Tropical cyclone rainbands can trigger meteotsunamis

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Shi, L., Olabarrieta, M., Nolan, D. S., & Warner, J. C. Tropical cyclone rainbands can trigger meteotsunamis. Nature Communications, 11(1), (2020): 678, doi:10.1038/s41467-020-14423-9.Tropical cyclones are one of the most destructive natural hazards and much of the damage and casualties they cause are flood-related. Accurate characterization and prediction of total water levels during extreme storms is necessary to minimize coastal impacts. While meteotsunamis are known to influence water levels and to produce severe consequences, their impacts during tropical cyclones are underappreciated. This study demonstrates that meteotsunami waves commonly occur during tropical cyclones, and that they can contribute significantly to total water levels. We use an idealized coupled ocean–atmosphere–wave numerical model to analyze tropical cyclone-induced meteotsunami generation and propagation mechanisms. We show that the most extreme meteotsunami events are triggered by inherent features of the structure of tropical cyclones: inner and outer spiral rainbands. While outer distant spiral rainbands produce single-peak meteotsunami waves, inner spiral rainbands trigger longer lasting wave trains on the front side of the tropical cyclones.We thank all the developers of COAWST, ROMS, WRF, and SWAN models. D.N. was supported by NSF grant AGS-1654831. We would like to thank Dr. K. Bagamian for her editorial and writing suggestions. We would like to thank Dr. A. Aretxabaleta for the internal US Geological Survey internal revision and suggestions

The role of morphology and wave-current interaction at tidal inlets : an idealized modeling analysis

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8818–8837, doi:10.1002/2014JC010191.The outflowing currents from tidal inlets are influenced both by the morphology of the ebb-tide shoal and interaction with incident surface gravity waves. Likewise, the propagation and breaking of incident waves are affected by the morphology and the strength and structure of the outflowing current. The 3-D Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system is applied to numerically analyze the interaction between currents, waves, and bathymetry in idealized inlet configurations. The bathymetry is found to be a dominant controlling variable. In the absence of an ebb shoal and with weak wave forcing, a narrow outflow jet extends seaward with little lateral spreading. The presence of an ebb-tide shoal produces significant pressure gradients in the region of the outflow, resulting in enhanced lateral spreading of the jet. Incident waves cause lateral spreading and limit the seaward extent of the jet, due both to conversion of wave momentum flux and enhanced bottom friction. The interaction between the vorticity of the outflow jet and the wave stokes drift is also an important driving force for the lateral spreading of the plume. For weak outflows, the outflow jet is actually enhanced by strong waves when there is a channel across the bar, due to the “return current” effect. For both strong and weak outflows, waves increase the alongshore transport in both directions from the inlet due to the wave-induced setup over the ebb shoal. Wave breaking is more influenced by the topography of the ebb shoal than by wave-current interaction, although strong outflows show intensified breaking at the head of the main channel.We are grateful to the Career Training Interexchange program that facilitated the training period of Maitane Olabarrieta within the USGS. Maitane Olabarrieta also acknowledges funding from the “Cantabria Campus International Augusto Gonzalez Linares Program.”WRG was supported by ONR grant N00014-13-1–0368.2015-06-2

Implementation of the vortex force formalism in the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system for inner shelf and surf zone applications

