98 research outputs found
Impacto del cambio climático global : estado de situación
No full textFil: 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
Organización Meteorológica Mundial (OMM) y el Programa de las
Naciones Unidas para el Medio Ambiente (PNUMA) crearon el Panel
Intergubernamental de Expertos sobre el Cambio Climático (IPCC,
por sus siglas en inglés) en 1988. El IPCC sintetiza en sus informes
regulares el estado del conocimiento del cambio climático a lo largo
de la historia, lo que sucede en el presente y hace proyecciones de
lo que sucederá en el futuro de acuerdo con diferentes escenarios
posibles que dependen del modo en que interactuarán los diversos
factores, naturales y asociados con las actividades humanas, que
influyen en el clima y por lo tanto en el medio ambiente y la vida que
se desarrolla en la Tierra
Variabilidad regional de las temperaturas de superficie en intervalos diarios y cuatridiurnos
No full textFil:Rusticucci, Matilde. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Attribution and projections of temperature extreme trends in South America based on CMIP5 models
No full textTemperature extreme indices were analyzed for five continental regions of southern South America defined according to their climatic characteristics. Gridded observations, reanalysis, and global-coupled climate models from CMIP5 were used with the approach of temperature extreme trend attribution analysis on fixed-threshold and percentile-based temperature extremes indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). The largest positive trends are exhibited in the tropical nights index, and a clear anthropogenic signal is evident in the subtropical region. In the subtropical central Andes, there is a decrease in the frost days index and increases in the tropical nights and summer days indices, and an anthropogenic signal is evident. In the Patagonian region, all trends from the historical runs were significant, while the ones from the natural experiment were nonsignificant, showing the marked effect of anthropogenic forcing in this region in the extreme temperature events. Projected changes in extreme indices for the 21st century are consistent with a warming climate, and larger changes are expected in the warm nights index.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: Zazulie, Natalia. 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
Observed and simulated variability of extreme temperature events over South America
No full textThis invited review paper tends to summarise the results based on the variability of occurrence of temperature extremes in South America. The first thing to note is that there is a geographical imbalance with respect to the number of published studies on temperature extremes. Most of the results come from the southern part of South America, east of the Andes, and a few from the northern part of the continent and for the Altiplano. The workshop organised by the ETCCDMI in Brazil was the first time to have the opportunity to collect information in a regional way and present trends in extreme daily temperatures. A better geographical picture enhanced with more data show significant geographical trends in warm (positive) and cold (negative) nights over Southern South America and over the northern South America coast. All other studies based on smaller regions also agree in finding the most significant trends in the evolution of the minimum temperature, with positive trends in almost all studies on the occurrence of warm nights (or hot extremes of minimum temperature) and negative trend in the cold extremes of the minimum. On the other hand, there is little agreement on the variability of maximum temperature. Generally the maximum temperature in southern South America has decreased, in opposition to the case of northern South America where it has increased. Strong decadal and interannual variability have been found in the occurrence of cold extremes. Reanalysis and climate models underestimate the intensity of extremes, mainly near the Andes. The studies trying to understand the dynamics of the circulation that leads to the occurrence of these extremes are analysed from its occurrence in almost all scales from the synoptic, intraseasonal, seasonal, annual, and multi-year linear trend with different methodologies, also, indentifying the local and remote forcing. A gap was found in studies that relate some specific local forcing (like changes in land use) and compare it with the remote ones. Different aspects of the occurrence of the temperature extremes are still missing in some regions of the continent.Fil: 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
Climate and Health in Buenos Aires: A Review on Climate Impact on Human Health Studies Between 1995 and 2015
No full textIn 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
Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation
No full textWe analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Niño phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Niño connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Niño evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation.Fil: Renom Molina, Madeleine. Universidad de la República. Facultad de Ciencias; UruguayFil: 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: Barreiro, Marcelo. Universidad de la República. Facultad de Ciencias; Urugua
Regional climate of the subtropical central Andes using high-resolution CMIP5 models—part I: past performance (1980–2005)
No full textThis study assesses the performance of 15 high resolution global climate models (GCMs) over the complex orographic region of the subtropical central Andes from available simulations of the Fifth Coupled Model Intercomparison Project (CMIP5). The simulated past climate (1980–2005) was compared against the Climate Research Unit (CRU) dataset and the ERA-Interim reanalysis, considered as reference datasets, to evaluate regional and seasonal surface temperature and precipitation, as well as sea level pressure and circulation. A good agreement was found between the simulations and the reference datasets for winter precipitation and for temperature over both seasons. Whilst all models correctly reproduce the annual cycle of precipitation, some of them overestimate winter totals. ERA-Interim does not adequately represent summer precipitation over the region, and some of the models analyzed also show the same deficiency. All models correctly reproduce the northward migration of the South Pacific subtropical high during winter, although some of them underestimate the maximum central pressure. During summer, most models fail to show the low level north–south flow parallel to the eastern foothills of the Andes, a feature known as the Low Level Jet. Further analysis of the results of the simulations led to the selection of a sub-set of five CMIP5 GCMs to construct a reduced ensemble. This reduced ensemble is a better representation than the multi-model mean of the 15 GCMs of the past climate at this region and would be recommended for future studies.Fil: Zazulie, Natalia. 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. 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: Raga, Graciela B.. Universidad Nacional Autónoma de México; Méxic
