Suchergebnisse

Violence and instability, punctuated by terrorism and subversion, characterize political life in many nations today. Throughout most of the postwar period few countries, and this includes the liberal democracies, have been spared the many faces of violence and terrorism, whether from the Left, the Right, or both.
With the continuing spread of terror and counterterror, with increasing violence and instability, personal insecurity and fear become widespread. Then hard-won gains in human rights come under heavy attack. In this situation violence and terror become self-justifying because through them society will be purged of its alleged evils. Or so it is argued.
Yet the moral conscience of the Americas originates in, and is built upon, respect for human rights. Our Hemisphere differs in a privileged way from other regions of the globe in that this is the guiding principle under which our nations came into being.

9 pages, 7 figures. ; [EN]We studied the influence of the topography on the oceanic response to a traveling atmospheric disturbance and the relevance of its propagation direction on the generation of seiche oscillations. A primitive equation ocean model was used to analyze the response of two harbors located in insular systems to a pressure disturbance. The spectral component at the frequency of fundamental harbor resonance was determined from these data for different propagation directions of the incoming atmospheric disturbance. A conceptual model of interferences of resonantly generated ocean waves was introduced in order to explain energy maxima obtained by the numerical model close to the most affected areas. ; [ES]En este trabajo estudiamos la influencia de la topografía en la respuesta oceánica generada por una perturbación atmosférica en movimiento y la importancia de la dirección de propagación de ésta en la generación de meteotsunamis. Para ello, se analiza la respuesta de la superficie del mar en la bocana de dos puertos ubicados en sistemas insulares utilizando un modelo de circulación de ecuaciones primitivas. Para diferentes ángulos de incidencia de la perturbación atmosférica, se estudia la amplitud de la respuesta espectral a la frecuencia de resonancia de cada uno de los puertos. Los resultados numéricos proporcionan amplificaciones máximas en cada uno de los puertos para ángulos que concuerdan con las observaciones. ; The authors are grateful for financial support from the Spanish MICINN through the projects CTM2006-12072 and CTM2010-16915, and from the Port de les Balears (Balearic Islands Government). Comments from Drs. S. Monserrat, M. Olabarrieta, J. Tintore and M. Marcos are greatly acknowledged. Kind advice from Dr. I. Vilibic and an anonymous referee helped to improve the final version of the manuscript. ; Peer reviewed

The system described employs a nonlinear forecasting technique based on a combination of genetic algorithms and empirical orthogonal function (EOF) analysis. The genetic algorithm identifies the equations that best describe the behaviour of the different temporal orthogonal functions in the EOF decomposition and therefore, enables global forecasting of future time variability. The method is applied to obtain a one-month ahead forecast of the monthly mean space-time variability of the sea surface temperature (SST) of the Tuscan Archipelago, northwest coast of Italy. The system performance has been validated comparing forecast fields with real satellite observations. Results indicate that the system provides better predictions than those based on climatology. Future research is oriented to make the system applicable to military operations, environmental control and fisheries activities. ; The work has been supported by the North Atlantic Treaty Organization and the EVK3-CT-2000-00028 European Project ; Peer Reviewed

© 2015 Elsevier Ltd. This work studies the wave energy availability in the Western Mediterranean Sea using wave simulation from January 1983 to December 2011. The model implemented is the WAM, forced by the ECMWF ERAInterim wind fields. The Advanced Scatterometer (ASCAT) data from MetOp satellite and the TOPEX-Poseidon altimetry data are used to assess the quality of the wind fields and WAM results respectively. Results from the hindcast are the starting point to analyse the potentiality of obtaining wave energy around the Balearic Islands Archipelago. The comparison of the 29 year hindcast against wave buoys located in Western, Central and Eastern basins shows a high correlation between the hindcasted and the measured significant wave height (H s ), indicating a proper representation of spatial and temporal variability of H s . It is found that the energy flux at the Balearic coasts range from 9.1 kW/m, in the north of Menorca Island, to 2.5 kW/m in the vicinity of the Bay of Palma. The energy flux is around 5 and 6 times lower in summer as compared to winter ; GS is supported from the Spanish Government through the Ramon y Cajal program ; Peer reviewed

Post print. -- 32 páginas, 13 figuras, 5 tablas ; A fully nonlinear Boussinessq-type model with several free coefficients is considered as a departure point. The model is monolayer and low order so as to simplify numerical solvability. The coefficients of the model are here considered functions of the local water depth. In doing so, we allow to improve the dispersive and shoaling properties for narrow banded wave trains in very deep waters. In particular, for monochromatic waves the dispersion and shoaling errors are bounded by ~ 2.8% up to kh = 100, being k the wave number and h the water depth. The proposed model is fully nonlinear in weakly dispersive conditions, so that nonlinear wave decomposition in shallower waters is well reproduced. The model equations are numerically solved using a fourth order scheme and tested against analytical solutions and experimental data ; Authors would like to thank support from MICINN through Project 445 CGL2011-22964. G. Simarro and R. Minguez are supported by the Spanish government through the "Ramón y Cajal" program ; Peer reviewed

