Wave Climate Variability Research Articles

Spectral Ocean Wave Climate Variability Based on Atmospheric Circulation Patterns

Abstract Traditional approaches for assessing wave climate variability have been broadly focused on aggregated or statistical parameters such as significant wave height, wave energy flux, or mean wave direction. These studies, although revealing the major general modes of wave climate variability and trends, do not take into consideration the complexity of the wind-wave fields. Because ocean waves are the response to both local and remote winds, analyzing the directional full spectra can shed light on atmospheric circulation not only over the immediate ocean region, but also over a broad basin scale. In this work, the authors use a pattern classification approach to explore wave climate variability in the frequency–direction domain. This approach identifies atmospheric circulation patterns of the sea level pressure from the 31-yr long Climate Forecast System Reanalysis (CFSR) and wave spectral patterns of two selected buoys in the North Atlantic, finding one-to-one relations between each synoptic pattern (circulation type) and each spectral wave energy distribution (spectral type). Even in the absence of long-wave records, this method allows for the reconstruction of long-term wave spectra to cover variability at several temporal scales: daily, monthly, seasonal, interannual, decadal, long-term trends, and future climate change projections.

Surfing wave climate variability

International surfing destinations are highly dependent on specific combinations of wind–wave formation, thermal conditions and local bathymetry. Surf quality depends on a vast number of geophysical variables, and analyses of surf quality require the consideration of the seasonal, interannual and long-term variability of surf conditions on a global scale. A multivariable standardized index based on expert judgment is proposed for this purpose. This index makes it possible to analyze surf conditions objectively over a global domain. A summary of global surf resources based on a new index integrating existing wave, wind, tides and sea surface temperature databases is presented. According to general atmospheric circulation and swell propagation patterns, results show that west-facing low to middle-latitude coasts are more suitable for surfing, especially those in the Southern Hemisphere. Month-to-month analysis reveals strong seasonal variations in the occurrence of surfable events, enhancing the frequency of such events in the North Atlantic and the North Pacific. Interannual variability was investigated by comparing occurrence values with global and regional modes of low-frequency climate variability such as El Niño and the North Atlantic Oscillation, revealing their strong influence at both the global and the regional scale. Results of the long-term trends demonstrate an increase in the probability of surfable events on west-facing coasts around the world in recent years. The resulting maps provide useful information for surfers, the surf tourism industry and surf-related coastal planners and stakeholders.

A method for finding the optimal predictor indices for local wave climate conditions

In this study, a method to obtain local wave predictor indices that take into account the wave generation process is described and applied to several locations. The method is based on a statistical model that relates significant wave height with an atmospheric predictor, defined by sea level pressure fields. The predictor is composed of a local and a regional part, representing the sea and the swell wave components, respectively. The spatial domain of the predictor is determined using the Evaluation of Source and Travel-time of wave Energy reaching a Local Area (ESTELA) method. The regional component of the predictor includes the recent historical atmospheric conditions responsible for the swell wave component at the target point. The regional predictor component has a historical temporal coverage (n-days) different to the local predictor component (daily coverage). Principal component analysis is applied to the daily predictor in order to detect the dominant variability patterns and their temporal coefficients. Multivariate regression model, fitted at daily scale for different n-days of the regional predictor, determines the optimum historical coverage. The monthly wave predictor indices are selected applying a regression model using the monthly values of the principal components of the daily predictor, with the optimum temporal coverage for the regional predictor. The daily predictor can be used in wave climate projections, while the monthly predictor can help to understand wave climate variability or long-term coastal morphodynamic anomalies.

Control of wave climate and meander dynamics on spit breaching and inlet migration

Chaumillon E., Ozenne F., Bertin X., Long N., Ganthy F., 2014. Wave climateand inlet channel meander bend control spit breaching and migration of a new inlet: La Coubre Sandspit, France. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 109–114, ISSN 0749-0208.This study focuses on the mid-term (infra annual and pluri annual; over the period 1999–2013) morphological evolutions of a sandspit (La Coubre Sandspit, West coast of France), with a particular emphasis on spit breaching, new inlet opening and migration. Morphological evolutions are observed from a large number of aerial photographs and satellite images and are compared with wave parameters and extreme events (periods where significant wave height exceeds the 1% largest waves with water level exceeding the 90% highest water level) obtained from a high resolution hindcast wave modelling. It appears that extreme events are likely to be responsible for spit breaching and new inlet opening. Once opened, the new inlet migrates downdrift, but its migration rate is not correlated with the wave climate variations. Detailed geomorphological observations suggest that the main control on downdrift inlet migration is related to orientation of the meander bend of the tidal inlet main channel. When the meander bend is convex in an updrift direction, it counteracts the littoral drift and slows the inlet migration. Oppositely, when the meander bend is convex in a downdrift direction, the meander-induced transport is in the same direction as wave-induced longshore transport, which allows the inlet to migrate much faster.

