Numerical Analysis and Diagnosis of the Hydrodynamic Effects Produced by Hurricane Gordon along the Coast of Spain

This paper presents a detailed hindcast for the generation and propagation of sea state variables—significant wave heightHs, peak period Tp,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 Cadiz, Spain. This study presents the results of a comprehensive analysis developed to reconstruct the events produced by Hurricane Gordon (2012) along the coast of Cadiz. 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 theMOPLA—taken fromthe 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.This work was partially funded by projects ‘‘GRACCIE’’ (SD 2007- 00067, CONSOLIDER INGENIO2010) and ‘‘iMar21’’ (BiA2011-2890) from the Spanish government

Regression models for outlier identification (Hurricanes and typhoons) in wave hindcast databases

ABSTRACT: he development of numerical wave prediction models for hindcast applications allows a detailed description of wave climate in locations where long-term instrumental records are not available. Wave hindcast databases (WHDBs) have become a powerful tool for the design of offshore and coastal structures, offering important advantages for the statistical characterization of wave climate all over the globe (continuous time series, wide spatial coverage, constant time span, homogeneous forcing, and more than 60-yr-long time series). However, WHDBs present several deficiencies reported in the literature. One of these deficiencies is related to typhoons and hurricanes, which are inappropriately reproduced by numerical models. The main reasons are (i) the difficulty of specifying accurate wind fields during these events and (ii) the insufficient spatiotemporal resolution used. These difficulties make the data related to these events appear as "outliers" when compared with instrumental records. These bad data distort results from calibration and/or correction techniques. In this paper, several methods for detecting the presence of typhoons and/or hurricane data are presented, and their automatic outlier identification capabilities are analyzed and compared. All the methods are applied to a global wave hindcast database and results are compared with existing hurricane and buoy databases in the Gulf of Mexico, Caribbean Sea, and North Atlantic Ocean

Preface Sea hazards

This Special Issue (SI) collects papers that were presented in different symposia related with sea hazards at the European Geosciences Union (EGU) General Assembly that was held in Vienna from 3-8 April 2011. Tsunamis are the most known and most disastrous sea hazards and can occur in all world oceans as well as in closed or almost closed seas like the Mediterranean. Interest in tsunamis has substantially increased in the last few years, especially after the case of the 2004 Indian Ocean tsunami that devastated the coasts of several near-field and far-field countries and that claimed a death toll of about 220 thousands human lives mostly in Indonesia, India, Sri Lanka and Thailand. Since then and even more after the big Japan tsunami of 11 March 2011, the issues of what we can learn from past experiences and of how coastal communities can be protected from the attack of catastrophic tsunamis have become of paramount importance. This SI collects a number of papers on the Tohoku tsunami that address different aspects of this event and papers on how to improve the response promptness and accuracy of the Tsunami Early Warning Systems. The SI addresses further the topic of rogue waves providing new contributions to the experimental and theoretical work that has been done in the last years. The third main topic of the SI regards sea level rise, storm surges and coastal floods that are subjects of particular interest to researchers, planners, and disaster control managers, since this type of natural hazard can represent an enormous threat to human life and economic assets

Global extreme wave height variability based on satellite data

ABSTRACT: The spatial and temporal variability of the extreme significant wave height (SWH) in the ocean is presented. The study has been performed using a highly reliable dataset from several satellite altimeter missions, which provide a good worldwide coverage for the period 1992 onwards. A non-stationary extreme value analysis, which models seasonality and interannual variations, has been applied to characterize the extreme SWH. The interannual variability is explained through variations in the atmosphere and ocean systems, represented by different climate indices, allowing a quantitative contribution of the climate-related patterns. Results demonstrate the strong relationship between the interannual variability of extreme SWH and different ocean and atmosphere variations. A contribution of the AO and NAO indices in the North Atlantic ocean (e.g., every positive unit of the AO explains up to 70 cm of extreme wave height south of Iceland), the NINO3 in the Pacific (every negative unit of NINO3 explains up to 60 cm of extreme wave height in the Drake Passage), the SAM in the Southern ocean and the DMI in the Indian ocean reveal these climate patterns as the most relevant in the interannual extreme wave climate.The work was partially funded by projects “GRACCIE” (CSD2007‐00067, CONSOLIDER‐INGENIO 2010) from the Spanish Ministry of Science and Technology, “MARUCA” (200800050084091) from the Spanish Ministry of Public Works and “C3E” (E17/08) from the Spanish Ministry of Environment, Rural and Marine Affairs

Análisis numérico del huracán Gordon y diagnóstico de sus efectos hidrodinámicos en las costas de Cádiz.

El objetivo del estudio es evaluar numéricamente el comportamiento espacio-temporal de las variables medioambientales oceánicas (altura de ola significante Hs, periodo de pico Tp, dirección media ? y forma espectral y), su generación y propagación, asociados al huracán Gordon, acontecido durante la segunda mitad del mes de agosto de 2012, con el objetivo general de poder realizar un diagnostico de los efectos hidrodinámicos de este evento ciclónico sobre las costas de Cádiz, España. La acción de los vientos extremales asociados al huracán sobre la superficie del océano, fomentaron la adición de energía en frecuencias atípicamente bajas del espectro del oleaje (alrededor de 14 s), en la zona costera de Cádiz. Este efecto se tradujo en la creación de una componente de mar de fondo que llego a acoplarse con el oleaje preexistente en la zona, llegando a inducir un importante y súbito aumento en las corrientes costeras del litoral Gaditano. En el presente estudio se presentan los resultados de un análisis integral para analizar los eventos relacionados a la generación del oleaje y su propagación hacia las costas de Cádiz, en relación con el paso del huracán Gordon (2012). A través del empleo de la modelación numérica de la generación, propagación e interacción del oleaje en costa en el dominio oceánico del Atlántico Nororiental

Análisis numérico del huracán Gordon y diagnóstico de sus efectos hidrodinámicos en las costas de Cádiz.

El objetivo del estudio es evaluar numéricamente el comportamiento espacio-temporal de las variables medioambientales oceánicas (altura de ola significante Hs, periodo de pico Tp, dirección media ? y forma espectral y), su generación y propagación, asociados al huracán Gordon, acontecido durante la segunda mitad del mes de agosto de 2012, con el objetivo general de poder realizar un diagnostico de los efectos hidrodinámicos de este evento ciclónico sobre las costas de Cádiz, España. La acción de los vientos extremales asociados al huracán sobre la superficie del océano, fomentaron la adición de energía en frecuencias atípicamente bajas del espectro del oleaje (alrededor de 14 s), en la zona costera de Cádiz. Este efecto se tradujo en la creación de una componente de mar de fondo que llego a acoplarse con el oleaje preexistente en la zona, llegando a inducir un importante y súbito aumento en las corrientes costeras del litoral Gaditano. En el presente estudio se presentan los resultados de un análisis integral para analizar los eventos relacionados a la generación del oleaje y su propagación hacia las costas de Cádiz, en relación con el paso del huracán Gordon (2012). A través del empleo de la modelación numérica de la generación, propagación e interacción del oleaje en costa en el dominio oceánico del Atlántico Nororiental

Multivariate wave climate using self-organizing maps

ABSTRACT: The visual description of wave climate is usually limited to two-dimensional conditional histograms. In this work, self-organizing maps (SOMs), because of their visualization properties, are used to characterize multivariate wave climate. The SOMs are applied to time series of sea-state parameters at a particular location provided by ocean reanalysis databases. Trivariate (significant wave height, mean period, and mean direction), pentavariate (the previous wave parameters and wind velocity and direction), and hexavariate (three wave parameters of the sea and swell components; or the wave, wind, and storm surge) classifications are explored. This clustering technique is also applied to wave and wind data at several locations to analyze their spatial relationship. Several processes are established in order to improve the results, the most relevant being a preselection of data by means a maximum dissimilarity algorithm (MDA). Results show that the SOM identifies the relevant multivariate sea-state types at a particular location spanning the historical variability, and provides an outstanding analysis of the dependency between the different parameters by visual inspection. In the case of wave climate characterizations for several locations the SOM is able to extract the qualitative spatial sea-state patterns, allowing the analysis of the spatial variability and the relationship between different locations. Moreover, the distribution of sea states over the reanalysis period defines a probability density function on the lattice, providing a visual interpretation of the seasonality and interannuality of the multivariate wave climate.The work was partially funded by projects GRACCIE (CSD2007-00067, CONSOLIDERINGENIO 2010) from the Spanish Ministry of Science and Technology, MARUCA(200800050084091) from the Spanish Ministry of Public Works, and C3E(E17/08) from the Spanish Ministry of Environment, Rural and Marine Environs. The authors thank Puertos del Estado (Spanish Ministry of Public Works) for providing the reanalysis database

