1,720,987 research outputs found
A reply to McMahon et al.(2008)
Get PDFRecently, McMahon et al. (2008) criticized our article concerning the impacts of climate variability on the reproductive parameters of southern elephant seals (Vergani et al., 2008). We characterized El Niño–Southern Oscillation (ENSO) climate anomalies in the periphery of Antarctica using reanalysed global atmospheric data from Kalnay et al. (1996) encompassing over 40 years of observations. We considered existing evidence for ENSO signals in delineated regions of Antarctica and the current understanding of propagation mechanisms from the source region in the tropical Pacific Ocean to high latitudes of the Southern Hemisphere.Fil: Vergani, Daniel Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Centro de Estudios Territoriales; ArgentinaFil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Statistical downscaling estimation of recent rainfall trends in the eastern slope of the Andes mountain range in Argentina
Get PDFStatistical models for rainfall downscaling based on multiple linear regression techniques have been developed and tested in the Andean Region of west Argentina, an extended mountainous region where three different rain regimes predominate and rainfall has great spatial and temporal variability. The verification procedure was focused on the model's ability to reproduce observed rainfall trends in recent decades. In the northwest of Argentina, domain of the tropical summer rain regime, the monthly rainfall variance accounted for by downscaling models was 77% on average and models reproduced satisfactorily the negative linear trend observed in the last two decades of the past century. In the arid central-west Argentina, a region of rapid transition between two different rain regimes, model performance was rather poor (an average of 50% of explained variance), even so models were able to capture outstanding differences in the linear trend between the northern and southern sectors of the region. In the southwest of Argentina, domain of the mid-latitude winter rain regime, the monthly variance accounted for by downscaling models was 71% on average and models were capable to reproduce a singular change in the onset of the rainy season that occurred during the 1990s. The results achieved demonstrate that it is feasible to establish significant and useful statistical relationships between atmospheric variables and rainfall at monthly and river basin scales, even for a topographically complex region like western Argentina.Fil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Simulation capability of tropical and extratropical seasonal climate anomalies over South America
Get PDFAn ensemble of 20 extended integrations of the atmospheric model CSIRO Mark 2, forced with the sea surface temperature observed during the 1986–1998 period, was performed to analyze the simulation capability of seasonal climate anomalies over South America and adjacent oceanic areas. Variations of the simulation skill within the region and during the experimental period were assessed through standard statistical measures and compared to the signal-to-noise ratio distribution. Before the skill assessment, model systematic errors were thoroughly evaluated. The results confirm that the simulation skill is very high in tropical oceanic areas, and decreases rapidly towards middle and high latitudes. Model performance at mid and high atmospheric levels is substantially better than at low levels. Relatively high simulation capability was found over the Pacific Ocean between the equator and the Antarctic coast, which is coherent with the presence of three relative maximums in the signal-to-noise ratio, similar to the increase of the forced variance found by several authors over much of the Pacific–North American pattern region. Rainfall rate and second-order moments associated with the cyclonic activity and the meridional eddy fluxes of heat and humidity are better simulated in a narrow strip parallel to the SPCZ and extending further southeast into mid latitudes of the continent. The simulation skill noticeably improves during the warm and cold ENSO phases, in correspondence with an intensification of the signal-to-noise ratio, and useful rainfall anomaly simulations can be obtained over the Amazonas and Rio de la Plata river basins.Fil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Climate in the Monte Desert: Past trends, present conditions, and future projections
Get PDFThis paper documents the main features of climate and climate variability across the Monte Desert for the Last Glacial Maximum, the Glacial-Interglacial transition, and the Holocene on the basis of proxy records and for the 20th century using instrumental observations. The climate in the Monte is determined by interactions between regional physiography and atmospheric circulation in the 25-45°S sectors of South America. Although arid and semi-arid conditions prevail across the Monte, its large latitudinal extent and complex topography introduce many particularities at local scales. Paleoclimatic records and model simulations of past climates suggest significant variations in the atmospheric circulation, temperature and rainfall patterns since the Last Glacial Maximum. High-resolution proxy records east of the Andes support the existence of complex climatic patterns with similar temperature changes across the whole region but opposite precipitation variations between subtropical and mid-latitude sectors in the Monte during the past millennium. The present-day climate is depicted in terms of the space and time variability of the near-surface temperature, rainfall and tropospheric wind patterns. Uneven temperature trends over the Monte were recorded for two separate (1920-44 and 1977-2001) global warming periods in the 20th century. Additional warming evidence in the region is provided by extreme temperature records. The non-homogeneous regional pattern of precipitation shows a positive long-term increase between 30 and 40°S during the interval 1985-2001. Ensemble of climate experiments accomplished with general circulation models provide the most likely changes in temperature and rainfall to occur by the end of this century in relation to present climate. Temperature increases, larger in summer than in winter, will be concurrent with more abundant precipitations in summer, but almost no changes or even small reductions in winter across the Monte.Fil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin
Scenarios of Future Climate and Land-Management Effects on Carbon Stocks in Northern Patagonian Shrublands
Get PDFWe analyzed the possible effects of grazing management and future climate change on carbon (C) stocks in soils of northern Patagonian shrublands. To this aim, we coupled the outputs of three (HadCM3, CSIRO Mk2, and CCSR/NIES) global climate models to the CENTURY (v5.3) model of terrestrial C balance. The CENTURY model was initialized with long-term field data on local biome physiognomy, seasonal phenologic trends, and prevailing land-management systems and was validated with recent sequences of 1-km Normalized Difference Vegetation Index (MODIS-Terra) images and soil C data. In the tested scenarios, the predicted climate changes would result in increased total C in soil organic matter (SOMTC). Maximum SOMTC under changed climate forcing would not differ significantly from that expected under baseline conditions (8 kg m−2). A decrease in grazing intensity would result in SOMTC increases of 11% to 12% even if climate changes did not occur. Climate change would account for SOMTC increases of 5% to 6%.Fil: Carrera, Analía Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Ares, Jorge Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Thurner, Stephanie. Universitat Technical Zu Munich; AlemaniaFil: Bertiller, Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Advances in the climatic forecast of rainfall anomalies in the Pampa Region
Get PDFLos modelos globales de la circulación general de la atmósfera (MCGA) son capaces de simular anomalías climáticas estadísticamente significativas de escala estacional o mayor, asociadas con anomalías en la temperatura de la superficie del mar. Los MCGA pueden estimar efectivamente el signo y la probabilidad de tales anomalías climáticas cuando su extensión es varias veces mayor que la resolución espacial del modelo. En este trabajo se presentan algunos avances en la estimación de las anomalías de la lluvia en 22 localidades de la Región Pampeana Argentina mediante downscaling estadístico de la información producida por un ensamble de veinte simulaciones con el MCGA CSIRO-9, prescribiendo la temperatura de la superficie del mar de acuerdo con los valores diarios observados en el período 1987-1998. El downscaling estadístico de la lluvia produjo una mayor correlación con las observaciones locales que los datos de lluvia del MCGA interpolados sobre cada sitio. Los resultados de un Análisis de las Componentes Principales aplicado a los datos observados y estimados indican que este método de downscaling permite discernir áreas con diferente comportamiento de la lluvia dentro de la región de estudio.Atmospheric general circulation models (AGCM) are able to simulate statistically significant climate anomalies of seasonal or larger time-scales, associated with anomalies in the sea surface temperature. AGCMs can effectively estimate the sign and probability of such climate anomalies whenever their extent is several times greater than the spatial resolution of the model. Some progress attained in the estimation of rainfall anomalies in 22 sites of the Pampa Region, Argentina, by means of statistical downscaling of the output from an AGCM are presented in this work. Downscaling models were based in the multiple lineal regression method. Climatic anomalies of the atmospheric independent variables required in the rainfall downscaling procedure were obtained from the ensemble average of twenty simulations carried out with the AGCM CSIRO-9, prescribing the sea surface temperature according to observed daily values in the period 1987-1998. The statistical downscaling of rainfall produced greater correlation with local observation than the AGCM rainfall data interpolated over each location. The results of a Principal Component Analysis applied to the observed and estimated data reveal that this downscaling approach is able to distinguish areas with different rainfall behavior within the study region.Fil: Labraga, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Brandizi, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Lopez, Monica Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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