Wave climate variability of Taiwan waters

Global sea surface wind field data derived from NCEP reanalysis were used in driving a SWAN wave model to reconstruct historical wave records from 1948 to 2008. The reconstructed wave data were compared and verified by the observation of the data buoys of the Central Weather Bureau and the Water Resources Agency, Taiwan, and the National Data Buoy Center/National Oceanic and Atmospheric Administration, United States. Over the past six decades, the wave climate in Taiwan waters has undergone considerable changes. The annual mean significant wave heights have reduced an average of 0.31 cm/year. Winter wave heights have gradually dropped 0.86 cm/year, which are related to the weakening of winter monsoons. Regarding the inter-annual wave climate variation, the influence of El Nino/southern oscillation was substantial; the wave heights increased in La Nina years and decreased in El Nino years. In the past 60 years, extreme wave events have been concentrated in two periods: 1967–1974 and 2000–2008. More severe extreme wave events occurred in the latter compared with the former, and all were induced by typhoons. A clear trend, in which the summer (winter) extreme wave events have increased (decreased) gradually, has been identified. The 1980s was the transition period. After the transition period, the annual occurrence of extreme wave events caused by typhoons exceeded those caused by an intense outbreak of winter cold surges, although the total number of the annual extreme wave events has not changed substantially.

Probabilistic modelling of extreme storms along the Dutch coast

Due to the unprecedented growth in population and economic development along the coastal zone all over the world, knowledge about future extreme oceanographic events will assist in ensuring human and property safety. This will be a task with increasing significance in the light of projected climate change impacts. A joint estimation of extreme storm events' variates of deep water wave conditions was performed. It can be used for multivariate descriptions of wave climate variates, such as wave height, period, steepness, and storm duration. The storm sequences can be simulated and extrapolated from limited observational data for optimal structure protection strategies and various disaster risk analysis, like erosion or overtopping. The analysis not only shows the effectiveness of the proposed statistical approaches for improving multivariate modelling of the storm parameters but also highlights the most compatible approach for the Dutch wave climate data from 1979 to 2009. We used the Monte-Carlo method and four methods to construct the dependency structures, based on copula functions, physical relationship and extreme value theory. The marginal probabilistic distribution functions of wave climate variables and the joint probability were then obtained. The simulated data group performs a reasonable similarity to the field measurements according to the goodness-of-fit test, and the Gaussian copula model was found to be the best wave climate simulation method for the Dutch coast.

Ocean Waves and Teleconnection Patterns in the Northern Hemisphere

Abstract Understanding long-term, ocean wave climate variability is important to assess climate change impacts on coastal and ocean physics and engineering. Teleconnection patterns can represent wave climate variability in the context of climate change. The objective of this study is to identify how large-scale spatial distributions of wave heights vary on a monthly basis and how they are influenced by various teleconnection patterns using reanalysis datasets. The wave height climate responses to teleconnection patterns in the eastern part of the North Pacific and North Atlantic are more sensible than in the corresponding western parts. The dominant spatial patterns of monthly averaged wave height variability in winter were obtained by empirical orthogonal function analysis. The three dominant patterns in the North Pacific and North Atlantic are similar. It is remarkable that one of the three dominant patterns, a band-shaped pattern, exhibits a strong relation to the teleconnection pattern in each ocean. The band-shaped pattern for the North Pacific was investigated in detail and found to be related to the west Pacific (WP) pattern. Where and how each teleconnection pattern influences wave climate becomes apparent especially during winter.

