Biblioteca Digital da Memória Científica do INPE

    Interpretação dos gases traços medidos em São Paulo através das trajetórias de parcelas do ar

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    Backward trajectories have been calculated from June to August, 1999, in São Paulo using a three dimensional kinematic trajectory model. The trajectories were obtained using the three .components of wind velocity (u, v, w) simulated by the Regional Atmospheric Modeling System Version 4.3-RAMS. Backward trajectories were classitied based on latitude and longitude trajectory at 12 h intervals (00 e 12 UTC) over four days. The robustness of the analysis was assessed using an ensemble of back trajectories calculated for tive points in the neighborhood of the Metropolitan Area do São Paulo

    Modelagem do impacto de modificacoes recentes da cobertura vegetal amazonica no clima regional

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    No decorrer das ultimas decadas o territorio brasileiro, como um todo, tem apresentado diferentes transformacoes no padrao espacial e uso e cobertura da terra, as quais vao desde altas taxas de desflorestamento da floresta tropical na regiao Norte e desertificacao no Nordeste. Essas diferentes transformacoes ocorridas na cobertura da superficie, associadas `as praticas de uso da terra, exercem uma grande influencia na hidrologia, clima e ciclos biogeoquimicos em diferentes regioes do Brasil (Salati e Vose, 1984; Nobre et al., 1991; Nepstad et al., 1994). A Bacia Amazonica cont´em aproximadamente 60% das florestas tropicais restantes no mundo e desempenha papel fundamental na manutencao da biodiversidade, clima e hidrologia regional, e armazenagem de carbono terrestre (Fearnside, 1999; Houghton et al., 2000). Essa regiao tambem tem apresentado nas ´ultimas d´ecadas as maiores taxas de desmatamento. Na Amazonia brasileira, que compreende aproximadamente 70% da bacia, as taxas de desflorestamento desde 1995 tiveram uma media de 2 milhoes de hectares por ano, o equivalente a sete campos de futebol por minuto (INPE, 2002; Laurance et al., 2001a). Diante das constantes modificacoes que vem ocorrendo no uso da terra na regiao amazonica, algumas questoes podem ser levantadas, tais como: Essas mudancas poderiam causar impactos no clima? E, quais seriam estes impactos? Em respostas a estas questoes um grande numero de estudos tem usado modelos de circulacao geral da atmosf´erica (MCGA) para examinar os possiveis efeitos do desmatamento amazonico de grande escala no clima regional e global (Nobre et al., 1991; Dickinson e Kennedy, 1992; Henderson-Sellers, 1993; Lean e Rowntree, 1993, Sud et al., 1996; Hahmann e Dickinson, 1997; Costa e Foley, 2000). Todos esses experimentos com MCGA mostraram um significativo aumento da temperatura da superficie e diminuicao da evapotranspiracao sobre a bacia apos os desmatamento. Diante desses resultados, uma outra questao que pode ser abordada e a consideracao de um panorama mais realista da cobertura vegetal para a Amazonia, e consequentemente a verificacao dos efeitos climaticos detectados. Dessa maneira, simulacoes com modelos de circulacao geral (MCG/CPTEC) e regional (Eta/CPTEC) da atmosfera, utilizando informacoes mais realista da cobertura vegetal da Amazonia brasileira (desflorestamento) em relacao `aquelas utilizadas nos modelos numericos de previsao de clima e tempo, estao sendo atualmente realizadas. No intuito de melhorar arepresentacao das condicoes e dos processos da superficie continental durante as simulacoes, realizou-se a calibracao do esquema superficie (Simplified Simple Biosphere Model - SSiB) acoplado aos modelos atmosfericos, utilizando dados medidos em sitio de pastagem (Fazenda Nossa Senhora - RO) e floresta (Reserva Biologica do Jaru - RO)

    Integrating Manufacturing Process Planning with Scheduling via Operation-Based Time-Extended Negotiation Protocols

