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Search Results: 1 - 10 of 462347 matches for " Yanina García Skabar "
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Verificación de los pronosticos del modelo BRAMS centrado en la region subtropical de Sudamerica BRAMS forecast verification over a region of subtropical Southamerica
Yanina García Skabar,Paola Salio,Matilde Nicolini
Revista Brasileira de Meteorologia , 2012, DOI: 10.1590/s0102-77862012000300004
Abstract: El objetivo del presente trabajo es realizar una verificación de los pronósticos generados en el Departamento de Ciencias de la Atmósfera y los Océanos de la Universidad de Buenos Aires con el modelo Brazilian Regional Atmospheric Modeling System(BRAMS). Utilizando dicho modelo, desde 2006, se realizan dos pronósticos al día por un plazo de 72 horas en dos retículas anidadas con una resolución horizontal de 80 y 20km. La retícula de mayor resolución abarca Paraguay, Uruguay, Sur de Brasil y Bolivia y el centro y norte de Argentina y Chile. En este trabajo se realiza la verificación sobre el dominio de mayor resolución para el período desde abril de 2006 a diciembre de 2008. El interés se centra en verificar los pronósticos de precipitación, y de los perfiles verticales de temperatura, humedad y viento en las localidades donde se dispone de datos de radiosondeos. La verificación de los pronósticos de precipitación se realiza mediante estadísticos calculados frente a las observaciones convencionales disponibles y frente a estimaciones de precipitación CMORPH. Los resultados son similares a los obtenidos en la región con modelos de aproximadamente la misma resolución. Además se identifican las deficiencias principales de los pronósticos lo que permitirá realizar ajustes en la configuración del mismo para mejorar su desempe o. The aim of this work is to verify the forecasts generated in the Department of Atmospheric Sciences and Ocean, University of Buenos Aires with the Brazilian model Regional Atmospheric Modeling System (BRAMS). Since year 2006, every day two different forecasts that extend for 72 hours have been performed using two nested grids with an horizontal resolution of 80 and 20 km. The higher resolution domain covers Paraguay, Uruguay, southern Brazil and Bolivia and the central and northern part of Argentina and Chile. This paper presents the results of the verification of the model in the higher resolution domain for the period April 2006 to December 2008. The focus is in the precipitation and vertical profiles of temperature and wind forecasts in the locations where soundings are available. Verification of precipitation forecast is based on statistics computed against observations and precipitation estimates from CMORPH. The results are close to those obtained in the region with models of similar resolution. It is also possible to identify the main forecast deficiencies, contributing to future adjustments in its configuration to improve the model performance.
Evaluación de la representación de un sistema convectivo de mesoescala utilizando el modelo RAMS
Ruiz,Juan José; Saulo,A. Celeste; García Skabar,Yanina; Salio,Paola V;
Meteorologica , 2006,
Abstract: this work concentrates in the evaluation of rams model's representation of a mesoscale convective system associated with a strong low level jet event. diverse products derived from satellite data are used to measure precipitation amounts and to characterize the system internal structure. the synoptic environment associated to system genesis and growing stages is also analyzed through the description of mechanisms favoring both, convective instability and low level convergence. rams model correctly represents the environmental conditions where the system develops, the accumulated precipitation fields and precipitation rates at particular moments when precipitation radar data were available. however the model fails to capture the stratiform precipitation area behind the convective one. it is considered that the approach adopted to verify model performance, seems suitable to identify which could be the main culprits for model deficiencies in the representation of rain and its distribution and consequently aid in developing a strategy to improve their prediction.
Evaluación de la representación de un sistema convectivo de mesoescala utilizando el modelo RAMS The representation of a mesoscale convective system using RAMS model
Juan José Ruiz,A. Celeste Saulo,Yanina García Skabar,Paola V Salio
Meteorologica , 2006,
Abstract: En este trabajo se evalúa la capacidad del modelo RAMS en representar un sistema convectivo en mesoescala asociado con la ocurrencia de una intensa corriente en chorro en capas bajas. Para realizar la verificación y debido a las limitaciones de la red observacional operativa, se propone aquí la utilización de productos derivados de sensores remotos de microondas pasivas y activas. También se efectúa un análisis del entorno en escala sinóptica de este evento, con énfasis en el análisis de la evolución de la inestabilidad convectiva y la convergencia en capas bajas. El modelo representa correctamente la circulación de mayor escala, y también simula adecuadamente la precipitación total acumulada. No obstante en las resoluciones utilizadas el modelo presenta dificultad en representar la estructura interna del sistema convectivo. Se considera que la estrategia adoptada para analizar el desempe o del modelo, es útil para identificar los mayores problemas en la reproducción de la distribución de precipitación asociada al sistema convectivo y su ubicación y consecuentemente, para establecer pautas para una mejora de la predicción de los mismos. This work concentrates in the evaluation of RAMS model's representation of a mesoscale convective system associated with a strong low level jet event. Diverse products derived from satellite data are used to measure precipitation amounts and to characterize the system internal structure. The synoptic environment associated to system genesis and growing stages is also analyzed through the description of mechanisms favoring both, convective instability and low level convergence. RAMS model correctly represents the environmental conditions where the system develops, the accumulated precipitation fields and precipitation rates at particular moments when precipitation radar data were available. However the model fails to capture the stratiform precipitation area behind the convective one. It is considered that the approach adopted to verify model performance, seems suitable to identify which could be the main culprits for model deficiencies in the representation of rain and its distribution and consequently aid in developing a strategy to improve their prediction.