Regional winter climate of the southern central Andes: Assessing the performance of ERA-Interim for climate studies
No full textIn order to determine the feasibility of using reanalysis (ERA‐Interim) for climate studies over the southern central Andes in South America, we have compared the most recent version of different data sets available to the community. The data sets include gridded in situ observations: Climate Research Unit (CRU), Global Precipitation Climatology Centre (GPCC), and University of Delaware; merged satellite and in situ data: Global Precipitation Climatology Project; and satellite estimates: Tropical Rainfall Measuring Mission. We pay particular attention to the region between 30° and 37°S and also the period 1970–1976 to evaluate the data sets. This is the period of maximum availability of meteorological stations in the region. Whereas all data sets provide an adequate representation of mean winter, GPCC provides the best for winter precipitation due to the large number of stations included in gridding. The CRU data set has fewer observations throughout the period. Although it cannot reproduce the localized maxima in the Andes, it provides a better representation of the regional precipitation and is best suited to evaluate trends. The temperature in the region is best estimated by CRU. We evaluate the ERA‐Interim reanalysis to determine potential shortcomings. The trends in the region were analyzed during the period 1979–2010, and while CRU indicates a significant decrease in winter precipitation, ERA‐Interim shows virtually no significant trends. Interannual variability is well represented by ERA‐Interim, and the El Niño–Southern Oscillation, which has been proven to be the principal source of year to year precipitation variability in the region, is highly correlated there.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: Zazulie, Natalia. 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: Raga, Graciela B.. Universidad Nacional Autónoma de México; Méxic
Regionalisation of heat waves in southern South America
No full textThis study describes the climatological characteristics of regional heat waves (HWs) over southern South America (SSA) for the warm seasons (October–March) of 1979–2018 based on daily maximum temperature series from 131 weather stations. Clustering of stations with high co-occurrence of simultaneous HW days is employed to identify regional HW events over five homogeneous regions: northern, central-eastern and southern SSA regions, central Argentina, and central Chile. When all regions are considered, we find a mean frequency of ∼4 HWs per year. Transitional regions (northern SSA, central-eastern SSA and central Argentina) are characterised by longer, albeit less intense, HWs than the southernmost region (southern SSA), whereas central Chile events display the lowest duration, intensity and extension. By aggregating these single HW attributes into a combined severity index, a ranking of historical HWs has been obtained, with the March 1980 event standing as the most severe one of SSA. The assessment of long-term changes reveals significant increases in the frequency of regional HW days over central Argentina and central Chile only. Trends in HW characteristics are also region dependent, and the southernmost region is the only one where HW severity has increased significantly.We report similarities and differences in the synoptic circulation patterns associated with regional HW events. Southern SSA HWs have the most distinctive signatures, related to extratropical high-pressure systems blocking the westerly flow. In the remaining regions, HWs are associated with anomalies in the South Atlantic (northern SSA, central-eastern SSA and central Argentina) or South Pacific (central Chile) High, and the intensification of the northerly low-level flow by regional thermal lows and South American Low Level Jet events. Regional HWs often migrate from northern to central-eastern SSA and central Argentina, following the displacement/intensification of the South Atlantic High, which partially explains the similarity of their associated patterns
Changes in climate at high southern latitudes: a unique daily record at Orcadas spanning 1903–2008
No full textThe climate observations at Orcadas represent the only southern high-latitude site where data span more than a century, and its daily measurements are presented for the first time in this paper. Although limited to a single station, the observed warming trends are among the largest found anywhere on the earth, facilitating the study of changes in extreme temperatures as well as averages. Factors that may influence Antarctic climate include natural variability; changes in greenhouse gases; and, since about the mid-1970s, the development of the ozone hole. The seasonality of observed warming and its temporal evolution during the century are both key for interpretations of Antarctic climate change. No statistically significant climate trends are observed at Orcadas from 1903 to 1950. However, statistically significant warming is evident at Orcadas throughout all four seasons of the year since 1950. Particularly in austral fall and winter, the warming of the cold extremes (coldest 5% and 10% of days) substantially exceeds the warming of the mean or of the warmest days, providing a key indicator for cold season Antarctic climate change studies. Trends in the summer season means and extremes since 1970 are approximately twice as large as those observed earlier, supporting suggestions of additional regional warming in that season because of the effects of ozone depletion on the circulation. Further, in the spring and summer seasons, significant mean warming also occurred prior to the development of the Antarctic ozone hole (i.e., 1950–70), supporting an important role for processes other than ozone depletion, such as greenhouse gas increases, for the climate changes.Fil: Zazulie, Natalia. 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; ArgentinaFil: Solomon, Susan. State University Of Colorado Boulder; Estados Unido
- …
