fernando mendez - Academia.edu (original) (raw)

Papers by fernando mendez

Coastal Engineering, 2004

A simple and innovative method to solve explicitly the dispersion equation for water waves over d... more A simple and innovative method to solve explicitly the dispersion equation for water waves over dissipative media is presented. The roots of this equation are themselves complex and difficult to obtain by standard numerical methods. A general structure for the dispersion relation is given, the dimensionless wave number, x, depending on the value of a dissipation parameter, φ, which is a function of the dissipative medium. Based on the hypothesis that a small perturbation in the dissipation parameter, δφ, produces a small variation in the dimensionless wave number, δx, a simple approach is proposed to calculate explicitly in an iterative manner the complex roots. The new method improves upon the unreliability of standard numerical schemes in the calculation of the roots in dissipative media.

Analogies between the noncommutative harmonic oscillator and noncommutative fields are analyzed. ... more Analogies between the noncommutative harmonic oscillator and noncommutative fields are analyzed. Following this analogy we construct examples of quantum fields theories with explicit CPT and Lorentz symmetry breaking. Some applications to baryogenesis and neutrino oscillation are also discussed

Global and Planetary Change, 2014

International surfing destinations are highly dependent on specific combinations of wind-wave for... more 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.

OCEANS 2010 MTS/IEEE SEATTLE, 2010

ABSTRACT A global framework, than can be applied worldwide, has been developed to determine waver... more ABSTRACT A global framework, than can be applied worldwide, has been developed to determine waver energy resources at shallow water with high spatial and long temporal resolution in order to analyze the seasonality, interannual variability (correlation of wave power with climate-related indices, such as the North Atlantic Oscillation) and spatial long-term trends along the Spanish coast. The proposed methodology combines instrumental and numerical databases, wave numerical models (dynamical downscaling) and sophisticated mathematical tools (statistical downscaling), which includes a selection algorithm and an interpolation technique to reconstructed time series. The validation of the results in deep water and coastal buoys locations confirm the ability of the methodology developed.

Coastal Engineering, 2015

This study presents a comprehensive methodology for the reanalysis, characterization and propagat... more This study presents a comprehensive methodology for the reanalysis, characterization and propagation of wave bound infragravity waves (1/300 Hz to 1/30 Hz) in the nearshore. A deep water short wave reanalysis has been modified analytically to include the energy input associated with infragravity waves (full spectrum), through the decomposition and energy balance of the radiation stress of waves in deep water. A hybrid clustering-numerical wave propagation downscaling technique was used, forced by the modified full wave spectra previously obtained, resulting in hourly series of high spatial resolution nearshore ocean waves, including short and bound long waves. The methodology has been applied to the northern coast of Spain and validated by comparing buoy and pressure gauge records in the coast, for short wave (agitation) and infragravity wave (resonance) responses in open harbours, with very satisfactory results.

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

Coastal Engineering 2006 - Proceedings of the 30th International Conference, 2007

This paper presents a statistical model to characterize the long-term extreme value distribution ... more This paper presents a statistical model to characterize the long-term extreme value distribution of significant wave height, conditioning to the duration of the storm and accounting for seasonality. A time-dependent version of the peak over threshold (POT) approach is used to build the model, which is then applied to specific reanalysis time series and NOAA buoy records. The model considers the annual and semiannual cycles which are parameterized in terms of harmonic functions. The inclusion of seasonal variabilities substantially reduces the residuals of the fitted model. The information obtained in this study can be useful to design maritime works, because (a) the model improves the understanding of the variability of extreme wave climate along a year and (b) the model accounts for the duration of the storm, which is a key parameter in several formulations for rubble mound breakwater design. r

OCEANS 2011 IEEE - Spain, 2011

... Paula Camus, Antonio Tomas, Cesar Vidal, Fernando J. Mendez, Raul Medina, Inigo J .Losada. ..... more ... Paula Camus, Antonio Tomas, Cesar Vidal, Fernando J. Mendez, Raul Medina, Inigo J .Losada. ... Adv. Comput. Math. 11, pp 193-210.G. Eason, B. Noble, and IN Sneddon, “On certain integrals of Lipschitz-Hankel type involving products of Bessel functions,” Phil. Trans. Roy. Soc. ...

