1,720,959 research outputs found
Non-Tidal Atmosphere and Ocean Background Modelling for Satellite Gravimetry: Development of AOD1B RL07
No full textThe satellite gravimetry missions GRACE and its successor GRACE-FO measure large-scale mass redistributions in the Earth system, including changes in terrestrial water storage, ice shelves, the oceans and atmosphere as well as the solid Earth. As the measurements are typically accumulated over one month before the computation of a gravity solution, high-frequency mass variations need to be accounted for using a-priori background models. The Atmosphere and Ocean Dealiasing Level 1B (AOD1B) data product routinely provides the necessary simulated non-tidal mass variations in the atmosphere and oceans.
While progress towards better background models has been made over the past years, residual errors in the simulated atmospheric and oceanic mass variations are still among the largest limiting factors to the overall GRACE accuracy. As a result, further improvements of these data-products are directly linked to improvements in the final gravity solutions and thus subsequent geophysical analyses.
This thesis summarizes the most recent improvements to the AOD1B product, including an updated ocean model configuration considering the effects of self-attraction and loading, an updated atmospheric component as well as an improved post-processing and tidal analysis. All of these changes are shown to result in a better representation of the simulated mass variations and are thus combined into a new release RL07 of AOD1B.
Additionally, the new release is examined in terms of its stability and consistency over long and short time-scales. Spurious trends, low-frequency signals or bias jumps in the background model data can, if unaccounted for, introduce biases into the global gravity solutions which are prone to be interpreted erroneously in subsequent geophysical analyses. Consequently, the analysis focuses on signals that might be induced into the final gravity field solutions such as trends but also possible discontinuities caused by changes is the employed atmospheric datasets. It is shown that AOD1B RL07 is free from such artifacts and can thus safely be used as a background model in satellite gravimetry.
Finally, an analysis of the residual errors in AOD1B RL07 is presented. The estimation is based on ensemble statistics derived from different atmospheric reanalyses. For the oceans, the impact of both the forced and intrinsic variability is investigated through differences in simulation experiments. The atmospheric and oceanic information is then combined to produce a new time-series of true errors, called AOe07, which is applicable in combination with AOD1B RL07 and can be used both as stochastic information in the gravity field retrieval process, as well as in simulation studies in preparation for future satellite gravimetry missions.Die Satellitenmission GRACE und ihre Nachfolgemission GRACE-FO messen großskalige Umverteilungen der Massen im Erdsystem. Diese beinhalten unteranderem Veränderungen in terrestrischen Wasserspeichern, Schelfeis, den Ozeanen und der Atmosphäre sowie der festen Erde. Da die Satellitendaten vor der Berechnung einer Schwerefeldlösung typischerweise über einen Monat akkumuliert werden, müssen hochfrequente Massenvariationen durch a-priori Hintergrundmodelle berücksichtigt werden. Das Atmosphere and Ocean Dealiasing Level 1B (AOD1B) Datenprodukt stellt eben diese gezeitenunabhängigen Massenvariationen in der Atmosphäre und den Ozeanen routiniert zur Verfügung.
Obwohl die Hintergrundmodelle der Sattellitengravimetrie über die Jahre hinweg regelmäßig verbessert wurden, sind Fehler in den Modellen immernoch eine der größten Limitierungen für GRACE und GRACE-FO. Im Gegenzug haben Verbesserungen in den Modellen einen direkten positiven Einfluss auch die Genauigkeit der Schwerefeldlösungen und damit auch indirekt auf die darauf basierenden geophysikalischen Anwendungen.
In dieser Arbeit wird die Weiterentwicklung von AOD1B hin zu einem neuen Release AOD1B RL07 zusammengefasst. Der Fokus liegt dabei auf einer aktualisierten Konfiguration des Ozeanmodells, inklusive der Berücksichtigung der Effekte der Selbstanziehung und Auflast der Wassersäule, einem Update der atmosphärischen Komponente und einer verbesserten Datenprozessierung mit verbesserter Behandlung atmosphärischer Gezeiten. Es wird gezeigt, dass diese Veränderungen zu einer besseren Darstellung der atmosphärischen und ozeanischen Massenveränderungen führen und somit zu einer verringerung der GRACE Unsicherheiten beitragen können.
Zusätzlich wird der neue Datensatz auf seine Stabilität und Konsistenz auf sowohl langen als auch kurzen Zeitskalen hin untersucht. Fälschliche Trends oder Diskontinuitäten in den Hintergrundmodellen können bei der Prozessierung der Satellitendaten in die Schwerefeldlösung gebracht werden und anschließend in geophysikalischen Anwendungen zu Fehlinterpretationen führen. Es wird ein Fokus auf bekannte Übergänge in den atmosphärischen Daten von AOD1B sowie lineare Trends gelegt, und gezeigt, dass AOD1B keine entsprechenden problematischen Artefakte aufweist und daher für die Anwendung in der Satellitengravimetrie geeignet ist.
Abschließend werden die residuellen Unsicherheiten des neuen Datensatzes abgeschätzt. Die Analyse basiert dabei auf der statistischen Auswertung verschiedener atmosphärischer Reanalysen und ozeanischer Ensemble-Simulationen, wobei sowohl die atmosphärisch induzierte Variabilität, als auch die intrinsische Variabilität berücksichtigt werden. Die Ergebnisse beider Komponenten werden anschließend kombiniert, um eine neue Zeitreihe echter Fehler, AOe07 genannt, zur Verfügung zu stellen. Diese ist dabei auf AOD1B RL07 abgestimmt und kann daher sowohl als stochastische Information in der Berechnung der Schwerefeldlösungen verwendet, als auch in Simulationsstudien für zukünftige Schwerefeldmissionen genutzt werden
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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