conversion scheme to be deployed on the northern coast of Brazil, a long-term wave climate analysis is under development. A 5-year pitch-roll buoy data series has been investigated through an adaptive technique to enhance spatial resolution and allow for accurate wave directionality evaluation. Device design most influential variables such as extreme significant wave height, peak period and directionality were considered. Temporal variability in wave energy levels was particularly investigated for energy resource assessment. The major findings of this work include the narrow directional amplitude of the incident wave and higher significant wave heights of locally generated waves. The estimated energy resource levels agreed well with literature, also showing little annual fluctuation. The wave climate demonstrated to be in full agreement with the large-scale Equatorial Atlantic atmospheric variability, dominated by either local wind waves or by distant storm swells.

Wave climate change in the Gulf of Bothnia

2021 ◽  
Author(s):  
Jan-Victor Björkqvist ◽  
Jani Särkkä ◽  
Hedi Kanarik ◽  
Laura Tuomi
Keyword(s):  
Climate Change ◽  
Wave Model ◽  
Wave Climate ◽  
Atmospheric Forcing ◽  
Simulation Data ◽  
Significant Wave ◽  
Gulf Of Bothnia ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Projected Changes

<p>Wave climate change in the Gulf of Bothnia in 2030–2059 was investigated using regional wave climate projections. For the simulations we used wave model WAM. As the atmospheric forcing for the wave model we had three global climate scenarios (HADGEM2-ES, MPI-ESM, EC-EARTH) downscaled with RCA4-NEMO regional model. The ice concentration for the wave model was obtained from NEMO ocean model simulations using the same atmospheric forcing. We used both RCP4.5 and RCP8.5 greenhouse gas scenarios. The spatial resolution of the simulation data was 1.8 km, enabling detailed analyses of the wave properties near the coast. From the simulation data we calculated statistics and return levels of significant wave heights using extreme value analysis, and assessed the projected changes in the wave climate in the Gulf of Bothnia. The projected increase in the significant wave heights is mainly due to the decreasing ice cover, especially in the Bothnian Bay. Projected changes in the most prevalent wind direction impacts the spatial pattern of the wave heights in the Bothnian Sea.</p>

Covariate Extreme Value Analysis Using Wave Spectral Partitioning

2020 ◽  
Vol 37 (5) ◽  
pp. 873-888 ◽  
Author(s):  
Jesús Portilla-Yandún ◽  
Edwin Jácome
Keyword(s):  
Extreme Values ◽  
Wind Waves ◽  
Spectral Energy Distribution ◽  
Wave Spectrum ◽  
Wave Climate ◽  
Extreme Value ◽  
Extreme Value Analysis ◽  
Spectral Energy ◽  
Value Analysis ◽  
Spectral Partitioning

AbstractAn important requirement in extreme value analysis (EVA) is for the working variable to be identically distributed. However, this is typically not the case in wind waves, because energy components with different origins belong to separate data populations, with different statistical properties. Although this information is available in the wave spectrum, the working variable in EVA is typically the total significant wave height Hs, a parameter that does not contain information of the spectral energy distribution, and therefore does not fulfill this requirement. To gain insight in this aspect, we develop here a covariate EVA application based on spectral partitioning. We observe that in general the total Hs is inappropriate for EVA, leading to potential over- or underestimation of the projected extremes. This is illustrated with three representative cases under significantly different wave climate conditions. It is shown that the covariate analysis provides a meaningful understanding of the individual behavior of the wave components, in regard to the consequences for projecting extreme values.

Characteristics of the Infragravity Wave Climate

2008 ◽  
Author(s):  
Stephen Masterton ◽  
Kevin Ewans
Keyword(s):  
Oil And Gas ◽  
Wind Waves ◽  
Wave Climate ◽  
Peak Period ◽  
Infragravity Waves ◽  
Design Practices ◽  
The Us ◽  
Near Shore ◽  
Wave Models ◽  
Infragravity Wave

