The Fresnel space imager as a disk evolution watcher     

Ana In��s G��mez de Castro 《Experimental Astronomy》2011,30(2-3):205-216

The Fresnel Diffractive Imaging Arrays form high resolution images by diffraction with low radiometric efficiencies. They are extremely good devices to make high resolution imaging and integral field spectroscopy of bright sources. Thirty meter arrays will provide a spatial resolution of 0.8 mas at Lyman-?? that will open a completely new field of research: the study of matter distribution around disks and their gravitational drives. In this contribution, the potentials of the 3.6 m precursors (or probes) for astrophysical disks and jets research, are described. Main emphasis is made on young planetary disks.  相似文献   

Pre main sequence stars as UV sources for the World Space Observatory-UV mission     

Ana I. Gomez de Castro  Sergei A. Lamzin 《Astrophysics and Space Science》2011,335(1):61-68

Pre-main sequence stars are bright UV (UV) sources compared with their main sequence analogues. The source of this excess is the high energy processes associated with the physics of accretion/outflow during early stellar evolution. In this review, the main sources of UV excess are described as well as the most significant “unknowns” in the field. Special emphasis is made on the results from the last observations carried out with the Hubble Space Telescope and on the relevance of future dedicated monitoring programs with the World Space Observatory-UV.  相似文献   

Seasonal trends in phytoplankton biomass over the Uruguayan Shelf     

Ana Martínez  Leonardo Ortega 《Continental Shelf Research》2007

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Modelling shallow landslide susceptibility: a new approach in logistic regression by using favourability assessment   总被引：2，自引：0，他引：2  

María José Domínguez-Cuesta  Montserrat Jiménez-Sánchez  Ana Colubi  Gil González-Rodríguez 《International Journal of Earth Sciences》2010,99(3):661-674

A new method for estimating shallow landslide susceptibility by combining Geographical Information System (GIS), nonparametric kernel density estimation and logistic regression is described. Specifically, a logistic regression is applied to predict the spatial distribution by estimating the probability of occurrence of a landslide in a 16 km² area. For this purpose, a GIS is employed to gather the relevant sample information connected with the landslides. The advantages of pre-processing the explanatory variables by nonparametric density estimation (for continuous variables) and a reclassification (for categorical/discrete ones) are discussed. The pre-processing leads to new explanatory variables, namely, some functions which measure the favourability of occurrence of a landslide. The resulting model correctly classifies 98.55% of the inventaried landslides and 89.80% of the landscape surface without instabilities. New data about recent shallow landslides were collected in order to validate the model, and 92.20% of them are also correctly classified. The results support the methodology and the extrapolation of the model to the whole study area (278 km²) in order to obtain susceptibility maps.  相似文献   

Interpretation and modelling of regional gravity data of the Aveiro Basin (Northwest Portugal)     

František Mantlík  Manuel J.S. Matias 《Comptes Rendus Geoscience》2010,342(11):823-836

The gravity map of the Aveiro Basin, North West Portugal was produced in 2000/2001 and some limited two dimensional (2D) interpretation was carried out. It is intended in this article to advance the interpretation and modelling of the original Aveiro basin gravity data. Thus, the data were processed and the horizontal gradient, the second vertical derivative and downward continued field computed. The corresponding maps have been processed and a new interpretation of the basin tectonic features has been proposed. This is compared with the previous geological and tectonic information obtained from former surveys and local boreholes. As the next step a more detailed modelling of the Aveiro Basin took place. Bearing the interpretation of the basin tectonic features in mind, several north–south and east–west gravity profiles were established and modelled. The proposed models were presented and discussed. As a result, a comprehensive mass distribution model for the basin was proposed. Finally, comparison was made between the new gravity model and the previously published tectonic features map. This modelling is particularly useful for groundwater protection, exploration and exploitation and also for the dimensioning of drilling operations. Bearing in mind the geomorphology of the basin the gravity method is a very economical tool for the investigation of basin structures.  相似文献   

Land use dynamics in Brazilian La Plata Basin and anthropogenic climate change     

Ana Carolina F. de Vasconcelos  Sandro L. Schlindwein  Marcos A. Lana  Alfredo C. Fantini  Michelle Bonatti  Luiz R. D’Agostini  Sergio R. Martins 《Climatic change》2014,127(1):73-81

The La Plata Basin (LPB) is one of the most important regions for agriculture and livestock production in South America, playing a central role in the world food production and food security. Within its borders is also located the whole Brazilian Pantanal region. Identifying the most important land use sectors in LPB as well as the changes observed in the past years is fundamental to recognize which areas of the basin might be more vulnerable to climate change in order to design adaptation strategies. A general characterization of land use and livestock production of Brazilian LPB was done by using the System of Automatic Retrieving (SIDRA) of Brazilian Institute of Geography and Statistics (IBGE) platform as the major source of data. It was observed expressive increases in land areas used for temporary crops, such as soybean, sugarcane, and maize, as well as increases in poultry and swine production. These important changes in agricultural land use and livestock production are currently associated to non-climatic drivers, but this dynamic might be strongly affected by the consequences of climate change and variability, with negative socio-economic impacts for the whole region.  相似文献   

