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Browsing by Author "Lizano, O"

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Algunas características de las corrientes marinas en Golfo de Nicoya
(Revista de Biología Tropical, 2004) Lizano, O; Alfaro, E
The spatial and vertical structure of the water currents and its relationship with the tidal cycles were studied using current meters in the Gulf of Nicoya. In the upper gulf, the vertical marine current differences increase as the depth increases. The water column at the station near Chira Island (upper gulf) shows the smaller changes in currents and in temperature. The flow at the station between San Lucas Island and Puntarenas (middle gulf) is the most stratified in this region. Currents with magnitudes over 100 cm/seg were measured during spring tides. Changes in the lags of the surface and bottom tidal flows were measured on the order of 100 minutes. In general, in this upper region the flows are toward the head of the gulf when the tide is flooding and toward the mouth when the tide is ebbing. In the lower gulf the circulation is more complex. Along an axis between Tárcoles and Negritos Islands, changes of velocity vectors are identified between surface and bottom. The current rotates in a different way in the water column in this region and their patterns cannot be explained only by the tidal cycles predicted for Puntarenas. These results demonstrate that the spatial and vertical variation of the marine currents of the Gulf of Nicoya is not only related to the thermohaline structure, but also to the tidal cycles and tide ranges that take place in this estuary.
Algunas características de las mareas en la costa Pacífica y Caribe de Centroamérica
(Ciencia y Tecnología, 2006) Lizano, O
Tidal levels were studied in 48 stations using tidal predictions along the coasts of the Pacific and Caribbean of Central America. Statistics of basic mean values were analyzed to characterize the stations. These values are useful in coastal design structures as marines, ports, breakwaters, and for planning of marine operations in ports and piers. The tidal wave in the Pacific is simidiurnal, while in the Caribbean varies according to the latitude and the bathymetric basin in which it is found. In this last region the tidal wave can be mixed (a combination of semidiurnal and diurnal types) or semidiurnal pure. Some stations may show seasonal variations in the tidal wave according to the phases of the moon. It was found that the stations positioned in open coasts in the Pacific Ocean had smaller tidal range than those stations inside of semi-enclosed bodies of waters as bays and gulfs. Some stations in the interior of the Gulf of Panama showed very high tidal ranges associated possibly to resonance interactions of the tidal wave with the continental shelf and the geometry of the gulf. In the Caribbean Sea the tides seemed to resonance according to the basin and sea floor batimetry in which they are found. In some stations the oceanic and atmospheric forces as wind, atmospheric pressure, waves and currents, might generate the so called "weather tides" that could explain the major tidal range found in some of them.
Algunas características de las tormentas tropicales y de los huracanes que atravesaron o se formaron en el Caribe adyacente de Costa Rica durante el periodo 1886-1988
(Tópicos Meteorológicos y Oceanográficos, 1996) Lizano, O; Fernández, W
Se estudian algunas características de las tormentas tropicales y de los huracanes en el Caribe adyacente a Costa Rica, en el área localizada entre 70-850 Oy 8-180 N. En particular, utilizando un registro para el período 1886-1988, se presentan análisis de frecuencias para los parámetros usuales que caracterizan a los huracnes: presión atmosférica en el ojo, magnitud del viento máximo y velocidad y dirección de desplazamiento. También se estudian las frecuencias con las que las tormentas tropicales y los huracanes se forman y atraviesan en dicha área.
Algunas relaciones entre las zonas de surgencia del Pacífico Centroamericano y los Océanos Pacífico y Atlántico Tropical
(Revista de Biología Tropical, 2001) Alfaro, E; Lizano, O
In order to explore the influence of the surrounding tropical oceans on the Central American Pacific coast, a Transfer Function Model was fixed to Sea Surface Temperature Anomalies (SSTA) of the Gulf of Tehuantepec, Papagayo, Panama and Quepos time series. As independent variables the following were used: Niño 3.4, Tropical North and South Atlantic indices. These models show that Niño 3.4 has the most important influence over the region when compared with the influence of the other indices, having positive correlation with all the SSTA series. It shows an influence of this index on the relative termocline’s depth in front of the Central American Pacific Coast.
