The host galaxies of long-duration gamma-ray bursts in a cosmological hierarchical scenario     

Sebastián E. Nuza  Patricia B. Tissera  Leonardo J. Pellizza  Diego G. Lambas  Cecilia Scannapieco †  María E. De Rossi 《Monthly notices of the Royal Astronomical Society》2007,375(2):665-672

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Seasonal trends in phytoplankton biomass over the Uruguayan Shelf     

Ana Martínez  Leonardo Ortega 《Continental Shelf Research》2007

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Linking geomorphology and hydrodynamics: a case study from Península Valdés, Patagonia, Argentina   总被引：1，自引：0，他引：1  

María del Pilar Alvarez  Nilda E. Weiler  Mario A. Hernández 《Hydrogeology Journal》2010,18(2):473-486

A case study is presented to assess the relevance of geomorphology in hydrogeological phenomena in an arid coastal area in the Argentinean extra-Andean Patagonia (Península Valdés) with an average rainfall of 232 mm/year and a soil moisture deficit of about 472 mm/year. Various geomorphic units were identified by interpreting Landsat 7 satellite images processed with ER Mapper software and then surveyed in the field, as well as by geological characterization. The hydrodynamic analysis was based on a survey of 89 wells, the construction of equipotential maps, and the interpretation of pumping-test results by a non-equilibrium method. The hydrochemical characterization was based on chemical tests analyzed with the Easy_Quim 6.0 application. The combination of geomorphological, geological, hydrodynamic and hydrochemical elements allowed the definition of hydromorphological units that are typical of recharge, circulation and discharge areas, the latter both for coastal and inland areas in wetlands (salt pans) with elevations to ?40 m relative to sea level. These units and the criteria used for their definition allow immediate recognition of hydrogeological phenomena in arid regions such as the extra-Andean Patagonia, with low information density but with near-optimal satellite imaging of landforms due to the lack of vegetation cover.  相似文献   

Phytoplankton Interannual Variability at Cassino Beach, Southern Brazil (1992–2007), with Emphasis on the Surf Zone Diatom Asterionellopsis glacialis     

Clarisse Odebrecht  Marli Bergesch  Leonardo Rubi R?rig  Paulo C. Abreu 《Estuaries and Coasts》2010,33(2):570-583

A long-term study (monthly sampling, 1992 to 2007) was conducted in the surf zone of Cassino Beach, Southern Brazil, in order to detect possible natural and/or anthropogenic disturbances. Surface water temperature (6–29°C) was the only parameter with predictable seasonal variation; salinity (14–38) was inversely related to rainfall (3.1–485.2 mm month⁻¹) and low values followed extreme precipitation periods in 1997/1998 and 2002/2003 (El Ni?o years). Asterionellopsis glacialis and chlorophyll a presented high concentrations and peak frequency until 1998, when an intense mud deposition occurred with concomitant extreme rainfall. It affected the surf zone and beach, changing the hydrology and dissolved inorganic nutrient availability. Six phytoplankton species groups were recognized with distinct responses to this mud deposition. We conclude that large-scale climatic changes, like El Ni?o Southern Oscillation, in conjunction with human activities significantly altered the phytoplankton ecology of the highly dynamic Cassino Beach surf zone.  相似文献   

Energy balance and evaporation loss of an irrigation reservoir equipped with a suspended cover in a semiarid climate (south‐eastern Spain)     

B. Gallego‐Elvira  A. Baille  B. Martin‐Gorriz  J. F. Maestre‐Valero  V. Martínez‐Alvarez 《水文研究》2011,25(11):1694-1703

The main objective of this study was to assess the impact of a suspended cover on the evaporation loss of an agricultural water reservoir (AWR). To this aim, a detailed data collection was carried out in a typical AWR located in south‐eastern Spain during 2 consecutive years. During the first year, the reservoir remained uncovered, while during the second year it was covered with a double black polyethylene (PE) shade cloth. On an annual scale, it was observed that the cover can provide a reduction of evaporation loss of 85%. Two approaches, energy balance and mass transfer, were used to analyse the effect of the cover on the evaporation process. Important modifications were observed on the magnitude, sign, annual trend and relative weight of the components of the energy balance. The changes were ascribed to the strong reduction of net radiation and to the substantial weight of the heat storage and sensible heat flux in the energy balance. A relevant finding was the contrast between the patterns of the annual evaporation curve for open‐water and covered conditions. The mass transfer approach allowed discriminating between the wind‐ and radiation‐shelter effects on the evaporation term. The reduction in water‐to‐air vapour deficit was the main factor explaining the high efficiency of the cover, whereas the reduction of the mass transfer coefficient was a modulating factor that accounted for the wind‐shelter effect. Overall, both approaches provided a sound basis to describe and explain the physical mechanisms underlying the high performance of the tested cover. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Generative Adversarial Network Applied to Ore Type Modeling in Complex Geological Environments     