Abstract. Every year the Caribbean Sea faces the passage of several tropical cyclones that generate coastal extreme sea levels with potential strong and hazardous impacts. In this work we simulate the storm surges and wind waves induced by a set of 1000 tropical cyclones over the Caribbean Sea that are representative of the present-day climate. These events have been extracted from a global database of synthetic tropical cyclones spanning a 10 000-year period. The atmospheric forcing fields, associated with the set of tropical cyclones, are used to feed a coupled hydrodynamic–wave model with high resolution (∼ 2 km) along the continental and island coasts. Given the large number of events modelled, our results allow detailed statistical analyses of the magnitude and mechanisms of coastal extreme sea levels, as well as the identification of one of the most exposed areas to both storm surges and extreme wind waves.

24 pages, 15 figures, 9 tables, 1 appendix ; A new approach to infer the bathymetry from coastal video monitoring systems is presented. The methodology uses principal component analysis of the Hilbert transform of video images to obtain the components of the wave propagation field and their corresponding frequency and wavenumber. Incident and reflected constituents and subharmonics components are also found. Local water depth is then successfully estimated through wave dispersion relationship. The method is first applied to monochromatic and polychromatic synthetic wave trains propagated using linear wave theory over an alongshore uniform bathymetry in order to analyze the influence of different parameters on the results. To assess the ability of the approach to infer the bathymetry under more realistic conditions and to explore the influence of other parameters, nonlinear wave propagation is also performed using a fully nonlinear Boussinesq-type model over a complex bathymetry. In the synthetic cases, the relative root mean square error obtained in bathymetry recovery (for water depths 0.75m⩽h⩽8.0m ) ranges from ∼1% to ∼3% for infinitesimal-amplitude wave cases (monochromatic or polychromatic) to ∼15% in the most complex case (nonlinear polychromatic waves). Finally, the new methodology is satisfactorily validated through a real field site vide ; This research was funded by the Spanish Government (MINECO/MICINN/FEDER) grant numbers CTM2015-66225-C2-1-P, CTM2015-66225-C2-2-P, RTI2018-093941-B-C31, RTI2018-093941-B-C32, and RTI2018-093941-B-C33 ; Peer Reviewed

Presentation given at the 11th River, Coastal and Estuarine Morphodynamics Symposium, held on November 16-21th, 2019, in Auckland (Australia). ; Scientists and managers of the coastal zone need to know the coastal bathymetry to understand the behaviour of the beaches and be able to predict their evolution. Intensive monitoring programs through campaigns of direct measurements of the bathymetry are excessively expensive, so that in the last decades alternative methodologies have been developed. Many of them are based on video monitoring stations, and among the different existing algorithms, cBathy (Holman et al., 2013) is the algorithm that achieves the best results. In a first step, cBathy gets the dominant frequencies and their corresponding wave numbers from the Cross Spectral Matrices (CSMs) of a given set of frequency bands. An estimation of the local water depth is then obtained from the dispersion equation. In the second step, the estimated bathymetries obtained for each video are smoothed through a Kalman filter to obtain the final hourly estimates. This algorithm, which has been used in a number of studies (e.g., Bergsma et al., 2016; Rutten et al., 2017) to obtain 2-D bathymetries, presents however some limitations and/or known problems that have been reported in the literature (Rutten et al., 2017). The work being presented here is an alternative to the first step of cBathy. It consists of performing a Principal Component Analysis (PCA) to the matrix made of pixel intensities from a series of snaps. The result of the PCA is the decomposition of the video into a set of modes associated with the components of the wave field. The spatial part (the Empirical Orthogonal Function, EOF), is associated with the spatial phase of the wave from which a wave number can be derived. The amplitude of the mode (Principal Component, PC) is associated with the frequency of the wave component. To facilitate the decomposition of the videos in modes of travelling waves, a Hilbert transformation in time of the matrix of intensities has been carried out. The objective of this work is to apply the PCA of video images to obtain beach bathymetries. To this end, videos from different camera/field sites have been used and the bathymetry derived from videos has been compared with direct measurements. It has been studied the influence on the results of: the image lighting, the camera position, wave characteristics and study area size. ; This research was partly funded by the Spanish Government projects CTM2015-66225-C2-1-P, and CTM2015-66225-C2-2-P (MINECO/FEDER).