Atmospheric forcing in the Eastern Tropical Pacific: A review
(Progress in Oceanography, 2006) Amador, J; Alfaro, E; Lizano, O; Magaña, V
The increase in marine, land surface, atmospheric and satellite data during recent decades has led to an improved understanding of the air–sea interaction processes in the eastern tropical Pacific. This is also thanks to extensive diagnoses from conceptual and coupled ocean–atmosphere numerical models. In this paper, mean fields of atmospheric variables, such as incoming solar radiation, sea level pressure, winds, wind stress curl, precipitation, evaporation, and surface energy fluxes, are derived from global atmospheric data sets in order to examine the dominant features of the low level atmospheric circulations of the region. The seasonal march of the atmospheric circulations is presented to depict the role of radiative forcing on atmospheric perturbations, especially those dominating the atmosphere at low levels. In the tropics, the trade winds constitute an important north–south energy and moisture exchange mechanism (as part of the low level branch of the Hadley circulation), that determines to a large extent the precipitation distribution in the region, i.e., that associated with the Inter-Tropical Convergence Zone (ITCZ). Monsoonal circulations also play an important role in determining the warm season precipitation distribution over the eastern tropical Pacific through a large variety of air–sea–land interaction mechanisms. Westward traveling waves, tropical cyclones, low latitude cold air intrusions, and other synoptic and mesoscale perturbations associated with the ITCZ are also important elements that modulate the annual rainfall cycle. The low-level jets of the Gulf of California, the Intra-Americas Sea (Gulf of Mexico and Caribbean Sea) and Choco´, Colombia are prominent features of the eastern tropical Pacific low-level circulations related to sub-regional and regional scale precipitation patterns. Observations show that the Intra-Americas Low-Level Jet intensity varies with El Niño/Southern Oscillation (ENSO) phases, however its origin and role in the westward propagation and development of disturbances that may hit the eastern tropical Pacific, such as easterly waves and tropical cyclones, are still unclear. Changes in the intensity of the trade winds in the Caribbean Sea and the Gulf of Mexico (associated with eastern tropical Pacific wind jets) exert an important control on precipitation by means of wind–topography interactions. Gaps in the mountains of southern Mexico and Central America allow strong wind jets to pass over the continent imprinting a unique signal in sea surface temperatures and ocean dynamics of the eastern tropical Pacific. The warm pools of the Americas constitute an important source of moisture for the North American Monsoon System. The northeastern tropical Pacific is a region of intense cyclogenetic activity, just west of the coast of Mesoamerica. Over the oceanic regions, large-scale properties of key variables such as precipitation, moisture, surface energy fluxes and wind stress curl are still uncertain, which inhibits a more comprehensive view of the region and stresses the importance of regional field experiments. Progress has been substantial in the understanding of the ocean and atmospheric dynamics of the eastern tropical Pacific, however, recent observational evidence such as that of a shallow meridional circulation cell in that region, in contrast to the classic concept of the Hadley-type deep meridional circulation, suggests that more in situ observations to validate theories are still necessary. This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific Ocean.
Batimetría de la plataforma insular alrededor de la Isla del Coco, Costa Rica
(Revista de Biología Tropical, 2001) Lizano, O
The bathymetry of Coco’s Island (UNESCO Natural and Cultural World Patrimony), located approximately 500 km from the Pacific coast of Costa Rica, is not well known. It has a high marine biodiversity and also represents a meeting site for many species traveling throughout the Pacific Ocean. The insular shelf is irregular in extension and also in bathymetric features. The northeast limit is defined by the 109.8-128.1 m contours (60-70 fathoms) while the 183 m contour (100 fathoms) practically defines the rest of the island, from which the depth gradient is steep. The maximum extension is to the northeast with a longitude of 13 km. In this context the present limits of the marine park (5 km), are insufficient to protect the whole insular shelf. Current regulation should be modified to prevent fishing activities less than 15 km from the Island.
Batimetría, modelos de elevación digital y sus aplicaciones
(Azimuth, 2009) Lizano, O
En este trabajo se resume la historia de los sondeos batimétricos y los equipos utilizados en el estudio de la rugosidad marina. Se hace referencia a las distintas instituciones internacionales a cargo de la elaboración de cartas batimétricas, los formatos disponibles y las distintas casas comerciales que las distribuyen. Se discute sobre los distintos niveles mareográficos utilizados en algunos países y sobre el más común nivel de mareas usado para referenciar los sondeos batimétricos. Se mencionan algunos ejemplos de aplicaciones locales en los que las batimetrías son los datos de entrada para elaborar modelos de elevación digital. Estos son los datos necesarios en modelos numéricos para estudios de marinas, puertos y atracaderos en Costa Rica.
