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Decomposition in tropical forests: a pan-tropical study of the effects of litter type, litter placement and mesofaunal exclusion across a precipitation gradient

POWERS, Jennifer S.; MONTGOMERY, Rebecca A.; ADAIR, E. Carol; BREARLEY, Francis Q.; DEWALT, Saara J.; CASTANHO, Camila T.; CHAVE, Jerome; DEINERT, Erika; GANZHORN, Joerg U.; GILBERT, Matthew E.; GONZALEZ-ITURBE, Jose Antonio; BUNYAVEJCHEWIN, Sarayudh; GRA
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.45%
1. Litter decomposition recycles nutrients and causes large fluxes of carbon dioxide into the atmosphere. It is typically assumed that climate, litter quality and decomposer communities determine litter decay rates, yet few comparative studies have examined their relative contributions in tropical forests. 2. We used a short-term litterbag experiment to quantify the effects of litter quality, placement and mesofaunal exclusion on decomposition in 23 tropical forests in 14 countries. Annual precipitation varied among sites (760-5797 mm). At each site, two standard substrates (Raphia farinifera and Laurus nobilis) were decomposed in fine- and coarse-mesh litterbags both above and below ground for approximately 1 year. 3. Decomposition was rapid, with >95% mass loss within a year at most sites. Litter quality, placement and mesofaunal exclusion all independently affected decomposition, but the magnitude depended upon site. Both the average decomposition rate at each site and the ratio of above- to below-ground decay increased linearly with annual precipitation, explaining 60-65% of among-site variation. Excluding mesofauna had the largest impact on decomposition, reducing decomposition rates by half on average, but the magnitude of decrease was largely independent of climate. This suggests that the decomposer community might play an important role in explaining patterns of decomposition among sites. Which litter type decomposed fastest varied by site...

Identificação da ocorrência em Bagé (RS) entre 1961 – 2009

Silva, Mirian Rejane Machado da
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
Português
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36.54%
As estiagens fazem parte da história do clima do Rio Grande do Sul (RS) e a frequência desse fenômeno não é baixa. O desenvolvimento socioeconômico de uma região pode ser afetado pela falta dos recursos hídricos necessários para as atividades como a agrícolas e uso doméstico. Estudos climáticos têm buscado compreender a dinâmica da distribuição e variabilidade da precipitação pluviométrica, bem como a ocorrência de eventos extremos. O objetivo desse trabalho é investigar a ocorrência de estiagens no município de Bagé, Rio Grande do Sul (RS) entre 1961 e 2009. Bagé (31°19′51″ S; 54°6′25″ W) situando-se em um dos setores de menor precipitação média anual da região sul do RS, oscilando entre 1300 mm a 1500 mm a-1. A precipitação pluviométrica mensal média é de 118,7 mm e relativamente bem distribuída ao longo do ano. No entanto, identificou-se a presença de uma estação úmida (abril a outubro), e outra propensa à ocorrência de estiagens (novembro a março). A precipitação média anual (1961-2009) é 1425 mm, com tendência de aumento de 7,9 mm a-1. As análises das médias sazonais, anuais, decenais e das anomalias constataram que esse aumento ocorreu a partir da década 1981 – 1990...

Interannual variability of precipitation distribution patterns in Southern Portugal

Mourato, Sandra; Moreira, Madalena; Corte-Real, João
Fonte: Royal Meteorological Society Publicador: Royal Meteorological Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.42%
Southern Portugal is characterized by an irregular distribution of precipitation which is highly variable from year to year, requiring a clear ascertaining if the pattern of the precipitation is changing due to climate variability or climate change. In this paper, the authors applied several statistical methods to annual and seasonal time series of precipitation during the period 1931–2006, in order to detect trends and evaluate the variability in the frequencies of occurrence of dry and wet periods and also to assess spatial distribution patterns. The statistical methods include homogeneity tests, Mann–Kendall test, simple moving averages and cluster analysis. In spring, the authors detected a lack of homogeneity in the precipitation time series and a significant decreasing trend of precipitation was identified, by using simple moving averages and the Mann–Kendall test. Cluster analyses also confirmed the results and identified significant trends in the interannual and spatial distributions of dry, normal and wet years. It is concluded that the annual precipitation regime in the North interior sector is becoming drier, as the winter and spring also become drier. The only season in which a precipitation increase is observed is at fall and near the sea...