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    Traditionally the process planning and scheduling functions are executed in a sequential way, and alternative resources are not usually considered. In this paper it is proposed the on-line adaptation of the process plan with alternatives, through the application of a feature-based time-extended negotiation protocol for decision-making about real-time routing of job orders of parts composed of machining features in a job-shop environment. The protocol is modified from the contract net protocol to cater for the multiple-task and many-to-many negotiations. The grouping of the machining features enables gains in the setup times, and these earnings are associated with the lower number of setups usually caused by unnecessary machines changes. The proposed architecture comprises the following types of agents: part, resource, server, failure, order, and synchronizer agents. For each part, all feasible routings are considered as alternative process plans provided the different manufacturing times are in each machine are taken into account. The time-extended negotiation period, which allows the visualization of all of the times involved in the manufacture of each part, including those times that are not considered in systems of this nature, such as the negotiation times among agents. Through the inclusion of a failure agent it is possible to verify the robustness of the system and to measure the impact caused by production disturbances, such as machine breakdowns. A dynamic Gantt chart is generated starting with each of the simulations, having as input the changes of status of the system, such as the beginning and end of processes, as well as production disturbances. The proposed system is already being used, and extensive experiments have been conducted and the performance measures, including routings, makespan and flowtime, are compared with those obtained by the following approaches found in the literature: traditional hierarchical approach, an existing cooperative co-evolutionary algorithm, and the search technique base on the co-evolutionary algorithm.Pages: 319-32

    A new technique for developing k-distributions

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    This work is devoted to a new technique, which finds the shortest k-distribution series achievable in practice. Its novelty consists in the use of real atmospheric flux calculations to guide both the position of spectral bands and the k terms within each band. Wavenumber subintervals which have similar atmospheric absorption behavior are chosen, then a representative absorption coefficient is set to the value which best fit the results of line-by-line calculations of fluxes. This method of choosing one absorption coefficient to represent a large number of wavenumber subinterval contrasts with other published methods, and is responsible in large part for the improved computational efficiency. Moreover this technique works as well in the stratosphere as the troposphere and it permits a more accurate treatment of cloud scattering and absorption properties than other methods

    Resonant photoacoustic cell for low temperature measurements

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    This paper describes a resonant photoacoustic cell for low temperature measurements. It has the shape of the Helmholtz resonator, with the microphone separated from the sample by a resonant tube. In this way the microphone is kept at room temperature while the sample temperature is lowered. When the sample is placed in a liquid nitrogen tank it is possible to change its temperature from 77 K to 300 K, with the aid of a furnace, which surrounds the sample holder. Two optical fibres lead the laser light to both sides of the sample, making possible the determination of the thermal diffusivity in all temperature intervals, by using the photoacoustic phase-lag method. (C) 1999 Elsevier Science Ltd. All rights reserved.Pages: 193-19

    The Diurnal Cycle of Precipitation over South America based on CMORPH

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    The diurnal cycle of precipitation over the region of South America is examined using high spatial and temporal resolution analyses that have been produced by NOAAs Climate Prediction Center morphing technique (CMORPH) (Joyce et al. 2004). The 8-km spatial resolution (at the equator) and 30-minute temporal resolution of these analyses permit an in-depth look at the diurnal cycle of precipitation. Major features of the summertime diurnal cycle, as depicted by CMORPH for the South American Monsoon, include an afternoon maximum in precipitation over the Andes and the high terrain in central and eastern Brazil, a nocturnal maximum in precipitation over areas just east of the Andes (western Argentina, central Bolivia and western Paraguay), and a nocturnal maximum over the Atlantic Ocean in the vicinity of the South Atlantic Convergence Zone (Fig. 1). A remarkable diurnal cycle in precipitation occurs in coastal areas of northern and northeastern South America. With daytime heating, precipitation rapidly develops along and just inland from the coast (Fig. 1, lower left panel), probably related to the sea breeze. This precipitation advances westward and southward, producing a nocturnal maximum in areas approximately 500 km inland from the coast. The inland propagation of sea-breeze-induced rainfall systems is a feature most frequently found during late SH summer (December-February) and fall (March-May). The seasonal average diurnal cycle for equatorial South America (Eq. 5\ub0N) for March-May 2003 indicates that sea-breeze-induced precipitation systems propagate westward, reaching the western Amazon Basin in about two days. As these systems propagate inland they contribute to a nocturnal precipitation maximum in some areas and a diurnal precipitation maximum in other areas. A nocturnal or early morning precipitation maximum also occurs along the immediate coast and offshore in the vicinity of the Atlantic ITCZ and over the Pacific near the west coast of South America. The seasonality of the diurnal cycle will also be included in this presentation.Pages: 1113-111