Ocean Dynamics, 2014

The description of wave climate at a local scale is of paramount importance for offshore and coas... more The description of wave climate at a local scale is of paramount importance for offshore and coastal engineering applications. Conditions influencing wave characteristics at a specific location cannot, however, be fully understood by studying only local information. It is necessary to take into account the dynamics of the ocean surface over a large 'upstream' wave generation area. The goal of this work is to provide a methodology to easily characterize the area of influence of any particular ocean location worldwide. Moreover, the developed method is able to characterize the wave energy and travel time in that area. The method is based on a global scale analysis using both geographically and physically based criteria. The geographic criteria rely on the assumption that deep water waves travel along great circle paths. This limits the area of influence by neglecting energy that cannot reach a target point, as its path is blocked by land. The individual spectral partitions from a global wave reanalysis are used to reconstruct the spectral information and apply the physically based criteria. The criteria are based on the selection of the fraction of energy that travels towards the target point for each analysed grid point. The method has been tested on several locations worldwide. Results provide maps that inform about the relative importance of different oceanic areas to the local wave climate at any target point. This information cannot be inferred from local parameters and agrees with information from other approaches. The methodology may be useful in a number of applications, such as statistical downscaling, storm tracking and grid definition in numerical modelling.

OCEANS 2010 MTS/IEEE SEATTLE, 2010

Recent studies reveal important trends in mean values, high percentiles and extreme events of sig... more Recent studies reveal important trends in mean values, high percentiles and extreme events of significant wave height (SWH) in the northeast (NE) Pacific using buoy measurements. However, the spatial variability of these trends has not been well addressed since the sparse and uneven coverage of wave buoys makes it difficult to assess spatial patterns. In this work, we analyze the

Weather and Forecasting, 2014

This paper presents a detailed hindcast for the generation and propagation of sea state variables... more This paper presents a detailed hindcast for the generation and propagation of sea state variables-significant wave height H s , peak period T p , mean direction u, and spectral shape g -s -associated with cyclonic events to numerically diagnose their possible hydrodynamic effects over the northeastern Atlantic. An example of such cyclonic events is Hurricane Gordon, which occurred during the second half of August 2012. Extreme hurricane-strength winds produced new and atypically low-frequency (about 14 s) packs of energy. The preexistent wave spectrum suddenly experienced an addition of low-frequency energy along the coast of C adiz, Spain. This study presents the results of a comprehensive analysis developed to reconstruct the events produced by Hurricane Gordon (2012) along the coast of C adiz. The analysis features the use of (i) parametric models for the characterization of hurricane winds and pressure fields, (ii) implementation of the Simulating Waves Nearshore (SWAN) model for the generation and propagation of waves in the northeast Atlantic Ocean, and (iii) its coupling with the MOPLA-taken from the Spanish acronym for wave propagation model, current, and morphodynamic evolution of beaches-model for the evaluation of longshore currents. The numerical wave characterization, generation, and propagation were validated with instrumental data from deep-water and coastal buoys.

Journal of Geophysical Research, 2006

1] Recent evidence suggests long-term changes in the intensity and frequency of extreme wave clim... more 1] Recent evidence suggests long-term changes in the intensity and frequency of extreme wave climate around the globe. These changes may be attributable to global warming as well as to the natural climate variability. A statistical model to estimate long-term trends in the frequency and intensity of severe storm waves is presented in this paper. The model is based on a time-dependent version of the Peak Over Threshold model and is applied to the Washington NOAA buoy (46005) significant wave height data set. The model allows consideration of the annual cycle, trends, and relationship to atmosphereocean-related indices. For the particular data set analyzed the inclusion of seasonal variability substantially improves the correlation between the model and the data. Also, significant correlations with the Pacific-North America pattern, as well as long-term trend, are detected. Results show that the model is appropriate for a rigorous analysis of long-term trends and variability of extreme waves and for providing time-dependent quantiles and confidence intervals. Citation: Méndez, F. J., M. Menéndez, A. Luceño, and I. J. Losada (2006), Estimation of the long-term variability of extreme significant wave height using a time-dependent Peak Over Threshold (POT) model,

Continental Shelf Research, 2008

In the last years, new tools have been developed to describe wave climate. In particular, wave hi... more In the last years, new tools have been developed to describe wave climate. In particular, wave hindcast models allow a very detailed description in time and space. However, the data bases generated from these models require calibration with instrumental observations. In this work, a methodology for spatial calibration of wave hindcast data bases is developed. It is based on an Empirical Orthogonal Function decomposition and a non-linear transformation of the spatial–time modes. The method is applied to monthly long-term distribution of significant wave height in the Western Mediterranean. The calibration (transformation of the modes) is carried out using existing buoys in the area. After calibration, the validation with satellite data shows that this methodology is useful to better define wave climate from hindcast data bases.

