Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations     

Robert P. C. Wiersma  Joop Schaye  Tom Theuns  Claudio Dalla Vecchia  Luca Tornatore 《Monthly notices of the Royal Astronomical Society》2009,399(2):574-600

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C-, Sr-isotope and Hg chemostratigraphy of Neoproterozoic cap carbonates of the Sergipano Belt,Northeastern Brazil     

Alcides Nobrega Sial  Claudio Gaucher  Marinho Alves da Silva Filho  Valderez P. Ferreira  Marcio M. Pimentel  Luiz D. Lacerda  Emmanoel V. Silva Filho  Wilker Cezario 《Precambrian Research》2010

Two cap carbonates overlying glaciogenic diamictites crop out extensively in the eastern Vaza Barris Domain of the Sergipano Belt, northeastern Brazil. They are represented by carbonates of the Jacoca Formation, resting on top of diamictite of the Ribeiropolis Formation, and by the Olhos D’Agua Formation (carbonates, organic-rich towards the top), which overlies diamictite of the Palestina Formation. These two sequences were deformed and metamorphosed at sub-greenschist facies-conditions during the Brasiliano cycle (650–600 Ma).  相似文献   

Families of first kind periodic solutions of the spatial and planar elliptic restricted three-body problem with collision     

Lúcia Brandão Dias  Claudio Vidal 《Celestial Mechanics and Dynamical Astronomy》2010,106(4):339-370

We consider a restricted three-body problem where the primaries are moving in an elliptic collision orbit and the infinitesimal mass moves in a three dimensional space. This paper is devoted to prove analytically the existence of several families of symmetric periodic solutions as continuation of Keplerian circular orbits. In our approach the perturbing parameter is related with the energy of the primaries.  相似文献   

Denudation history of the Bocaina Plateau, Serra do Mar, southeastern Brazil: Relationships to Gondwana breakup and passive margin development   总被引：1，自引：0，他引：1  

Silvio T. Hiruma  Claudio Riccomini  May C. Modenesi-Gauttieri  Peter C. Hackspacher  Julio C. Hadler Neto  Ana O.B. Franco-Magalhes 《Gondwana Research》2010,18(4):674-687

The Bocaina Plateau, which is situated on the eastern flank of the continental rift of southeastern Brazil, is the highest part of the Serra do Mar. Topographic relief in this area is suggested to be closely related to its complex tectono-magmatic evolution since the breakup of Western Gondwana and opening of the South Atlantic Ocean. Apatite fission track ages and track length distributions from 27 basement outcrops were determined to assess these hypotheses and reconstruct the denudation history of the Bocaina Plateau. The ages range between 303 ± 32 and 46 ± 5 Ma, and are significantly younger than the stratigraphic ages. Mean track lengths vary from 13.44 ± 1.51 to 11.1 ± 1.48 μm, with standard deviations between 1.16 and 1.83 μm. Contrasting ages within a single plateau and similar ages at different altitudes indicate a complex regional tectonothermal evolution. The thermal histories inferred from these data imply three periods of accelerated cooling related to the Early Cretaceous continental breakup, Early Cretaceous alkaline magmatism, and the Paleogene evolution of the continental rift of southeastern Brazil. The oldest fission track ages (> 200 Ma) were obtained in the Serra do Mar region, suggesting that these areas were a long-lived source of sediments for the Paraná, Bauru, and Santos basins.  相似文献   

Geo-environmental mapping using physiographic analysis: constraints on the evaluation of land instability and groundwater pollution hazards in the Metropolitan District of Campinas,Brazil     

Paulo Cesar Fernandes-da-Silva  Ricardo Vedovello  Claudio Jose Ferreira  John Canning Cripps  Maria Jose Brollo  Amelia Joao Fernandes 《Environmental Earth Sciences》2010,61(8):1657-1675

Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper, a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow. Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of ground properties. The paper also discusses constraints on- and limitations of- the approaches taken.  相似文献   