Caracterización de los manglares de Centroamérica con sensores remotos
(Revista de Biología Tropical, 2001) Lizano, O; Amador, J; Soto, R
Satellite images were used to study the mangrove distribution patterns in two different climatic regions of Central America: Gulf of Fonseca in Honduras-El Salvador and Sierpe-Térraba in Costa Rica. The Gulf of Fonseca has higher temperature and solar radiation, and lower precipitation, which can explain the higher structural development and species mixing of the Sierpe-Térraba mangrove. In the latter the transition between species or between heights in the same species is clear. The automatic classification made by the Geographic Information System (IDRISI) fits well the field mangrove distribution, but it was necessary to regroup some subdivisions that represent the same land use as identified by transects and an aerial video. Mixed species and clouds produced less satisfactory results in Sierpe-Térraba indicating a need for better satellite image resolution.
Composición de sedimentos en las Zonas Costeras de Costa Rica utilizando Fluorescencia de Rayos-X (FRX)
(Revista de Biología Tropical, 2004) Salazar, A; Lizano, O; Alfaro, E
Using an energy dispersive X-Ray fluorescence analysis, simultaneous evaluation of K, Ca, Ti, Cr, Mn, Ge, Ni, Cu, Zn, Br, Rb, Sr and Pb in 74 marine sediment samples from the Costa Rica intertidal zones was conducted. Samples were collected between June 1999 and December 2001, from Caribbean and Pacific beaches of Costa Rica. Calcium and iron showed the highest abundances and are indicators of the natural origin of the sediments. Calcium is associated with biogenic processes such as coral reefs near the sampling sites and iron indicates a terrigenous origin. In general, the beaches of the Caribbean and North Pacific regions showed the greatest concentration of calcium. This is indicative of the abundant reef structures near these beaches. The beaches of the Central and South Pacific show the greatest iron concentrations, indicating an important lithosphere contribution and/or little contribution of calcium carbonate due to the poor development of coralline structures near the sampling sites. Finally, the analyses did not show evidence of elements associated with anthropogenic pollution. Only a northern section of Puerto Viejo beach showed high concentrations of lead, zinc and titanium, perhaps associated with hydrothermal sources.
Dinámica de aguas alrededor de la Isla del Coco, Costa Rica
(Revista de Biología Tropical, 2008) Lizano, O
Surface and sub-surface data were analyzed using chemical and physical parameters, nutrients and dissolved oxygen in the eastern tropical Pacific, based on databases, numerical models and satellite observations. The surface marine current pattern during the first quarter of the year was different from the rest. It is known that the North Equatorial Countercurrent does not reach the island at this time, and a clockwise gyre centered on Isla del Coco (Cocos Island) was stabilized with an intense coastal current generated south of the Gulf of Panama, initially moving in a south direction and then west. It is at this time when the Inter-tropical Convergence Zone is at its most northerly position (around 10°N), and the dynamics of the eastern tropical Pacific is driven by the surface Caribbean easterly wind stress crossing the topographic gaps in Central America. The upwelling in the Gulf of Papagayo is evident and from the surface spatial distributions of temperature, salinity and nutrients, an advection towards Isla del Coco is identi fied. When the Inter-tropical Convergence Zone is displaced to the south (around 5°N), the Papagayo upwelling disappears, the southern trade winds intensify and a strong Equator-Peru upwelling is developed. Nevertheless, from the latitudinal depth profiles and the spatial distributions of physical parameters and nutrients, no advection is evident in the monthly averages from this zone. Between May and October the island was always reached by the North Equatorial Countercurrent. On average, the waves that reach Isla del Coco arrive from the southwest. However, during the boreal winter, the storms generate waves with sufficient energy to reach the island from the northwest. Additionally, at this time of the year, Trade Winds from the Caribbean blow strong across the topographical Papagayo and Panama gaps, generating waves towards the southwest that can reach the island and the remote swell from the southwest losses energy.
Dinámica de las aguas en la parte interna del Golfo de Nicoya ante altas descargas del Río Tempisque
(Revista de Biología Tropical, 1998) Lizano, O
The water dynamics of the upper part of the Gulf of Nicoya were studied under high discharges of the Tempisque river. The salinity values close to freshwater found north of Chira island are the lowest reported for this lone. and have importance in mariculture planing. A salinity gradient is developed during low tide, indicating a strong stratification in the inner Gulf. High freshwater river discharge is coup led with an upstream bottom flow (sail wedge) that reacher; the head of the estuary. Under high river discharges, surface and bottom salinity values are correlated with depth, where vertical shear and tidal pumping must explain the high salinity values found in the bottom inward flow. A fish distribution pattern is proposed based on the observed salinity distribution and some field data. Salinity gradients appear to influence the concentration of fish in several relatively deep areas in the inner Gulf of Nicoya.