Coastal Engineering, 2004

... Fernando J Mendez Corresponding Author Contact Information , E-mail The Corresponding Author ... more ... Fernando J Mendez Corresponding Author Contact Information , E-mail The Corresponding Author , Inigo J Losada, Raul Medina. ... The bore approach for random waves (fi [Battjes and Janssen, 1978] and [Thornton and Guza, 1983] ) or dissipation proportional to the difference ...

Coastal Engineering, 2007

A model for the depth-limited distribution of the highest wave in a sea state is presented. The d... more A model for the depth-limited distribution of the highest wave in a sea state is presented. The distribution for the extreme wave height is based on a probability density function (pdf) for depth-limited wave height distribution for individual waves [Méndez, F.J., Losada, I.J., . Transformation model of wave height distribution. Coastal Eng, Vol. 50, 97:115.] and considers the correlation between consecutive waves. The model is validated using field data showing a good representation of the extreme wave heights in the surf zone. Some important statistical wave heights are parameterized obtaining useful expressions that can be used in further calculations.

Coastal Engineering, 2011

Long-term time series of sea state parameters are required in different coastal engineering appli... more Long-term time series of sea state parameters are required in different coastal engineering applications. In order to obtain wave data at shallow water and due to the scarcity of instrumental data, ocean wave reanalysis databases ought to be downscaled to increase the spatial resolution and simulate the wave transformation process. In this paper, a hybrid downscaling methodology to transfer wave climate to coastal areas has been developed combining a numerical wave model (dynamical downscaling) with mathematical tools (statistical downscaling). A maximum dissimilarity selection algorithm (MDA) is applied in order to obtain a representative subset of sea states in deep water areas. The reduced number of selected cases spans the marine climate variability, guaranteeing that all possible sea states are represented and capturing even the extreme events. These sea states are propagated using a state-of-the-art wave propagation model. The time series of the propagated sea state parameters at a particular location are reconstructed using a non-linear interpolation technique based on radial basis functions (RBFs), providing excellent results in a high dimensional space with scattered data as occurs in the cases selected with MDA. The numerical validation of the results confirms the ability of the developed methodology to reconstruct sea state time series in shallow water at a particular location and to estimate different spatial wave climate parameters with a considerable reduction in the computational effort.

Coastal Engineering, 2006

Coastal Engineering, 2013

ABSTRACT A coastal structure is usually designed with the final objective to guarantee its functi... more ABSTRACT A coastal structure is usually designed with the final objective to guarantee its functionality and stability throughout its life cycle. Regarding stability, the three main failure modes are sliding, overturning and failure of the foundations. To accomplish the design objectives, a design sea state is usually used when calculating the loads and scour around the structure. This design sea state corresponds to a certain sea state with specific return period values of a significant wave height. However, the combination of different simultaneous sea state parameters can produce other critical situations compromising the stability of the structure which then require the calculation of long time series of wave forces corresponding to long-term historical wave situations. Moreover, a design force associated to a certain return period can be defined from the time series of the stability parameters. The most accurate techniques which can be used to estimate structure stability are based on numerical and physical models, but these are very time consuming and the calculation of long time series is therefore unfeasible. Here, we propose a hybrid methodology to transform wave conditions into wave forces acting upon vertical structures and scour around it. The methodology consists of a selection of a subset of sea states representative of wave climate at the structure location, using a maximum dissimilarity algorithm, The wave forces acting upon the structure and scour around it, for the wave situations selected, are then estimated as is the reconstruction of the calculated parameters corresponding to historical sea states using an interpolation technique based on radial basis function. The validation of the results, through a direct comparison between reconstructed series and analytically (semi-empirical formulations) calculated ones, confirms the ability of the developed methodology to reconstruct time series of stability parameters on vertical breakwaters. This methodology allows its application to numerical and physical models.

Journal of High Energy Physics, 2003

Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of q... more Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of quantum field theory based on the concept of ``noncommutative fields''. Our description permits to break the usual particle-antiparticle degeneracy at the dispersion relation level and introduces naturally an ultraviolet and an infrared cutoff. Phenomenological bounds for these new energy scales are given.

