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Entradas con etiqueta swan .

Evaluation of extreme waves associated with cyclonic activity in San Andres Island on the Caribbean Sea since 1900

Ortiz J.C, Plazas J.M  and Lizano O.

Journal of Coastal Research - JCR (sep. 2014)

Abstract

San Andrés Island is one of the most important tourist destinations in the Caribbean. The extreme waves associated with storms and hurricanes since 1900 were studied. A total of 17 important events were identified in the last 100 years. During seven of these events, the eye of the storm was located less than 150 km from the coast: hurricanes Hattie (1961), Alma (1970), Irene (1971), Joan (1988), Cesar (1996), Katrina (1999), and, the most recent, Beta (2005). Most commonly, the storms approached from the southeast, these storms affected the northern and southern portions of the island. Using the parametric hurricane wind model and SWAN wave model, the wind and wave fields were modeled for the aforementioned hurricanes. The results showed that the western area of the island was unaffected by extreme waves, except for the waves caused by Beta in 2005, which were less than 2 m in height (on the 50 m isobath). However, the situation is different in the east. The wide insular shelf and coral reefs located along the northeastern coast act as a natural barrier dissipating the extreme waves so that most of the wave energy is dispersed before reaching the coastline. The southeastern coast is totally exposed to wave energy because of its narrow insular shelf and the limited presence of coral reefs. The maximum estimated significant heights were as much as 5 m on the 50 m isobath and occurred during Hurricane Joan (1988), the peak wave period was 12 s, and most of the hurricanes came from the southeast. The present paper establishes a fundamental basis for implementing management plans during emergencies related to hurricanes, considering that the island has been affected by at least one hurricane every 10 years for the last 50 years.

Full text: http://www.jcronline.org/doi/abs/10.2112/JCOASTRES-D-14-00072.1

AN INTERCOMPARISON OF SWAN AND WAVEWATCH III MODELS WITH DATA FROM NDBC-NOAA BUOYS AT OCEANIC SCALES

 Juan C. Ortiz and A. Mercado

Coastal Engeneering Journal, March (2008)

A simulation of wind-wave activity in the North Atlantic Basin, between June to August of 2002, has been performed using the SWAN model. The results of the simulations were compared with data obtained from the National Data Buoy Center and the results from NOAA’s WAVEWATCH III (WW3) wave model. This study tested the applicability of the SWAN model at oceanic scales. The SWAN model was developed for coastal areas, but in version (40.11), spherical coordinates have been included in the code for oceanic applications. It was found that, in general, WW3 produces a somewhat better fit to the observations than SWAN. The same conclusion holds even when global scale WW3 results were used as boundary conditions in the SWAN simulations. Since the same wind forcing was used, we could conclude that this difference in significant wave height, Hs, could be due to the way wind energy is transferred to wave energy and its dissipation due to whitecapping in the models. The wind input parameterization in WW3 (Tolman and Chalikov, 1996) shows a better response to relatively fast changes in wind speed than the parameterization of Komen et al. (1984) used in SWAN. Although comparison between buoy observations and model output tends to favor WW3 over SWAN in deep water, we argue that the ease of use of SWAN, together with the simplification offered by just having to learn to use one model, makes the SWAN model a good option for simulations all the way from deep water up to the near shore.

Full text: http://www.worldscientific.com/doi/abs/10.1142/S0578563408001739?prevSearch=ortiz-royero&searchHistoryKey=

Estudio del Oleaje Generado por el Huracán Joan en la Costa Caribe Colombiana en 1988, Incluyendo a la Isla Andrés

Juan C. Ortiz, Fernando López, Ernesto Díaz y Luis F. Bacca (2008)

Se realizó la simulación del huracán JOAN, que alcanzó la categoría cuatro (en Centroamérica) y que pasó muy cerca de la costa Caribe Colombiana en el mes de octubre del año 1988. Se utilizaron dos modelos de simulación: HURWIN para simular el campo de vientos del huracán y el modelo SWAN para simular el oleaje producido, ambos modelos fueron validados, simulando el huracán OPAL (Golfo de México, 1995). Se simularon 36 horas de propagación, con un paso de tiempo de 1,5 horas y un tamaño de celda de 0,06667 grados. Se distribuyeron boyas virtuales a los largo de la Costa Caribe, incluyendo a San Andrés Isla, para evaluar las carácteristicas del oleaje producido en aguas profundas.

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