Amazon forest biomass density maps: tackling the uncertainty in carbon emission estimates     

Jean Pierre Ometto  Ana Paula Aguiar  Talita Assis  Luciana Soler  Pedro Valle  Graciela Tejada  David M. Lapola  Patrick Meir 《Climatic change》2014,124(3):545-560

As land use change (LUC), including deforestation, is a patchy process, estimating the impact of LUC on carbon emissions requires spatially accurate underlying data on biomass distribution and change. The methods currently adopted to estimate the spatial variation of above- and below-ground biomass in tropical forests, in particular the Brazilian Amazon, are usually based on remote sensing analyses coupled with field datasets, which tend to be relatively scarce and often limited in their spatial distribution. There are notable differences among the resulting biomass maps found in the literature. These differences subsequently result in relatively high uncertainties in the carbon emissions calculated from land use change, and have a larger impact when biomass maps are coded into biomass classes referring to specific ranges of biomass values. In this paper we analyze the differences among recently-published biomass maps of the Amazon region, including the official information used by the Brazilian government for its communication to the United Nation Framework on Climate Change Convention of the United Nations. The estimated average pre-deforestation biomass in the four maps, for the areas of the Amazon region that had been deforested during the 1990–2009 period, varied from 205?±?32 Mg ha^?1 during 1990–1999, to 216?±?31 Mg ha^?1 during 2000–2009. The biomass values of the deforested areas in 2011 were between 7 and 24 % higher than for the average deforested areas during 1990–1999, suggesting that although there was variation in the mean value, deforestation was tending to occur in increasingly carbon-dense areas, with consequences for carbon emissions. To summarize, our key findings were: (i) the current maps of Amazonian biomass show substantial variation in both total biomass and its spatial distribution; (ii) carbon emissions estimates from deforestation are highly dependent on the spatial distribution of biomass as determined by any single biomass map, and on the deforestation process itself; (iii) future deforestation in the Brazilian Amazon is likely to affect forests with higher biomass than those deforested in the past, resulting in smaller reductions in carbon dioxide emissions than expected purely from the recent reductions in deforestation rates; and (iv) the current official estimate of carbon emissions from Amazonian deforestation is probably overestimated, because the recent loss of higher-biomass forests has not been taken into account.  相似文献   

A high resolution hindcast of the meteorological sea level component for Southern Europe: the GOS dataset     

Alba Cid  Sonia Castanedo  Ana J. Abascal  Melisa Menéndez  Raúl Medina 《Climate Dynamics》2014,43(7-8):2167-2184

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Hybrid Model for Urban Air Pollution Forecasting: A Stochastic Spatio-Temporal Approach     

Ana Russo  Amílcar O. Soares 《Mathematical Geosciences》2014,46(1):75-93

Air pollution is usually driven by a complex combination of factors in which meteorology, physical obstacles, and interactions between pollutants play significant roles. Considering the characteristics of urban atmospheric pollution and its consequent impacts on human health and quality of life, forecasting models have emerged as an effective tool to identify and forecast air pollution episodes. The overall objective of the present work is to produce forecasts of pollutant concentrations with high spatio-temporal resolution and to quantify the uncertainty in those forecasts. Therefore, a new approach was developed based on a two-step methodology. Firstly, neural network models were used to generate short-term temporal forecasts based on air pollution and meteorology data. The accuracy of those forecasts was then evaluated against an independent set of historical data. Secondly, local conditional distributions of the observed values with respect to the predicted values were used to perform spatial stochastic simulations for the entire geographic area of interest. With this approach the spatio-temporal dispersion of a pollutant can be predicted, while accounting for both the temporal uncertainty in the forecast (reflecting the neural networks efficiency at each monitoring station) and the spatial uncertainty as revealed by the spatial variograms. Based on an analysis of the results, our proposed method offers a highly promising alternative for the characterization of urban air quality.  相似文献   

The state of the environment in Mexico     

Manuel Bollo Manent  José Ramón Hernández Santana  Ana Patricia Méndez Linares 《Central European Journal of Geosciences》2014,6(2):219-228

The present work evaluates the state of the environment in Mexico based on indicators of the present status of the country’s natural resource management, social and economical conditions and anthropogenic modifications. The Mexican environment is interpreted as a spatially open system having a historical character that is essentially determined by the continual interaction between nature, society and economy. The landscape approach is followed, considering as units of territorial analysis each one of the 145 biophysical environmental units included in the national physiographic regionalization. The assessment of 16 indicators for each biophysical environmental unit was made considering their regional environmental integrity problems, the degree of disarticulation of their structure and function, and the alteration of their territorial structure, all of which determine whether or not they accomplish their environmental functions and achieve environmental stability. The classification of the state of the environment included 5 categories in 8 combinations represented in the map of the state of the environment in Mexico for the year 2008. The map shows that nearly 47.10% of the country’s surface has an environmental status ranging between unstable and critical, the problematic areas being mostly concentrated in the southeast and center of the national territory.  相似文献