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Ocean Modelling 47 (2012): 65-95, doi:10.1016/j.ocemod.2012.01.003.The coupled ocean-atmosphere-wave-sediment transport modeling system (COAWST) enables simulations that integrate oceanic, atmospheric, wave and morphological processes in the coastal ocean. Within the modeling system, the three-dimensional ocean circulation module (ROMS) is coupled with the wave generation and propagation model (SWAN) to allow full integration of the effect of waves on circulation and vice versa. The existing wave-current coupling component utilizes a depth dependent radiation stress approach. In here we present a new approach that uses the vortex force formalism. The formulation adopted and the various parameterizations used in the model as well as their numerical implementation are presented in detail. The performance of the new system is examined through the presentation of four test cases. These include obliquely incident waves on a synthetic planar beach and a natural barred beach (DUCK’ 94); normal incident waves on a nearshore barred morphology with rip channels; and wave-induced mean flows outside the surf zone at the Martha’s Vineyard Coastal Observatory (MVCO). Model results from the planar beach case show good agreement with depth-averaged analytical solutions and with theoretical flow structures. Simulation results for the DUCK’ 94 experiment agree closely with measured profiles of cross-shore and longshore velocity data from Garcez-Faria et al. (1998, 2000). Diagnostic simulations showed that the nonlinear processes of wave roller generation and wave-induced mixing are important for the accurate simulation of surf zone flows. It is further recommended that a more realistic approach for determining the contribution of wave rollers and breaking induced turbulent mixing can be formulated using non-dimensional parameters which are functions of local wave parameters and the beach slope. Dominant terms in the cross-shore momentum balance are found to be the quasi-static pressure gradient and breaking acceleration. In the alongshore direction, bottom stress, breaking acceleration, horizontal advection and horizontal vortex forces dominate the momentum balance. The simulation results for the bar / rip channel morphology case clearly show the ability of the modeling system to reproduce horizontal and vertical circulation patterns similar to those found in laboratory studies and to numerical simulations using the radiation stress representation. The vortex force term is found to be more important at locations where strong flow vorticity interacts with the wave-induced Stokes flow field. Outside the surf zone, the three-dimensional model simulations of wave-induced flows for non- breaking waves closely agree with flow observations from MVCO, with the vertical structure of the simulated flow varying as a function of the vertical viscosity as demonstrated by Lentz et al. (2008).The first two authors were supported by a NOAA/IOOS Grant (Integration of Coastal Observations and Assets in the Carolinas in Support of Regional Coastal Ocean Observation System Development in the Southeast Atlantic) and a cooperative agreement between U.S. Geological Survey and University of South Carolina as part of the Carolinas Coastal Change Processes Project. Also G. Voulgaris was partially supported by the National Science Foundation (Awards: OCE-0451989 and OCE-0535893)

Ocean–atmosphere dynamics during Hurricane Ida and Nor’Ida : an application of the coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system

This paper is not subject to U.S. copyright. The definitive version was published in Ocean Modelling 43-44 (2012): 112–137, doi:10.1016/j.ocemod.2011.12.008.The coupled ocean–atmosphere–wave–sediment transport (COAWST) modeling system was used to investigate atmosphere–ocean–wave interactions in November 2009 during Hurricane Ida and its subsequent evolution to Nor’Ida, which was one of the most costly storm systems of the past two decades. One interesting aspect of this event is that it included two unique atmospheric extreme conditions, a hurricane and a nor’easter storm, which developed in regions with different oceanographic characteristics. Our modeled results were compared with several data sources, including GOES satellite infrared data, JASON-1 and JASON-2 altimeter data, CODAR measurements, and wave and tidal information from the National Data Buoy Center (NDBC) and the National Tidal Database. By performing a series of numerical runs, we were able to isolate the effect of the interaction terms between the atmosphere (modeled with Weather Research and Forecasting, the WRF model), the ocean (modeled with Regional Ocean Modeling System (ROMS)), and the wave propagation and generation model (modeled with Simulating Waves Nearshore (SWAN)). Special attention was given to the role of the ocean surface roughness. Three different ocean roughness closure models were analyzed: DGHQ (which is based on wave age), TY2001 (which is based on wave steepness), and OOST (which considers both the effects of wave age and steepness). Including the ocean roughness in the atmospheric module improved the wind intensity estimation and therefore also the wind waves, surface currents, and storm surge amplitude. For example, during the passage of Hurricane Ida through the Gulf of Mexico, the wind speeds were reduced due to wave-induced ocean roughness, resulting in better agreement with the measured winds. During Nor’Ida, including the wave-induced surface roughness changed the form and dimension of the main low pressure cell, affecting the intensity and direction of the winds. The combined wave age- and wave steepness-based parameterization (OOST) provided the best results for wind and wave growth prediction. However, the best agreement between the measured (CODAR) and computed surface currents and storm surge values was obtained with the wave steepness-based roughness parameterization (TY2001), although the differences obtained with respect to DGHQ were not significant. The influence of sea surface temperature (SST) fields on the atmospheric boundary layer dynamics was examined; in particular, we evaluated how the SST affects wind wave generation, surface currents and storm surges. The integrated hydrograph and integrated wave height, parameters that are highly correlated with the storm damage potential, were found to be highly sensitive to the ocean surface roughness parameterization.Primary funding for this study was furnished by the US Geological Survey, Coastal and Marine Geology Program, under the Carolinas Coastal Processes Project