A precipitation-based regionalization for Western Iran and regional drought variability

Raziei, T.; Bordi, I.; Pereira, L.S.
Fonte: European Geosciences Union Publicador: European Geosciences Union
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
Relevância na Pesquisa
46.28%
Abstract. The spatial distribution of the seasonal and annual precipitation was analyzed in western Iran using data from 140 stations covering the period 1965–2000. Applying the Precipitation Concentration Index (PCI), the intraannual precipitation variability was also studied. Furthermore, nine precipitation-derived parameters were used to regionalize climate in western Iran using principal component analysis and clustering techniques. Results suggest that five spatially homogenous sub-regions can be identified characterized by different precipitation regimes. The spatial pattern of seasonal precipitation seems to be highly controlled by the wide latitudinal extent of the region and by the pronounced orographic relieves, and the time of occurrence of the maximum precipitation varies from spring in the north to winter in the south. The time variability of dry and wet periods in the identified sub-regions was analyzed using the Precipitation Index (PI) and the existence of any long-term trend was tested. Results show that the northern and southern regions of western Iran are characterized by different climatic variability. Furthermore, a negative long-term linear trend in the north and a weak positive trend in the south of the study area have been detected though they are not statistically significant

Sensitivity of Temperate Desert Steppe Carbon Exchange to Seasonal Droughts and Precipitation Variations in Inner Mongolia, China

Yang, Fulin; Zhou, Guangsheng
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 05/02/2013 Português
Relevância na Pesquisa
36.47%
Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO2 flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO2 throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of −7.2, −22.9, and 26.0 g C m−2 yr−1 in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEEsat) and the temperature sensitivity coefficient of ecosystem respiration (Reco) exhibited significant variations. The values of NEEsat were −2.6...

Mean Annual Precipitation Explains Spatiotemporal Patterns of Cenozoic Mammal Beta Diversity and Latitudinal Diversity Gradients in North America

Fraser, Danielle; Hassall, Christopher; Gorelick, Root; Rybczynski, Natalia
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 09/09/2014 Português
Relevância na Pesquisa
46.16%
Spatial diversity patterns are thought to be driven by climate-mediated processes. However, temporal patterns of community composition remain poorly studied. We provide two complementary analyses of North American mammal diversity, using (i) a paleontological dataset (2077 localities with 2493 taxon occurrences) spanning 21 discrete subdivisions of the Cenozoic based on North American Land Mammal Ages (36 Ma – present), and (ii) climate space model predictions for 744 extant mammals under eight scenarios of future climate change. Spatial variation in fossil mammal community structure (β diversity) is highest at intermediate values of continental mean annual precipitation (MAP) estimated from paleosols (∼450 mm/year) and declines under both wetter and drier conditions, reflecting diversity patterns of modern mammals. Latitudinal gradients in community change (latitudinal turnover gradients, aka LTGs) increase in strength through the Cenozoic, but also show a cyclical pattern that is significantly explained by MAP. In general, LTGs are weakest when continental MAP is highest, similar to modern tropical ecosystems in which latitudinal diversity gradients are weak or undetectable. Projections under modeled climate change show no substantial change in β diversity or LTG strength for North American mammals. Our results suggest that similar climate-mediated mechanisms might drive spatial and temporal patterns of community composition in both fossil and extant mammals. We also provide empirical evidence that the ecological processes on which climate space models are based are insufficient for accurately forecasting long-term mammalian response to anthropogenic climate change and inclusion of historical parameters may be essential.

