809 research outputs found
Seasonal prediction of climate extremes of temperature in Argentina
No full textLa sociedad se ve afectada por fenómenos meteorológicos y climáticos extremos. La habilidad de predecir dichos extremos permitirá tomar medidas de precaución para evitar o reducir sus impactos. El presente trabajo de tesis tiene como objetivo identificar posibles predictores locales y remotos de la ocurrencia de extremos de temperatura y realizar un pronóstico estacional de dichos extremos. En particular, se analizaron tres aspectos específicos: la búsqueda de predictores, el modelado estadístico y la verificación de los pronósticos. Para ello, se utilizaron datos de temperatura mínima y máxima de Argentina al norte de 40◦S en el período 1970-2015. La búsqueda de predictores consistió en detectar cuáles de los índices representativos de la circulación atmosférica global y regional, de la temperatura superficial del mar y de las condiciones de humedad del suelo presentaron correlaciones significativas con índices de extremos de temperatura desfasados en un mes. Asimismo, se identificaron predictores de los extremos de temperatura bajo condiciones neutrales de El Niño-Oscilación del Sur. Para el modelado de las series de extremos de temperatura se aplicaron distintas técnicas estadísticas, muchas de las cuales realizan selección de variables que permiten escoger el mejor subconjunto de predictores y eliminar predictores redundantes que introducen ruido a la estimación. Luego, se identificaron los modelos con mayor habilidad para la predicción y se realizó un ensamble de los mismos. Este ensamble permitió elaborar el pronóstico estacional por terciles al cuantificar el porcentaje de modelos que pronostican cada una de las categorías: por encima de lo normal, cerca de lo normal y por debajo de lo normal. Por último, se verificó la calidad de los pronósticos mediante el cálculo de distintas métricas que permitieron cuantificar un conjunto de atributos: la confiabilidad, la resolución, la discriminación y el sesgo. Con los resultados obtenidos en esta tesis doctoral, se avanzó con la construcción de un pronóstico estacional operativo de los índices de extremos de temperatura en Argentina.Society is affected by extreme weather and climate events. The ability to predict these extremes will allow you to take precautionary measures to avoid or reduce their impacts. The objective of this thesis is to identify possible local and remote predictors of the occurrence of extreme temperature, and to make a seasonal forecast with them. In particular, three specific aspects were analyzed: the search for predictors, statistical modeling, and the forecast verification. For this, minimum and maximum temperature data from Argentina were used north of 40 ◦S in the period 1970-2015. In order to search for predictors, we detected which of the representative indices of the global and regional atmospheric circulation, the sea surface temperature and the soil moisture conditions presented significant correlations with extreme temperature indices considering a one-month lag. Moreover, predictors of extreme temperature were identified under neutral El Niño-Southern Oscillation conditions. For the modeling of the temperature extremes series, different statistical techniques were applied, many of which perform a selection of variables that allow choosing the best subset of predictors and eliminating redundant predictors that introduce noise to the estimation. Then, the models with a greater ability for prediction were identified and an ensemble of them was made. This ensemble allowed to elaborate the seasonal forecast by terciles when quantifying the percentage of models that predict each of the categories: above normal, near normal and below normal. Finally, the quality of the forecasts was verified by calculating different metrics which quantify a set of attributes: reliability, resolution, discrimination, and bias. With the results obtained in this doctoral thesis, progress was made with the construction of an operational seasonal forecast of the extremes of temperature in Argentina.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Temperature extremes in the Argentina central region and their monthly relationship with the mean circulation and ENSO phases
No full textThe aim of this study is to analyse the interannual variability of monthly climatic indices of extreme daily temperature in the central-north region of Argentina throughout a year and its relationship with the atmospheric circulation. The impact of El Niño-Southern Oscillation (ENSO) over different temperature indices throughout the year is specially analysed. Globally used indices in the 1970–2010 period are utilized for this purpose. The trends of temperature extremes show warming conditions in several months, especially in October and November. In order to find possible forcings of extreme temperature in the region at monthly scale, the co-variability with other circulation monthly time series such as changes in the intensity of Southern Hemisphere semi-permanent anticyclones and the intensity of the subtropical jet were studied. The main finding was a systematic shift of the South Atlantic anticyclone towards the west over the decades in June and August, which might hinder the cold advections over the region surveyed. Moreover, the influence of the variation on the intensity of the subtropical jet over extreme events showed significant positive (negative) correlations between the intensity of the jet and the frequency of cold (warm) indices in a great number of months. Finally, the influence of the ENSO phases on each of the temperature extremes analysed was studied. It was found that under El Niño conditions, minimum temperatures are affected quite evenly throughout the year, fostering the occurrence of warm nights. The impact of the El Niño event on the maximum extreme temperatures, however, shows seasonal differences. Between July and September warm days conditions are fostered, while between November and February the opposite (cold days) can be seen. This results in a decrease in the temperature range in the region surveyed during the summer months under El Niño conditions.Fil: Rusticucci, Matilde Monica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: Barrucand, Mariana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: Collazo, Soledad Maribel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentin
Capability of the SMHI-RCA4 RCM driven by the ERA-Interim reanalysis to simulate heat waves in Argentina
No full textThe aim of the work was to evaluate the capability of the SMHI-RCA4 regional climate model (RCM) driven by the ERA-Interim reanalysis to simulate heat waves in Argentina. Firstly, we evaluated simulations of summer daily maximum temperature (Tmax) against observed data from nine stations. The model showed a warm Tmax bias at six locations and the smallest and/or negative biases were located over regions with complex topography. Heat waves were defined based on exceedances of the daily 90th percentile of Tmax at individual stations. The model overestimated the intensity, duration, and number of heat waves at all locations, but more intense heat waves were underestimated. In particular, we analysed the extreme heat wave that occurred in November 1985 in northeastern Argentina and found out that a possible reason for its underestimation was an inaccurate simulation of the sea level pressure gradient in the region. The weaker pressure gradient in the model caused a reduction of the warm northerly advection. Finally, we studied how the parameters of heat waves varied among different phases of El Niño-Southern Oscillation (ENSO) for observed and modelled data. At five stations, the strongest heat waves occurred during La Niña years and were probably associated with the decrease in precipitation.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lhotka, Ondřej. Czech Academy of Sciences; República ChecaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kyselý, Jan. Czech Academy of Sciences; República Checa. Czech University of Life Sciences; República Chec
Summer seasonal predictability of warm days in Argentina: statistical model approach
No full textPredicting extreme temperature events can be very useful for different sectorsthat are strongly affected by their variability. The goal of this study is toanalyze the influence of the main atmospheric, oceanic, and soil moistureforcing on the occurrence of summer warm days and to predict extremetemperatures in Argentina northern of 40°S by fitting a statistical model. In apreliminary analysis, we studied trends and periodicities. Significant positivetrends, fundamentally in western Argentina, and two main periodicities ofsummer warm days were detected: 2?4 years and approximately 8 years.Lagged correlations allowed us to identify the key predictors: ElNiño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), andStandardized Precipitation Indices (SPI). We also noticed that the frequency ofwarm days in spring acts as a good predictor of summer warm days. Due to thecollinearity among many predictors, principal component regression was usedto simulate summer warm days. We obtained negative biases (i.e., the modeltends to underestimate the frequency of summer warm days), but the observedand simulated values of summer warm days were significantly correlated,except in northwest Argentina. Finally, we analyzed the predictability of thesummer warm days under ENSO neutral conditions, and we found newpredictors: the geopotential height gradient in 850 hPa (between the AtlanticAnticyclone and the Chaco Low) and the Atlantic Multidecadal Oscillation(AMO), while the PDO and SPI lost some relevance.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Barrucand, Mariana Graciela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentin
Association between El Niño and extreme temperatures in southern South America in CMIP5 models. Part 1: model evaluation in the present climate
No full textClimate variability might temporarily improve or mitigate the effects of increasingglobal warming. Understanding and estimating internal variability is just as important as understandingthe role of anthropogenic forcing, as the combination of both drives climate events in thereal world. The objective of this work is to analyze the relationship between the SST of the equatorialPacific and 4 extreme temperature indices in southern South America considering griddedobservational data (HadEX3), reanalyses (ERA-Interim, NCEP1, NCEP2), and global climatemodels participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) in the historicalperiod 1979−2005. For this, correlations and quantile regression for the 90th percentilewere estimated between the variables. Moreover, to assess the performance of the reanalysis andCMIP5 models, multiple metrics were calculated. The observations showed that warm conditionsin the equatorial Pacific are mainly associated with a higher occurrence of warm nights in thenorth and center of Argentina and Chile in winter and spring. However, the different reanalysesconsidered in this study showed discrepancies in representing these relationships. Several CMIP5models were generally able to simulate correlation patterns for the warm extremes of the minimumand maximum temperature in comparison to HadEX3. These types of studies are critical tounderstanding whether climate models simulate temperature extremes in association with physicalprocesses, providing greater confidence in their future projections.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barrucand, Mariana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; ArgentinaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Un modelo cada vez más excluyente. Las políticas de comunicación del gobierno de Cambiemos
No full textEn síntesis, las políticas cambiemitas de comunicación se caracterizan por la devolución de favores a Clarín y un intento de equilibrio ante presiones de otras grandes corporaciones avaladas por el lobby de los gobiernos de sus países de origen como Telefónica y Claro. Esto deriva en una brutal concentración de la propiedad en desmedro de los medios PyME, comunitarios, y cooperativos; y en una crítica centralización de la producción con desprecio por lo regional y local. Practican también una "austeridad selectiva" (Rivero, 2017): mientras restringen la inversión en medios públicos, la promoción de la producción de contenidos y el fomento a medios comunitarios y de pueblos originarios, incrementan el gasto en publicidad oficial en las empresas amigas.Aún con todas las reformas de leyes por decretos y resoluciones, se siguen incumpliendo las leyes y los tratados internacionales a los que Argentina ha suscripto y tienen valor constitucional. No es casualidad que tengan abiertas causas judiciales en Argentina y en el sistema interamericano de derechos humanos. Como en otras áreas, impulsan políticas más represivas de la expresión para ver "si pasa, pasa", pero ante la reacción social y organizacional, dan marcha atrás. Es de destacar, en este sentido, la acción de la sociedad civil organizada y de los/as académicos/as de comunicación que se mantienen alertas y encienden las alarmas públicas ante estas tentativas.No es novedad en las políticas de comunicación la lógica de premiar a los medios afines y castigar a los opositores con la asignación de publicidad oficial, las prácticas secretistas en acceso a la información, y el intercambio de favores entre medios y gobiernos en la radiodifusión. Sin embargo, la particularidad de este gobierno es que ha alcanzado niveles desconocidos en cada uno de estos temas; y no ha disimulado, ni ha intentado negociar o compensar a los otros actores que salen perjudicados.Fil: Segura, Maria Soledad. Universidad Nacional de Córdoba. Facultad de Ciencias de la Comunicación; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Sociales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Identidades “reescritas”: autotraducción y retraducción en la poesía mapuche contemporánea
No full textMapuche authors have been self-translating their literary work extensively for the last three decades. Among the different motivations for this practice, the repossession of the Indigenous language as an element of identity-affirmation features prominently. This essay analyzes self-translation as a space where the identity of each author is rewritten or edited, as well as the links this practice shares with retranslation, both the author's own and allograph retranslation. The analysis will first focus on Mapuche writer Elicura Chihuailaf's reediting of a series of bilingual poems throughout his career. Additionally, the criteria of untranslatability between languages and cultures espoused by poet Liliana Ancalao will be contrasted with the allograph retranslations of her work into Mapudungun carried out by Víctor Cifuentes. The differences examined across self-translations and retranslations tend to respond to changes in the author's ideological positioning as well as to the emendation of semantic calques and instances of linguistic incommensurability.Fil: Stocco, Melisa Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo; Argentin
Mobile payments for remittances in Africa: Benchmarking with Latin America
No full textIn this article the author seeks to explain the reasons backing the success of mobile technology in money transfers comparing Africa and Latin America.Remittances, Africa, Latin America, mobile phones
Seasonal forecast of the percentage of days with extreme temperatures in central-northern Argentina: An operational statistical approach
No full textSeveral socio-economic sectors are sensitive to the occurrence of extreme climate events. The ability to predict these extremes will allow precautionary measures to reduce their impacts. This work aims to disseminate a seasonal statistical forecast of daily temperature extremes in Argentina to the international scientific community. At the local level, this forecast is shared at monthly meetings organized by the Argentine National Meteorological Service and attended by different users. For the temperature extremes modeling, several predictors and statistical techniques were applied. We estimated the probability of each tercile category (above-normal, near-normal, and below-normal) by quantifying the percentage of models that predict each of them. The forecasts were verified by calculating different metrics. In general, we observed that the forecast system has less skill to discriminate the near-normal category in all seasons, and the other categories present a skill highly variable according to the season, region, and extreme index. The verification process revealed that predictability increases for all extreme indices with a previous La Niña phase. This product represents an advance towards an operational seasonal forecast of extreme temperatures in Argentina because it offers predictions based on a detailed study of predictors in the region, the incorporation of multiple statistical methodologies, and the predicted variables are not the most typical ones offered by forecasting centers. Finally, it is highlighted that the accuracy rate obtained with this product exceeds a forecast based on climatology, i.e., despite the uncertainties, our forecasts provide additional information to users for decision making.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Barrucand, Mariana Graciela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentin
Variability and predictability of winter cold nights in Argentina
No full textExtreme cold events can cause crop damage as well as an increase in energy demand and even in the mortality rate. Identifying the atmospheric processes associated with the occurrence of these extremes would allow decision-makers to implement preventive and mitigation actions. The goal of this study is to identify predictors of cold extremes of minimum temperature during winter in Argentina (north of 40 °S), and their modulation by the different El Ni~no-Southern Oscillation (ENSO) phases for the period 1970?2015. Lagged correlation analysis between winter cold nights and several global and regional climate indices identified ENSO, subtropical jet intensity, position and intensity of the South Pacific Anticyclone (SPA), and a blocking index as the dominating forcings. The El Niño phase is associated with a decrease in the occurrence of cold extremes. In addition, an increase in the number of blocking events together with a weaker subtropical jet and, a less intense and northward shift of the SPA also inhibit the occurrence of cold extremes of the minimum temperature. Our results indicate persistence in the winter cold nights series compared with the previous season in eastern Argentina. Twowinters with opposite extreme conditions (high and low frequency of cold nights) were selected as case studies. Since both cases occurred under ENSO neutral conditions, we also searched for cold nights predictors consideringonly neutral years. We detected the presence of an equivalent barotropic structure located in southeastern Pacific in both events, which confirmed the importance of the SPA intensity and blocking events as predictors in absenceof an active El Niño.Fil: Collazo, Soledad Maribel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barrucand, Mariana Graciela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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