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The article focuses on the surface ocean waves interannual variability and trends in Southern Hemisphere (SH). It states that satellite altimetry and global ocean wave models were used to observe SH's wave climate. It examines the correlation between SH's wave height and variability with the Southern Annular Mode (SAM). It also considers the importance of Western Pacific Ocean wave energy flux's directional variability in the sand transport along New Zealand and south-eastern Australian margin.

The influence of ocean surface currents on the global wind-wave field is revisited. State-of-the-art numerical spectral wave model simulations with and without surface currents taken from an eddy resolving global ocean reanalysis were compared. As a global average, simulations forced with currents display significantly better agreement with altimeter derived wave heights. The bias and root mean square error in significant wave heights are mostly reduced when including current forcing, especially in the Southern Ocean. An overall improvement in wave periods and wave direction is also seen when comparing model outputs with the Australian and United States buoy network observations. Including surface ocean current forcing in wave simulations reduces the simulated wave heights in most areas of the world, due to a decreased relative wind given by co-flowing winds and currents. Current-induced refraction generates important changes in wave direction in western boundary current and tropical regions. Furthermore, large and broad changes in friction velocity, atmosphere-to-ocean energy flux, whitecap cover and Stokes drift velocities are observed in equatorial regions. Finally, the importance of the wave model resolution for representing wave–current interactions was tested by comparing results from eddy-permitting (lower resolution) and eddy-resolving (higher resolution) configurations. We conclude that the main patterns of current-induced refraction are well represented in both cases, albeit that the higher resolution simulation represents these in a more detailed manner. Finally, the implications that the observed wave–current interactions have on several ocean processes are discussed. • Wave model performance improves significantly by including surface currents forcing. • Equatorial and Western Boundary Current areas show great changes in wave direction. • Wave–current interactions help to better model intense wave events in East Australia. • There are great changes in friction velocity and whitecap cover in Tropical areas. • Eddy-permitting simulations properly depict the current-induced refraction patterns. [ABSTRACT FROM AUTHOR]

As the tidal energy industry looks to expand into commercial-scale array installations, uncertainty in methodology and outcome for environmental impact assessments can encumber tidal energy developments. Incorporating environmental monitoring measures into site characterisation campaigns can provide baseline information about biophysical relationships and help recognise potential impacts to the marine environment early in the development process. Concurrent measurements of fish and tidal currents were taken at a tidal energy candidate site in Australia over ∼ 2.5 months during its tidal resource assessment. Fish aggregation metrics (density, abundance, centre-of-mass (CM), dispersion, %-water column occupied, evenness, and relative aggregation) were investigated for their relation to environmental conditions (current speed, shear, temperature, diel stage, and tidal stage). Diel stage was the most significant indicator for fish density, abundance, and %-water column occupied. Fish density and abundance were elevated during strong currents, with vertical fish distribution (CM and dispersion) also influenced by current speed. Environmental conditions were able to explain up to 25% of variation in fish aggregation metrics using linear models. This study shows that early-stage environmental monitoring can successfully provide baseline information about fish aggregation responses to prevailing environmental conditions, thus reducing uncertainty risks for stakeholders of tidal energy developments. • Environmental impact assessment was coupled with tidal resource characterisation in Australia. • Fish were more abundant, higher in the water column, and more dispersed at peak flows. • Fish were most influenced by diel stage with densities nearly two-times higher at night vs. day. • At high temperatures, fish were more abundant and closer to the bottom. • Environmental conditions explained 25% of variance in fish density using linear models. [ABSTRACT FROM AUTHOR]

The ocean economy is experiencing rapid growth that will provide benefits but will also pose environmental and social risks. With limited space and degraded resources in coastal areas, offshore waters will be a particular focus of Blue Economy expansion over the next decade. When emerging and established economic sectors expand in offshore waters (within national Exclusive Economic Zones), different potential Blue Economy opportunities and challenges will arise. Following a series of interdisciplinary workshops, we imagine two technically possible futures for the offshore Blue Economy and we identify the actions required to achieve the more sustainable outcome. Under a business as usual scenario the focus will remain on economic growth, the commodification of nature, the dominance of private over public and cultural interests, and prioritisation of the interests of current over future generations. A more sustainable scenario would meet multiple UN Sustainable Development Goals and ensure inclusive economic developments, environmental sustainability, and fair and equitable access to resources and technologies across users, nations, and generations. Challenges to this more sustainable future are a lack of infrastructure and technology to support emerging offshore sectors, limited understanding of environmental impacts, inequitable outcomes, and a lack of planning and governmental oversight. Addressing these challenges will require a shift in societal values, a more balanced allocation of funding to offshore activities, transparency in information sharing between industries and across nations, and adjustment of international legal and institutional mechanisms. The sustainable and equitable offshore Blue Economy we envisage is achievable and provides a unique opportunity to build global capacity and partnership. [ABSTRACT FROM AUTHOR]