Spatio-Temporal Analysis of the Accuracy of Tropical Multisatellite Precipitation Analysis 3B42 Precipitation Data in Mid-High Latitudes of China

Cai, Yancong; Jin, Changjie; Wang, Anzhi; Guan, Dexin; Wu, Jiabing; Yuan, Fenghui; Xu, Leilei
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 01/04/2015 Português
Relevância na Pesquisa
36.44%
Satellite-based precipitation data have contributed greatly to quantitatively forecasting precipitation, and provides a potential alternative source for precipitation data allowing researchers to better understand patterns of precipitation over ungauged basins. However, the absence of calibration satellite data creates considerable uncertainties for The Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) 3B42 product over high latitude areas beyond the TRMM satellites latitude band (38°NS). This study attempts to statistically assess TMPA V7 data over the region beyond 40°NS using data obtained from numerous weather stations in 1998–2012. Comparative analysis at three timescales (daily, monthly and annual scale) indicates that adoption of a monthly adjustment significantly improved correlation at a larger timescale increasing from 0.63 to 0.95; TMPA data always exhibits a slight overestimation that is most serious at a daily scale (the absolute bias is 103.54%). Moreover, the performance of TMPA data varies across all seasons. Generally, TMPA data performs best in summer, but worst in winter, which is likely to be associated with the effects of snow/ice-covered surfaces and shortcomings of precipitation retrieval algorithms. Temporal and spatial analysis of accuracy indices suggest that the performance of TMPA data has gradually improved and has benefited from upgrades; the data are more reliable in humid areas than in arid regions. Special attention should be paid to its application in arid areas and in winter with poor scores of accuracy indices. Also...

Decomposition in tropical forests: a pan-tropical study of the effects of litter type, litter placement and mesofaunal exclusion across a precipitation gradient; Journal of Ecology

Powers, Jennifer S.; Montgomery, Rebecca A.; Adair, E. Carol; Brearley, Francis Q.; DeWalt, Saara J.; Castanho, Camila T.; Chave, Jerome; Deinert, Erika; Ganzhorn, Jörg U.; Gilbert, Matthew E.; González-Iturbe, José Antonio; Bunyavejchewin, Sarayudh; G
Fonte: Pontifícia Universidade Javeriana Publicador: Pontifícia Universidade Javeriana
Formato: 801–811
Português
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46.45%
97-4; 1. descomposición de la hojarasca recicla los nutrientes y provoca grandes flujos de dióxido de carbono a la atmósfera. Se asume generalmente que las comunidades de clima, calidad de la cama y descomponedores determinan las tasas de descomposición de basura, sin embargo, pocos estudios comparativos han examinado sus contribuciones relativas de los bosques tropicales. 2. Se utilizó un experimento de hojarasca corto plazo para cuantificar los efectos de la calidad de la cama, la colocación y la exclusión mesofauna en descomposición en 23 bosques tropicales en 14 países. La precipitación anual varía entre los sitios (760-5797 mm). En cada sitio, dos sustratos estándar (Raphia farinifera y Laurus nobilis) se descompusieron en bolsas de basura Fine- y grueso de malla por encima y por debajo de la tierra durante aproximadamente 1 año.3. La descomposición fue rápida, con> 95% de pérdida de masa dentro de un año en la mayoría de los sitios. Calidad de la cama, la colocación y la exclusión mesofauna todas afectadas de forma independiente la descomposición, pero la magnitud dependían sitio. Tanto la tasa de descomposición promedio en cada sitio y la relación de anteriormente a la caries por debajo del suelo aumentaron linealmente con la precipitación anual...

