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Validation of the Hydro-Estimator (HE) and the Next Generation Radar (NEXRAD) during heavy storms over Puerto Rico (PR) is reported. The HE is a high resolution rainfall retrieval algorithm based on satellite and numerical weather... more
Validation of the Hydro-Estimator (HE) and the Next Generation Radar (NEXRAD) during heavy storms over Puerto Rico (PR) is reported. The HE is a high resolution rainfall retrieval algorithm based on satellite and numerical weather prediction model data. The accuracy of the HE ...
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utilizando cuatro radares o nodos, cuya localización fue seleccionada estratégicamente para cubrir esta área [Ríos-Olmo,2009, MS Tesis]. usualmente más susceptibles a precipitación que otros lugares del mundo debido a la humedad y la... more
utilizando cuatro radares o nodos, cuya localización fue seleccionada estratégicamente para cubrir esta área [Ríos-Olmo,2009, MS Tesis]. usualmente más susceptibles a precipitación que otros lugares del mundo debido a la humedad y la localización geográfica en donde la formación de nubes es mucho más probable. Ésta es la primera vez que un radar marino es modificado para aplicaciones meteorológicas y operado e instalado utilizando energía renovable. Los sistemas fotovoltaicos producen energía limpia y confiable sin emitir gases de invernadero como los combustibles fósiles. Los radares OTG son sistemas de baja potencia en banda X, lo que los hace una solución versátil para las necesidades energéticas de muchas aplicaciones. El diseño de un sistema fotovoltaico incluye la estimación de la carga eléctrica, especificación del banco de baterías, módulos solares, controlador de carga, inversor y el tamaño de los cables para el alambrado. Cabe señalar que, al determinar las baterías, es ne...
ABSTRACT: A rain gauge network (28 rain gauges) was installed in western Puerto Rico (PR) within a 4x4 km GOES satellite pixel. Located within the pixel is a well monitored sub-watershed of 3.55 km2, referred to here as the testbed... more
ABSTRACT: A rain gauge network (28 rain gauges) was installed in western Puerto Rico (PR) within a 4x4 km GOES satellite pixel. Located within the pixel is a well monitored sub-watershed of 3.55 km2, referred to here as the testbed subwatershed(TBSW). The rain ...
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Validation of the Hydro-Estimator (HE) and the Next Generation Radar (NEXRAD) during heavy storms over Puerto Rico (PR) is reported. The HE is a high resolution rainfall retrieval algorithm based on satellite and numerical weather... more
Validation of the Hydro-Estimator (HE) and the Next Generation Radar (NEXRAD) during heavy storms over Puerto Rico (PR) is reported. The HE is a high resolution rainfall retrieval algorithm based on satellite and numerical weather prediction model data. The accuracy of the HE ...
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Rain gauge networks are used to calibrate and validate quantitative precipitation estimation (QPE) methods based on remote sensing, which may be used as data sources for hydrologic models. The typical approach is to adjust (calibrate) or... more
Rain gauge networks are used to calibrate and validate quantitative precipitation estimation (QPE) methods based on remote sensing, which may be used as data sources for hydrologic models. The typical approach is to adjust (calibrate) or compare (validate) the rainfall in ...
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ABSTRACT
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ABSTRACT
Abstract Natural variations in raindrop size distribution (DSD) were studied for simulated X band radar response from October 2004 to July 2005 (normal no-storm conditions) and during September 15th to 16th, 2004 when the tropical storm... more
Abstract Natural variations in raindrop size distribution (DSD) were studied for simulated X band radar response from October 2004 to July 2005 (normal no-storm conditions) and during September 15th to 16th, 2004 when the tropical storm Jeanne passed over the ...
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ABSTRACT
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A short term rainfall prediction algorithm for intense storms is introduced in this work. The algorithm uses high spatial and temporal resolution radar data to predict the evolving distribution of rainfall rate. It is assumed that for a... more
A short term rainfall prediction algorithm for intense storms is introduced in this work. The algorithm uses high spatial and temporal resolution radar data to predict the evolving distribution of rainfall rate. It is assumed that for a short time period, a rain cloud behaves as a rigid object, with all parts moving in the same direction at a constant speed. Thus, the most likely future rainfall areas are estimated by tracking rain cell centroid advection in consecutive radar images. To achieve this estimation, a nonlinear regression model varying in the time and space domain is proposed to predict the most likely rainfall patterns. This model is based on the assumption that the current radar reflectivity is a function of the previous reflectivity observed in surrounding areas centered on the location of a predicted pixel. A second assumption is that the ratio of reflectivity of a given pixel to reflectivity of convective core is a fundamental predictor for rainfall estimation. This...
It is well documented in the literature that there is an under-sampling limitation of the lower atmosphere from long-range weather radars when observing at distant regions from the instrument's location [NRC, 1995, NRC, 2002,... more
It is well documented in the literature that there is an under-sampling limitation of the lower atmosphere from long-range weather radars when observing at distant regions from the instrument's location [NRC, 1995, NRC, 2002, Westrick, 1999]. This problem is evident in the west part of Puerto Rico where the earth curvature and other NOAA radar operational specifications do not allow observations in the lower tropo-sphere below 10,000 feet, and this is exactly where dangerous weather occurs. See Figure 1. This radar gap in the lower atmosphere cannot be properly sampled by the NexRAD radar which is located in Cayey, ap-proximately 70 miles east from Mayagüez (western part of PR). For this reason, many events, such as the water spout de-picted in the photo below (Figure 2), which occurred in Sep-tember 2005 in the Mayagüez bay, are completely invisible to the NexRAD radar which is used by the NWS Office in San Juan, PR. One option to overcome this problem is to create a network of...
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The Collaborative Adaptive Sensing of the Atmosphere (CASA) Engineering Research Center (ERC) at UPRM developed an Off-The-Grid (OTG) X-band single polarized radar network deployed in the Puerto Rico west coast. With this kind of radar it... more
The Collaborative Adaptive Sensing of the Atmosphere (CASA) Engineering Research Center (ERC) at UPRM developed an Off-The-Grid (OTG) X-band single polarized radar network deployed in the Puerto Rico west coast. With this kind of radar it is possible to observe some meteorological events that might not be detected by NEXRAD radar due to earth curvature. The main goal of this research is to break with the paradigm and limitations of using X-band OTG radars as a reliable forecast system, where the principal issue is the attenuation due to rain along the path. To overcome this problem the attenuated signal could be rectified through a correction algorithm based on reflectivity and also an ideal polarization (vertical or horizontal) will be identified to certain effects of rain attenuation. To correct for attenuation a hybrid between Hitschfeld – Bordan (HB) method and a Surface Reference Technique (SRT) would be used where the reference signal is the NEXRAD radar data because is consid...
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Characterization of the microphysical properties of non-precipitating stratus clouds including their suspended-water droplet size distribution and the cloud's liquid water content are estimated in this work. The dual wavelength... more
Characterization of the microphysical properties of non-precipitating stratus clouds including their suspended-water droplet size distribution and the cloud's liquid water content are estimated in this work. The dual wavelength ratio, DWR, and the differential extinction, DE, were computed at two millimeter frequencies, 33 GHz and 95 GHz, using UMass Cloud Profiling Radar System (CPRS) to estimate the drop size distribution. Data from radiosonde observations (Raob) is used as input in a recently calibrated model for estimation of the gaseous attenuation at Ka.-band and Liebe's model at W-band. Integrated specific humidity from a radiometer is used to constrain the radiosonde specific humidity. The radar reflectivity is corrected to take into account the effect of the wind speed, the difference of beamwidth at both frequencies and the difference in sampled range cells. Radar reflectivity and ancillary data are combined to obtain the differential extinction and the estimated cloud's liquid water density. Profiles of the processed data, such as DE, the DWR and the cloud's liquid water density are presented. Cloud's water density and radar reflectivity were used for the size distribution estimation of the suspended water droplets and the median drop diameter.
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An improved model for the microwave brightness temperature seen from space over calm ocean is presented. This model can be divided into two sub-models, the atmospheric absorption model and the ocean surface emissivity model. An improved... more
An improved model for the microwave brightness temperature seen from space over calm ocean is presented. This model can be divided into two sub-models, the atmospheric absorption model and the ocean surface emissivity model. An improved model for the absorption of the atmosphere near the 22 GHz water vapor line is