Wave Climate

Nigeria is currently experiencing energy deficit in terms of electrification. Development of renewable energy sources such as Sea wave energy may help augment this deficit. This paper set to investigate wave energy potential of the coast of Nigeria. Data required for estimating the wave energy potential of the coastal waters of Nigeria were obtained from WAVEWATCH III © wave generation model. The wave climate data were analyzed using basic statistical analysis such as average, mean, and range. Due to the scarcity of reliable measured wave climate data, an effort was made to investigate the relationship the mean monthly wave power may have with mean monthly rainfall. Establishing a good level of correlation will provide an alternative mean of forecasting wave power for the coastal region. The results show that the mean annual wave power magnitude generally decreases from the west coast (at 10.74 kW/m) to the east coast (at 5.64 kW/m) for the reference points considered. The most energetic months occurs during the rainy season while the least energetic months occur during the dry season. There is a strong positive correlation between mean monthly wave power and mean monthly rainfall at 5% significant level. ARTICLE HISTORY

The study investigates cross-shore outer sand bar dynamics in an open-coast non-tidal beach at the Bulgarian Black Sea due to wave climate. On seasonal to short-term (1–2 years) time scale, monthly field measurements of the outer bar profiles were related to respective modeled nearshore wave data. Hereby, seaward-shoreward bar migration was examined depending on the wave forcing, wave non-linearity, wave transformation scenarios, storms and direction of wave incidence. Analysis revealed that intra-annually highly non-linear waves were responsible for outer bar displacement, while the direction of migration depended on wave period, duration of conditions with wave steepness >0.04, angle of approach and total duration of storms. Short-term bar evolution was mainly governed by wave height and storms’ parameters as the angle of approach and duration. The correlation between the outer bar location and wave height annual variations initiated the first
for the explored Black Sea region examination of possible connection between wave height’s temporal fluctuations and the variability of climatic indices the North Atlantic Oscillation (NAO), the Atlantic
Multi-decadal Oscillation (AMO), the East Atlantic Oscillation (EA), the Arctic Oscillation (AO), the East Atlantic-Western Russia (EA/WR) and the Scandinavian (SCAND) patterns. According to the results the inter-annual outer bar location may vary depending on periods of maximum annual wave fluctuations, which in turn predominantly depend on indices the EA (4–5, 10–11, 20–30 years), the EA/WR (2–4, 9–13 years) and the NAO (15 years).

The paper analyzed the impact generated by the construction of a port on the adjacent coasts. In particular, the case study of Marina of Badolato (Italy) will be analyzed. The paper evaluates the shoreline changes and the influence of deep water wave climate and of the longshore and river transport on the coastal dynamics of the study area. The port construction has altered about 4.5 km of coastline with relevant advancement to the South areas and erosion to the North areas. Finally, the paper shows how the construction of a port can alter the coast even at considerable distances from the port itself, so that during the design phase it is necessary to correctly evaluate
all the possible alterations of the coastal dynamics.

Wind generated waves at the sea surface are of outstanding importance for both their practical relevance in many aspects, such as coastal erosion, protection, or safety of navigation, and for their scientific relevance in modifying fluxes at the air-sea interface. So far long-term changes in ocean wave climate have been studied mostly from a regional perspective with global dynamical studies emerging only recently. Here a global wave climate study is presented, in which a global wave model (WAM) is driven by atmospheric forcing from a global climate model (ECHAM5) for present day and potential future climate conditions represented by the IPCC (Intergovernmental Panel for Climate Change) A1B emission scenario. It is found that changes in mean and extreme wave climate towards the end of the twenty-first century are small to moderate, with the largest signals being a poleward shift in the annual mean and extreme significant wave heights in the mid-latitudes of both hemispheres, more pronounced in the Southern Hemisphere, and most likely associated with a corresponding shift in mid-latitude storm tracks. These changes are broadly consistent with results from the few studies available so far. The projected changes in the mean wave periods, associated with the changes in the wave climate in the mid to high latitudes, are also shown, revealing a moderate increase in the equatorial eastern side of the ocean basins. This study presents a step forward towards a larger ensemble of global wave climate projections required to better assess robustness and uncertainty of potential future wave climate change.

