Ergebnisse von Interferenzfiltermessungen der Sonnenstrahlung von 350 bis 1000 nm

Zusammenfassung Es werden aktinometrische Messungen der Sonnenstrahlung mit Interferenzfiltern, die am Observatorium Freiburg i. Br. gewonnen wurden, einer kritischen Betrachtung unterzogen. Die Me?werteverifizieren an sich bekannte Tatsachen über das Verhalten der Sonnenstrahlung in ihren einzelnen Spektralbereichen gegenüber ?nderungen der Sonnenh?he, der atmosph?rischen Trübung und der H?henlage des Beobachtungsortes. Die leistungsf?higkeit und Empfindlichkeit der Me?methodik wird an Beispielen dargestellt. Für das anzustrebende Ziel, aus Interferenzfiltermessungen die ?ngstr?mschen Trübungsparameter für einzelne ann?hernd monochromatische Spektralgebiete zu gewinnen, erscheinen die technischen Voraussetzungen zwar noch nicht ausreichend, aber erreichbar.

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Summary The author presents a critical study of actinometric measurements of the solar radiation with interference filters, carried out at the Freiburg/Br. Observatory. The measured values verify well-known facts on the reaction of the solar radiation in its different spectral regionsto variations of the sun's elevation, the atmospheric turbidity and the altitude of the place of observation. The efficiency and the sensibility of the measuring method are discussed. The technical assumptions for the aim of obtaining the ?ngstr?m turbidity parameters for some nearly monochromatic spectral regions from measurements with interference filters seem to be, if not yet sufficient, though attainable.

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Résumé L'auteur discute la méthode de mesures actinométriques du rayonnement solaire au moyen de filtres à interférences exécutées à l'Observatoire de Fribourg en Br. Ces mesures confirment les faits connus concernant le comportement des radiations solaires des diverses parties spectrales en fonction de la hauteur du soleil, du trouble atmosphérique et de l'altitude du lieu d'observation. Exemples du rendement et de la sensibilité de la méthode. S'il s'agit de déterminer les paramètres de trouble de ?ngstr?m pour certaines régions spectrales à peu près monochromatiques au moyen de filtres à interférences, on constate que les exigences techniques ne sont pas encore satisfaites, mais qu'elles pourront le devenir.

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Herrn Dr.Anders K. ?ngstr?m zu seinem 70. Geburtstag gewidmet.     

Contribution de l'étude exoscopique des quartz à la reconstitution paléogéographique des derniers épisodes du Quaternaire littoral du Congo

The paleogeographic and particularly palaeoclimatic evolution in the Congo at the end of the Quaternary has been investigated thoroughly with a study of grain surfaces using the scanning electron microscope. The succession of distinct physicochemical environment marks is characterized with the help of other methods (radiocarbon, micropaleontology). During a still-existing tropical climate, arid periods are contemporaneous with regressive phases (eolian, fluviatile, or pedogenetic reliefs of the grains) and humid periods correspond to transgressive phases (infratidal, intertidal, deltaic, lagoonal marks).     

Isotope spectroscopy

The measurement of isotopic ratios provides a privileged insight both into nucleosynthesis and into the mechanisms operating in stellar envelopes, such as gravitational settling. In this article, we give a few examples of how isotopic ratios can be determined from high‐resolution, high‐quality stellar spectra. We consider examples of the lightest elements, H and He, for which the isotopic shifts are very large and easily measurable, and examples of heavier elements for which the determination of isotopic ratios is more difficult. The presence of ⁶Li in the stellar atmospheres causes a subtle extra depression in the red wing of the ⁷Li 670.7 nm doublet which can only be detected in spectra of the highest quality. But even with the best spectra, the derived ⁶Li abundance can only be as good as the synthetic spectra used for their interpretation. It is now known that 3D non‐LTE modelling of the lithium spectral line profiles is necessary to account properly for the intrinsic line asymmetry, which is produced by convective flows in the atmospheres of cool stars, and can mimic the presence of ⁶Li. We also discuss briefly the case of the carbon isotopic ratio in metal‐poor stars, and provide a new determination of the nickel isotopic ratios in the solar atmosphere. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Review of solutions for 3D hydrodynamic modeling applied to aquaculture in South Pacific atoll lagoons

A workshop organized in French Polynesia in November 2004 allowed reviewing the current methods to model the three-dimensional hydrodynamic circulation in semi-enclosed atoll lagoons for aquaculture applications. Mollusk (e.g. pearl oyster, clam) aquaculture is a major source of income for South Pacific countries such as French Polynesia or Cook Islands. This aquaculture now requires a better understanding of circulation patterns to improve the spatial use of the lagoons, especially to define the best area to set larvae collectors. The pelagic larval duration of the relevant species (<20 days) and the size of the semi-closed lagoons (few hundreds of km2) drive the specifications of the model in terms of the spatial and temporal scale. It is considered that, in contrast with fish, mollusk larvae movements are limited and that their cycle occurs completely in the lagoon, without an oceanic stage. Atolls where aquaculture is productive are generally well-bounded, or semi-closed, without significant large and deep openings to the ocean. Nevertheless part of the lagoon circulation is driven by oceanic water inputs through the rim, ocean swells, tides and winds. Therefore, boundary conditions of the lagoon system are defined by the spatial structure of a very shallow rim (exposition and number of hoas), the deep ocean swell climate, tides and wind regimes. To obtain a realistic 3D numerical model of lagoon circulation with adequate forcing, it is thus necessary to connect in an interdisciplinary way a variety of methods (models, remote sensing and in situ data collection) to accurately represent the different components of the lagoon system and its specific boundary conditions. We review here the current methods and tools used to address these different components for a hypothetical atoll of the Tuamotu Archipelago (French Polynesia), representative of the semi-closed lagoons of the South Pacific Ocean. We hope this paper will serve as a guide for similar studies elsewhere and we provide guidelines in terms of costs for all the different stages involved.     

