Ein neues Gerät für störungsfreie meteorologische Messungen auf dem Meer

Zusammenfassung Die Bedeutung ungestörter meteorologischer Beobachtungen auf offener See wird erörtert und die Anforderungen an den dafür notwendigen Instrumententräger werden fixiert. Die konstruktive Lösung wird geschildert: 2,5 m hoher Schwimmkörper, etwa elliptischer Querschnitt (Längsachse des Querschnitts in allen Höhen 1,5 m, Querachse an der Oberfläche 1 m, unten 0,5 m), mit (auf 7,5 m Tiefgang) ausfahrbarem Stabilisierungsgewicht von 500 kg, Leitflossen, Dämpfungsplatten und Handwinde zum Fieren des Gewichtes; 9 m langer Aluminiummast mit waagrechten Spieren zur Gerätehalterung. Eigenschwingungsperiode der Apparatur ist etwa 10 sec.Bei mehreren mehrwöchigen Einsätzen bis Windstärke 6 anläßlich von Messungen der Wind-, Temperatur- und Feuchteschichtung in der maritimen Grenzschicht der Atmosphäre zeigte das Gerät (auf der Deutschen Bucht und Ostsee) maximale Schwankungen des Mastes von 10° und Vertikalbewegungen von ±25 cm, es folgte dem Wellengang auch bei kurzen Wellen gut. Die Apparatur wird vom Forschungsschiff geschleppt, Messungen geschehen (über Kabel) im Treiben, wobei das Gerät sich (etwa 50 m entfernt) automatisch in Luv des Schiffes legt. Man erhält so ungestörte Messungen.Beispiele für die Windabhängigkeit der Driftgeschwindigkeit des Systems Forschungsschiff-Meßboje (relativ zur Wasseroberfläche) und für die Windgeschwindigkeitsunterschiede in derselben Höhe am Forschungsschiff und an der Tonne (als Beispiel für die Größe der Schiffsstörung) werden mitgeteilt. Ein charakteristisches Viertelstundenprofil von Windgeschwindigkeit, Lufttemperatur und Luftfeuchtigkeit zwischen 0,8 und 16 m Wasserabstand wird gezeigt.

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Summary The importance of undisturbed meteorological observations on the open sea is discussed and the requirements for an adequate instrument buoy are specified. The constructive solution is as follows: a floater 2,5 m high, approximately elliptical cross section (longer axis of the cross section at all heights 1,5m, transverse axis on the surface 1 m, below 0,5 m) with a stabilizing weight of 500 kg, movable (to 7,5 m draught), guiding fins, damping plates, and windlass for hoisting the weight; mast of aluminium 9 m long, with horizontal spars on which the instruments are fixed. Characteristic period of the apparatus about 10 sec.It was used (in the German Bay and in the Baltic Sea) at various times for several weeks up to wind-force 6 for measuring wind, temperature, and humidity distributions in the maritime boundary layer of the atmosphere and it showed maximum oscillations of the mast of 10 degrees and vertical movements of ±25 cm, following well the wave motion even with short waves. The instrument buoy is trailed by the research ship, measurements are carried out (by cable) in drifting while the buoy places itself automatically on the windward side of the ship (at a distance of about 50 m). In this way undisturbed measurements were obtained.Examples are communicated showing the influence of the wind on the drifting velocity of the system research ship — instrument buoy (relative to the water surface) and the difference of wind velocity at the same height at the ship and the buoy (from which the disturbing influence of the ship can be seen). A characteristic quarter-hour profile of wind velocity, air temperature, and air humidity between the levels 0,8 m and 16 m above water is given.

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Résumé Considérant l'importance de mesures météorologiques exemptes d'erreurs en haute mer, l'auteur a développé un support à instruments adéquat dont les caractéristiques sont les suivantes: flotteur de 2,5 m. de haut à section elliptique, muni d'une dérive escamotable de 500 kg. et de 7,5 m. de tirant d'eau; gouverhails, ailerons amortisseurs et treuil; mât d'aluminium de 9 m. muni de petites vergues à instruments. La période propre de l'engin est de 10 s. env.Lors d'essais dans la baie d'Helgoland et en mer Baltique par vent de force 6 en vue de mesures de vent, de température et d'humidité de la couche limite au-dessus de l'eau, le mât de l'engin a oscillé de 10 degrés et les déplacement verticaux furent de ±25 cm.; le flotteur suit la houle, même par vagues courtes. L'engin est remorqué par le bateau explorateur et les mesures se font en dérive; distant d'environ 50 m. de son remorqueur, le flotteur se place automatiquement au vent du bateau ce qui assure des mesures correctes.L'effet perturbateur du remorqueur ressort d'exemples illustrant comment la vitesse du système bateau-flotteur dépend du vent et montrant les différences de vitesse du vent au même niveau sur l'un et sur l'autre. Un profil caracteristique d'un quart d'heure de la vitesse du vent, de la température et de l'humidité de l'air entre 0,8 et 16 m. au-dessus de l'eau est montré.