Offshore wind energy and wave energy are two exploitable sources of renewable energy available in the same marine environment. A co-located energy harvesting system of these two resources has the potential to play a leading role in the recent renewable energy mix mandate. A co-located system of mature offshore wind technology and a nascent wave energy technology can exploit the synergies of the two technologies, including the reduced cost, the easy operation and maintenance, and more importantly the potential of decreased power variability. This paper deals with a multi-site analysis of wind and wave power resources, and the estimation of exploitable energy through different wind turbines and wave energy converters (WECs). Results are presented for NSW Australia, but the devised strategy is generic and can be implemented in any region. Ten WECs, with different operating principles, are used for the estimation of the exploitable wave power, and the best performing converter is considered for the co-located wind-wave farm. A power fluctuation factor is introduced to quantify the reduction in power variability of the co-located wind-wave farm. Different percentage mixes of wind and wave energy are evaluated for the co-located wind-wave farm in the multi-site analysis. •A multi-site analysis of wind and wave for estimation of exploitable energy. •Performance evaluation of wind and wave energy conversion technologies. •Power variability representation with power fluctuation factor for a co-located farm. •Characterization of percentage share of wind and wave in a co-located farm. [ABSTRACT FROM AUTHOR]

Consistent projected decreases in significant wave heights ( H S ) over the North Atlantic sub-basin under climate change scenarios have been endorsed by recent scientific literature. Here, the underlying causes of these projected decreases are investigated, by statistically characterizing the relationship between atmospheric circulation patterns, and wind generated waves. We apply a non-hierarchical partitioning method to the historical reference ERA5 mean sea level pressure (MSLP ) over the North Atlantic, defining Weather Types (WTs) at annual and seasonal scales. The H S fields related to those WTs are then characterized. Projected changes in the WTs frequencies of occurrence and related H S , towards the end of twenty-first century, are analyzed for the RCP4.5 and RCP8.5 scenarios using a 10-member multi-model ensemble. Results show projected increases in the occurrence of WTs dominated by high-latitude storm tracks (above 50° N) and atmospheric blocking patterns, and projected decreases in the occurrence of WTs dominated by lower-latitude storm tracks and NAO− patterns, over the North Atlantic, consistent with generalized projected decreases in H S . [ABSTRACT FROM AUTHOR]

Australia has significant offshore wind resources that can support ever-increasing power demand and hence provide a long-term contribution to the net-zero target by 2050. Although some offshore wind farm projects are proposed in Australia, the industry is not mature enough to justify the benefits and display economic opportunities. More specifically, the techno-economic analysis of offshore wind energy has not been systematically mapped in Australia. Therefore, the investigation of the spatial variation of technical feasibility and economic potential of offshore wind is vital to identify the potential regions and to develop strategies for future offshore wind farm developments in Australia. This paper presents detailed mappings of the techno-economic potential of offshore wind energy in Victoria-Tasmania's exclusive economic zone. Offshore wind energy resources are assessed in the paper in terms of energy availability and variability and the feasibility of various offshore wind technologies is investigated, including turbines, foundation types and transmission topologies. In addition, the high-fidelity life-cycle cost models and two innovative evaluation matrices are developed to assess the economic potential of offshore energy farms in South-eastern Australia. The impact of local power system regulation costs and future carbon prices on the viability of offshore wind is also investigated in this paper. It is concluded that the detailed mapping approach and analysis in the paper can provide a systematic tool for industry partners, investors and policymakers at the pre-planning stage of developing offshore renewable energy systems. • The technical feasibility of offshore wind is mapped under various constraints. • The novel LACE and high-fidelity LCC assessment models are developed. • The techno-economic potential is systemically mapped in South-eastern Australia. • The impacts of electricity market regulation and future carbon prices are studied. [ABSTRACT FROM AUTHOR]

Over the last two decades, a large body of academic scholarship has been generated on wave and tidal energy related topics. It is therefore important to assess and analyse the research direction and development through horizon scanning processes. To synthesise such large-scale literature, this review adopts a bibliometric method and scrutinises over 8000 wave/tidal energy related documents published during 2003–2021. Overall, 98 countries contributed to the literature, with the top ten mainly developed countries plus China produced nearly two-thirds of the research. A thorough analysis on documents marked the emergence of four broad research themes (dominated by wave energy subjects): (A) resource assessment, site selection, and environmental impacts/benefits; (B) wave energy converters, hybrid systems, and hydrodynamic performance; (C) vibration energy harvesting and piezoelectric nanogenerators; and (D) flow dynamics, tidal turbines, and turbine design. Further, nineteen research sub-clusters, corresponding to broader themes, were identified, highlighting the trending research topics. An interesting observation was a recent shift in research focus from solely evaluating energy resources and ideal sites to integrating wave/tidal energy schemes into wider coastal/estuarine management plans by developing multicriteria decision-making frameworks and promoting novel designs and cost-sharing practices. The method and results presented may provide insights into the evolution of wave/tidal energy science and its multiple research topics, thus helping to inform future management decisions. • An analysis on over 8000 wave/tidal energy articles over the last 20 years is provided. • The evolution of literature, network of contribution, and influential entities are scrutinised. • 98 nations contributed to research with 4 major themes and 19 sub-themes emerged. • Recent research integrates energy assessment into wider coastal management plans. • Findings can inform knowledge gaps, policy decisions, and future research efforts. [ABSTRACT FROM AUTHOR]