Presentation given at the 11th River, Coastal and Estuarine Morphodynamics Symposium, held on November 16-21th, 2019, in Auckland (Australia). ; Scientists and managers of the coastal zone need to know the coastal bathymetry to understand the behaviour of the beaches and be able to predict their evolution. Intensive monitoring programs through campaigns of direct measurements of the bathymetry are excessively expensive, so that in the last decades alternative methodologies have been developed. Many of them are based on video monitoring stations, and among the different existing algorithms, cBathy (Holman et al., 2013) is the algorithm that achieves the best results. In a first step, cBathy gets the dominant frequencies and their corresponding wave numbers from the Cross Spectral Matrices (CSMs) of a given set of frequency bands. An estimation of the local water depth is then obtained from the dispersion equation. In the second step, the estimated bathymetries obtained for each video are smoothed through a Kalman filter to obtain the final hourly estimates. This algorithm, which has been used in a number of studies (e.g., Bergsma et al., 2016; Rutten et al., 2017) to obtain 2-D bathymetries, presents however some limitations and/or known problems that have been reported in the literature (Rutten et al., 2017). The work being presented here is an alternative to the first step of cBathy. It consists of performing a Principal Component Analysis (PCA) to the matrix made of pixel intensities from a series of snaps. The result of the PCA is the decomposition of the video into a set of modes associated with the components of the wave field. The spatial part (the Empirical Orthogonal Function, EOF), is associated with the spatial phase of the wave from which a wave number can be derived. The amplitude of the mode (Principal Component, PC) is associated with the frequency of the wave component. To facilitate the decomposition of the videos in modes of travelling waves, a Hilbert transformation in time of the matrix of intensities has been carried out. The objective of this work is to explore the feasibility of PCA of video images to obtain beach bathymetries. To this end, artificial videos have been generated by assigning pixel intensity to the elevation of the surface free of synthetic waves, both linear and nonlinear (Shi et al., 2012, for FUNWAVE), propagated over known bathymetries. ; This research was partly funded by the Spanish Government projects CTM2015-66225-C2-1-P, and CTM2015-66225-C2-2-P (MINECO/FEDER).

205 pages, 12 figures, 1 table, 3 appendixes.-- Data Availability Statement: All data are accessible from https://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=sfc/, https://www.cpc.ncep.noaa.gov/data/teledoc/telecontents.shtml and from https://resources.marine.copernicus.eu/?option=com_csw&view=details&product_id=SEALEVEL_MED_PHY_L4_REP_OBSERVATIONS_008_051 ; Effects of wind and waves on the surface dynamics of the Mediterranean Sea are assessed using a modified Ekman model including a Stokes-Coriolis force in the momentum equation. Using 25 years of observations, we documented intermittent but recurrent episodes during which Ekman and Stokes currents substantially modulate the total mesoscale dynamics by two nonexclusive mechanisms: (a) by providing a vigorous input of momentum (e.g., where regional winds are stronger) and/or (b) by opposing forces to the main direction of the geostrophic component. To properly characterize the occurrence and variability of these dynamical regimes, we perform an objective classification combining self-organizing maps and wavelet coherence analyses. It allows proposing a new regional classification of the Mediterranean Sea based on the respective contributions of wind, wave, and geostrophic components to the total mesoscale surface dynamics. We found that the effects of wind and waves are more prominent in the northwestern Mediterranean, while the southwestern and eastern basins are mainly dominated by the geostrophic component. The resulting temporal variability patterns show a strong seasonal signal and cycles of 5–6 years in the total kinetic energy arising from both geostrophic and ageostrophic components. Moreover, the whole basin, specially the regions characterized by strong wind- and wave-induced currents, shows a characteristic period of variability at 5 years. This can be related to climate modes of variability. Regional trends in the geostrophic and ageostrophic currents show an intensification of 0.058 ± 1.43 · 10−5 cm/s per year ; Authors acknowledge financial support from MINECO/FEDER through projects MOCCA (RTI2018-093941-B-C31) and from the Balearic Islands Goverment Project ADAPTA. V. Morales-Márquez is supported by an FPI grant from the Ministerio de Ciencia, Innovación y Universidades. I. Hernandez-Carrasco acknowledges the Vicenç Mut contract funded by the Government of the Balearic Island and the European Social Fund (ESF) Operational Programme and the financial support from the Fundacion Universidad Empresa de las Islas Baleares, Spain, through project ALERTA (REF-190121). V. Rossi acknowledges financial support from the European project SEAMoBB, funded by ERA-Net Mar-TERA and managed by ANR (number ANR_17_MART-0001_01, P.I.: A.C.). This work was partially performed while V. Morales-Márquez was staying in MIO (Marseille, France) with the support of FPI grant from the Ministerio de Ciencia, Innovación y Universidades. In addition, this work was carried out in part when A. Orfila was a visiting scientist at the Earth, Environmental and Planetary Sciences Department at Brown University through a Ministerio de Ciencia, Innovación y Universidades fellowship (PRX18/00218) ; With the institutional support of the 'Severo OchoaCentre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed