Impacto del cambio climático global : estado de situación

Fil: Rusticucci, Matilde. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina.Al detectar el problema del cambio climático mundial, la\nOrganización Meteorológica Mundial (OMM) y el Programa de las\nNaciones Unidas para el Medio Ambiente (PNUMA) crearon el Panel\nIntergubernamental de Expertos sobre el Cambio Climático (IPCC,\npor sus siglas en inglés) en 1988. El IPCC sintetiza en sus informes\nregulares el estado del conocimiento del cambio climático a lo largo\nde la historia, lo que sucede en el presente y hace proyecciones de\nlo que sucederá en el futuro de acuerdo con diferentes escenarios\nposibles que dependen del modo en que interactuarán los diversos\nfactores, naturales y asociados con las actividades humanas, que\ninfluyen en el clima y por lo tanto en el medio ambiente y la vida que\nse desarrolla en la Tierra

Variabilidad regional de las temperaturas de superficie en intervalos diarios y cuatridiurnos

Fil:Rusticucci, Matilde. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Analysis of interdecadal Variability of Temperature Extreme Events in Argentina applying EVT

La frecuencia de ocurrencia de los eventos extremos de temperatura ha sufrido variaciones a lo largo del último siglo: se han observado tendencias positivas significativas en las noches cálidas y tendencias negativas en las noches frías en todo el mundo. En Argentina, la probabilidad de ocurrencia de extremos cálidos anuales de la temperatura máxima disminuyó en las últimas décadas, mientras que hubo un incremento en la probabilidad de ocurrencia de extremos cálidos anuales de la temperatura mínima. El objetivo principal de este trabajo es evaluar la variabilidad interdecadal observada en la distribución de los eventos de temperatura que superan un determinado umbral en cinco estaciones meteorológicas de Argentina durante el periodo 1941-2000, mediante la aplicación de la teoría de valores extremos. La disponibilidad de datos diarios permite el ajuste de la distribución generalizada de Pareto (DGP) a las anomalías diarias de temperatura que exceden el percentil 90 o que no alcanzan el percentil 10 con el propósito de estimar los valores de retorno de los eventos extremos. Las series de anomalías diarias de temperatura se dividen en tres subperiodos consecutivos sin superposición de 20 años cada uno. La DGP se ajusta en cada uno de los tres subperiodos en forma independiente y se comparan los valores de retorno estimados en cada subperiodo. Los resultados muestran que hay una disminución en la intensidad de eventos extremos cálidos durante todo el periodo de estudio, junto con un incremento en su frecuencia de ocurrencia durante los últimos 20 años del siglo XX. Los extremos fríos también muestran una disminución en intensidad. Sin embargo, los cambios en su frecuencia de ocurrencia no son tan consistentes entre las diferentes estaciones estudiadas.The frequency of occurrence of temperature extreme events has changed throughout the last century: significant positive trends in warm nights and negative trends in cold nights have been observed all over the world. In Argentina, the probability of occurrence of warm annual extremes of maximum temperature has decreased in the last decades, while there has been an increase in warm annual extremes of minimum temperature. The main objective of this paper is to evaluate observed interdecadal changes in the distribution of temperature events that exceed a fixed threshold in five meteorological stations from Argentina over the period 1941-2000, by applying the extreme value theory (EVT). The availability of daily data allows fitting a generalized Pareto distribution (GPD) to daily temperature anomalies over the 90th or below the 10th percentile, in order to estimate return values of extreme events. Daily temperature anomalies are divided into three consecutive and non-overlapping subperiods of 20 years. GPD is fitted to each subperiod independently and a comparison is made between return values estimated in each subperiod. Results show that there is a decrease in the intensity of warm extreme events during the whole period, together with an increase in its frequency of occurrence during the last 20 years of the twentieth century. Cold extremes also show a decrease in their intensity. However, changes in their frequency of occurrence are not so consistent between the different stations analyzed.Fil: Tencer, Barbara. 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

Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation

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Climate and Health in Buenos Aires: A Review on Climate Impact on Human Health Studies Between 1995 and 2015