This paper provides a description of the wave climate off the Brazilian coast based on an eleven-year time series (Jan/1997-Dec/2007) obtained from the NWW3 operational model hindcast reanalysis. Information about wave climate in Brazilian waters is very scarce and mainly based on occasional short-term observations, the present analysis being the first covering such temporal and spatial scales. To define the wave climate, six sectors were defined and analyzed along the Brazilian shelf-break: South (W1), Southeast (W2), Central (W3), East (W4), Northeast (W5) and North (W6). W1, W2 and W3 wave regimes are determined by the South Atlantic High (SAH) and the passage of synoptic cold fronts; W4, W5 and W6 are controlled by the Intertropical Convergence Zone (ITCZ) and its meridional oscillation. The most energetic waves are from the S, generated by the strong winds associated to the passage of cold fronts, which mainly affect the southern region. Wave power presents a decrease in energy levels from south to north, with its annual variation showing that the winter months are the most energetic in W1 to W4, while in W5 and W6 the most energetic conditions occur during the austral summer. The information presented here provides boundary conditions for studies related to coastal processes, fundamental for a better understanding of the Brazilian coastal zone.

In this paper, we investigate changes in the wave climate of the west-European shelf seas under global warming scenarios. In particular, climate change wind fields corresponding to the present (control) time-slice 1961–2000 and the future (scenario) time-slice 2061–2100 are used to drive a wave generation model to produce equivalent control and scenario wave climate. Yearly and seasonal statistics of the scenario wave climates are compared individually to the corresponding control wave climate to identify relative changes of statistical significance between present and future extreme and prevailing wave heights. Using global, regional and linked global–regional wind forcing over a set of nested computational domains, this paper further demonstrates the sensitivity of the results to the resolution and coverage of the forcing. It suggests that the use of combined forcing from linked global and regional climate models of typical resolution and coverage is a good option for the investigation of relative wave changes in the region of interest of this study. Coarse resolution global forcing alone leads to very similar results over regions that are highly exposed to the Atlantic Ocean. In contrast, fine resolution regional forcing alone is shown to be insufficient for exploring wave climate changes over the western European waters because of its limited coverage. Results obtained with the combined global–regional wind forcing showed some consistency between scenarios. In general, it was shown that mean and extreme wave heights will increase in the future only in winter and only in the southwest of UK and west of France, north of about 44–45° N. Otherwise, wave heights are projected to decrease, especially in summer. Nevertheless, this decrease is dominated by local wind waves whilst swell is found to increase. Only in spring do both swell and local wind waves decrease in average height.

Long-term changes in the mean and extreme wind wave conditions as they may occur in the course of anthropogenic climate change can influence and endanger human coastal and
offshore activities. A set of ten wave climate projections derived from time slice and transient simulations of future conditions is analyzed to estimate the possible impact of anthropogenic climate change on mean and extreme wave conditions in the North Sea. This set includes different combinations of IPCC SRES emission scenarios (A2, B2, A1B and B1), global and regional models and initial states. A consistent approach is used to provide a more robust assessment of expected changes and uncertainties. While the spatial patterns and the magnitude of the climate change signals vary, some robust features among the ten projections emerge: mean and severe wave heights tend to increase in the eastern parts of the North Sea towards the end of the twenty-first century in nine to ten projections, but the magnitude of the increase in extreme waves varies in the order of decimeters between these projections. For the western parts of the North Sea more than half of the projections suggest a decrease in mean and extreme wave heights. Comparing the different sources of uncertainties due to models, scenarios and initial conditions it can be inferred that the influence of the emission scenario on the climate change signal seems to be less important. Furthermore, the transient projections show strong multidecadal fluctuations, and changes towards the end of the twenty-first century might partly be associated with internal variability rather than with systematic changes.

