Climate change and upwelling: response of Iberian upwelling to atmospheric forcing in a regional climate scenario   总被引：1，自引：1，他引：0  

P. M. A. Miranda  J. M. R. Alves  N. Serra 《Climate Dynamics》2013,40(11-12):2813-2824

The regional ocean modeling system is used, at a resolution of 1/12°, to explicitly simulate the ocean circulation near the Iberian coast during two 30-year simulations forced by atmospheric fields produced by the RACMO regional climate model. The first simulation is a control run for the present climate (1961–1990) and the second is a scenario run from the IPCC A2 scenario (2071–2100). In the control run, the model reproduces some important features of the regional climate but with an overestimation of upwelling intensity, mainly attributable to inaccuracies in the coastal wind distributions when compared against reanalysis data. A comparison between the scenario and control simulations indicates a significant increase in coastal upwelling, with more frequent events with higher intensity, leading to an overall enhancement of SST variability on both the intra- and inter-annual timescales. The increase in upwelling intensity is more prominent in the northern limit of the region, near cape Finisterre, where its mean effect extends offshore for a few hundred kms, and is able to locally cancel the effect of global warming. If these results are confirmed, climate change will have a profound impact on the regional marine ecosystem.  相似文献   

Combining Robustness with Efficiency in?the?Estimation of the Variogram     

Hil��rio Miranda  Manuela Souto?de?Miranda 《Mathematical Geosciences》2011,43(3):363-377

In the present paper, we propose a new method for the estimation of the variogram, which combines robustness with efficiency under intrinsic stationary geostatistical processes. The method starts by using a robust estimator to obtain discrete estimates of the variogram and control atypical observations that may exist. When the number of points used in the fit of a model is the same as the number of parameters, ordinary least squares and generalized least squares are asymptotically equivalent. Therefore, the next step is to fit the variogram by ordinary least squares, using just a few discrete estimates. The procedure is then repeated several times with different subsets of points and this produces a sequence of variogram estimates. The final estimate is the median of the multiple estimates of the variogram parameters. The suggested estimator will be called multiple variograms estimator. This procedure assures a global robust estimator, which is more efficient than other robust proposals. Under the assumed dependence structure, we prove that the multiple variograms estimator is consistent and asymptotically normally distributed. A simulation study confirms that the new method has several advantages when compared with other current methods.  相似文献   

Climatic change and rainfall patterns: Effects on semi-arid plant communities of the Iberian Southeast     

J.D. Miranda  C. Armas  F.M. Padilla  F.I. Pugnaire 《Journal of Arid Environments》2011,75(12):1302-1309

The structure and functioning of semi-arid ecosystems are strongly influenced by precipitation patterns. Water availability in such environments is highly pulsed, and discrete rainfall events interspersed with drought periods are important components of the annual water supply. Plant communities do not only respond to rainfall quantity, but also to variations in time, so that relatively small changes in rainfall frequency (i.e., pulsed inputs) may have strong effects on communities. Within the Mediterranean basin, climate change models forecast a decrease in mean annual precipitation and more extreme events (i.e., less rainy days and longer drought periods between events), along with seasonal changes. However, little is known on the consequences of these future precipitation changes on plant communities, especially in semi-arid environments. Here, we summarize the few experiments that have manipulated rainfall patterns in arid and semi-arid areas worldwide, and introduce the first results of a pioneer, long-term rainfall exclusion in the semi-arid southeast region of the Iberian Peninsula. The experiment is not only manipulating the amount of rainfall, but also its frequency and seasonal distribution in a grassland-shrubland in the Tabernas desert (Almería, Spain). This work monitored the effect of precipitation changes on different ecosystem processes for five years, at the species and community level, concluding that this plant community (as other communities studied in the same area) exhibited great resilience to changes in rainfall availability, likely caused by plant adaptation to large intra- and inter-annual precipitation variability.  相似文献   

Special issue: The Iberian Southeast     

C. Armas  J.D. Miranda  F.M. Padilla  F.I. Pugnaire 《Journal of Arid Environments》2011,75(12):1241-1243

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Brazilian Decimetric Array (Phase-I)     

H. S. Sawant  R. Ramesh  J. R. Cecatto  C. Faria  F. C. R. Fernandes  R. R. Rosa  M. C. Andrade  S. Stephany  L. B. T. Cividanes  C. A. I. Miranda  L. C. L. Botti  J. W. S. V. Boas  J. H. Saito  C. E. Moron  N. D. Mascarenhas  K. R. Subramanian  M. S. Sundararajan  E. Ebenezer  M. R. Sankararaman 《Solar physics》2007,242(1-2):213-220

An East – West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira Paulista (longitude 45°0′20″ W, latitude 22°41′19″ S) for observations of the Sun and some of the strong sidereal sources by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array and can be operated at any frequency in the range 1.2 – 1.7 GHz. The instrument has been in operation since November 2004 onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ∼3′ and 100 ms, respectively. Details of the array, analog/digital receiver system, and a preliminary East – West one-dimensional solar image at the 1.6 GHz are presented in this paper.  相似文献   

Antibiotic resistant bacteria in fish from the Concepción Bay, Chile.     