Spatial and temporal variability in species richness in a temperate intertidal community

Understanding changes in estuarine benthic communities has important implications for conservation and yet it is a challenge due to the high natural variability of these systems. We addressed this challenge through the study of temporal and spatial patterns of species richness in an intertidal benthic community in New Zealand North Island. Five different locations within the estuary were monitored seasonally over 12 yr. This data set allowed the study of species–time–area relationships (STAR) and the delineation of patterns in species richness, heterogeneity and turnover in space and time. The site with the highest species richness also had the highest within‐site heterogeneity in species richness, a high number of species occurring infrequently in time, the lowest mud content and the most variable wave climate. Similarities and differences between sites were generally maintained over time, although seasonal and multi‐year patterns in species richness occurred at all sites. The STAR showed a significant negative interaction between space and time, with species accumulation rates in space and time being equivalent at 4 spatial replicates (250 m2) and 2 temporal replicates (6 months). The lowest source of variability in species turnover was within site, and the highest source was over years. This was reflected in the lack of an asymptotic relationship in the species accumulation curve despite the 12 yr of monitoring. These results contribute to the knowledge of the variability in diversity patterns in estuaries and have important implications for long‐term monitoring of natural communities and the estimation of diversity for conservation.

Climate-driven episodes of dune mobilization and barrier growth along the central coast of Portugal

Abstract Here, we explore the evolution of the coastal stretch between Mira Beach and Quiaios Beach in Portugal to understand how it adapted to climatic oscillations. To accomplish this, we integrate subsurface radar images, and sedimentological and chronological data, of the emerged coastal barrier. Our results show the installation and progradation of a stable barrier anchored to transgressive dunes 400 years ago. This is just the last pulse of barrier growth within a complex approximately 5000 year-long history of shoreline stability/instability. Episodes of inland dune mobility have been related to instabilities in the beach sediment budget driven by enhanced storminess and wave rotation around 4.25 and 1.14 ka ago. Conversely, lagoonal deposits documented in the literature suggest periods of relative barrier stability and growth around 4.3 and 2.7 cal ka BP. Wave and wind climate variability are driven by shifts in one of the major modes of atmospheric circulation in the North Atlantic, the North Atlantic Oscillation (NAO). Episodes of persistent positive mode of the NAO related to barrier growth and enhanced longshore sediment transport; those of persistent negative mode contributed to instabilities in the beach sediment budget and aeolian activity by enhancing storminess, but reduced effective longshore sediment transport.

Wave climate simulation for southern region of the South China Sea

This study investigates long-term variability and wave characteristic trends in the southern region of the South China Sea (SCS). We implemented the state-of-the art WAVEWATCH III spectral wave model to simulate a 31-year wave hindcast. The simulation results were used to assess the inter-annual variability and long-term changes in the SCS wave climate for the period 1979 to 2009. The model was forced with Climate Forecast System Reanalysis winds and validated against altimeter data and limited available measurements from an Acoustic Wave and Current recorder located offshore of Terengganu, Malaysia. The mean annual significant wave height and peak wave period indicate the occurrence of higher wave heights and wave periods in the central SCS and lower in the Sunda shelf region. Consistent with wind patterns, the wave direction also shows southeasterly (northwesterly) waves during the summer (winter) monsoon. This detailed hindcast demonstrates strong inter-annual variability of wave heights, especially during the winter months in the SCS. Significant wave height correlated negatively with Nino3.4 index during winter, spring and autumn seasons but became positive in the summer monsoon. Such correlations correspond well with surface wind anomalies over the SCS during El Nino events. During El Nino Modoki, the summer time positive correlation extends northeastwards to cover the entire domain. Although significant positive trends were found at 95 % confidence levels during May, July and September, there is significant negative trend in December covering the Sunda shelf region. However, the trend appears to be largely influenced by large El Nino signals.

An insight into headland sand bypassing and wave climate variability from shoreface bathymetric change at Byron Bay, New South Wales, Australia

Abstract The headland sand bypassing mechanisms in the Eastern Australian longshore sand transport system are investigated at Cape Byron, in response to wave climate variability. The mechanisms are interpreted from shoreface bathymetric change between surveys in 1883, 2002 and 2011 CE. They involve a split in the sand transport to follow a nearshore path along the inner bar and a cross-embayment path connecting the up-coast and down-coast outer bars. The relative magnitude of the net sand transported via the two pathways is controlled by a rotation in directional wave conditions. Two bypassing mechanisms were interpreted: (i) a predominantly cross embayment transport during unimodal east–southeast wave climate such as those interpreted for the period prior to 1883; and, (ii) a split transport between the inner nearshore and cross-embayment paths during a bimodal dominant south–south-easterly and sub-dominant east–north-easterly wave climate such as in the 2000s. The net sand transport bypassing Cape Byron was dominated by a connected outer bar system prior to 1883 and conversely, a stronger inner bar system during the 1960s to 2000s. This is manifest in the 10° rotation in seabed morphology and shoreline planforms. These changes are in accordance with decadal climate variability described by the Interdecadal Pacific Oscillation (IPO). The switching between headland sand bypassing mechanisms on interannual to decadal timescales determines the geometry of the bypass strand with the downcoast littoral zone and has important implications for understanding the shoreline rotation and the application of the headland-bay beach concept to predicting planform curvature in open compartments.