Im Rahmen des Verbundprojekts „KLIWAS - Auswirkungen des Klimawandels auf Wasserstraßen und Schifffahrt – Entwicklung von Anpassungsoptionen“ des Bundesministeriums für Verkehr, Bau und Stadtentwicklung (BMVBS) wurden im Rahmen einer Kooperation zwischen dem Helmholtz-Zentrum Geesthacht Zentrum für Material und Küstenforschung GmbH (HZG) und dem Bundesamt für Seeschifffahrt und Hydrographie (BSH) Seegangsszenarien für die Nordsee für unterschiedliche Klimaprojektionen erstellt.
Eine genaue Abschätzung von möglichen Seegangsänderungen in der Nordsee durch Klimaänderung ist wichtig, um mögliche Auswirkungen sowohl für den Offshore- als auch für den Küstenbereich frühzeitig zu erkennen und gegebenenfalls Anpassungsoptionen einleiten zu können. Die Untersuchungen wurden in drei Abschnitten durchgeführt: Im ersten Abschnitt wurden detaillierte Seegangsberechnungen bis 2100 mit Hilfe der Version 4.5.3 des Wellenmodells WAM durchgeführt. Dabei wurden Windfelder aus zwei unterschiedlichen regionalen Klimamodellen verwendet, um die Spannbreite bedingt durch unterschiedliche Regionalmodelle besserer abschätzen zu können. Wie im Verbundprojekt KLIWAS vereinbart, wurden nur Windfelder die unter dem Emissionsszenario A1B simuliert wurden verwendet. Im zweiten Abschnitt wurde mit Hilfe eines statistischen Modells die Spannbreite möglicher Seegangsänderungen aufgrund unterschiedlicher Modelle und Anfangszustände untersucht. Im Gegensatz zur dynamischen Modellierung im ersten Abschnitt ist es mit einem statistischen Modell m
öglich, mit Hilfe einer Vielzahl von unterschiedlichen Modellen, Emissionsszenarien und Anfangszuständen die Unsicherheit der Spannbreite möglicher Seegangsänderungen besser abzuschätzen. Im dritten Abschnitt wurde die Sensitivität des Seegangs aufgrund eines geänderten Meeresspiegels untersucht. Dabei wurden unter jeweils extremen Windbedingungen voll entwickelte Seegangszustände mit Hilfe des Seegangsmodells WAM erzeugt, um Obergrenzen möglicher Veränderungen abzuschätzen.

Storms are one of the most important phenomena producing coastal hazards and endangering human life and activities. In recent decades storm climate has become a subject of increased public awareness and knowledge of this issue can help the society to meet future challenges related to extreme storm manifestation. Therefore, the goal of this study is to assess trends in past and recent storminess in the western Black Sea. The analysis of storm climate is based on a continuous hindcast dataset covering a substantial historical time-span of 63 yr . It was used to create a storm population and to estimate properties describing storminess (proxies). This was done by introduction of criteria allowing separation of events with low probability of occurrence and at the same time keeping the information on their pattern, i.e. properties of storm phases. Eleven storminess proxies were analysed and the most indicative appeared to be storm duration; integral, mean and specific storm wave energy; and wind velocity and direction, which were obtained for each storm season.

Empirical Mode Decomposition (EMD) analysis was performed on wave height data recorded between years 2010-15 by NDBC and CariCOOS wave buoys located north of Puerto Rico. The analysis revealed that the eleventh intrinsic mode function (IMF) named C11 shows an annual time scale; this physical signal corresponds to the wave season on Puerto Rico. The peak and period between zero-crossings in C11 corresponds to the peak and duration of the wave season, respectively. The peak's position can shift from late January to early November. The duration of the wave season ranged between 5 to 8 months. The shift of the peak towards the month of November increased the wave activity during the month of November when the amplitude of the annual tidal constituent is larger and mean sea level is higher. These conditions were favorable for coastal erosion during the 2010-2011 wave season. Our results revealed the true exact form and variability of the wave season on Puerto Rico. The gradual increase of the annual wave heights in combination with the gradual increase in the annual tidal water levels could have an important effect on coastal erosion in Puerto Rico.

Existem poucos dados de ondas registados sobre a costa Moçambicana. O clima de ondas para a costa de Moçambique foi estudado por Theron & Barwell (2012) usando resultados de simulações do modelo WAVEWATCH III da National Oceanic and Atmospheric Administration (NOAA), em uma grade global com resolução de 1 grau de latitude por 1,25 graus em longitude e resolução direccional de 15°, para o período de 1997 a 2009. No presente trabalho caracteriza-se o clima de ondas usando resultados de 30 anos (1982 -2011) de simulações do modelo WAVEWATCH III, implementado no Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo, em uma grade global de 1 grau de latitude e 1 grau de longitude e resolução direccional de 10°, o que representa um avanço em termos de representação numérica. O clima de ondas foi analisado, para oito pontos ao longo da costa de Moçambique e um ponto ao sul da costa da Tanzânia (totalizando nove pontos), a partir de estatísticas básicas da altura significativa, período de pico e direcção média de propagação das ondas, avaliando variações espaciais e sazonais destas variáveis. Ondas com maiores alturas significativas são registadas na região Sul, diminuindo em direcção ao Norte de Moçambique, as ondas aumentam novamente na parte Sul da Tanzânia (Mtwara), como resultado da redução do efeito de protecção de Madagáscar. Maiores ondas ocorrem, em média, na região sul durante o verão, embora valores elevados também ocorram nos meses de inverno. Nas regiões centro e norte, maiores ondas ocorrem nos meses de inverno com excepção para Beira que apresenta o máximo em Outubro. A região central apresenta pouca variabilidade na direcção de proveniência das ondas, enquanto as regiões sul e norte, que se localizam nas aberturas do canal de