Infragravity waves are very long period waves below the frequency of typical wind waves. They are most significant in shallow water locations and therefore have a high impact on the response of moored vessels. For the Oil and Gas business this can be an important consideration for tanker on/offloading operations (including LNG vessels) — these larger vessels, with longer natural periods, are particularly susceptible. There are implications for both the design and operation including the calculation of extreme loading on the mooring system, extreme vessel motions, fatigue of mooring systems and the availability of on/offloading operations. There are currently limited design practices to account for the effect of infragravity waves. This may be attributed to two main factors: The development of infragravity waves is difficult to model and is sensitive to many factors, including the magnitude and shape of the incident wind and swell spectra, local bathymetry, directionality and near shore wave breaking. Secondly, very little measured data exist since the infragravity wave frequencies lie below the conventional range of commonly deployed wave measurement devices. The present paper will provide a description of the infragravity waves acting on the US coast at two locations, Duck, North Carolina, and Baja, California. The results will characterize parameters including the significant wave height, peak period, and comparison of infragravity waves through time. In addition, the relationships between the spectral shape will be examined including directionality. This type of information is needed to set design criteria for infragravity waves, and in the longer term to develop and enhance infragravity wave models e.g. Reniers 2002 (1) and ultimately contribute to establishing design practices.

scholarly journals Loss of connectivity among island-dwelling Peary caribou following sea ice decline

2016 ◽  
Vol 12 (9) ◽  
pp. 20160235 ◽  
Author(s):  
Deborah A. Jenkins ◽  
Nicolas Lecomte ◽  
James A. Schaefer ◽  
Steffen M. Olsen ◽  
Didier Swingedouw ◽  
...  
Keyword(s):  
Sea Ice ◽  
Population Connectivity ◽  
Future Climate Change ◽  
Landscape Resistance ◽  
Population Mixing ◽  
Sea Ice Decline ◽  
Rapid Changes ◽  
High Emission ◽  
High Emission Scenario

Global warming threatens to reduce population connectivity for terrestrial wildlife through significant and rapid changes to sea ice. Using genetic fingerprinting, we contrasted extant connectivity in island-dwelling Peary caribou in northern Canada with continental-migratory caribou. We next examined if sea-ice contractions in the last decades modulated population connectivity and explored the possible impact of future climate change on long-term connectivity among island caribou. We found a strong correlation between genetic and geodesic distances for both continental and Peary caribou, even after accounting for the possible effect of sea surface. Sea ice has thus been an effective corridor for Peary caribou, promoting inter-island connectivity and population mixing. Using a time series of remote sensing sea-ice data, we show that landscape resistance in the Canadian Arctic Archipelago has increased by approximately 15% since 1979 and may further increase by 20–77% by 2086 under a high-emission scenario (RCP8.5). Under the persistent increase in greenhouse gas concentrations, reduced connectivity may isolate island-dwelling caribou with potentially significant consequences for population viability.

scholarly journals COMPREHENSIVE MONITORING OF A BEACH RESTORATION PROJECT

1976 ◽  
Vol 1 (15) ◽  
pp. 86
Author(s):  
O.H. Shemdin ◽  
H.K. Brooks ◽  
Z. Ceylanli ◽  
S.L. Harrell
Keyword(s):  
East Coast ◽  
Wind Waves ◽  
Monitoring Program ◽  
Barrier Island ◽  
Beach Nourishment ◽  
Wave Climate ◽  
Littoral Drift ◽  
Restoration Project ◽  
Two Stages

This paper outlines the results obtained from monitoring the Beach Nourishment Project at Jupiter Island, Florida. Jupiter Island is a 16 mile long barrier island on the east coast of Florida. Five miles of the beach were nourished in two stages in 1973 and 1974. A total of 3.4 million cubic yards of sand were dredged from an offshore borrow area and placed on the beach. The monitoring program included: seasonal hydrographic surveys of beach and offshore profile to 3000 feet offshore; climatological monitoring of wind, waves, tides and currents over a oneyear period; tracer and dye studies; and sand sampling and coring at selected beach and offshore locations. The results indicate that beach restoration has a groin effect in the sense of producing favorable changes in littoral drift due to shore alignment changes. A net accretion updrift of the restored area occurs. The results demonstrate the importance of the offshore profile in accounting for the total sedimentary balance. Shoreline recession coupled by a build up in the offshore profile may reflect accretion rather than erosion. Finally, the results show that the littoral drift formula using the wave climate as input provides inadequate prediction estimates for erosion or deposition following construction of a beach restoration project.

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