Through assessment of wind-wave directional spectra, we provide a comprehensive explanation of the projected 21st Century changes in the global wind-wave climatology under a high green-house emissions scenario. Using a seven-member wave climate projection ensemble, we estimate wave climate changes by comparing present and projected climatologies. Clustering techniques are applied to define regional patterns of change with homogenous behavior. The underlying mechanisms behind the changes are also explored by exploiting the relationship between the wave generation area and the effective energy flux propagating toward a target location. A robust transition from positive to negative trends in Southern Ocean westerly swells is observed around 45°S. The increasing signal found in the southernmost swells propagates north beyond 30°N, contributing significantly to the projected changes in tropical regions such as the tropical southern Atlantic and tropical southeastern Pacific. Results highlight the great complexity of the Pacific Ocean due to the convergence of multiple wave systems with different geneses. In the northern basins, the combined effect of the ice melting and a poleward shift of the storm track drives an increase of the northernmost westerly swells. This is countered by a decreasing trend projected in the main wave systems propagating in the North Atlantic Ocean. A poleward shift of trade-induced waves due to the Hadley cell expansion can also be observed globally, causing a clear dipole change pattern in the tropical southern Atlantic and tropical Indian oceans. • The effect of climate change on wave climate is assessed based on directional spectra. • The climate change signals of the main swell systems are described. • Sixteen ocean regions with a similar pattern of change are found. [ABSTRACT FROM AUTHOR]

We present a global wind wave climate model ensemble composed of eight spectral wave model simulations forced by 3-hourly surface wind speed and daily sea ice concentration from eight different CMIP6 GCMs. The spectral wave model uses ST6 physics parametrizations and a global three-grid structure for efficient Arctic and Antarctic wave modeling. The ensemble performance is evaluated against a reference global multi-mission satellite altimeter database and the recent ECMWF IFS Cy46r1 ERA5 wave hindcast, ERA5H. For each ensemble member three 30-year slices, one historical, and two future emission scenarios (SSP1-2.6 and SSP5-8.5) are available, and cover two distinct periods: 1985-2014 and 2071-2100. Two models extend to 140 years (1961-2100) of continuous wind wave climate simulations. The present ensemble outperforms a previous CMIP5-forced wind wave climate ensemble, showing improved performance across all ocean regions. This dataset is a valuable resource for future wind wave climate research and can find practical applications in offshore and coastal engineering projects, providing crucial insights into the uncertainties connected to wind wave climate future projections., (© 2024. The Author(s).)

The dataset consists of ocean surface wind speed and direction at 10 m height and 1 km spatial resolution around the wider Australian coastal areas, spanning 4 years (2017 to 2021) of measurements from Sentinel-1 A and B imaging Synthetic Aperture Radar (SAR) platforms. The winds have been derived using a consistent SAR wind retrieval algorithm, processing the full Sentinel-1 archive in this region. The data are appropriately quality controlled, flagged, and archived as NetCDF files representing SAR wind field maps aligned with satellite along-track direction. The data have been calibrated against Metop-A/B Scatterometer buoy-calibrated, wind measurements and examined for potential changes in calibration over the duration of the data. The calibrated data are further validated by comparisons against independent Altimeter (Cryosat-2, Jason-2, Jason-3, and SARAL) wind speeds. Several methods for data access are also listed. The database is potentially useful for offshore industries (oil and gas, fisheries, shipping, offshore wind energy), public recreational activities (fishing, sailing, surfing), and protection and management of coasts and natural habitats., (© 2023. The Author(s).)

This dataset, produced through the Coordinated Ocean Wave Climate Project (COWCLIP) phase 2, represents the first coordinated multivariate ensemble of 21 st Century global wind-wave climate projections available (henceforth COWCLIP2.0). COWCLIP2.0 comprises general and extreme statistics of significant wave height (H S ), mean wave period (T m ), and mean wave direction (θ m ) computed over time-slices 1979-2004 and 2081-2100, at different frequency resolutions (monthly, seasonally and annually). The full ensemble comprising 155 global wave climate simulations is obtained from ten CMIP5-based state-of-the-art wave climate studies and provides data derived from alternative wind-wave downscaling methods, and different climate-model forcing and future emissions scenarios. The data has been produced, and processed, under a specific framework for consistency and quality, and follows CMIP5 Data Reference Syntax, Directory structures, and Metadata requirements. Technical comparison of model skill against 26 years of global satellite measurements of significant wave height has been undertaken at global and regional scales. This new dataset provides support for future broad scale coastal hazard and vulnerability assessments and climate adaptation studies in many offshore and coastal engineering applications.