1,720,954 research outputs found
Analysis of two MCS in the Mediterranean induced by cyclonic rotation
No full textHeavy rainfall and flood episodes in Europe are related to cyclogenesis and frontal systems. When cyclones develop in the Mediterranean, often deep convection is associated: large and long lasting cell clusters are forced by larger scale disturbances during the warm season and even Mesoscale Convective Systems are detected.
Deep, organized convective systems were studied and their link with cyclonic development in the Mediterranean region was analyzed. We studied a one-month period (25 Aug. - 25 Sep. 1998) when 4 cyclonic episodes and several convective clusters occurred in the Mediterranean. In particular two MCS induced by cyclonic motion are studied (28-29 August, 8-9 September 1998). The analysis is based on Meteosat imagery (IR and WV) and on meteorological conventional data (ECMWF data). We analyzed the PVA (potential vorticity anomalies) at 250 and 200 hPa, in conjunction with the geopotential height at 850 hPa, the wet-bulb potential temperature at 500 and 850 hPa, the relative topography 300-700 hPa, the wind fields and radiosoundings. We proposed and evaluated a conceptual model of develop of such systems in the Mediterranean.
The proposed conceptual model consists of two interlocking flows. The first is a radial flux of cold-dry air caused by the coupling of the low pressure at low levels (850 hPa) with the potential vorticity anomaly (tropopause sink) at high levels (250-200 hPa). This flow is visible by a decreasing of the thickness 300-700 hPa. The flux of clod-dry air travels eastward and interacts with the second warm-moist air flux, advected from south-west from the cyclonic rotation. The convection develops within few hundreds kilometers east of the surface low. In fact the dry air pushes the warm-moist air up, triggering new thunderstorms few kilometers ahead. The coupling between the PVA and the pressure low is less marked in the last phase of the system development
PROBABILITY OF PRECIPITATION ESTIMATION USING SEVIRI DATA AND ARTIFICIAL NEURAL NETWORKS
No full textThe estimation of precipitation from geostationary satellite data has always been pursued because of their high spatial and temporal resolution and full disc coverage. The SEVIRI upgraded set of VIS/NIR/IR channels provides new means to address this challenge. As an initial step in that direction this work proposes a SEVIRI-based statistical algorithm to estimate Probability of Precipitation (PoP) for the UK area for summer daytime periods. This work moves on from previous work, presented at EUMETSAT-2004, where the capability to distinguish rain from no-rain of SEVIRI-like channels was assessed by considering the MODIS sensor. A MODIS–based algorithm is still used here in order to provide secondary support for validation of the main SEVIRI algorithm. The UK radar network provides precipitation data for calibration and validation. The statistical approach is based on Artificial Neural Networks (ANNs).
A large supervised data set for June, July and August 2004 has been built. Radar precipitation estimation data (with 5-minute temporal resolution) have been collected from the Met Office Nimrod archive. SEVIRI data (between 8.00 UTC and 18.00 UTC, with 15-minute temporal resolution) have been provided by the EUMETSAT archive facility. MODIS data (AQUA and TERRA overpasses between 10.30 UTC and 13.30 UTC: around 100 cases) have been retrieved from the DAAC/NASA online archive. All the data are mapped on to the Nimrod 5 km grid.
The analysis has been carried out in two parts: 1) around 12.00 UTC both SEVIRI and MODIS PoP estimators are defined, validated and compared, 2) between 8.00 UTC and 18.00 UTC a SEVIRI PoP estimator is defined and validated. The Equitable Threat Score (ETS) parameter is used as the skill indicator, with a data set independent from the one used during the ANN training and testing phases.
The sensitivity of the SEVIRI-based algorithm to the diurnal cycle and different months is also investigated and discussed.
The main results are that: 1) SEVIRI and MODIS PoP estimators perform in a comparable way, 2) The group of channels: VIS0.6 (0.64 μm), VIS0.8 (0.81μm), NIR1.6 (1.64μm), IR3.9 (3.9μm), IR8.7 (8.7μm) and IR12.0 (12.0μm) perform a summer rain no-rain classification with a mean ETS around 46% (for cloudy and clear sky pixels and for a dry to wet ratio around 10), 3) The largest contribution to this performance comes from the combination of VIS0.8 and NIR1.6 channels
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
