1,721,186 research outputs found
Global Warming perspectives and new solutions- Editorial
No full textThe Editorial of The Special Issue of The International Journal of Global Warming, "Global Warming perspectives and new solutions
Determination of water quality parameters and their usefulness on lake modelling
No full textThe successful launch of ENVISAT in March 2002 has given a great opportunity to understand the optical changes of water surfaces, including inland waters such as lakes and reservoirs, through the use of the Medium Resolution Imaging Spectrometer (MERIS). The potential of this instrument to describe variations of optically active substances has been examined in the Alqueva reservoir, located in the south of Portugal, where satellite spectral radiances are corrected for the atmospheric effects to obtain surface spectral reflectance. In order to validate these spectral reflectances, several field campaigns were carried out, with a portable spectroradiometer, during the satellite overpasses. The retrieved lake surface spectral reflectance was combined with limnological laboratory data to obtain empirical algorithms and with the resulting equations, spatial maps of biological quantities and turbidity were built up
Simulações Numéricas sobre a Formação e Evolução de Nevoeiros na Região Alentejo
No full textThe effect of fog on human life was recognized in the early ages of mankind but its impact has significantly increased
during recent decades due to increasing air, marine, and road traffic. In fact, the financial and human losses related to
fog and low visibility became comparable to the losses from other weather events, e.g., tornadoes or, in some situations,
even hurricanes, mainly, because they occur more frequently. For example, in aviation a fog phenomenon often cause
delays, diversions or cancellations that have various impacts on society, mainly economic impacts.
As visibility is one of the most difficult weather variables to predict, its understanding becomes very important. The fog
formation involves several processes, such as cloud physics, aerosols chemistry, radiation, turbulence, the large and
small scale dynamics and surface conditions, including water bodies, topography, vegetation and soil type. High
moisture, condensation nuclei and cooling process are the conditions for its formation. Often occurs in atmospheric
stability situations during clear sky nights and with light to calm wind. It can be enhanced if air pollutants are present.
Therefore, numerical simulations of fog events in Alentejo Region are presented, using capabilities of MESO -NH
(Non-Hydrostatic Mesoscale Model) model.
Surface observations of the Air Base No. 11 weather station in Beja were used in the model validation as well as Remote
Sensing data from the satellite METEOSAT-10.
Visual analysis of meteorological patterns observed by satellite and modeled with the Meso-NH provides a good
approximation, and also there is a satisfactory correspondence between data obtained by meteorological observation at
Air Base No. 11 and the analogous model point
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modeling Saharan desert dust radiative effects on clouds
No full textThis work intends to study the Saharan desert dust storms effects on clouds. This is done through the estimation of the cloud radiative forcing in the presence of mineral desert dust aerosols during a strong desert dust event that occured in the end of May 2006. The assessment of the cloud radiative forcing is made at a regional scale both at the top of the atmosphere (TOA) and at the surface levels.
The results are obtained from numerical simulations with a mesoscale atmospheric model (MesoNH) over Portugal area and nearby Atlantic Ocean.
From the results obtained it is possible to observe that, for all days under study, a cooling effect is always found both at the TOA and surface levels. Also, for these two levels and for clouds developing in a dusty atmosphere, a more pronounced cooling effect (more negative cloud radiative forcing values) is found compared with the corresponding cloud radiative forcing values for clouds developing in a dust free atmosphere
Rios Atmosféricos e precipitação na Ilha da Madeira: Análise de 10 anos
No full textThe purpose of this work is to bring more evidence about the Atmospheric Rivers (ARs) occurrence in the North Atlantic
Ocean (NAO) and their relationship with significant precipitation in the Madeira Island during 10 winter seasons. In
this study, the meridional water vapor transport associated to the ARs is visually identified from total precipitable water
field extracted from the Atmospheric Infrared Sounder (AIRS) data. The IPMA national meteorological network of
Madeira surface stations provide the precipitation data over the island used here. The detection of long and narrow
moisture plumes associated with ARs that passed over Madeira, between winter 2002/2003 and winter 2011/2012, is
made over a domain covering the NAO (latitudes between 10°N and 60°N and longitudes between 5°E and 100°W). The
image analysis show that moist air emanating mainly from the Caribbean Sea and central region of the Tropical
Atlantic may flow northward or eastward, usually in the form of a narrow band with an intense horizontal gradient of
precipitable water, and throughout the winter periods. However, large part of these filamentary structures intersects the
Madeira Archipelago in a dissipating stage. In addition, the analysis also allowed for the development of a conceptual
model related to this meridional transport passing over the island
Inter annual variability of surface solar radiation over Iberian Peninsula
No full textIn this study, the variability and trends of surface radiation over the Iberian Peninsula using ERA40 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) are examined. Monthly means of surface incident and net shortwave radiation for 40 years are computed and analyzed. Deviations from the temporal mean for each month and for each year are computed and variations discussed. The relation between the interannual variability of solar radiation over Iberian Peninsula and the cloud cover is analyzed. The trends of surface radiation for each month during the past decades are computed and discussed
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