In this review, seven pieces of research on climate variability and its impact on human health in Buenos Aires City between 1995 and 2015 were evaluated. The review highlighted continuities and ruptures in the methodology, variables, and statistics data of the research, considering their similarities and differences in the period of study and the methodology applied. Contributions, pending issues, and public policies on climate change challenges in the city aimed at improving living conditions were considered. Six studies contributed evidence on the relationship between climate and health and its impacts on the population; two studies suggested the development of early warning systems and one study is a preliminary approach.Fil: Fontan, Silvia Graciela. Universidad Nacional de La Matanza; ArgentinaFil: Rusticucci, Matilde Monica. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Summer seasonal predictability of warm days in Argentina: statistical model approach

Predicting 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

Atmospheric circulation influence on temperature and precipitation individual and compound daily extreme events: Spatial variability and trends over southern South America

Southern South America (SSA) is an extended region where temperature and precipitation daily extreme events have several impacts on the different socio-economic activities. In this work, their individual and compound occurrence over SSA and their association with atmospheric circulation were studied during 1979–2015, using meteorological stations and the CPC gridded dataset. Results were generally in good agreement between both datasets. The occurrence of a warm night (minimum temperature exceeding the 90th percentile) or a cold day (maximum temperature below the 10th percentile) significantly increases the probability of heavy precipitation (daily precipitation exceeding the 75th percentile) in southern Chile and southeastern South America. These compound events were regionally conditioned by specific circulation types. In addition, both individual and compound extremes showed trends in the different sub-regions. On one hand, heavy precipitation exhibited a significant increase over central-eastern Argentina and Uruguay, northeastern Argentina and southern Brazil during the warm season, and a significant decrease in central and southern Chile during the cold season. On the other hand, warm (cold) extremes generally presented significant upward (downward) trends. Compound events showed significant positive trends for selected regions, in some cases coincident with trends in individual extremes. Changes in the frequency of circulation patterns were found to partly influence some of these trends, like the increases in heavy precipitation and warm extremes during the warm season.Fil: Olmo, Matías Ezequiel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Instituto Franco-Argentino sobre Estudios del Clima y sus Impactos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bettolli, Maria Laura. 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; Argentina. Instituto Franco-Argentino sobre Estudios del Clima y sus Impactos; ArgentinaFil: Rusticucci, Matilde Monica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Franco-Argentino sobre Estudios del Clima y sus Impactos; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentin

Association between El Niño and extreme temperatures in southern South America in CMIP5 models. Part 1: model evaluation in the present climate

Climate 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

Variability and predictability of winter cold nights in Argentina

Extreme 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

Efecto de la ciudad y el rio sobre la temperatura de superficie en Buenos Aires

El objetivo de este trabajo es estudiar algunas estructuras climáticas de la temperatura y las perturbaciones provocadas por la ubicación de las estaciones. Se toman tres estaciones en las inmediaciones y dentro de la ciudad de Buenos Aires. y se analizan las temperaturas de las horas 02:00, 08:00, 14:00 y 20:00. Se muestra que la influencia de la dirección del viento en la manifestación de los efectos de la ciudad o el río en la temperatura, depende de la hora y de la época del año. Sin embargo la estación de referencia no está influenciada por la ciudad, en la mayoría de las veces. El efecto de la ciudad sobre los promedios de temperatura, es máximo en horas de la noche. La influyencia del río, en cambio, es más notable a las 14:00. Ambos efectos se reflejan sobre la distribución de las anomalías de las estaciones estudiadas. Los procesos que dominan estas series son más homogéneos entre estaciones, si se consideran las temperaturas diarias.The alm of this paper is to study the effect of the station location on the six-hourly temperatures climatic structures. The observed temperature (at 02:00. 08:00, 14:00, 20:00, local time), for three stations within the metropolitan area of Buenos Aires, is studied. Local influences depend on the day time and the season. In the analysis of the wind direction, in most oí the situations the reference station is not influenced by the city. The urban effect is maximum al night hours and the river influence is maximum at 14:00. Both effects are still present in the anomalies frequency distribution. The daily anomalies processes are more homogeneous than the six-hourly ones between stations.Asociación Argentina de Geofísicos y Geodesta