C D Miranda  R Zemelman 《Marine pollution bulletin》2001,42(11):1096-1102

Antibiotic resistant bacteria from commercial demersal and pelagic fish captured in the Concepción Bay, Chile were investigated. Viable counts of antibiotic resistant bacteria isolated from gill and intestinal content samples showed high frequencies of resistance to ampicillin, streptomycin and tetracycline, while the proportion of chloramphenicol resistance was rather low. A high incidence of resistance to ampicillin, streptomycin, tetracycline and nitrofurantoin, as well as almost an absence of resistance to gentamicin, amikacin and cotrimoxazole was found among selected isolates which represented the resistant bacterial population. These strains mainly belonged to Vibrionaceae and Enterobacteriaceae and were predominantly resistant to 3 and 4 antibacterials. Isolates from demersal fish exhibited resistance to as many as 8-10 compounds, whereas those from pelagic fish were resistant to seven or fewer antibiotics. These results suggest that Chilean commercial fishes residing in waters near the disposals of urban sewage might play a role as carriers of antibiotic resistant bacteria prompting a health risk to public health for fish consumers.  相似文献   

Role of shellfish hatchery as a reservoir of antimicrobial resistant bacteria     

Claudio D. Miranda  Rodrigo Rojas  Marcela Garrido  Julieta Geisse  Gerardo González 《Marine pollution bulletin》2013

The main aim of this study was to determine the occurrence of resistant bacteria in florfenicol-treated and untreated scallop larval cultures from a commercial hatchery and to characterize some selected florfenicol-resistant strains. Larval cultures from untreated and treated rearing tanks exhibited percentages of copiotrophic bacteria resistant to florfenicol ranging from 0.03% to 10.67% and 0.49–18.34%, respectively, whereas florfenicol resistance among oligotrophic bacteria varied from 1.44% to 35.50% and 3.62–95.71%, from untreated and treated larvae, respectively. Florfenicol resistant microbiota from reared scallop larvae mainly belonged to the Pseudomonas and Pseudoalteromonas genus and were mainly resistant to florfenicol, chloramphenicol, streptomycin and co-trimoxazole. This is the first study reporting antimicrobial resistant bacteria associated to a shellfish hatchery and the results suggest that a continuous surveillance of antimicrobial resistance even in absence of antibacterial therapy is urgently required to evaluate potential undesirable consequences on the surrounding environments.  相似文献   

Spatial structure of the evolution of surface temperature (1951–2004)     

Pedro M. A. Miranda  António R. Tomé 《Climatic change》2009,93(1-2):269-284

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Point defects and pre-dose requirements for sensitization of the 300°C TL peak in natural quartz     

Pedro L. Guzzo  Helen J. Khoury  Milena R. Miranda  Sandra B. Barreto  Armando H. Shinohara 《Physics and Chemistry of Minerals》2009,36(2):75-85

This paper discusses the structural features required to stimulate a strong thermoluminescence (TL) glow peak near 300°C in clear natural quartz. For that reason, fresh TL data taken from several specimens prepared from five single crystals with known impurity content are shown. The TL emission was measured with a test dose of 10 mGy of γ-rays in the readout intervals 50–160 and 160–320°C. The readings were carried out prior and after the administration of a pre-dose of 175 kGy of γ-rays followed by heat-treatments at 400°C. For each single specimen, the OH content and the population of inclusions were evaluated by infrared spectroscopy and optical microscopy, respectively. The darkening induced by high γ dose was evaluated by optical spectroscopy. It was observed that the absorption at 475 nm and TL responses decrease with increase of the OH. It was shown that both smoky darkening and TL signals were better explained in terms of Li/Al and Li/OH content ratios rather than the absolute values of aluminum and alkali concentrations. The sensitization with high γ dose and heating is essential to create and stabilize a class of defects sites with Li⁺ ions dislodged from [AlO₄/Li]⁰ and Li-dependent OH centers. It is suggested that the defect sites formed with Li⁺ act as electron traps during test dose irradiation, whereas electron-hole recombination occurs essentially at [AlO₄]⁰ centers during the TL output near 300°C.  相似文献   

For the sake of the children: coping strategies of women in Swaziland's domestic service sector     

Miranda Miles 《GeoJournal》1996,39(1):81-88

This article examines the coping strategies of domestic workers in the city of Manzini. The Swaziland government has made many efforts to improve the social and economic conditions of the Swazi people after independence in 1968. Yet a failure to recognise domestic work as paid employment has minimised the effect of government policy in improving the lives of women who dominate this sector. The anomalies that it raises as paid housework has meant that conditions in the domestic service sector have changed little since the colonial era. Domestic workers are in practical terms, not protected by legal systems of labour relations. Coupled with other barriers that prohibit their access to land and shelter and dismally low wages, they have adopted many coping strategies in the city to maintain their families and their dignity.  相似文献