Coastal Engineering, 2004

A simple and innovative method to solve explicitly the dispersion equation for water waves over d... more A simple and innovative method to solve explicitly the dispersion equation for water waves over dissipative media is presented. The roots of this equation are themselves complex and difficult to obtain by standard numerical methods. A general structure for the dispersion relation is given, the dimensionless wave number, x, depending on the value of a dissipation parameter, φ, which is a function of the dissipative medium. Based on the hypothesis that a small perturbation in the dissipation parameter, δφ, produces a small variation in the dimensionless wave number, δx, a simple approach is proposed to calculate explicitly in an iterative manner the complex roots. The new method improves upon the unreliability of standard numerical schemes in the calculation of the roots in dissipative media.

Analogies between the noncommutative harmonic oscillator and noncommutative fields are analyzed. ... more Analogies between the noncommutative harmonic oscillator and noncommutative fields are analyzed. Following this analogy we construct examples of quantum fields theories with explicit CPT and Lorentz symmetry breaking. Some applications to baryogenesis and neutrino oscillation are also discussed

Global and Planetary Change, 2014

International surfing destinations are highly dependent on specific combinations of wind-wave for... more 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.

OCEANS 2010 MTS/IEEE SEATTLE, 2010

ABSTRACT A global framework, than can be applied worldwide, has been developed to determine waver... more ABSTRACT A global framework, than can be applied worldwide, has been developed to determine waver energy resources at shallow water with high spatial and long temporal resolution in order to analyze the seasonality, interannual variability (correlation of wave power with climate-related indices, such as the North Atlantic Oscillation) and spatial long-term trends along the Spanish coast. The proposed methodology combines instrumental and numerical databases, wave numerical models (dynamical downscaling) and sophisticated mathematical tools (statistical downscaling), which includes a selection algorithm and an interpolation technique to reconstructed time series. The validation of the results in deep water and coastal buoys locations confirm the ability of the methodology developed.

Coastal Engineering, 2015

This study presents a comprehensive methodology for the reanalysis, characterization and propagat... more This study presents a comprehensive methodology for the reanalysis, characterization and propagation of wave bound infragravity waves (1/300 Hz to 1/30 Hz) in the nearshore. A deep water short wave reanalysis has been modified analytically to include the energy input associated with infragravity waves (full spectrum), through the decomposition and energy balance of the radiation stress of waves in deep water. A hybrid clustering-numerical wave propagation downscaling technique was used, forced by the modified full wave spectra previously obtained, resulting in hourly series of high spatial resolution nearshore ocean waves, including short and bound long waves. The methodology has been applied to the northern coast of Spain and validated by comparing buoy and pressure gauge records in the coast, for short wave (agitation) and infragravity wave (resonance) responses in open harbours, with very satisfactory results.

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

Coastal Engineering 2004 - Proceedings of the 29th International Conference, 2005

Coastal Engineering 2006 - Proceedings of the 30th International Conference, 2007

This paper presents a statistical model to characterize the long-term extreme value distribution ... more This paper presents a statistical model to characterize the long-term extreme value distribution of significant wave height, conditioning to the duration of the storm and accounting for seasonality. A time-dependent version of the peak over threshold (POT) approach is used to build the model, which is then applied to specific reanalysis time series and NOAA buoy records. The model considers the annual and semiannual cycles which are parameterized in terms of harmonic functions. The inclusion of seasonal variabilities substantially reduces the residuals of the fitted model. The information obtained in this study can be useful to design maritime works, because (a) the model improves the understanding of the variability of extreme wave climate along a year and (b) the model accounts for the duration of the storm, which is a key parameter in several formulations for rubble mound breakwater design. r

OCEANS 2011 IEEE - Spain, 2011

... Paula Camus, Antonio Tomas, Cesar Vidal, Fernando J. Mendez, Raul Medina, Inigo J .Losada. ..... more ... Paula Camus, Antonio Tomas, Cesar Vidal, Fernando J. Mendez, Raul Medina, Inigo J .Losada. ... Adv. Comput. Math. 11, pp 193-210.G. Eason, B. Noble, and IN Sneddon, “On certain integrals of Lipschitz-Hankel type involving products of Bessel functions,” Phil. Trans. Roy. Soc. ...