Jordão  Helga  Azevedo  Leonardo  Sousa  António Jorge  Soares  Amílcar 《Mathematical Geosciences》2022,54(7):1165-1182

Mathematical Geosciences - In complex geological environments, the spatial domain characterization of different ore types has been one of the most important challenges in the assessment of mineral...  相似文献   

Assessment of WRF numerical model forecasts using different lead time initializations during extreme precipitation events over Macaé city,Rio de Janeiro (Brazil)     

da Silva  Fabricio Polifke  da Silva  Alfredo Silveira  da Silva  Maria Gertrudes Alvarez Justi  Pires  Gisele Dornelles 《Natural Hazards》2022,110(1):695-718

Natural Hazards - The ability to forecast extreme precipitation events has become increasingly important over the last decades due to their significant impacts on society and properties. In this...  相似文献   

Estimating Buoyancy Heat Flux Using the Surface Renewal Technique over Four Amazonian Forest Sites in Brazil     

Marcelo Zeri  Leonardo D. A. Sá  Carlos A. Nobre 《Boundary-Layer Meteorology》2013,149(2):179-196

The surface renewal (SR) method was applied for the first time to measurements of air temperature over four Amazonian forest sites and different seasons in order to obtain estimates of buoyancy heat flux. The required calibration of this method against eddy covariance resulted in a value for a specific parameter that is close to the range reported in other studies, contributing to the generalization of the SR method to different kinds of canopies. The comparison with fluxes obtained using the eddy covariance technique revealed a good match between the two methods for different sites, heights and seasons. Sites with high levels of non-stationarity in the signals of temperature and wind speed presented higher scatter in the regression with fluxes from eddy covariance. For a particular site with previously reported influence of low-frequency motions, the regression was only satisfactory, i.e., slope parameter close to unity and small offset, when oscillations with periods longer than $\approx $ ≈ 13 min were filtered out. The SR method has a great potential due to the simplicity of the instrumentation required. However, care should be taken when measuring under the influence of mesoscale motions, which can lead to high levels of non-stationarity, compromising the fundamental concepts of the SR theory.  相似文献   

Modeling monthly mean air temperature for Brazil   总被引：1，自引：1，他引：0  

Clayton Alcarde Alvares  José Luiz Stape  Paulo Cesar Sentelhas  José Leonardo de Moraes Gonçalves 《Theoretical and Applied Climatology》2013,113(3-4):407-427

Air temperature is one of the main weather variables influencing agriculture around the world. Its availability, however, is a concern, mainly in Brazil where the weather stations are more concentrated on the coastal regions of the country. Therefore, the present study had as an objective to develop models for estimating monthly and annual mean air temperature for the Brazilian territory using multiple regression and geographic information system techniques. Temperature data from 2,400 stations distributed across the Brazilian territory were used, 1,800 to develop the equations and 600 for validating them, as well as their geographical coordinates and altitude as independent variables for the models. A total of 39 models were developed, relating the dependent variables maximum, mean, and minimum air temperatures (monthly and annual) to the independent variables latitude, longitude, altitude, and their combinations. All regression models were statistically significant (α?≤?0.01). The monthly and annual temperature models presented determination coefficients between 0.54 and 0.96. We obtained an overall spatial correlation higher than 0.9 between the models proposed and the 16 major models already published for some Brazilian regions, considering a total of 3.67?×?10⁸?pixels evaluated. Our national temperature models are recommended to predict air temperature in all Brazilian territories.  相似文献   

Present warming within the context of cooling–warming cycles observed since 1854 in the Bay of Biscay     

M. deCastro  M. Gómez-Gesteira  I. Alvarez  J.L.G. Gesteira 《Continental Shelf Research》2009,29(8):1053-1059

The warming trend observed during the last decades in the Bay of Biscay is put within the context of sea surface temperature (SST) changes observed in the area since 1854. Macroscopically, two consecutive warming–cooling cycles were detected during this period of time: cooling from 1867 to 1910; warming from 1910 to 1945; cooling from 1945 to 1974; and warming from 1974 to nowadays. Warming rates of 0.17 and 0.22 °C per decade were measured during the warming sub-periods and cooling rates of ?0.14 and ?0.10 °C per decade were measured during the cooling sub-periods. The present warming period is on the same order of magnitude although slightly more intense than the one observed from 1910 to 1945, which is consistent with previous analysis carried for the North Atlantic. Finally, the thermal amplitude defined as the difference between the maximum and minimum annual values has increased since 1974 at a rate of 0.06 °C per decade due to the different increasing rates of the maximum (0.26 °C per decade) and minimum (0.20 °C per decade) SSTs.  相似文献