Análisis del entorno sinóptico asociado con eventos de Bow-Echo en la Provincia de Buenos Aires
Torres Brizuela,Marcela; Vidal,Ricardo; García Skabar,Yanina; Nicolini,Matilde; Vidal,Luciano;
Meteorologica , 2011,
Abstract: during the morning hours on october 21 2008, three convective lines developed over the buenos aires province, and were captured by the meteorological radars located at ezeiza and pergamino. the spatial structure and temporal evolution of the reflectivity field of these convective systems present the attributes of the particular convective system referred to as a “bow-echo”. ezeiza doppler radar images, captured winds stronger than 20 m.s-1 behind these arc lines, a phenomenon that frequently characterizes the presence of a bow-echo. the main objective of this study is to understand the synoptic weather conditions accompanying the occurrence of these bow echo events to enhance the weather forecasting of these systems. on this particular case the specific humidity field over the northern part of the buenos aires province (q≥ 12-14 g.kg-1) and also the environmental vertical wind shear values below 700 hpa meet the required conditions to develop a bow-echo event, although the available surface level cape values do not promote this event.
A cut-off low in southern South America: dynamic and thermodynamic processes
Godoy, Alejandro Anibal;Possia, Norma Edit;Campetella, Claudia Marcela;García Skabar, Yanina;
Revista Brasileira de Meteorologia , 2011, DOI: 10.1590/S0102-77862011000400001
Abstract: the dynamic and thermodynamic processes involved in the life cycle of a cutoff low occurred in march 2007 are studied. these processes are analyzed using the vorticity and thermodynamic equations and a set of analyses generated with the brams model. the main processes that explain the segregation of the subtropical part of the trough are the horizontal advection of cyclonic vorticity at high levels and warm horizontal advection at middle levels, both over the pacific ocean extending south to the patagonia region, building the ridge located upstream of the trough. increased intensity of the upper level low pressure system is mainly explained by intensification of the ridges down and upstream. the divergence effect is opposed to the horizontal advection of vorticity which explains the stagnation of the cut-off low windward of the andes. the decay stage is dominated by warm vertical advection. assuming the conservation of potential vorticity the analysis of parcel trajectories , allowed detecting the entrance of stratospheric air to middle levels of the lower troposphere around the cut-off low.
Análisis del entorno sinóptico asociado con eventos de Bow-Echo en la Provincia de Buenos Aires Synoptic Environment Analysis Associated With Bow - Echo Events In The Province Of Buenos Aires
Marcela Torres Brizuela,Ricardo Vidal,Yanina García Skabar,Matilde Nicolini
Meteorologica , 2011,
Abstract: Durante la madrugada del día 21 de Octubre de 2008 se desarrollaron tres líneas convectivas en la provincia de Buenos Aires, captadas por los radares meteorológicos de las localidades de Ezeiza y Pergamino. La estructura espacial y evolución temporal del campo de reflectividad de estos sistemas, configuración de línea en arco, responde al modo convectivo conocido con el nombre de “bow-echo”. La imagen doppler del radar de Ezeiza registró un fenómeno típico en la parte posterior de estas líneas en arco: los vientos intensos mayores a 20 m.s-1. El objetivo principal de este estudio es comprender las condiciones sinópticas que acompa aron la ocurrencia de estos sistemas para poder contribuir al pronóstico de su ocurrencia. En este evento las condiciones de humedad especifica en la zona del norte de la provincia de Buenos Aires (q≥ 12-14 g.kg-1), así como la de cortante vertical del viento por debajo del nivel de 700 hPa (Us>15 m.s-1) coinciden en indicar al entorno como favorable al desarrollo del mismo, aunque no así los valores disponibles de CAPE evaluados para parcelas que se elevan desde superficie. During the morning hours on October 21 2008, three convective lines developed over the Buenos Aires province, and were captured by the meteorological radars located at Ezeiza and Pergamino. The spatial structure and temporal evolution of the reflectivity field of these convective systems present the attributes of the particular convective system referred to as a “bow-echo”. Ezeiza doppler radar images, captured winds stronger than 20 m.s-1 behind these arc lines, a phenomenon that frequently characterizes the presence of a bow-echo. The main objective of this study is to understand the synoptic weather conditions accompanying the occurrence of these bow echo events to enhance the weather forecasting of these systems. On this particular case the specific humidity field over the northern part of the Buenos Aires province (q≥ 12-14 g.kg-1) and also the environmental vertical wind shear values below 700 hPa meet the required conditions to develop a bow-echo event, although the available surface level CAPE values do not promote this event.