Ocean Dynamics, 2014

The description of wave climate at a local scale is of paramount importance for offshore and coas... more The description of wave climate at a local scale is of paramount importance for offshore and coastal engineering applications. Conditions influencing wave characteristics at a specific location cannot, however, be fully understood by studying only local information. It is necessary to take into account the dynamics of the ocean surface over a large 'upstream' wave generation area. The goal of this work is to provide a methodology to easily characterize the area of influence of any particular ocean location worldwide. Moreover, the developed method is able to characterize the wave energy and travel time in that area. The method is based on a global scale analysis using both geographically and physically based criteria. The geographic criteria rely on the assumption that deep water waves travel along great circle paths. This limits the area of influence by neglecting energy that cannot reach a target point, as its path is blocked by land. The individual spectral partitions from a global wave reanalysis are used to reconstruct the spectral information and apply the physically based criteria. The criteria are based on the selection of the fraction of energy that travels towards the target point for each analysed grid point. The method has been tested on several locations worldwide. Results provide maps that inform about the relative importance of different oceanic areas to the local wave climate at any target point. This information cannot be inferred from local parameters and agrees with information from other approaches. The methodology may be useful in a number of applications, such as statistical downscaling, storm tracking and grid definition in numerical modelling.

OCEANS 2010 MTS/IEEE SEATTLE, 2010

Recent studies reveal important trends in mean values, high percentiles and extreme events of sig... more Recent studies reveal important trends in mean values, high percentiles and extreme events of significant wave height (SWH) in the northeast (NE) Pacific using buoy measurements. However, the spatial variability of these trends has not been well addressed since the sparse and uneven coverage of wave buoys makes it difficult to assess spatial patterns. In this work, we analyze the

Weather and Forecasting, 2014

This paper presents a detailed hindcast for the generation and propagation of sea state variables... more This paper presents a detailed hindcast for the generation and propagation of sea state variables-significant wave height H s , peak period T p , mean direction u, and spectral shape g -s -associated with cyclonic events to numerically diagnose their possible hydrodynamic effects over the northeastern Atlantic. An example of such cyclonic events is Hurricane Gordon, which occurred during the second half of August 2012. Extreme hurricane-strength winds produced new and atypically low-frequency (about 14 s) packs of energy. The preexistent wave spectrum suddenly experienced an addition of low-frequency energy along the coast of C adiz, Spain. This study presents the results of a comprehensive analysis developed to reconstruct the events produced by Hurricane Gordon (2012) along the coast of C adiz. The analysis features the use of (i) parametric models for the characterization of hurricane winds and pressure fields, (ii) implementation of the Simulating Waves Nearshore (SWAN) model for the generation and propagation of waves in the northeast Atlantic Ocean, and (iii) its coupling with the MOPLA-taken from the Spanish acronym for wave propagation model, current, and morphodynamic evolution of beaches-model for the evaluation of longshore currents. The numerical wave characterization, generation, and propagation were validated with instrumental data from deep-water and coastal buoys.

Journal of Geophysical Research, 2006

1] Recent evidence suggests long-term changes in the intensity and frequency of extreme wave clim... more 1] Recent evidence suggests long-term changes in the intensity and frequency of extreme wave climate around the globe. These changes may be attributable to global warming as well as to the natural climate variability. A statistical model to estimate long-term trends in the frequency and intensity of severe storm waves is presented in this paper. The model is based on a time-dependent version of the Peak Over Threshold model and is applied to the Washington NOAA buoy (46005) significant wave height data set. The model allows consideration of the annual cycle, trends, and relationship to atmosphereocean-related indices. For the particular data set analyzed the inclusion of seasonal variability substantially improves the correlation between the model and the data. Also, significant correlations with the Pacific-North America pattern, as well as long-term trend, are detected. Results show that the model is appropriate for a rigorous analysis of long-term trends and variability of extreme waves and for providing time-dependent quantiles and confidence intervals. Citation: Méndez, F. J., M. Menéndez, A. Luceño, and I. J. Losada (2006), Estimation of the long-term variability of extreme significant wave height using a time-dependent Peak Over Threshold (POT) model,

Continental Shelf Research, 2008

In the last years, new tools have been developed to describe wave climate. In particular, wave hi... more In the last years, new tools have been developed to describe wave climate. In particular, wave hindcast models allow a very detailed description in time and space. However, the data bases generated from these models require calibration with instrumental observations. In this work, a methodology for spatial calibration of wave hindcast data bases is developed. It is based on an Empirical Orthogonal Function decomposition and a non-linear transformation of the spatial–time modes. The method is applied to monthly long-term distribution of significant wave height in the Western Mediterranean. The calibration (transformation of the modes) is carried out using existing buoys in the area. After calibration, the validation with satellite data shows that this methodology is useful to better define wave climate from hindcast data bases.