The formation and evolution of a coastal alluvial fan in eastern Taiwan caused by rainfall-induced landslides

The formation and evolution of a coastal fan in eastern Taiwan associated with a sequence of rainfall-induced landslides during the 2009–2013 period are explored in this study. The evolution of these landslides is mainly attributed to the head-cutting process initiated by Typhoon Parma in October 2009. During the attack of Typhoon Megi in October, 2010, a subaerial coastal fan with a surface slope of 8.9° was formed after the mobilization of the rainfall-induced landslides. The geomorphic features both in the steep gully and on the coastal fan were categorized as the sequence of granular debris flows and sheet floods. Severe fan toe erosion occurred thereafter due to the wind-wave forcing. Even if the variations of both the cumulative rainfalls and the drainage areas are one or two orders of magnitude among devastating fan-forming landslides worldwide, the mean annual precipitation and the basin ruggedness index (Melton ratio) are effective indicators to normalize the rainfall threshold and to characterize the fan surface slope, respectively. Severe catastrophic landslides generally occur when the normalized cumulative rainfalls with respect to mean annual precipitation are greater than 0.1. The fan slope generally increases with the increasing Melton ratio for the catchment. Uchiogi’s empirical model is applicable for predicting the rainfall-induced area ratio of newly generated landslides. In this case study, the relationship of the fan area to the total landslide area follows a linear regressive curve when the ratio of landslide area with respect to the drainage area exceeds 0.0056.     

Application of sky view factor technique to the interpretation and reactivation assessment of landslide activity

High-resolution digital elevation models are crucial to the investigation of natural disasters, and a variety of methods based on visualization and relief map compilations have been proposed. In this study, the sky view factor (SVF) is applied to slope maps and a digital elevation model (DEM) of the Oso landslide, a deadly landslide that occurred in Washington State on March 22, 2014, to demonstrate the effectiveness of SVF-enhanced relief maps in mapping and evaluating large-scale or deep-seated landslide hazards. A procedure for combining the SVF-enhanced DEM with slope and elevation maps is also presented. Then the maps are used to extract the landslide-prone areas and perform a reactivation analysis of the post-Oso landslide using an analytic hierarchy process (AHP). By using the SVF-enhanced DEM to perform the AHP assessment on multi-period images, we accurately evaluate hazard of the landslide for both pre and post-2014 conditions. Finally, different visualization maps, limitation and recommend parameters for generating SVF relief map are presented in the paper.     

Spatial patterns of car sales and their socio-economic attributes in China

Using data from the Economic Advisory Center of the State Information Center (SIC), we examined the spatial patterns of car sales in China at the prefectural level in 2012. We first analyzed the spatial distributions of car sales of different kinds of automakers (foreign automakers, Sino-foreign joint automakers, and Chinese automakers), and then identified spatial clusters using the local Moran’s indexes. Location quotient analysis was applied to examine the relative advantage of each type of automaker in the local markets. To explain the variations of car sales across cities, we collected several socioeconomic variables and conducted regression analyses. Further, factor analysis was used to extract independent variables to avoid the problem of multicollinearity. By incorporating a spatial lag or spatial error in the models, we calibrated our spatial regression models to address the spatial dependence problem. The analytical results show that car sales varied significantly across cities in China, and most of the cities with higher car sales were the developed cities. Different automakers exhibit diverse spatial patterns in terms of car sales volume, spatial clusters, and location quotients. The scale and incomes factor were extracted and verified as the two most significant and positive factors that shape the spatial distributions of car sales, and together with the spatial effect, explained most of the variations of car sales across cities.     

Variability of Surface Air Temperature in Italy 1870–1980

Summary The trends and the fluctuations in variability of surface air temperature in Italy has been investigated by statistical analysis of historical data covering the recent 100 years. 27 stations were used for the analysis and these were distributed all over the Italian territory divided into two climatically homogeneous zones. The temperature trends are different in each climatic zone and season, while the interannual variability shows a similar seasonal dependence for the North and South of Italy. In particular, summer temperature shows a characteristic pattern with alternating minima and maxima reaching significant values in the period 1940–1970: a maximum for the North between 1940–1960 and a minimum for the South between 1960–1970. Received February 1, 1996 Revised June 7, 1997     

Climate Variability, Climate Change and Water Resource Management in the Great Lakes

Water managers always have had to cope with climate variability. All water management practices are, to some extent, a response to natural hydrologic variability. Climate change poses a different kind of problem. Adaptation to climate change in water resource management will involve using the kinds of practices and activities currently being used. However, it remains unclear whether or not practices and activities designed with historical climate variability will be able to cope with future variability caused by atmospheric warming. This paper examines the question of adaptation to climate change in the context of Canadian water resources management, emphasizing issues in the context of the Great Lakes, an important binational water resource.