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Mit 8 Textabbildungen     

Das Gondwana-Inlandeis in Südbrasilien

Zusammenfassung Entgegen den früheren Annahmen wird gezeigt, daß das südbrasilianische Gondwana-Inlandeis vom Süden (Riograndensischer Schild) stammt. Die mächtige, weder durch Glazialstauchungen noch durch glaziale oder interglaziale Erosion gestörte und unterbrochene Ablagerungsfolge, die damit ein vom europäischen Glazialdiluvium völlig abweichendes Verhalten zeigt, ist dadurch bedingt, daß das Eis in ein weiträumiges, fortschreitende epirogene Absenkung zeigendes Becken hineinfloß.Mit Unterstützung des Conselho Nacional d. Pesquisas, Rio de Janeiro.     

Exploring socio-hydrological determinants of crop yield in under-performing irrigation schemes: pathways for sustainable intensification

ABSTRACT

Understanding the human–water–food–climate nexus is central to achieving sustainable intensification (SI) in agriculture. This research uses a socio-hydrological approach to understand the underpinning for implementing SI in the Gezira Irrigation Scheme, Sudan, by integrating vegetation indices derived from remote sensing, ancillary, gridded soil and precipitation data, supplemented by interviews with 393 farmers. The productivity gap was estimated as the difference between the potential and actual productivities. Based upon data on farmers’ socio-economic status and field practices, a regression tree model was built to determine the factors that control the sorghum yield. The model revealed that the financial status of farmers and access to water are the most influential factors on sorghum yield. A conceptual framework that elucidates SI and its bi-directional feedback to the environment, society and the economy is proposed. Implementing SI in the scheme has implications on water and food security in Sudan and beyond its borders.     

Narrow-band photometry and the stellar populations in elliptical galaxies

The modified Strömgrenuvby filter system, which has been used to investigate the spectrophotometric evolution of elliptical galaxies, is also found to be a powerful tool for the determination of stellar parameters in elliptical galaxies, especially metal content and the stellar type of the dominant population. We present an introduction to the behaviour of the filter system based on comparison to stellar libraries and then explore the results with respect to composite systems: globular clusters, spirals, and ellipticals.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Platform-induced clay-mineral fractionation along a northern Tethyan basin-platform transect: implications for the interpretation of Early Cretaceous climate change (Late Hauterivian-Early Aptian)

High-resolution clay-mineral analyses were performed on upper Hauterivian to lower Aptian sediments along a platform-to-basin transect through the northern Tethyan margin from the Neuchâtel area (Switzerland), to the Vocontian Trough (France) in order to investigate links between climate change, carbonate platform evolution, and fractionation patterns in clay minerals during their transport.During the Hauterivian, the northern Tethyan carbonate platform developed in a heterozoan mode, and the associated ramp-like topography facilitated the export of detrital material into the adjacent basin, where clay-mineral assemblages are dominated by smectite and kaolinite is almost absent, thereby suggesting dry-seasonal conditions. During the Late Hauterivian Balearites balearis ammonite zone, a change to a more humid climate is documented by the appearance of kaolinite, which reaches up to 30% of the clay fraction in sediments in the Vocontian Trough. This prominent change just preceded the Faraoni Oceanic Anoxic Event and the onset of the demise of the Helvetic Carbonate Platform, which lasted to the late early Barremian.From the Late Barremian onwards, the renewed growth of the northern Tethyan carbonate platform in a photozoan mode and the associated development of a marginally confined platform topography fractionated the clay-mineral assemblages exported into hemipelagic settings: kaolinite particles were preferentially retained in proximal, platform settings, due to their size and their relatively high specific weight. In the inner platform environment preserved in the Swiss Jura, an average of 32% of kaolinite in the clay fraction is observed during the latest Barremian–earliest Aptian, whereas clay-mineral assemblages of coeval sediments from deeper depositional settings are dominated by smectite and show only minor amounts of kaolinite.This signifies that besides palaeoclimate conditions, the morphology and ecology of the carbonate platform had a significant effect on the distribution and composition of clay assemblages during the Late Hauterivian–Early Aptian along the northern Tethyan margin.