High-resolution precipitation datasets in South America and West Africa based on satellite-derived rainfall, Enhanced Vegetation Index and Digital Elevation Model

CECCHERINI GUIDO; AMEZTOY ARAMENDI IBAN; ROMERO HERNÁNDEZ Claudia Patricia; CARMONA MORENO Cesar
Fonte: MDPI AG Publicador: MDPI AG
Tipo: Articles in periodicals and books Formato: Online
Português
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36.57%
Mean Annual Precipitation is one of the most important variables used in water resource management. However, quantifying Mean Annual Precipitation at high spatial resolution, needed for advanced hydrological analysis, is challenging in developing countries which often present a sparse gauge network and a highly variable climate. In this work, we present a methodology to quantify Mean Annual Precipitation at 1 km spatial resolution using different precipitation products from satellite estimates and gauge observations at coarse spatial resolution (i.e., ranging from 4 km to 25 km). Examples of this methodology are given for South America and West Africa. We develop a downscaling method that exploits the relationship among satellite-derived rainfall, Digital Elevation Model and Enhanced Vegetation Index. At last, we validate its performance using rain gauge measurements: comparable annual precipitation estimates for both South America and West Africa are retrieved. Validation indicates that high resolution Mean Annual Precipitation downscaled from CHIRP (Climate Hazards Group Infrared Precipitation) and GPCC (Global Precipitation Climatology Centre) datasets present the best ensemble of performance statistics for both South America and West Africa. Results also highlight the potential of the presented technique to downscale satellite-derived rainfall worldwide.; JRC.H.1-Water Resources

Species‐specific adaptations explain resilience of herbaceous understorey to increased precipitation variability in a Mediterranean oak woodland

Jongen, Marjan; Hellmann, Christine; Unger, Stephan
Fonte: John Wiley and Sons Inc. Publicador: John Wiley and Sons Inc.
Tipo: Artigo de Revista Científica
Publicado em 09/09/2015 Português
Relevância na Pesquisa
36.48%
To date, the implications of the predicted greater intra‐annual variability and extremes in precipitation on ecosystem functioning have received little attention. This study presents results on leaf‐level physiological responses of five species covering the functional groups grasses, forbs, and legumes in the understorey of a Mediterranean oak woodland, with increasing precipitation variability, without altering total annual precipitation inputs. Although extending the dry period between precipitation events from 3 to 6 weeks led to increased soil moisture deficit, overall treatment effects on photosynthetic performance were not observed in the studied species. This resilience to prolonged water stress was explained by different physiological and morphological strategies to withstand periods below the wilting point, that is, isohydric behavior in Agrostis, Rumex, and Tuberaria, leaf succulence in Rumex, and taproots in Tolpis. In addition, quick recovery upon irrigation events and species‐specific adaptations of water‐use efficiency with longer dry periods and larger precipitation events contributed to the observed resilience in productivity of the annual plant community. Although none of the species exhibited a change in cover with increasing precipitation variability...

Relationship between sunspot number and total annual precipitation at Izana (Tenerife): Maximum precipitation prediction with three year lagged sunspots?

Calbet, Xavier; Romero, Maria Carmen; Sancho, Juan Manuel; Ripodas, Pilar; Quintero, Victor Jesus
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/10/2001 Português
Relevância na Pesquisa
46.51%
A possible relationship between sunspot number and total annual precipitation from the Izana Observatory has been found. The annual precipitation period ranges from 1916 to 1998, thus including nearly eight 11-year solar cycles. When points of total precipitation for a given year at Izana are plotted on the ordinate axis versus the yearly sunspot number on the abcisa axis three years back from the precipitation one, nearly all of them lie in the lower left hand corner of the diagram. This seems to indicate a relationship between the above mentioned variables. If this relationship is confirmed it would permit the prediction of a maximum annual precipitation at Izana three years in advance.; Comment: 10 pages, 4 figures

Estimation of a non-stationary model for annual precipitation in southern Norway using replicates of the spatial field

