1,720,963 research outputs found
Training on NOAA-AVHRR of robust satellite techniques for next generation of weather satellites: An application to the study of space-time evolution of Pinatubo's stratospheric volcanic cloud over Europe.
No full textA new, self-adaptive approach (RAT), at the same time reliable and exportable, has been successfully applied to several environmental emergencies (forest fires, volcanic eruption, etc.). Through this paper its application to volcanic stratospheric aerosol monitoring will be described with reference to the Mount Pinatubo eruption (June 1991) whose stratospheric cloud interested Europe about six months later. By using only NOAA/AVHRR data, the proposed method permitted to trace in time and space the growth and decay of Pinatubo's stratospheric aerosol cloud in good agreement with independent ground based observations
SATELLITE REMOTE SENSING OF VOLCANIC AEROSOLS: A NEW, AVHRR-BASED, APPROACH
No full textThrough this paper the authors propose a new approach for volcanic aerosols detection by satellite. By using only NOAA/AVHRR data at hands the proposed method seems able to detect eruptive volcanic clouds as well as long-period trends in stratospheric aerosol loading related to major eruptive events. Several examples of application to different events of volcanic emission (developing with different space/time dynamics) are presented; some cases of Etna and Stromboli volcanoes have been investigated and an historical analysis has been performed in order to recognize stratospheric aerosols produced by Mount Pinatubo's eruption. In all cases the technique was able to detect anomalous particle loading in atmosphere, in an automatic way, without need of any specific transmittance model for the atmosphere or ancillary ground-based measurements. The main merit of this new approach is its effectiveness in recognizing field anomalies also in the presence of a highly variable background as well as its intrinsic exportability ensured by the use of thresholds which are local (i.e. specific for the time and the place of the observation) but automatically generated by using only satellite data at hands. By this way the proposed technique can be numbered among the others environmental applications of RAT(1) (Robust AVHRR Technique) approach in which it finds its origin
Esperienze di integrazione di dati laserscannig aerei ed iperspettrali per lo studio del manto nevoso
No full textTelerilevamento e scansione laser costituiscono strumenti comprovati per lo studio qualitativo e quantitativo del manto nevoso. L’articolo descriveun esperimento di impiego sinergico delle due tecnologie, nel quale la componente radiometrica ad alta risoluzione viene acquisita assieme a quella geometrica mediante l’utilizzo simultaneo di un sensore iperspettrare AISA Eaglee di un laserscanner Optech ALTM 3100 montati su elicottero. L’area di studio riguarda la zona del Monte
Canin, nelle Alpi Giulie Occidentali. I primi risultati dell’esperimento consentono di quantificare
con precisione la copertura e l’altezza della neve al suolo, e di impostare una possibile mappatura di alcune sue caratteristiche fisiche di superficie
FOREST FIRE DANGER ESTIMATION IN THE ITALIAN PENINSULA BASED ON THE INTEGRATION OF SATELLITE AVHRR DATA AND TOPOGRAPHIC FACTORS
No full textThe main objective of this work has been to evaluate the potential of integration of satellite data and topographic factor, in order to achieve improved performance in forest fire danger estimation. Existing AVHRR-based fire danger estimation methods (a review is specifically made) aim at obtaining fire susceptibility classification exploiting, mainly, the temporal evolution of NDVI, and Surface Temperature (T-s). In this work fire danger estimation has been performed integrating satellite data with fuel type and topographic factors. In order to evaluate the reliability; of the estimated indices, the time-space distribution of actual forest fires, provided by the Italian Forestry service, has been used. Preliminary results are very promising; they have shown that in the summer of 1996, a large number of forest fires occurred in the estimated higher danger areas
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
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