Extreme wave climate variability in southern Europe using satellite data

ABSTRACT: A time-dependent generalized extreme value (GEV) model for monthly significant wave height maxima from satellite databases is used to model the seasonal and interannual variability of the extreme wave climate throughout southern Europe. In order to avoid a misleading use of the maxima time series, the classical extreme value model has been modified to cope with nonhomogeneous monthly observations. Seasonality is represented using intraannual harmonic functions in the model, while interannual variability is modeled including North Atlantic and Mediterranean regional scale sea level pressure predictors, such as the North Atlantic Oscillation (NAO), the east Atlantic (EA), or the east Atlantic/western Russian (EA/WR) patterns. The results quantify the strong spatial variability detected in the seasonal location and scale GEV parameters. In general, prominent zonal (west-east) and meridional (north-south) gradients of these location and scale parameters reveal the predominance of low-pressure centers located in the NAO region (e.g., a gradient of 4 m for the location parameter and 1.5 units for the scale parameter between north-south is shown in the month of September). The model also quantifies the influence of regional climate patterns on extreme wave climate. Results show a great influence of NAO and EA on the Atlantic basin (e.g., every unit of the monthly NAO index explains 25 cm of the extreme wave height in the Gulf of Biscay and the EA index explains 20 cm) while the negative phases of EA/WR contribute greatly to the western Mediterranean basin.The work was partially funded by projects “GRACCIE” (CSD2007–00067, CONSOLIDER‐INGENIO 2010) from the Spanish Ministry of Ciencia e Innovación, “MARUCA” from the Spanish Ministry of Fomento and “C3E” from the Spanish Ministry of Environment, Rural and Marine Affairs. Alberto Luceño acknowledges the support of the Spanish Dirección General de Investigación under grant MTM2008– 00759. The authors wish to thank the two anonymous reviewers for their constructive comments that helped to improve the manuscript

Wind wave footprint of tropical cyclones from satellite data

ABSTRACT: Tropical cyclones are associated with extreme winds, waves, and storm surge, being among most destructive natural phenomena. Developing capability for a rapid impact estimate is crucial for coastal applications and risk preparedness. When predicting waves characteristics associated to tropical cyclones, the traditional approach involves a two-step procedure (a) a Holland-type wind vortex model and (b) numerical simulations using a wave generation model, using buoy and satellite measurements for validation. In this work, we take advantage of the increasing amount of remote sensing observational data and propose a new empirical model to estimate the wind wave footprint of tropical cyclones. For this purpose, we construct a dataset with over a million satellite observations of waves triggered by tropical cyclones assuming a circular shape of the TC influence area and defining composites of significant wave height as a function of representative parameters of the track characteristics like the minimum pressure, its forward velocity, and its latitude. The validation against buoy data confirms the usefulness of the model for a first and rapid estimation of the wave footprint, although an underestimation of the most extreme events is observed due to the relatively small number of observations recorded. Due to its efficiency, the model can be applied for rapid estimations of wave footprints in operational systems, reconstruction of historical or synthetic events and risk assessments.This work would not have been possible without funding from the Strategic Environmental Research and Development Program's grant DOD/SERDP RC-2644 and from the Spanish Ministry of Science and Innovation, project Beach4cast PID2019-107053RB-I00. Ana Rueda funded by a Juan de la Cierva Incorporación Scholarship (IJC2020-04390). Laura Cagigal is funded by a scholarship from the University of Auckland. Open access publishing facilitated by The University of Auckland, as part of the Wiley - The University of Auckland agreement via the Council of Australian University Librarians