Extreme wave climate changes in Central-South America

The spatial and temporal variability of extreme wave climate along the Central- South American continent is analyzed. The study evaluates changes in the intensity of extreme significant wave height (SWH) throughout the year over the 1980-2008 period, using a calibrated long-term wave reanalysis database forced with NCEP/NCAR reanalysis. A non-stationary extreme value model, based on monthly maxima with a new approach for long-term trends, has been applied. Results show a common positive trend in the Pacific basin throughout all seasons and a significant decreasing trend pattern in the area of Surinam and north of Brazil, on the Atlantic border (up to �1.5 cm/year in March-April-May). A higher increase of the extreme wave heights is found in the austral summer (December- January-February) at Tierra de Fuego and the Falkland Islands, reaching 6.5 cm/year (which means 1.82 m for the 28 years studied). Furthermore, the complete reanalysis period (1948- 2008) is analyzed in order to compare results with the assimilation data period (1980-2008), resulting in some discrepancies, especially in the Atlantic basin.

Morphodynamic Environments of the Costa del Sol, Spain

Guisado, E., Malvárez, G. and Navas, F., 2013. Morphodynamic environments of the Costa del Sol, Spain.The morphodynamic environments of the Costa del Sol, in southern Spain, have never been investigated at a littoral cell scale. In the last half of the 20th century the tourism industry have transformed the coastal landscapes and, importantly, the natural processes inducing irreversible damages and changes. For the most part, a project-based view on engineering works has focussed on individual beach behaviour, but no assessment on morphodynamics has been reported at physiographic scale. Using an integrated modelling approach, which combines wave energy propagation and digital terrain integration (land and sea), in this paper a new characterisation of coastal morphodynamics for western Costa del Sol is presented. Methodologically, the challenge of integrating land and sea has been overcome using existing methods, which takes high-resolution interoperable bathymetric models of the continental shelf of this section of the Mediterranean, and couples it with the Official Digital Terrain Model. This allows for propagation of waves from deep water to realistic nearshore environments. Wave input is represented by wave spectra from the recording network of the Spanish Port Authority, and the wave propagation model SWAN is used to propagate wave parameters onshore. Given the variability of wave climate in the region, characterised by long periods of calms (over 77% per year) followed by high energy events (dominated by high frequency storm waves with periods of less than 7 seconds and maximum wave heights exceeding 5 metres), a wave power index is used to identify and provide input data for extreme wave conditions of great significance for beach morphodynamics in the region. Results show that at littoral cell scale, even in the presence of the steep nearshore (i) the adaptation of the system tends towards generating dissipative environments, (ii) the presence of abrupt changes in local bathymetry affects significantly wave orbital velocities even at depths beyond wave base potentially inducing nearshore sediment transport, and (iii) high energy events affect the coastal stretch in complex ways, where highly active short-crested/high-frequency wave conditions induce transitional morphodynamic states.

Sensitivity analysis of the methodology for quantifying cliff erosion using airborne LiDAR – examples from Cornwall, UK.

Earlie, C.S., Masselink, G., Russell, P.A., and Shail, R.K., 2013. Sensitivity analysis of the methodology for quantifying cliff erosion using airborne LiDAR – examples from Cornwall, UK.The widespread problem of coastal cliff erosion and the management of the risk to infrastructure and property calls for robust quantification of cliff erosion rates. Quantification of sea-cliff rates of retreat on an annual to decadal time scale has typically been limited to rapidly eroding soft rock coastlines. This study uses airborne LiDAR technology to estimate cliff volume changes in hard rock environments to determine linear retreat rates. One epoch of LiDAR data was analysed (2007/2008–2010/2011) for ten sites around the coast of the southwest of England (Cornwall), selected due to the spatial variability in regional morphological processes, lithology and wave climate. Quantifying cliff recession rates using two LiDAR-derived Digital Elevation Models (DEM) requires selection of an elevation change threshold, below which the morphology is assumed to have undergone no significant change, referred to as the ‘vertical change threshold'. The errors inherent in using LiDAR and the various thresholds at which the data could be evaluated were tested. Linear rates of retreat were found to vary according to the threshold of error chosen, providing decreasing rates with an increase in threshold above 0.2–0.3 m. The rates of retreat observed at some low energy sites was of the same magnitude and in some cases lower (0.01–0.03 m yr−1) than the threshold of error inherent in the LiDAR data (0.03–0.1 m). The results were compared with the rates of retreat obtained from analysis of historic maps in Shoreline Management Plans which are non-statutory strategic assessments of the risks associated with coastal erosion that ultimately inform local and regional policy. Analysis of coastal erosion using LiDAR data tended to highlight the localised failures that occur episodically and which are averaged out in the rates derived from longer term analysis of historic maps.

Numerical modeling of shoreline undulations part 2: Varying wave climate and comparison with observations

The present work applies the shoreline model from part 1 to a real environment. In part 1, a numerical shoreline model which could handle the development of arbitrarily shaped shorelines was applied to consider the development of shoreline undulations on an unstable shoreline exposed to incoming waves with a directional spreading. In this paper, these findings are extended to firstly include the effect of a varying wave climate on the shoreline morphology and secondly, to tune the model to two naturally occurring shorelines. It is found that the effect of a variable wave climate is to slow down the development of the morphology and in some cases to inhibit the formation of shore-parallel spits at the crest of the undulations. On one of the natural shorelines, the west coast of Namibia, the shore is exposed to very obliquely waves from one main direction. Here, the shoreline model is able to describe the observed shoreline features qualitatively and quantitatively. The model slightly over-predicts the scale of the feature and, associated with this, slightly under-predicts the migration speeds of the features. On the second shoreline, the west coast of Denmark, the shore is exposed to waves with an angle close to the critical around 45°, and here the existence of undulations is discussed in detail.

MORPHOLOGICAL MODELING OF A HIGHLY DYNAMIC TIDAL INLET AT SHIPPAGAN GULLY, CANADA

This paper is presenting the results of an extensive field and numerical modeling investigation of a morphologically dynamic tidal inlet. Shippagan Gully is a tidal inlet located near Shippagan, New-Brunswick, Canada, on the Gulf of Saint Lawrence. It is a particularly complex tidal inlet due to the fact that its tidal lagoon transects the Acadian peninsula and is open to the Bay des Chaleurs at its opposite end. As such, two open boundaries with phase lagged tidal cycles drive flow through the inlet, alternating direction with each tide and reaching velocities in excess of 2 m/s. Hydrodynamic and morphological processes at the site are further complicated by the presence of a highly variable wave climate. Presently, shipping practices through the inlet are limited due to continual sedimentation within and immediately offshore from Shippagan Gully. As such, an extensive field study, desktop analysis and numerical and morphological modeling of Shippagan Gully have been conducted in order to provide guidance for future works. Modeling was conducted using the CMS-Wave and CMS-Flow numerical modeling system. Sedimentation inside the inlet was shown to be ebb tide-induced deposition; while wave induced deposition was demonstrated elsewhere. The methodology and selected results of this study are presented herein.

Global dynamical projections of surface ocean wave climate for a future high greenhouse gas emission scenario

A global 1° implementation of the spectral wave model, WaveWatch III, was forced with surface winds from two atmosphere–ocean general circulation models (AOGCMs: ECHAM5 and CSIRO Mk3.5), dynamically downscaled to 60km using the Cubic Conformal Atmospheric Model. Two 30-yr time slices were simulated: 1979–2009 representing current climate, and 2070–2099 representing a future climate scenario under a high greenhouse gas emission scenario (SRES A2). A further wave model simulation with forcing from the NCEP Climate Forecast System Reanalysis for 1979–2009, using the same model settings as the climate model forced runs, serves as a benchmark hindcast to assess skill of climate-model-derived wave fields. Climate model forced wave simulations for the 1979–2009 time-slice display biases relative to the benchmark wave climate – notably an overestimation of wave generation in the Southern Ocean, which influences broad regions of the Pacific which receive these waves as swell. Wave model runs were repeated following bias-adjustment of the climate model forcing winds with the aim to reduce biases, but model skill to simulate the monthly 99th percentile of significant wave heights deteriorates severely.Projected future changes in wave climate (between 1979–2009 and 2070–2099) under the SRES A2 greenhouse gas emission scenario are relatively insensitive to whether bias-adjustment of winds has been applied. Two robust features of projected change are observed from the two climate model sets which are qualitatively consistent with previous studies: a projected increase of Southern Ocean wave generation leading to approximately 10% increase in Southern Ocean mean significant wave heights (HSm), and a projected decrease in wave generation in the North Atlantic, with changes in HSm of similar magnitude.Interannual anomalies of monthly mean significant wave height, HSm, were regressed against climate indices (Southern Oscillation Index – SOI; North Atlantic Oscillation – NAO and the Southern Annular Mode – SAM) over each time-slice. Significant differences in the relationships between wave height variability and these climate indices between current and projected climates are observed. For example, a significant shift from negative to positive correlation between the NAO and HSm anomalies along the western European and north-west African coasts in the projected future climate is noted. The potential future changes in wind-wave characteristics, and the changing relationships between interannual variability of wave climate with identified climate indices, as a response to projected future climate scenarios have broad implications for a range of processes and activities in the coastal, near-and-off-shore environments.

Variability of multivariate wave climate in Latin America and the Caribbean

Wave climate is highly variable on the world's coast and its temporal changes and extremes usually imply consequences like erosion or impacts to infrastructures. Alterations in wave climate were little addressed in the four IPCC reports although variations in wave climate may cause extensive coastal impacts. Changes are also often related to climate pattern variability. This variability as well as long-term trends has been an issue of research in recent years. In the region of Latin America and the Caribbean (LAC) an understanding of wave climate and its variability is scant. In this paper we use an extensively calibrated and validated wave reanalysis to describe the wave climatology in the region at different time scales and for scalar and directional wave parameters. Long-term changes are identified in the wave heights and mean direction of the energy flux shows high spatial variability. Correlation patterns of the mean significant wave height and direction of mean energy flux lead to the detection of prominent modes of influence of several climate indices. A wave climate type approach is also used to identify wave variability along the region that allows an identification of different wave climate types in terms of wave parameters and occurrence frequency. In line with the results, the influence of El Niño events shows a higher frequency of occurrence of certain sea-states with respect to non ENSO years. We also explore how climate change affecting storm patterns may be translated into a modification of sea-state occurrence and therefore implying different consequences for coastal zones depending on local wave propagation.

Mixed extreme wave climate model for reanalysis databases

Hindcast or wave reanalysis databases (WRDB) constitute a powerful source with respect to instrumental records in the design of offshore and coastal structures, since they offer important advantages for the statistical characterization of wave climate variables, such as continuous long time records of significant wave heights, mean and peak periods, etc. However, reanalysis data is less accurate than instrumental records, making extreme data analysis derived from WRDB prone to under predict design return period values. This paper proposes a mixed extreme value model to deal with maxima, which takes full advantage of both (i) hindcast or wave reanalysis and (ii) instrumental records, reducing the uncertainty in its predictions. The resulting mixed model consistently merges the information given by both kinds of data sets, and it can be applied to any extreme value analysis distribution, such as generalized extreme value, peaks over threshold or Pareto–Poisson. The methodology is illustrated using both synthetically generated and real data, the latter taken from a given location on the northern Spanish coast.

A Global Ocean Wave (GOW) calibrated reanalysis from 1948 onwards

Wind wave reanalyses have become a valuable source of information for wave climate research and ocean and coastal applications over the last decade. Nowadays, wave reanalyses databases generated with third generation models provide useful wave climate information to complement, both in time and space, the instrumental measurements (buoys and alimetry observations). In this work, a new global wave reanalysis (GOW) from 1948 onwards is presented. GOW dataset is intended to be periodically updated and it is based on a calibration of a model hindcast with satellite altimetry data, after verification against historical data. The outliers due to tropical cyclones (not simulated due to insufficient resolution in the wind forcing) are identified and not taken into account in the process to correct the simulated wave heights with the altimeter data. The results are validated with satellite measurements in time and space. This new calibrated database represents appropriately the wave climate characteristics since 1948 and aims to be the longest and up-to-date wave dataset for global wave climate variability analysis as well as for many coastal engineering applications.