Wind-generated waves at the sea surface are of outstanding importance for both their practical relevance in many aspects, such as coastal erosion, protection, or safety of navigation, and for their scientific relevance in modifying fluxes at the air–sea interface. So far, long-term changes in ocean wave climate have been studied mostly from a regional perspective with global dynamical studies emerging only recently. Here a global wave climate study is presented, in which a global wave model [Wave Ocean Model (WAM)] is driven by atmospheric forcing from a global climate model (ECHAM5) for present-day and potential future climate conditions represented by the Intergovernmental Panel for Climate Change (IPCC) A1B emission scenario. It is found that changes in mean and extreme wave climate toward the end of the twenty-first century are small to moderate, with the largest signals being a poleward shift in the annual mean and extreme significant wave heights in the midlatitudes of both he...

Nigeria is currently experiencing energy deficit in terms of electrification. Development of renewable energy sources such as Sea wave energy may help augment this deficit. This paper set to investigate wave energy potential of the coast of Nigeria. Data required for estimating the wave energy potential of the coastal waters of Nigeria were obtained from WAVEWATCH III © wave generation model. The wave climate data were analyzed using basic statistical analysis such as average, mean, and range. Due to the scarcity of reliable measured wave climate data, an effort was made to investigate the relationship the mean monthly wave power may have with mean monthly rainfall. Establishing a good level of correlation will provide an alternative mean of forecasting wave power for the coastal region. The results show that the mean annual wave power magnitude generally decreases from the west coast (at 10.74 kW/m) to the east coast (at 5.64 kW/m) for the reference points considered. The most energetic months occurs during the rainy season while the least energetic months occur during the dry season. There is a strong positive correlation between mean monthly wave power and mean monthly rainfall at 5% significant level.

The study investigates cross-shore outer sand bar dynamics in an open-coast non-tidal beach at the Bulgarian Black Sea due to wave climate. On seasonal to short-term (1–2 years) time scale, monthly field measurements of the outer bar profiles were related to respective modeled nearshore wave data. Hereby, seaward-shoreward bar migration was examined depending on the wave forcing, wave non-linearity, wave transformation scenarios, storms and direction of wave incidence. Analysis revealed that intra-annually highly non-linear waves were responsible for outer bar displacement, while the direction of migration depended on wave period, duration of conditions with wave steepness >0.04, angle of approach and total duration of storms. Short-term bar evolution was mainly governed by wave height and storms’ parameters as the angle of approach and duration. The correlation between the outer bar location and wave height annual variations initiated the first for the explored Black Sea region ...

Using 38-years (January 1973-December 2010) of hourly wind records, the present paper aims at drawing the possible long-term trends of winds and ten surface wave parameters over the west region of Scotland, using the quadratic regression approach.
Four dominant wind components were determined: the southern, the western, the south-western and the north-western. Two opposite groups of oscillations were proven: one for the southern groups and one for the western groups.
The examined wave parameters were: the wave frequency, the wave angular frequency, the peak angular frequency, the wave spectral density, the significant wave height, the peak period, both the peak and group velocities and lastly the wave energy and the wave power.
Results revealed that every examined parameter tended to have a cyclic behaviour except the wave spectral density, which appeared to be linearly decreasing. All wave frequencies were in an inverse correlation to the mean monthly wind speed. All other wave parameters appeared to be highly correlated to the mean monthly wind speed with correlation factors exceeding 0.95 except the wave power, which had a correlation factor of 0.89.
In conclusion, the general behaviours of the dominant wind components over the west region of Scotland, and of the different wave parameters tend to be cyclic. A longer time series, than that presently used, will be advantageous in order to strengthen this outcome with more robust investigation. This concluded cyclic behaviour may positively have impact on the engineering work within the wave energy resource off the western coasts of Scotland.