Coastal Engineering, 2004

... Fernando J Mendez Corresponding Author Contact Information , E-mail The Corresponding Author ... more ... Fernando J Mendez Corresponding Author Contact Information , E-mail The Corresponding Author , Inigo J Losada, Raul Medina. ... The bore approach for random waves (fi [Battjes and Janssen, 1978] and [Thornton and Guza, 1983] ) or dissipation proportional to the difference ...

Coastal Engineering, 2007

A model for the depth-limited distribution of the highest wave in a sea state is presented. The d... more A model for the depth-limited distribution of the highest wave in a sea state is presented. The distribution for the extreme wave height is based on a probability density function (pdf) for depth-limited wave height distribution for individual waves [Méndez, F.J., Losada, I.J., . Transformation model of wave height distribution. Coastal Eng, Vol. 50, 97:115.] and considers the correlation between consecutive waves. The model is validated using field data showing a good representation of the extreme wave heights in the surf zone. Some important statistical wave heights are parameterized obtaining useful expressions that can be used in further calculations.

Coastal Engineering, 2011

Long-term time series of sea state parameters are required in different coastal engineering appli... more Long-term time series of sea state parameters are required in different coastal engineering applications. In order to obtain wave data at shallow water and due to the scarcity of instrumental data, ocean wave reanalysis databases ought to be downscaled to increase the spatial resolution and simulate the wave transformation process. In this paper, a hybrid downscaling methodology to transfer wave climate to coastal areas has been developed combining a numerical wave model (dynamical downscaling) with mathematical tools (statistical downscaling). A maximum dissimilarity selection algorithm (MDA) is applied in order to obtain a representative subset of sea states in deep water areas. The reduced number of selected cases spans the marine climate variability, guaranteeing that all possible sea states are represented and capturing even the extreme events. These sea states are propagated using a state-of-the-art wave propagation model. The time series of the propagated sea state parameters at a particular location are reconstructed using a non-linear interpolation technique based on radial basis functions (RBFs), providing excellent results in a high dimensional space with scattered data as occurs in the cases selected with MDA. The numerical validation of the results confirms the ability of the developed methodology to reconstruct sea state time series in shallow water at a particular location and to estimate different spatial wave climate parameters with a considerable reduction in the computational effort.

Coastal Engineering, 2006

Coastal Engineering, 2013

ABSTRACT A coastal structure is usually designed with the final objective to guarantee its functi... more ABSTRACT A coastal structure is usually designed with the final objective to guarantee its functionality and stability throughout its life cycle. Regarding stability, the three main failure modes are sliding, overturning and failure of the foundations. To accomplish the design objectives, a design sea state is usually used when calculating the loads and scour around the structure. This design sea state corresponds to a certain sea state with specific return period values of a significant wave height. However, the combination of different simultaneous sea state parameters can produce other critical situations compromising the stability of the structure which then require the calculation of long time series of wave forces corresponding to long-term historical wave situations. Moreover, a design force associated to a certain return period can be defined from the time series of the stability parameters. The most accurate techniques which can be used to estimate structure stability are based on numerical and physical models, but these are very time consuming and the calculation of long time series is therefore unfeasible. Here, we propose a hybrid methodology to transform wave conditions into wave forces acting upon vertical structures and scour around it. The methodology consists of a selection of a subset of sea states representative of wave climate at the structure location, using a maximum dissimilarity algorithm, The wave forces acting upon the structure and scour around it, for the wave situations selected, are then estimated as is the reconstruction of the calculated parameters corresponding to historical sea states using an interpolation technique based on radial basis function. The validation of the results, through a direct comparison between reconstructed series and analytically (semi-empirical formulations) calculated ones, confirms the ability of the developed methodology to reconstruct time series of stability parameters on vertical breakwaters. This methodology allows its application to numerical and physical models.

Journal of High Energy Physics, 2003

Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of q... more Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of quantum field theory based on the concept of ``noncommutative fields''. Our description permits to break the usual particle-antiparticle degeneracy at the dispersion relation level and introduces naturally an ultraviolet and an infrared cutoff. Phenomenological bounds for these new energy scales are given.