Ingebrigtsen, Rikke; Lindgren, Finn; Steinsland, Ingelin; Martino, Sara
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.25%
Estimation of stationary dependence structure parameters using only a single realisation of the spatial process, typically leads to inaccurate estimates and poorly identified parameters. A common way to handle this is to fix some of the parameters, or within the Bayesian framework, impose prior knowledge. In many applied settings, stationary models are not flexible enough to model the process of interest, thus non-stationary spatial models are used. However, more flexible models usually means more parameters, and the identifiability problem becomes even more challenging. We investigate aspects of estimation of a Bayesian non-stationary spatial model for annual precipitation using observations from multiple years. The model contains replicates of the spatial field, which increases precision of the estimates and makes them less prior sensitive. Using R-INLA, we analyse precipitation data from southern Norway, and investigate statistical properties of the replicate model in a simulation study. The non-stationary spatial model we explore belongs to a recently introduced class of stochastic partial differential equation (SPDE) based spatial models. This model class allows for non-stationary models with explanatory variables in the dependence structure. We derive conditions to facilitate prior specification for these types of non-stationary spatial models.

Determining the best fitting distribution of annual precipitation data in Serbia using L-moments method

Gocic, Milan; Velimirovic, Lazar; Stankovic, Miomir
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.3%
The monthly precipitation data from 29 meteorological stations for the period 1946–2012 from Serbia were used. To describe the behaviour of precipitation data at a specific location, it is necessary to identify the distribution that best fits the data. For this purpose, three distributions i.e. generalized extreme value (GEV), generalized Pareto (GPD) and generalized logistic (GLO) distribution were fitted using the method of L-moment. The goodness-of-fit for the selected three distributions was confirmed using L-moment ratio diagram and three tests namely relative root mean square error, relative mean absolute error and probability plot correlation coefficient. From the result of this analysis, the GEV distribution was selected as the best fitting distribution of annual precipitation data in Serbia. The 2, 5, 10, 20, 50, 100 and 1000-years return levels are provided.; Comment: This paper has been withdrawn by the author because input data (the number of meteorological stations, as well as the period observed) have to be changed in order to obtain correct results

Past Annual Variations of the Karst Denudation Rates

Shopov, Y.; Stoykova, D.; Tsankov, L. T.; Marinova, E.; Sauro, U.; Borsato, A.; Cucchi, F.; Forti, P.; Piccini, L.; Ford, D. C.; Yonge, Chas. J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/09/2009 Português
Relevância na Pesquisa
36.52%
We used the quantitative theory of solubility of karst rocks of Shopov et. al, (1989, 1991a) in dependence of the temperature and other thermodynamic parameters to make reconstructions of past carbonate denudation rates. This theory produced equations assessing the carbonate denudation rates in dependence on the temperature or on the precipitation. We estimated the averaged denudation rate in the region to 14 mm/kyr or 38 t/km2 per year. We used this estimate as starting point and substituted our proxy records of the annual temperature and the annual precipitation in the equations of dependence of karst denudation rate on precipitation and temperature. This way we reconstructed variations of the annual karst denudation rate for the last 280 years in dependence on the annual precipitation and for the last 1250 years in dependence on the temperature. Both reconstructions produce quite reasonable estimate of the variations of carbonate denudation, which is within observed variation of 8- 20 mm/kyr (86% variation). Precipitation dependence of carbonate denudation produces 79 % variation in the denudation rate in result of the reconstructed variation of 300 mm/yr from the driest to the wettest year during the last 280 years. Temperature dependence of carbonate denudation due to temperature dependence of solubility of the carbonate dioxide produce only 9.3% variation in the denudation rate in result of the reconstructed variation of 4.7 deg. C during the last 1250 years...