Soil-precipitation feedbacks during the South American Monsoon as simulated by a regional climate model   总被引：1，自引：0，他引：1  

Anna A. Sörensson  Claudio G. Menéndez  Patrick Samuelsson  Ulrika Willén  Ulf Hansson 《Climatic change》2010,98(3-4):429-447

We summarize the recent progress in regional climate modeling in South America with the Rossby Centre regional atmospheric climate model (RCA3-E), with emphasis on soil moisture processes. A series of climatological integrations using a continental scale domain nested in reanalysis data were carried out for the initial and mature stages of the South American Monsoon System (SAMS) of 1993–92 and were analyzed on seasonal and monthly timescales. The role of including a spatially varying soil depth, which extends to 8 m in tropical forest, was evaluated against the standard constant soil depth of the model of about 2 m, through two five member ensemble simulations. The influence of the soil depth was relatively weak, with both beneficial and detrimental effects on the simulation of the seasonal mean rainfall. Secondly, two ensembles that differ in their initial state of soil moisture were prepared to study the influence of anomalously dry and wet soil moisture initial conditions on the intraseasonal development of the SAMS. In these simulations the austral winter soil moisture initial condition has a strong influence on wet season rainfall over feed back upon the monsoon, not only over the Amazon region but in subtropical South America as well. Finally, we calculated the soil moisture–precipitation coupling strength through comparing a ten member ensemble forced by the same space–time series of soil moisture fields with an ensemble with interactive soil moisture. Coupling strength is defined as the degree to which the prescribed boundary conditions affect some atmospheric quantity in a climate model, in this context a quantification of the fraction of atmospheric variability that can be ascribed to soil moisture anomalies. La Plata Basin appears as a region where the precipitation is partly controlled by soil moisture, especially in November and January. The continental convective monsoon regions and subtropical South America appears as a region with relatively high coupling strength during the mature phase of monsoon development.  相似文献   

Resolution effects on regional climate model simulations of seasonal precipitation over Europe   总被引：5，自引：2，他引：3  

Sara A. Rauscher  Erika Coppola  Claudio Piani  Filippo Giorgi 《Climate Dynamics》2010,35(4):685-711

We analyze a set of nine regional climate model simulations for the period 1961–2000 performed at 25 and 50 km horizontal grid spacing over a European domain in order to determine the effects of horizontal resolution on the simulation of precipitation. All of the models represent the seasonal mean spatial patterns and amount of precipitation fairly well. Most models exhibit a tendency to over-predict precipitation, resulting in a domain-average total bias for the ensemble mean of about 20% in winter (DJF) and less than 10% in summer (JJA) at both resolutions, although this bias could be artificially enhanced by the lack of a gauge correction in the observations. A majority of the models show increased precipitation at 25 km relative to 50 km over the oceans and inland seas in DJF, JJA, and ANN (annual average), although the response is strongest during JJA. The ratio of convective precipitation to total precipitation decreases over land for most models at 25 km. In addition, there is an increase in interannual variability in many of the models at 25 km grid spacing. Comparison with gridded observations indicates that a majority of models show improved skill in simulating both the spatial pattern and temporal evolution of precipitation at 25 km compared to 50 km during the summer months, but not in winter or on an annual mean basis. Model skill at higher resolution in simulating the spatial and temporal character of seasonal precipitation is found especially for Great Britain. This geographic dependence of the increased skill suggests that observed data of sufficient density are necessary to capture fine-scale climate signals. As climate models increase their horizontal resolution, it is thus a key priority to produce high quality fine scale observations for model evaluation.  相似文献   

Sea level and shoreline reconstructions for the Red Sea: isostatic and tectonic considerations and implications for hominin migration out of Africa     

Kurt Lambeck  Anthony Purcell  Nicholas. C. Flemming  Claudio Vita-Finzi  Abdullah M. Alsharekh  Geoffrey N. Bailey 《Quaternary Science Reviews》2011,30(25-26):3542-3574

