1,721,073 research outputs found
Charakterisierung von Quellen und Transport von Saharastaub durch Fernerkundung und regionale Modellierung
Full text linkThe PhD-thesis aims to characterise the Saharan dust cycle at diffent seasons using satellite remote sensing techniques and regional modelling studies. A dust index based on 15-minute infrared satellite measurements provided by the SEVIRI instrument onboard the Meteosat Second Generation (MSG) satellite is used to infer spatio-temporal charcteristics of dust sources north of 5°N over Africa since March 2006. The spatial distribution of dust sources points towards the importance of endorehic drainage systems in mountain areas. The temporal distribution of the time-of-day when dust mobilisation starts shows maximum activity during local morning hours, pointing towards the role of the breakdown of the nocturnal low-level jet. Details of the role and ability of the low-level jet breakdown for dust entrainment were studied using regional modelling. Furthermore, the seasonal dust export towards the tropical North Atlantic is considered using regional modelling.Die Arbeit beschäftigt sich mit der Charakterisierung des atmosphärischen Kreislaufs von nordafrikanischen Wüstenstaub. Dazu wurde Satellitendaten auf einer zeitlichen Auflösung von 15 Minuten hinsichtlich der Aktivierung von Staubquellen nördlich von 5°N über Afrika ausgewertet. Der Auswertezeitraum beginnt im März 2006. Der erstellte Datensatz wurde hinsichtlich der raum-zeitlichen Verteilung aktiver Staubquellen untersucht. Die räumlich Verteilung der Staubquellen zeigt die Bedeutung von Trockentälern im Zuge der Staubmobilisierung auf. Die zeitliche Verteilung einsetzender Staubmobilisierung zeigt ein Maximum während der lokalen Morgenstunden. Mit Hilfe von regionaler Modellierung wurden diese Ereignisse im Zusammenhang mit dem Heruntermischen des nächtlichen Grenzschichtstrahlstroms untersucht. Im Weiteren wurde der saisonale Staubexport Richtung tropischen Atlantik mit untersucht
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
On the importance of Mongolian cyclones to East Asian dust storms
No full textIn East Asia, dust storms typically occur in spring with adverse impacts on socio-economic activities, loss of life, and climate. Mongolian cyclones that form downstream of the Altai-Sayan Mountain have been known for some time as drivers of spring dust storms in East Asia. The passage of Mongolian cyclones primarily induces dust-emitting winds in the Gobi Desert, leading to dust emissions and favoring the subsequent transport of dust aerosols across Northern China. Herein, the relative contributions of Mongolian cyclones to dust emissions in the Gobi Desert and subsequent dust storm activity in Northern China are assessed from a climatological perspective for the first time in this dissertation. Furthermore, this study provides the first evidence that dust activity in the Taklamakan Desert, which is located in the west of the Gobi Desert, is also supported by Mongolian cyclones. This assessment aims to illustrate the importance of Mongolian cyclones in generating spring dust storms across East Asia
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
Regional aerosol modeling in Europe: Evaluation with focus on vertical profiles and radiative effects
Full text linkIn this thesis the occurrence and the properties of atmospheric particles within Europe are studied by means of the regional transport model COSMO-MUSCAT (Consortium for Small-scale Modeling - MultiScale Atmospheric Transport Model). The model is used to perform calculations for a summer (19-26 July 2006) and a winter (16-26 February 2007) period.
Individual extinction coefficients are computed taking into account hygroscopic growth and mass extinction efficiencies of specific chemical compounds. The model study focuses on vertical backscatter profiles, aerosol optical depths, particle surface concentrations and radiative effects.
Different descriptions of the vertical distribution of chemical compounds at the lateral model boundaries are tested. The results show that for the tested model setup the influence of the aerosol distribution at the model boundaries on European aerosol is limited. Information from lidar profiles may improve the description at the lateral model boundaries. This may be more important for smaller model domains.
Space-based lidar (light detection and ranging) observations (CALIOP - Cloud-Aerosol Lidar with Orthogonal Polarization) observations are compared to the simulated backscatter profiles caused by the simulated anthropogenic aerosol. The model reproduces the shape and magnitude of the vertical backscatter profiles well for both time periods. Better agreements are found for night-time observations compared to day-time data. Satisfying agreements between the model results and experimental observations of ground-based vertical backscatter profiles, aerosol optical depths and particle surface concentrations are also found for the two time periods in Europe. Discrepancies between measurement and simulation highlight the difficulties to describe horizontal and vertical aerosol properties properly.
The direct and semi-direct radiative effects of the absorbing aerosol are studied for both summer and winter period. For both periods, an increase of the solar heating rate due to the aerosol forcing is determined. This heating leads to an average decrease of the total cloud cover of 1.0% (summer) and of 0.7% (winter). This semi-direct radiative effect causes a positive forcing at the surface and at the top-of-atmosphere in the European domain
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