Efectos del tamaño de rejilla y el número de frecuencias en un modelo espectral de pronóstico de olas
(Tópicos Meteorológicos y Oceanográficos, 1997) Lizano, O
En este trabajo se analizan el tamaño del área de simulación, el tamaño de la rejilla y el número de las frecuencias utilizadas para definir un espectro de energía en un modelo numérico de generación de olas, con el propósito de hacer una selección más juiciosa y obtener resultados más precisos en el pronóstico del oleaje, y a un menor costo computacional.
El Impacto de las Olas generadas por un Huracán sobre Arrecifes Coralinos: Inferencias basadas en Modelos Numéricos
(Revista Geofísica, 1993) Lizano, O; Mercado, A; Hernández, M
Se simuló la propagación de olas, desde agua profunda, para el caso del huracán David (agosto, 1979), sobre un arrecife coralino al suroeste de Puerto Rico. Las características y el patrón del oleaje son analizadas, y correlacionadas con los efectos producidos en el arrecife. Se especula acerca del impacto de un huracán según la dirección y posición respecto de un arrecife.
Evaluación de modelos numéricos de Tercera Generación para el pronóstico de oleaje en Centroamérica y México
(Tópicos Meteorológicos y Oceanográficos, 2001) Lizano, O; Ocampo, F; Alvarado, L; Puig, J; Vega, R
The evaluation and implementation of two public domain wave spectral models: SWAN and WAM to be used in hindcasting and forecasting in the Central American region are presented. The typical model characteristics are analyzed using simulations for simple bathymetric cases. The model responses are evaluated using boundary conditions in the Caribbean region including extreme meteorological conditions like hurricanes. Those natural phenomena’s are of great importance given the historical frequency impacts in the region. The SWAN model shows some difficulties to propagate wave energy in big areas generating some wave height and direction anomalies mainly around islands or in low interpolated depth values. The numerical schemes and the different model’s variable parameterizations are responsible for the different spatial energy propagation found in some applications in this study. An integrated system could be working for the whole region where the wave information is necessary in activities like fishing, marine transit and transport, port operations and tourist activities.
Interconexión a nivel ciclónico-atmosferico entre el Caribe y el Pacífico Centroamericano
(Revista de Biología Tropical, 1998) Banichevich, A; Lizano, O
Algunas propiedades de la atmósfera en el Pacífico y las cuencas marinas del Caribe cerca del Istmo Centroamericano y sus interconexiones posibles se analizan, en base a un estudio estadístico. La banda que describe el sur de Nicaragua se toma como referencia, ya que tiene menos características orográficas que pueden distorcionar los vientos alisios que fluyen desde el noroeste (NW) y desde el sureste (SE). Las propiedades de la atmósfera están asociados a la incidencia de los fenómenos sinópticos, como los ciclones tropicales y su probabilidad de atravesar el istmo con la pérdida de energía mínima. El calor de la Oscilación Sur de El Niño(ENOS produce un debilitamiento sistemático de los esporádicos eventos de tipo ciclón en el Atlántico occidental, mientras que en el Pacífico oriental, debido a las temperaturas de agua de superficie superiores a 27oC, se refuerzan. Durante la transmisión de caliente -ENSO a frío-ENSO, hay interconexiones entre ambos cuenca oceánica con los sistemas ciclónicos que cruzan el Istmo, principalmente a través de la Depresión de Nicaragua (desde el Atlántico hasta el Pacífico), y con un solo caso, a través de Tehuantepec (desde el Pacífico hasta el Atlántico). Durante la transmisión de caliente a frío-ENOS-eventos ENSO, hay interconexiones entre ambas cuencas oceánicas con los sistemas ciclónicos que cruzan el Istmo, principalmente a través de la Depresión de Nicaragua (desde el Atlántico hasta el Pacífico), y con un solo caso, a través de Tehuantepec (desde el Pacífico hasta el Atlántico). Durante los eventos ENSO -frío, condiciones similares a la etapa de transición se puede esperar, es decir, el número de eventos aumentó en la cuenca del Atlántico, mientras que en el Pacífico se redujo.