The history of sea level within the Red Sea basin impinges on several areas of research. For archaeology and prehistory, past sea levels of the southern sector define possible pathways of human dispersal out of Africa. For tectonics, the interglacial sea levels provide estimates of rates for vertical tectonics. For global sea level studies, the Red Sea sediments contain a significant record of changing water chemistry with implications on the mass exchange between oceans and ice sheets during glacial cycles. And, because of its geometry and location, the Red Sea provides a test laboratory for models of glacio-hydro-isostasy. The Red Sea margins contain incomplete records of sea level for the Late Holocene, for the Last Glacial Maximum, for the Last Interglacial and for earlier interglacials. These are usually interpreted in terms of tectonics and ocean volume changes but it is shown here that the glacio-hydro-isostatic process is an additional important component with characteristic spatial variability. Through an iterative analysis of the Holocene and interglacial evidence a separation of the tectonic, isostatic and eustatic contributions is possible and we present a predictive model for palaeo-shorelines and water depths for a time interval encompassing the period proposed for migrations of modern humans out of Africa. Principal conclusions include the following. (i) Late Holocene sea level signals evolve along the length of the Red Sea, with characteristic mid-Holocene highstands not developing in the central part. (ii) Last Interglacial sea level signals are also location dependent and, in the absence of tectonics, are not predicted to occur more than 1–2 m above present sea level. (iii) For both periods, Red Sea levels at ‘expected far-field’ elevations are not necessarily indicative of tectonic stability and the evidence points to a long-wavelength tectonic uplift component along both the African and Arabian northern and central sides of the Red Sea. (iv) The observational evidence is consistent with tectonic and isostatic processes both operating over the past 300,000 years without requiring changes in the time averaged (over a few thousand years) tectonic rates. (v) Recent bathymetric data for the Bab al Mandab region have been compiled to confirm the location and depth of the sill controlling flow in and out of the Red Sea. Throughout the last 400,000 years the Red Sea has remained open to the Gulf of Aden with cross sectional areas at times of glacial maxima about 2% of that today. (vi) The minimum channel widths connecting the Red Sea to the Gulf of Aden at times of lowstand occur south of the Hanish Sill. The channels are less than 4 km wide and remain narrow for as long as local sea levels are below ?50 m. This occurs for a number of sustained periods during the last two glacial cycles and earlier. (vii) Periods suitable for crossing between Africa and Arabia without requiring seaworthy boats or seafaring skills occurred periodically throughout the Pleistocene, particularly at times of favourable environmental climatic conditions that occurred during times of sea level lowstand.  相似文献   

Reviewing urban revitalisation strategies in Rio de Janeiro: from urban project to urban management approaches     

Claudio 《Geoforum》2001,32(4)

This paper describes key urban development strategies pursued during the last seven years by the Municipality of Rio de Janeiro, the second largest city in Brazil. It discloses internal processes, organisational restructuring of the municipality and institutional changes geared to increase effective urban management and resource mobilisation required to implement multiple sector programmes and key projects in several locations in the city like Favela Bairro and Rio Cidade Programmes, The Rio Strategic Plan, etc. It is argued that the formation of interdepartmental working groups for better horizontal articulation of policy making and implementation, the creation of the financial and accounting unit, the decentralisation of authority towards sub-municipality levels, and capacity strengthening of its personnel – among other things – have made a positive impact on the performance of local government. The paper further highlights a significant change towards policies of urban consolidation and revitalisation of declined areas of the city supported by heavy public investments and the effort towards broader civil society involvement in municipal projects. Municipal autonomy, problem-solving and result-oriented type of planning and management and organisational change are some of the lessons pinpointed by the paper for a city of that size and complexity.  相似文献   

Size distribution models of stratospheric particles in terms of the modified gamma function     

Dr. Francesco Tampieri  Dr. Claudio Tomasi 《Meteorology and Atmospheric Physics》1976,25(1):47-54

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