Precipitation in Aberdeen, SD: data analysis approach

Boris Shmagin; Carol A. Johnston; Dennis Todey
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Poster
Português
Relevância na Pesquisa
36.63%
The daily, monthly and annual sum of precipitation was analyzed for station Aberdeen-Airport, South Dakota (NOAA COOP #390020) with traditional normative statistical descriptions of precipitation variability and with methods of data analysis. The goal for research was formulated as finding a way to forecast extremes, such as the flooding of Aberdeen in May 2007 after a 30-hour, 8.42 inch rain event. Daily data were available, analyzed and cannot be considered as having any use for the forecast. The observations of 1423 monthly sums of precipitation have the following characteristics: mean = 1.802 in.; geometric mean = 0.856 in.; median = 1.26 in.; minimum = 0.0; maximum = 12.39 in. Simplified Fourier analysis was performed for monthly data, and 31 cyclic components were determined and used in a model to represent the data with periods from 4 to 379 months. The biggest amplitude from those components belongs to period of 12 months (1.396), and the next largest amplitude (0.261) had a period length of 6 months. The lowest amplitude (0.033) has a period of 75 months; the longest period 379 months has an amplitude of approximately twice that height (0.066). Fourteen periods have amplitudes higher that 0.1. The same analysis was performed on data obtained from the High Plains Regional Climate Center that was collected between January 1932 and April 2006. The model has mean equal 1.623 in. and the same two periods: 12 and 6 months...

The El Niño/Southern Oscillation and Precipitation Variability in Baja California, Mexico

MINNICH,RICHARD A.; FRANCO VIZCAÌNO,ERNESTO; DEZZANI,RAYMOND J.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 Português
Relevância na Pesquisa
36.46%
This study evaluates precipitation variability in Baja California in relation to the El Niño/Southern Oscillation (ENSO) using the Southern Oscillation Index (SOI). To evaluate precipitation climatology, data for 102 weather stations were analyzed. Data were directly averaged for stations with records longer than 30 years, but normalized for stations with shorter records. To test for uniformity of precipitation departures, the SOI was compared with average precipitation departures for long-term stations (established before 1960), in eight subregions of Baja California. The results revealed that, unlike California, the interannual variability of both annual and monthly precipitation is strongly linked to SOI. During El Niño events, above-normal precipitation occurs largely in February and March; but precipitation amounts are subnormal during La Niña events, and mostly limited to December and January. Gradients of precipitation departure tend to be uniform across Baja California during individual years. The variability of precipitation is attributed to the interannual dislocation by ENSO of the polar-front jet stream along the Pacific coast, as described in other studies. In El Niño events, the circulation acquires a positive-phase Pacific-North America (PNA) pattern...

Variability of extreme precipitation in coastal river basins of the southern mexican Pacific region

Pérez-Morga,Nancy; Kretzschmar,Thomas; Cavazos,Tereza; Smith,Stephen V.; Munoz-Arriola,Francisco
Fonte: Instituto de Geofísica, UNAM Publicador: Instituto de Geofísica, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 Português
Relevância na Pesquisa
36.51%
Extreme wet and dry years (± 1 standard deviation, respectively), as well as the top 95 percentile (P95) of daily precipitation events, derived from tropical cyclone (TC) and non-tropical cyclone (NTC) rainfall, were analyzed in coastal river basins in Southern Oaxaca, Mexico (Río Verde, Río Tehuantepec, and the Southern Coast). The study is based on daily precipitation records from 47 quality-controlled stations for the 1961 to 1990 period and TC data for the Eastern Tropical Pacific (EPAC). The aim of this study was to evaluate extreme (dry and wet) trends in the annual contribution of daily P95 precipitation events and to determine the relationship of summer precipitation with El Niño Southern Oscillation (ENSO) and the Pacifical Decadal Oscillation (PDO). A regionalization based on a rotated principal component analysis (PCA) was used to produce four precipitation regions in the coastal river basins. A significant negative correlation (significance at the 95% level) was only found with ONI in rainfall Region 3, nearest to the Gulf of Tehuantepec. Wet years, mainly linked to TC-derived P95 precipitation events, were associated with SST anomalies (≥-0.6°C) similar to weak La Niña and Neutral cool conditions, while dry years were associated with SST positive anomalies similar to Neutral warm conditions (≤-0.5°C). The largest contribution of extreme P95 precipitation derived from TCs to the annual precipitation was observed in Region 3. A significant upward trend in the contribution of TC-derived precipitation to the annual precipitation was found only in Region 1...