    Trends in streamflow and rainfall in tropical South America: Amazonia, eastern Brazil, and northwestern Peru

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    Long hydrological records, from the Amazon Basin, northeastern Brazil, and northwestern Peru spanning most of this century, are examined for trends in rainfall (three wettest months) and runoff (three months of highest flow) or stage, where no rating curves exist. Trends are tested for significance using the Mann-Kendall statistic. In basins where large soil, aquifer, or man-made reservoirs give rise to appreciable over-year storage, flows and water levels may be serially correlated. Where serial correlation exists, the usual statistical tests (linear regression, t-test, and Mann-Kendall) will overestimate the significance of trends, showing significance where none exists. Analysis for trend therefore requires particular care when data are serially correlated, and to avoid misleading results, additional supportive evidence must be sought. For example, rainfall records within the same river basin can be checked for trends; serial correlation in rainfall records, in particular, is less likely to be present, so the validity of any trends in rainfall is less open to question. Strong negative trends were found in flow data from the coast of northern Peru and the Sao Francisco River, while positive significant trends were detected in the Parnaiba River basin. No significant trends were found in the discharge or stage records from Amazonia, while rainfall in northeastern Brazil shows a slow increase over long periods. In the Parnaiba and in some rivers of northern Peru unusually large discharges at the beginning or end of the records seem to account for the direction and significance of trends.Pages: 1775-178

    Estimating soil water retention characteristics from limited data in Brazilian Amazonia

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    The application and validation of complex atmosphere-soil water transport models demands knowledge of the parameters that describe hydraulic properties over extensive areas. Such information is rarely available, but Pedo Transfer Functions (PTFs) provide a means of predicting these parameters from soil survey data, However, most PTFs have been derived and validated using information from soils of temperate regions and have nest been tested for the soils of tropical areas, for which chemical, physical, and pedogenetic processes are different. The equations of Rawls and colleagues, for example, overestimate water content when applied to the ails of Brazilian Amazonia. In this paper, we have developed a PTF to predict Brooks-Corey parameters from texture using data from soils of Amazonia. Multiple linear regressions were fitted to estimate, from soil texture (% sand, silt, and clay), the bulk density and porosity and the water content at a range of matric potentials. Brooks-Corey parameters were then derived and correlated independently with soil texture, providing a straightforward method for deriving son retention parameters from the percentage of clay and silt. The method was validated using an independent data set for which textural and water release data were available, The agreement between the observed and measured values was very significant, but the results showed that the differences between predictions and measurements also depended on bulk density, However, the Amazonian soil survey data, which may be used to extrapolate these results spatially, do not generally include bulk density, and for this reason they were not included in the regressions.Pages: 190-20

    Um estudo de caso de invasao de ar polar em latitutes medias associado a uma cilcogenesis intensa no rio da Prata

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    This work intends to improve extratropical cyclones forecasts. We studied the case of September 27th 1998 when were observed record values of precipitation in Argentina. Satellite data from September 27th to October 2nd were analyzed and CPTEC model analyses were studied to describe the processes involved into the formation of the system and its contribution for the polar outbreak. It was also calculated the terms of Sutcliffe equation. The results were compared with the observation and a good agreement was found. It is concluded that intense gradients of humidity and temperature in low levels and gradients of vorticity in high levels favored the cyclone formation and development

    Analise do tempo local durante o experimento IPE 2: abordagem observacional preliminar

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    As part of a broad experiment program to study the characteristics of the weather and the climate of the central region of Brazil, micrometeorological experiments are done in the South Matogrosso Pantanal, in a representative site near Miranda, MS, at 19o 57,729’S 57o 01,861W. A sky imagery methodology from the surface was applied, from September 14 to 23 in 1999, during the second Interdisciplinary Pantanal Experiment campaign (IPE 2). The purpose of this methodology improvement is twofold: (a) it helps the meteorological data analysis collected during scientific campaings and (b) it provides complementary imagery information required in quantitative investigations of atmospheric electrical features
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