Direction-of-Change Financial Time Series Forecasting using Bayesian Learning for MLPs
Andrew A. Skabar
Lecture Notes in Engineering and Computer Science , 2008,
Abstract:
Nevadas en el Sudeste Bonaerense: climatología sinóptica y un caso de estudio
Paola Salio,Claudia Campetella,Juan Ruiz,Yanina Garcia Skabar
Meteorologica , 2006,
Abstract: Este trabajo realiza una estadística de la frecuencia de las nevadas ocurridas sobre el sudeste de la provincia de Buenos Aires durante un período de 35 a os (1960-2004). Utilizando información de tiempo presente se detectaron 32 eventos de nevada, 7 de los cuales produjeron nieve en más de una estación sinóptica. A fin de comprender los patrones de circulación, se realiza una climatología sinóptica de las incursiones de aire frío que son responsables de nevadas en la región de estudio. Dichos patrones se caracterizan por anomalías extremas en las vaguadas asociadas a frentes fríos y en las cu as posfrontales que denotan la intensidad de dichos sistemas. El campo de anomalías de altura geopotencial muestra en los casos de nieve generalizada un mínimo sobre la vaguada frontal que duplica la intensidad de la obtenida en los casos de nieve aislada. El intenso régimen ciclónico favorece la convergencia en niveles bajos y el fuerte enfriamiento, evidente en las anomalías del campo térmico en niveles medios, indicando la inestabilidad generada en la masa de aire que es conducida hacia el norte sobre la costa patagónica y el Mar Argentino. En un caso particular de nevada generalizada, asociada a una fuerte incursión de aire frío ocurrida el 10 de julio de 2004 sobre el sudeste de la costa bonaerense, se analiza la situación sinóptica utilizando el modelo "Sistema de Modelado Atmosférico Regional" (RAMS) como herramienta de diagnóstico y se la relaciona con las muestras previamente encontradas, caracterizando la masa de aire polar y su evolución. La nevada se asocia a una inestabilización sostenida de la masa de aire, favorecida por calentamiento y humedecimiento en una trayectoria dominantemente marítima y por convergencia en un régimen ciclónico en niveles bajos. This paper presents a statistic of the frequency of snow-fall occurred over the southeast of Buenos Aires province over a 35 year period (1960-2004). Considering present weather information 32 events were found and only 7 events show snow over more than one synoptic station. A synoptic climatology of the cold air incursions that are responsible for snow-fall in the study region is shown in order to understand the circulation patterns. Atmospheric circulation patterns are characterized by extreme anomalies linked to the trough associated to cold front and the ridge in post-frontal areas that denote the intensity of these systems,. The anomalies field of geopotencial height shows a negative extreme over the frontal trough in the cases of generalized snow duplicate the intensity in cases with isolated s
Low-resolution optical spectra of ultracool dwarfs with OSIRIS/GTC
Yanina Metodieva,Antoaneta Antonova,Valeri Golev,Dinko Dimitrov,David García-álvarez,John Gerard Doyle
Physics , 2014, DOI: 10.1093/mnras/stu2370
Abstract: We present the results of low-resolution optical spectroscopy with OSIRIS/GTC (Optical System for Imaging and Low Resolution Integrated Spectroscopy / Gran Telescopio Canarias) for a sample of ultracool dwarfs. For a subsample of seven objects, based on 2MASS NIR photometric colours, a 'photometric' spectral type is determined and compared to the results of the optical spectroscopy. For the stars, showing H$\alpha$ line in emission, equivalent widths were measured, and the ratio of H$\alpha$ to bolometric luminosity were calculated. We find that two dwarfs show the presence of magnetic activity over long periods, LP 326-21 -- quasi-constant-like, and 2MASS J17071830+6439331 -- variable.
Nevadas en el Sudeste Bonaerense: climatología sinóptica y un caso de estudio
Salio,Paola; Campetella,Claudia; Ruiz,Juan; Garcia Skabar,Yanina; Nicolini,Matilde;
Meteorologica , 2006,
Abstract: this paper presents a statistic of the frequency of snow-fall occurred over the southeast of buenos aires province over a 35 year period (1960-2004). considering present weather information 32 events were found and only 7 events show snow over more than one synoptic station. a synoptic climatology of the cold air incursions that are responsible for snow-fall in the study region is shown in order to understand the circulation patterns. atmospheric circulation patterns are characterized by extreme anomalies linked to the trough associated to cold front and the ridge in post-frontal areas that denote the intensity of these systems,. the anomalies field of geopotencial height shows a negative extreme over the frontal trough in the cases of generalized snow duplicate the intensity in cases with isolated snow. the intense cyclonic regime favors the convergence at low levels and the strong cooling, evident in the anomalies of temperature at mid-levels, indicating the instability generated in the air mass that is lead towards the northern patagonian coast and the argentinean sea. a case study of a generalized snow-fall related to a strong cold air incursion occurred on 10 july 2004 over the southeast coast of the buenos aires province. the synoptic situation is analyzed in relation to the long period sample and the polar air mass evolution is characterized using rams model in a diagnostic mode. the snow-fall is related to a persistent destabilization favored by heating and moisturizing in a prevalently maritime trajectory and by convergence in a cyclonic regime.
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