1,720,977 research outputs found
The Decorrelation Length and Time Scale - Diagnostic Tools to Visualize Spatial and Temporal Variability in Geophysical Fields
No full textAtmospheric reanalyses and model data are becoming more commonly used. However, most reanalyses and global climate models have resolutions of ~50 km or lower --- scales too coarse to capture many topographic and coastal effects within various geophysical fields such as precipitation and wind speed. Although attempts have been made to assess the impact of horizontal model resolution, such as downscaling and power spectrum methods, it is still unclear how this impacts the representation of the spatial variability. This thesis presents the Decorrelation Length Scale (DCLS and Decorrelation Time Scale (DCTS), novel techniques to characterize and visualize spatial and temporal variability in geophysical fields at a grid-point level, that is able to investigate this impact. The main strength of the DCLS/DCTS provide insight into both the relative variability and geographical imprint of the source of variability. A set of reanalysis, hindcasts, and analysis datasets with a common lineage and with horizontal resolutions ranging from ~125 km to ~9 km were used in three case studies to validate and explore the utility of this new technique.
The first case study validated the DCLS's utility as a diagnostic by showing that there are changes in the spatial variability of the precipitation over the Eastern Pacific that are not reflected in its mean structure. The second case study applied the same analysis technique as the DCLS to visualize temporal variability as well, showing that even resolutions of ~30-km do not capture the wind field's variability, especially in coastal and mountainous regions and also support the historic choice of wind farm development in the UK, namely, the southern/south-western tip of England as well as off the southern shore. Since the DCLS is not subject to uniform model bias, the third case study used this technique to study the spatial variability of the Congo Basin's hydrological cycle. This region has been historically understudied due to a lack of validation data and an interesting candidate for the DCLS analysis. DCLS results revealed that the main source of spatial variability in the P-E field over the Basin was uniformly from the precipitation field and that the spatial scales of the variability are less than 10 km.Ph.D
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Dynamics of Extreme Wind Speeds in Canada and Their Response to Climate Change
No full textThe damaging impacts of extreme near-surface wind speeds in the midlatitudes makes it important to understand how they may be affected by anthropogenic climate change. Unfortunately, the magnitude, sign, and drivers of potential changes to strong wind events are highly uncertain. The combined effect of changes to several atmospheric processes that cause strong winds is unclear, and the typically coarse spatial resolution of climate models inhibits their ability to simulate extreme winds. This thesis investigates how a more finely resolved climate model represents the physical processes that drive synoptic-scale extreme wind events in the midlatitude regions of Canada, how these processes explain model-projected changes to extreme winds, and how these factors depend on refined spatial resolution.
Model representation of the synoptic-scale drivers of extreme winds is assessed by comparing composite extratropical cyclones (ETC) and upper-level jet streaks for simulated extreme events to reanalysis composites for observed events. While the coarse resolution model shows good skill for common event regimes in non-mountainous regions, refined spatial resolution offers improvements for other extreme event regimes and for wind speed itself.
The model projections of extreme winds under climate change reveal a discrepancy between the coarse and fine resolution models regarding the sign of the change to extreme wind intensity. The discrepancy is explained by identifying the physical mechanisms responsible for the changes. The coarse resolution model projects less intense strong winds related to weaker ETC intensity, and the refined model projects stronger extreme winds over land due to increased local turbulent mixing of momentum. The initial focus is on the North American Great Lakes region, but refined resolution simulations centred on the western and Atlantic regions of Canada confirm the resolution-dependence of the sign of the extreme wind response. The turbulent mixing mechanism partially explains the discrepancy in the additional study regions, but the separation of the synoptic-scale and local-scale mechanisms is less clear because of regional differences in the wind climate and the large-scale circulation response.
The findings of this thesis improve understanding of the physical mechanisms that cause extreme winds to respond to climate change and demonstrate the importance of using high-resolution models for studying extreme wind speeds.Ph.D
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
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