1,721,072 research outputs found
Long-term pan evaporation observations: a precious resource to understand the water cycle trend
No full textAcceleration of the global water cycle over recent decades remains uncertain because of the high inter-annual variability of its components. Observations of pan evaporation (Epan), a proxy of potential evapotranspiration (ETp), may help to identify trends in the water cycle over long periods. The complementary relationship (CR) states that ETp and actual evapotranspiration (ETa) depend on each other in a complementary manner, through land-atmosphere feedbacks in water-limited environments. Using a long-term series of Epan observations in Australia, we estimated monthly ETa by the CR and compared our estimates with ETa measured at eddy covariance Fluxnet stations. The results confirm that our approach, entirely data-driven, can reliably estimate ETa only in water-limited conditions. Furthermore, our analysis indicated that ETa did not show any significant trend in the last 30 years, while short-term analysis may indicate a rapid climate change that is not perceived in a long-term perspective.Editor Z.W. Kundzewicz; Associate editor D. GertenCitation Lugato, E., Alberti, G., Gioli. B., Kaplan, J.O., Peressotti, A., and Miglietta, F., 2013. Long-term pan evaporation observations as a resource to understand the water cycle trend: case studies from Australia. Hydrological Sciences Journal, 58 (6), 1287-1296. © 2013 IAHS Press
Il telerilevamento all'infrarosso termico per la mappatura delle temperature minime ad elevato dettaglio territoriale=Thermal infrared remote sensing for high-resolution minimum temperature mapping
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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
Compact EDDY: a compact, low consumption eddy covariance logging system
No full textCompact_Eddy is a handheld computer-based logging system developed for eddy covariance installations. It is flexible to support different types of sonic anemometers, it has storing capability on internal memory, and data processing capability. The software is written in the Visual Basic .NET platform, entirely based on standard Windows operating systems thus allowing easy installation and configuration for a wide range of handheld PCs. The software computes half hourly statistics and fluxes with a simplified procedure, stores binary data with efficient memory usage and can be configured to send periodically, to a remote control station, system status information and basic computations using a GSM modem. The use of a handheld computer resulted in an average real conditions power consumption of 2.9 W, very low if compared with other standard logging devices, allowing important savings especially when systems are powered with solar panels in remote areas. Compact_Eddy has been installed and tested in three locations, with very different environmental conditions ranging from eastern European mountain forests to African semi-desertic areas. The field results demonstrated that the system operated reliably, resulting to be a good low-cost alternative to laptop computers and dataloggers. © 2008 Elsevier B.V. All rights reserved
Methane and carbon dioxide fluxes and source partitioning in urban areas: the case study of Florence, Italy
No full textLong-term fluxes of CO2, and combined short-term fluxes of CH4 and CO2 were measured with the eddy covariance technique in the city centre of Florence. CO2 long-term weekly fluxes exhibit a high seasonality, ranging from 39 to 172% of the mean annual value in summer and winter respectively, while CH4 fluxes are relevant and don’t exhibit temporal variability. Contribution of road traffic and domestic heating has been estimated through multi-regression models combined with inventorial traffic and CH4 consumption data, revealing that heating accounts for more than 80% of observed CO2 fluxes. Those two components are instead responsible for only 14% of observed CH4 fluxes, while the major residual part is
likely dominated by gas network leakages. CH4 fluxes expressed as CO2 equivalent represent about 8% of CO2 emissions, ranging from 16% in summer to 4% in winter, and cannot therefore be neglected when assessing greenhouse impact of cities
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