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High resolution wind field modelling over complex topography : analysis and future scenarios
No full textDas Ziel der vorliegenden Arbeit ist die Untersuchung einer kombinierten dynamischen-diagnostischen downscaling Methode für bodennahen Wind (basierend auf dem dynamischen Modell MM5 und dem diagnostischen Modell CALMET), welche es ermöglicht Windklimatologien in komplexer Topographie auf der 100 m Skala zu erstellen. Ein zweites Ziel ist die Durchführung von Klimasimulationen zur Identifikation klimatologischer Prozesse, die das Langzeitverhalten von mittleren Windverhältnissen in den Europäischen Alpen und dem Wiener Becken bei steigenden Treibhausgaskonzentrationen bestimmen. Böen und Extremereignisse werden nicht betrachtet.Mehrere Varianten der Methode (angetrieben vom Re-Analysedatensatz ERA-40) wurden in den Hohen Tauern und dem Wiener Becken eingesetzt. Vergleiche zu Beobachtungsdaten zeigen, dass die Konzepte der Stationären Strömung und der Strömungsüberhöhung die dominantesten Klimamechanismen sind. Die Qualität der Windklimatologien wird hauptsächlich von der Fähigkeit, synoptische und regionale Prozesse abzubilden, beeinflusst. Im Wiener Becken hat die Stationäre Strömung mehr Validität und führt zu einer verstärkten systematischen Überschätzung der Windgeschwindigkeiten (Bias zw. 0,9 m/s und 2,1 m/s).Die Methode wurde erfolgreich auf eine Klimasimulation des Modells ECHAM5 (Perioden 1981 bis 1990 und 2041 bis 2050, IPCC Szenario IS92a) angewandt. Die Klimaänderungssignale zeigen rückläufige Jahreswindgeschwindigkeiten (bis zu -20,8 %, das sind -1,2 m/s, in den Alpen) und es kann gefolgert werden, dass a) Änderungen der synoptischen und regionalen Prozesse gradientenbedingte Strömungen beeinflussen, insbesondere im Winter, b) die Strömungsüberhöhung Änderungen der Geschwindigkeiten im Gebirge verstärkt und c) Wechselwirkungen zw. Atmosphäre und Erdoberfläche zu regional unterschiedlichen Effekten führen. Unabhängig von der Wahl der Modelle werden saisonale Windgeschwindigkeiten im Frühling und Sommer in den Alpen zurückgehen.The present thesis focuses on investigating and improving a hybrid dynamic-diagnostic downscaling method for near surface wind (based on the dynamic PSU/NCAR model MM5 and the diagnostic California Meteorological model CALMET), which enables to provide wind climatologies over complex topography on the 100 m scale. A second objective is to conduct climate simulations and to identify climatological main processes affecting the long-term behaviour of averaged near surface wind conditions in the European Alpine region and the Vienna Basin under increasing greenhouse-gas concentrations. Questions of wind gusts and extremes are not considered.Several variants of the method were applied (driven by the reanalysis dataset ERA-40) in two study regions, the Hohe Tauern region and the Vienna Basin. Comparisons to observations show that the steady-state flow concept and the orographic speed-up effect are the most dominant climatological mechanisms. The quality of the modelled climatologies is mostly affected by the ability to capture synoptic- and regional-scale processes. In the Vienna Basin the steady-state flow concept is more valid and leads to an enhanced systematic overestimation of wind speed (biases from 0.9 m/s to 2.1 m/s).The method has been successfully applied to the output of the climate model ECHAM5 (periods 1981 to 1990 and 2041 to 2050, IPCC scenario IS92a). The climate change signals show decreasing annual wind speeds (up to -20.8 %, i.e., -1.2 m/s, in the inner Alps) and it can be concluded that a) changes of synoptic- and large-scale processes are affecting gradient-forced synoptic- and regional-scale air flows, particularly during DJF, b) the speed-up effect amplifies changes of wind speeds in mountainous areas, and c) interactions between the atmosphere and the earth's surface lead to regionally varying climate change effects. There exists strong evidence for a robust model-independent reduction of wind speed during MAM and JJA in the inner Alps.vorgelegt von Heimo TruhetzZsfassung in dt. SpracheGraz, Univ., Diss., 201
Effects of a shallow convection scheme in perennial convection permitting CORDEX-FPS WRF simulations
No full textHigh resolution wind field modelling over complex topography : analysis and future scenarios