Observations and modeling of a tidal inlet dye tracer plume

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 7819–7844, doi:10.1002/2016JC011922.A 9 km long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on 7 May 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb-tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb-tidal jet because the obliquely incident breaking waves retarded the inlet-mouth ebb-tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to <4 m depth. Dye was then transported downcoast in the narrow (few 100 m wide) surfzone of the beach bordering the inlet at 0.3 inline image driven by wave breaking. Over 6 h, the dye plume is not significantly affected by buoyancy. Observed dye mass balances close indicating all released dye is accounted for. Modeled and observed dye behaviors are qualitatively similar. The model simulates well the evolution of the dye center of mass, lateral spreading, surface area, and maximum concentration, as well as regional (“inlet” and “ocean”) dye mass balances. This indicates that the model represents well the dynamics of the ebb-tidal dye plume. Details of the dye transport pathways across the ebb shoal are modeled poorly perhaps owing to low-resolution and smoothed model bathymetry. Wave forcing effects have a large impact on the dye transport.Littoral Geosciences and Optics Division of the Office of Naval Research as part of the Tidal Inlets and River Mouths Directed Research Initiativ

Tsunami Resonance in Palma Bay and Harbor, Majorca Island, as induced by the 2003 Western Mediterranean Earthquake

ABSTRACT: he tsunami induced by the May 21, 2003, Algerian Boumerde`s-Zemmouri earthquake (moment magnitude Mw=6.9) propagated across the western Mediterranean Basin, thereby causing material damages in some harbors and coastal areas. This was the case in the Balearic Islands and particularly the Palma harbor. Attempts to simulate the 2003 tsunami event found discrepancies between tsunami arrival times and wave amplitude when comparing tide gauge records with results from numerical models. To date, all published model results of the amplitude of the tsunami are underestimations, attributed to numerical limitations due to the lack of high-resolution bathymetry and poor definition of harbor geometry. Other views suggest the nappropriateness of the available seismic source parameterizations and the possible occurrence of submarine landsliding triggered by the earthquake that has not been included in the numerical simulations. In this article we present the results of a numerical study aimed at better understanding the response of the interacting Palma bay and harbor under the impact of the 2003 western Mediterranean tsunami. The transference of the tsunami energy from the generation area to the continental shelf, the bay, and the harbor has been studied and compared with the natural oscillation modes of the bay and harbor water bodies. Our work includes a sensitivity analysis of the source parameterization and the bathymetry grid size for the bay and harbor as a way to explain the discrepancies between simulations and observations. The Palma harbor tide gauge shows that energy from the tsunami concentrated mainly in periods that fitted to the natural modes of oscillations of the bay. Therefore, the significant wave amplification observed inside the harbor, mainly in its northern basin, was generated by a resonance effect induced by Palma bay. The improvement of the bathymetry grid resolution in the bay and harbor domains and the inclusion in the simulations of the exact harbor geometry and internal configuration result in a slight wave-high increment that is much below the wave height recorded in the tide gauge. Our results strongly point to a necessary revision of the tsunami seismic source parameters

Variaciones hiperanuales de parámetros medios de oleaje en el litoral mediterráneo español en los últimos cincuenta años: efectos sobre la costa

Ponencia presentada en: IV Congreso de la Asociación Española de Climatología "El Clima entre el Mar y la Montaña", celebrado en Santander del 2 al 5 de noviembre de 2004.[ES]Este artículo presenta el análisis de las tendencias, en el periodo comprendido entre 1958 y 2001, de los parámetros del régimen medio de oleaje en el Litoral Mediterráneo Español. Se ha comprobado que existe una ligera tendencia de variación del ángulo de la dirección del flujo medio de energía a lo largo de todo el litoral, siendo más acusada la variación en la zona de Cataluña y Almería. En los resultados preliminares se puede observar que el régimen medio de alturas de ola no ha variado en los últimos cincuenta años a excepción de la zona del Estrecho de Gibraltar. Estas tendencias deberán ser consideradas en un futuro como indicadores del cambio climático en la costa.[EN]In this paper, an analysis of trends (period 1958-2001) of long-term wave climate parameters in the Spanish Mediterranean Coast is presented. A weak variation of the averaged direction of the annual mean energy flux is detected along the littoral, although it is more remarkable in the vicinity of Cataluña and Almería. In this preliminary results, it is observed that the long-term wave height distribution is unmodified in the last 50 year except in the area near the Gibraltar straight. These trends can be considered as key indicators of climate change on the coast

