Generación de umbrales meteorológicos para la emisión de alertas en el Servicio Meteorológico Nacional: lineamientos para avanzar en el pronóstico por impacto

Fil: Anaya, Daniel. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad; Argentina.Fil: D´Amen, Daniela Lilian. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad; Argentina.Fil: Chasco, Julia. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad; Argentina.Fil: Saucedo, Marcos. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad. Dirección de Pronósticos del Tiempo y Avisos; Argentina.En este trabajo se presenta la metodología de establecimiento de umbrales meteorológicos desarrollada en el año 2018 para contribuir en la futura elaboración de alertas meteorológicos que implementará el Servicio Meteorológico Nacional a partir de la puesta en funcionamiento de la Plataforma Integral Meteorológica (Pimet). Esta metodología está basada no solamente en el conocimiento meteorológico sino que además toma en cuenta el marco de la reducción de riesgos de desastres.This work presents a methodology to establish meteorological thresholds carried out during 2018, needed for the development of weather warnings, to be implemented by the National Weather Service once the Integral Meteorological Platform (Pimet) is fully operational. Such methodology is not only based on meteorological knowledge, but also considers the disaster risk reduction framework

El tratamiento implícito de la incertidumbre en los pronósticos del SMN

Fil: De Elía, Ramón. Servicio Meteorológico Nacional. Dirección Nacional de Ciencia e Innovación en Productos y Servicios; Argentina.Fil: Lohigorry, Pedro Miguel. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad. Dirección de Pronósticos del Tiempo y Avisos. Coordinación de Pronósticos Inmediatos; Argentina.Los estudios sobre incertidumbres en pronósticos meteorológicos suelen limitarse a los problemas explícitos de predictibilidad de ciertas escalas o fenómenos específicos, como así también al tratamiento probabilístico de esta incertidumbre. Esta Nota Técnica apunta a describir las decisiones que deben tomar los pronosticadores --y aquellos que definen el sistema de pronóstico--, que implícitamente afectan el tratamiento que se da a la incertidumbre. Se puede observar que el pronosticador constantemente toma en cuenta la incertidumbre, mismo si a veces lo hace de forma automática. Es por ello que la expansión del uso de pronósticos probabilísticos --estimulada por la disponibilidad de ensambles-- no debe ser realizada ignorando estas condiciones.Uncertainty studies in weather forecasting are usually limited to explicit predictability issues at different scales or specific weather events, as well as its treatment through a probabilistic approach. This Technical Note aims at describing how decisions that forecasters --and those that define the forecast system-- have to carry out, implicitly affect the way uncertainty is handled. Forecasters are constantly dealing with uncertainty, even though in some cases this is not done in a fully conscious way. This suggests that extending the use of probabilistic forecasting should not be an automatic consequence of the availability of ensembles

Measurements of concentration differences between liquid mixtures using digital holographic interferometry

We present an alternative method to detect and measure the concentration changes in liquid solutions. The method uses Digital Holographic Interferometry (DHI) and is based on measuring refractive index variations. The first hologram is recorded when a wavefront from light comes across an ordinary cylindrical glass container filled with a liquid solution. The second hologram is recorded after slight changing the liquid’s concentration. Differences in phase obtained from the correlation of the first hologram with the second one provide information about the refractive index variation, which is directly related to the changes in physical properties related to the concentration. The method can be used − with high sensitivity, accuracy, and speed − either to detect adulterations or to measure a slight change of concentration in the order of 0.001 moles which is equivalent to a difference of 0.003 g of sodium chloride in solutions. The method also enables to measure and calculate the phase difference among each pixel of two samples. This makes it possible to generate a global measurement of the phase difference of the entire sensed region

Foucault test: shadowgram modeling from the physical theory for quantitative evaluations

The physical theory of the Foucault test has been investigated to represent the complex amplitude and irradiance of the shadowgram in terms of the wavefront error; however, most of the studies have limited the treatment for the particular case of nearly diffraction-limited optical devices (i.e., aberrations smaller than the wavelength). In this paper we discard this restriction, and in order to show a more precise interpretation from the physical theory we derive expressions for the complex amplitude and the irradiance over an optical device with larger aberrations. To the best of our knowledge, it is the first time an expression is obtained in closed form. As will be seen, the result of this derivation is obtained using some properties of the Hilbert transform that permit representing the irradiance in a simple form in terms of the partial derivatives of the wavefront error. Additionally, we briefly describe from this point of view a methodology for the quantitative analysis of the test

Real-time measurement of the average temperature profiles in liquid cooling using digital holographic interferometry

We present an alternative optical method to estimate the temperature during the cooling process of a liquid using digital holographic interferometry (DHI). We make use of phase variations that are linked to variations in the refractive index and the temperature property of a liquid. In DHI, a hologram is first recorded using an object beam scattered from a rectangular container with a liquid at a certain reference temperature. A second hologram is then recorded when the temperature is decreased slightly. A phase difference between the two holograms indicates a temperature variation, and it is possible to obtain the temperature value at each small point of the sensed optical field. The relative phase map between the two object states is obtained simply and quickly through Fourier-transform method. Our experimental results reveal that the temperature values measured using this method and those obtained with a thermometer are consistent. We additionally show that it is possible to analyze the heat-loss process of a liquid sample in dynamic events using DHI. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE

El uso de código de colores en alertas meteorológicos

Fil: de Elía, Ramón. Servicio Meteorológico Nacional. Dirección Nacional de Ciencia e Innovación en Productos y Servicios; Argentina.Fil: Lohigorry, Pedro Miguel. Servicio Meteorológico Nacional. Gerencia de Servicios a la Comunidad. División de Vigilancia Meteorológica por Sensoramiento Remoto; Argentina.Fil: Chasco, Julia. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad; Argentina.Fil: Anaya, Daniel. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad; Argentina.Fil: Saucedo, Marcos. Servicio Meteorológico Nacional. Dirección Nacional de Pronósticos y Servicios para la Sociedad. Dirección de Pronósticos del Tiempo y Avisos; Argentina.En la actualidad se encuentra muy difundido el uso de escalas de colores para transmitir alertas de todo tipo, y en la última década a estas se han incorporado las alertas meteorológicas. La presente Nota Técnica hace una revisión del uso de escalas de colores en un grupo de servicios meteorológicos del mundo con el fin de ilustrar el tipo de uso que se lleva adelante. Se encuentra que el uso de la escala de colores en alertas varía en sus significados dependiendo del servicio meteorológico que lo produce. La razón principal de esta divergencia se encuentra en que el concepto de alerta está asociado a por lo menos tres conceptos fundamentales que ayudan a definir sus características: la urgencia de la misma (tiempo disponible hasta el evento), el impacto esperado del evento si este ocurriera, y la probabilidad de ocurrencia del evento. En definitiva, la escala de colores es una variable unidimensional que debe representar un problema multidimensional, lo que deja muchas opciones sobre qué elemento priorizar. El SMN ha puesto en operaciones recientemente su propia escala de colores para la difusión de alertas, y se cierra la Nota Técnica con una discusión sobre su interpretación y uso.The use of a color-coded warning system is widespread in different organizations concerned with the security of the population, and in the last decade this is also the case for weather services. The present Technical Note reviews the use of color-coded warning systems in weather services around the world and significant differences were found in their usage. The main reason for these differences stems from the fact that warnings are associated with at least three key concepts: its urgency (time to event), event´s expected impact, and event´s probability of occurrence. As such, color-coded warnings are a unidimensional variable that must represent a multidimensional issue, which leaves many open options to the designer regarding their main priorities. The text closes with a discussion of the color-coded warning system recently implemented by the Weather Service of Argentina

Fast flame temperature estimation using a point diffraction interferometer and non-negative least square method

Some of the interferometry methods proposed for flame temperature measurements from its projection could be complex and demand so much computing time. Assuming a circular symmetric and smooth flame temperature distribution, it is possible to use a linear combination of Gaussian functions with weights constrained to non-negative values

Phase Unwrapping using Chebyshev Polynomials

Phase unwrapping is an intermediate step for interferogram analysis. The phase associated with an interferogram can be estimated using a curve mesh of functions. Each of these functions can be approximated by a linear combination of basis functions. Chebyshev polynomials in addition to being a family of orthogonal polynomials can be defined recursively. In this work a method for phase unwrapping using Chebyshev polynomials is proposed. Results show good performance when applied to synthetic images without noise and also to synthetic images with noise

Phase unwrapping using a regular mesh grid

Phase unwrapping is a key step in the fringe pattern analysis. Although there are many algorithms for recovering continuous phase from wrapped phase maps, many of them are computationaly heavy, even for smooth phase maps. The smoothness characteristics of a phase map allow the use of radial basis functions to model the unwrapped phase. This method helps to reduce the processing time when unwrapping the phase. The processing time can be reduced even more when the reconstruction does not take into account all the pixels of the phase map image. In this paper we describe an algorithm for phase unwrapping where the phase map is reconstructed from a subset of pixels of the phase image using radial basis functions (RBFs). The proposed method is compared with the algorithm based on the same radial basis functions (RBFs) but using all the phase image pixels

An alternative approach to the tomographic reconstruction of smooth refractive index distributions

Continuous, mathematically smooth Phase Objects with radial symmetry are reconstructed from cross sections of their refractive index distribution by a novel method, consisting of a linear combination of Gaussian basis functions, whose technical details are discussed. As an application example, this approach is used to get a fast and accurate estimation of the temperature distribution of an actual soldering tip