No full textDas Ziel der vorliegenden Arbeit ist die Untersuchung einer kombinierten dynamischen-diagnostischen downscaling Methode für bodennahen Wind (basierend auf dem dynamischen Modell MM5 und dem diagnostischen Modell CALMET), welche es ermöglicht Windklimatologien in komplexer Topographie auf der 100 m Skala zu erstellen. Ein zweites Ziel ist die Durchführung von Klimasimulationen zur Identifikation klimatologischer Prozesse, die das Langzeitverhalten von mittleren Windverhältnissen in den Europäischen Alpen und dem Wiener Becken bei steigenden Treibhausgaskonzentrationen bestimmen. Böen und Extremereignisse werden nicht betrachtet.Mehrere Varianten der Methode (angetrieben vom Re-Analysedatensatz ERA-40) wurden in den Hohen Tauern und dem Wiener Becken eingesetzt. Vergleiche zu Beobachtungsdaten zeigen, dass die Konzepte der Stationären Strömung und der Strömungsüberhöhung die dominantesten Klimamechanismen sind. Die Qualität der Windklimatologien wird hauptsächlich von der Fähigkeit, synoptische und regionale Prozesse abzubilden, beeinflusst. Im Wiener Becken hat die Stationäre Strömung mehr Validität und führt zu einer verstärkten systematischen Überschätzung der Windgeschwindigkeiten (Bias zw. 0,9 m/s und 2,1 m/s).Die Methode wurde erfolgreich auf eine Klimasimulation des Modells ECHAM5 (Perioden 1981 bis 1990 und 2041 bis 2050, IPCC Szenario IS92a) angewandt. Die Klimaänderungssignale zeigen rückläufige Jahreswindgeschwindigkeiten (bis zu -20,8 %, das sind -1,2 m/s, in den Alpen) und es kann gefolgert werden, dass a) Änderungen der synoptischen und regionalen Prozesse gradientenbedingte Strömungen beeinflussen, insbesondere im Winter, b) die Strömungsüberhöhung Änderungen der Geschwindigkeiten im Gebirge verstärkt und c) Wechselwirkungen zw. Atmosphäre und Erdoberfläche zu regional unterschiedlichen Effekten führen. Unabhängig von der Wahl der Modelle werden saisonale Windgeschwindigkeiten im Frühling und Sommer in den Alpen zurückgehen.The present thesis focuses on investigating and improving a hybrid dynamic-diagnostic downscaling method for near surface wind (based on the dynamic PSU/NCAR model MM5 and the diagnostic California Meteorological model CALMET), which enables to provide wind climatologies over complex topography on the 100 m scale. A second objective is to conduct climate simulations and to identify climatological main processes affecting the long-term behaviour of averaged near surface wind conditions in the European Alpine region and the Vienna Basin under increasing greenhouse-gas concentrations. Questions of wind gusts and extremes are not considered.Several variants of the method were applied (driven by the reanalysis dataset ERA-40) in two study regions, the Hohe Tauern region and the Vienna Basin. Comparisons to observations show that the steady-state flow concept and the orographic speed-up effect are the most dominant climatological mechanisms. The quality of the modelled climatologies is mostly affected by the ability to capture synoptic- and regional-scale processes. In the Vienna Basin the steady-state flow concept is more valid and leads to an enhanced systematic overestimation of wind speed (biases from 0.9 m/s to 2.1 m/s).The method has been successfully applied to the output of the climate model ECHAM5 (periods 1981 to 1990 and 2041 to 2050, IPCC scenario IS92a). The climate change signals show decreasing annual wind speeds (up to -20.8 %, i.e., -1.2 m/s, in the inner Alps) and it can be concluded that a) changes of synoptic- and large-scale processes are affecting gradient-forced synoptic- and regional-scale air flows, particularly during DJF, b) the speed-up effect amplifies changes of wind speeds in mountainous areas, and c) interactions between the atmosphere and the earth's surface lead to regionally varying climate change effects. There exists strong evidence for a robust model-independent reduction of wind speed during MAM and JJA in the inner Alps.vorgelegt von Heimo TruhetzZsfassung in dt. SpracheGraz, Univ., Diss., 201
Precipitation in a regional climate simulation ensemble at km-scale — Initial results from a CORDEX Flagship Pilot Study
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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
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