Las mareas extraordinarias de 1997 en la costa Pacífica de Costa Rica
(Tópicos Meteorológicos y Oceanográficos, 1997) Lizano, O
Se analiza el comportamiento de la marea astronómica en la costa Pacífica de Costa Rica, así como su relación con los procesos erosivos ocurridos en Isla Damas, Quepos durante agosto, septiembre y octubre de 1997. Se estudian los diferentes componentes mareográficos que podrían explicar las alturas extremas de las mareas durante 1997. Se discuten otros componentes ya presentes en el océano relacionados con actividades antropogénicas como el calentamiento global y la deforestación. Estos componentes podrían explicar algunos cambios en los procesos costeros ocurridos en el Pacífico de Costa Rica en los últimos años. Se discute la predicción astronómica de mareas para 1998 y su implicación en el nivel del mar con (y sin) el fenómeno de El Niño.
Modelo de viento ajustado a un modelo de generación de olas para el pronóstico durante huracanes
(Revista Geofísica, 1990) Lizano, O
Las características de tres modelos numéricos de predicción del viento en huracanes fueron estudiadas para compararlas con los efectos producidos al acoplarse a un modelo de generación de olas. La diferencia en la altura de ola producida por el modelo de generación de olas se obtuvo como respuesta a los diferentes perfiles de vientos y a su magnitud máxima alrededor del radio del huracán. Un nuevo modelo de viento fue adaptado al modelo de generación de olas para producir un mayor ajuste de la altura y espectro de energía de las olas, empleando datos observados durante el huracán Camille en 1969 a su paso por el Golfo de México (AU)
Radionucleidos naturales y antropogénicos en el estuario del Golfo de Nicoya, Costa Rica
(Tópicos Meteorológicos y Oceanográficos, 2002) Loría, L; Jiménez, R; Lizano, O
The activity of isotopes of the Uranium, and Thorium series (228Ac, 212Bi, 212Pb, 226Ra, 214Bi, 214Pb) as well as 40K and 137 Cs was monitored on sediment samples collected in the Gulf of Nicoya estuary (9 30 N 84 45 W), Pacific coast of Costa Rica, and using Low Level Gamma Spectrometry. Results show a high content ( range 10 to 20 Bq/kg) of most radionucleids in those sites north of Tárcoles River mouth, inside the Gulf of Nicoya. From the Tárcoles river mouth to the south, much lower quantities were detected (2 to 4 Bq/kg). Possible sources of such isotopes are natural ores, except in the 40K case where an antropogenic origin, possible from agricultural activities along the river is likely to be the cause. Caesium in the sediments has its origin from the nuclear explosions.
Simulación de oleaje de huracán usando modelos de vientos paramétricos en un modelo de olas de Tercera Generación
(Boletín Científico Centro de Investigaciones Oceanográficas e Hidrográficas del Caribe, 2006) Lizano, O
Dos modelos paramétricos de viento fueron usados para simular la distribución del oleaje en huracanes en uno de los, así llamados, modelos de tercera generación. Se usaron varias condiciones durante huracanes en el Golfo de México y frente a la península de Florida para probar y ajustar los modelos de viento. La información usualmente disponible en las oficinas meteorológicas, como: presión central, radio de viento máximo y las posiciones geográficas, es la única necesaria para crear un perfil de viento con estos modelos paramétricos. Se obtuvieron resultados comparables entre las alturas de olas medidas y las simuladas por el modelo de olas. Esto demuestra la utilidad de estas herramientas para realizar diagnóstico y pronóstico de oleaje durante huracanes en la región. Esta información es valiosa para las entidades gubernamentales como ayuda en la toma de decisiones apropiadas en la eventualidad de presentarse estos fenómenos meteorológicos, los cuales podrían ser más frecuentes e intensos en el futuro.
Un método gráfico para el pronóstico de oleaje durante huracanes en el Caribe adyacente a Costa Rica.
(Tópicos Meteorológicos y Oceanográficos, 1996) Lizano, O
Se presenta un método gráfico sencillo para hacer pronóstico de oleaje durante la ocurrencia de huracanes en el Caribe adyacente a Costa Rica Este método utiliza los parámetros básicos que son reportados por los servicios de información meteorotógica. Con base en el estudio de los parámetros que caracterizan un huracán: presión central, velocidad y dirección de movimiento y radio de vientos máximos, realizado por Lizano y Fernández (1996), se diseñaron combinaciones que cubran todos los tipos de huracanes que pueden generarse en la regron, Utilizando un modelo numérico de generación de olas, se simuló las condiciones de viento y oleaje de huracán asociadas con las distintas combinaciones de estos parámetros Se suministra un ejemplo (Huracán Joan en 1988) para realizar pronóstico de oleaje con los parámetros tipicos de un huracan.

Browsing by Author "Lizano, O"

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