Statistical analysis of the precipitation trends in the Patagonia region in southern South America

CASTAÑEDA,M; GONZÁLEZ,M
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2008 Português
Relevância na Pesquisa
46.47%
This paper describes the rainfall climatology in Argentinean Patagonia and faces with rainfall trends. Gridded precipitation dataset from Delaware University is used as an alternative data and they seem to reflect the same patterns that the observed ones. The mean annual precipitation shows maximum amplitude in Patagonia, winter values greater than in summer in the northwest, especially in the west and over the Andes. Both, principal component analysis (PCA) applied to the monthly anomalous precipitations and linear annual rainfall trends, show positive trends in north and south of Patagonia, meanwhile precipitation tends to decrease in the western and central zone. An alternative nonlinear methodology, a piecewise linear function, is used to detect a number of breakpoints in order to identify the moments at which the tendency changes its behavior. Northeast of the Patagonia region and a small zone to the Southeast of Santa Cruz experienced a change in the annual tendencies of precipitation later to the decade of 1960. To the northwest, a vast region denotes a change in precipitation in the 1970 decade, whereas in the environment of the Peninsula of Valdez, the decade of 1990 is in which the change seems to predominate.

Non-linear trends and low frequency oscillations in annual precipitation over Argentina and Chile, 1931-1999

Minetti,J. L.; Vargas,W. M.; Poblete,A. G.; Acuña,L. R.; Casagrande,G.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 Português
Relevância na Pesquisa
56.52%
Since the 1950's-1960's a large portion of Argentina has experienced a long period of high precipitation with important changes a 30-year period annual averages. Opposite conditions have taken place throughout the twentieth century in a large portion of Chile, with declining tendencies in annual precipitations. If such conditions prevail, the socio-economic implications of these phenomena could eventually gain importance due to the expansion of grain crops in the semi-arid borders of Argentina and a decline in the availability of reservoir water used for irrigation or energy generation in the central region of Chile and western Argentina. An accurate diagnosis of these phenomena is very important for applied purposes in medium term planning that should be undertaken by private and state-owned companies. These diagnoses are also important from a methodological point of view, in order to find out whether these changes in long-term averages are constant and represent a climatic change or if they are low frequency interdecadal fluctuations that would mean a return to opposite conditions. We suggest that the two intense La Niña events that took place during 19881989 and 1995-1996 caused a decline in the precipitation trends over a large region of semi-arid Argentina and intensified droughts in Central Chile. A regionalized local precipitation analysis of the 1931-1932/1998-1999 agricultural periods over large areas was performed. Afterwards...

Movements of the white-tailed deer and their relationship with precipitation in northeastern Mexico

Bello,Joaquín; Gallina,Sonia; Equihua,Miguel
Fonte: ASOCIACIÓN INTERCIENCIA Publicador: ASOCIACIÓN INTERCIENCIA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2004 Português
Relevância na Pesquisa
46.37%
Better management strategies can be designed through the medium and long-term evaluation of how inter- and intra-annual variations in environmental conditions affect deer behavior. The relationship between home range size and distances traveled by white-tailed deer (Odocoileus virginianus texanus) and precipitation were analyzed, both in terms of distribution and quantity, in the San Francisco Ranch, Northeastern Mexico. Possible differences between seasons, sexes and years were evaluated. The study area has a surface of 1000ha and high water availability (3.4 troughs/km²). Home range size and distances traveled were estimated during three biological seasons: reproductive, post-reproductive and fawning, over a period of four years (Sept 1994 to Aug 1998). Home range size was largest in 1997 (258± 18ha), when the highest precipitation was registered. Differences in home range size were found between sexes, it being larger for males (234± 14ha) than for females (193± 13ha). In 1998, the home range was larger in the fawning season than in the reproductive season because of a rain delay. The average total distance traveled daily was longest in 1997 (7016 ±354m). In the same year, the longest distance traveled was during the fawning season (8300 ±640m). When precipitation increased...