Impact of a 1755-like tsunami in Huelva, Spain

Abstract. Coastal areas are highly exposed to natural hazards associated with the sea. In all cases where there is historical evidence for devastating tsunamis, as is the case of the southern coasts of the Iberian Peninsula, there is a need for quantitative hazard tsunami assessment to support spatial planning. Also, local authorities must be able to act towards the population protection in a preemptive way, to inform “what to do” and “where to go” and in an alarm, to make people aware of the incoming danger. With this in mind, we investigated the inundation extent, run-up and water depths, of a 1755-like event on the region of Huelva, located on the Spanish southwestern coast, one of the regions that was affected in the past by several high energy events, as proved by historical documents and sedimentological data. Modelling was made with a slightly modified version of the COMCOT (Cornell Multi-grid Coupled Tsunami Model) code. Sensitivity tests were performed for a single source in order to understand the relevance and influence of the source parameters in the inundation extent and the fundamental impact parameters. We show that a 1755-like event will have a dramatic impact in a large area close to Huelva inundating an area between 82 and 92 km2 and reaching maximum run-up around 5 m. In this sense our results show that small variations on the characteristics of the tsunami source are not too significant for the impact assessment. We show that the maximum flow depth and the maximum run-up increase with the average slip on the source, while the strike of the fault is not a critical factor as Huelva is significantly far away from the potential sources identified up to now. We also show that the maximum flow depth within the inundated area is very dependent on the tidal level, while maximum run-up is less affected, as a consequence of the complex morphology of the area

Probabilistic Tsunami Hazard Assessment in Meso and Macro Tidal Areas. Application to the Cádiz Bay, Spain

ABSTRACT: Tsunami hazard can be analyzed from both deterministic and probabilistic points of view. The deterministic approach is based on a "credible" worst case tsunami, which is often selected from historical events in the region of study. Within the probabilistic approach (PTHA, Probabilistic Tsunami Hazard Analysis), statistical analysis can be carried out in particular regions where historical records of tsunami heights and runup are available. In areas where these historical records are scarce, synthetic series of events are usually generated using Monte Carlo approaches. Commonly, the sea level variation and the currents forced by the tidal motion are either disregarded or considered and treated as aleatory uncertainties in the numerical models. However, in zones with a macro and meso tidal regime, the effect of the tides on the probability distribution of tsunami hazard can be highly important. In this work, we present a PTHA methodology based on the generation of synthetic seismic catalogs and the incorporation of the sea level variation into a Monte Carlo simulation. We applied this methodology to the Bay of Cádiz area in Spain, a zone that was greatly damaged by the 1755 earthquake and tsunami. We build a database of tsunami numerical simulations for different variables: faults, earthquake magnitudes, epicenter locations and sea levels. From this database we generate a set of scenarios from the synthetic seismic catalogs and tidal conditions based on the probabilistic distribution of the involved variables. These scenarios cover the entire range of possible tsunami events in the synthetic catalog (earthquakes and sea levels). Each tsunami scenario is propagated using the tsunami numerical model C3, from the source region to the target coast (Cádiz Bay). Finally, we map the maximum values for a given probability of the selected variables (tsunami intensity measures) producing a set of thematic hazard maps. 1000 different time series of combined tsunamigenic earthquakes and tidal levels were synthetically generated using the Monte Carlo technique. Each time series had a 10000-year duration. The tsunami characteristics were statistically analyzed to derive different thematic maps for the return periods of 500, 1000, 5000, and 10000 years, including the maximum wave elevation, the maximum current speed, the maximum Froude number, and the maximum total forces

Estudio de los impactos en la costa española por efecto del cambio climático

Ponencia presentada en: IV Congreso de la Asociación Española de Climatología "El Clima entre el Mar y la Montaña", celebrado en Santander del 2 al 5 de noviembre de 2004.[ES]En este artículo se presenta el Estudio de investigación sobre impactos en la costa española por efecto del cambio climático, que la Dirección General de Calidad y Evaluación Ambiental del Ministerio de Medio Ambiente, a través de la Oficina Española del Cambio Climático, ha encargado a la Universidad de Cantabria. Este trabajo se presenta como resumen de dicho Estudio y es el primero de los cuatro artículos que se presentan en este congreso, cubriendo los restantes aspectos científico-técnicos de diversas partes del Estudio.[EN]The effects of climate change on the Spanish coast are analyzed in a Project leaded by the University of Cantabria and funded by the Spanish Agency of Climate Change (Ministry of Environment). This work is presented as a summary of the Project and is one of the four papers presented in this Conference. The three companion papers cover several scientific aspects of the study