Dynamics of medium-intensity dense water plumes in the Arkona Basin, Western Baltic Sea     

Hans Burchard  Hans Ulrich Lass  Volker Mohrholz  Lars Umlauf  Jürgen Sellschopp  Volker Fiekas  Karsten Bolding  Lars Arneborg 《Ocean Dynamics》2005,55(5-6):391-402

In this study, the dynamics of medium-intensity inflow events over Drogden Sill into the Arkona Sea are investigated. Idealised model simulations carried out with the General Estuarine Transport Model suggest that most of the salt transport during such inflow events occur north of Kriegers Flak, a shoal with less than 20 m water depth surrounded by water depths of more than 40 m. This assumption about the pathway is supported by recent ship-based observations in the Arkona Sea during a medium-intensity inflow event. The propagation of a saline bottom plume could be observed during several days after having passed Drogden Sill. In the area north of Kriegers Flak the plume was about 10 m thick, and propagated with more than 0.5 m s⁻¹ and a salinity of up to 20 psu (with ambient water salinity being 8 psu) eastwards. Although the model simulations were idealised, the structural agreement between the observation and model result was good. The structure and pathways of these medium-intensity inflow events are of specific interest due to the plans for erecting extensive offshore wind farms in the Arkona Sea which may under certain circumstances lead to increased entrainment of ambient water into the bottom plumes.  相似文献   

Effect of different tropospheric mapping functions on the TRF, CRF and position time-series estimated from VLBI     

Volker Tesmer  Johannes Boehm  Robert Heinkelmann  Harald Schuh 《Journal of Geodesy》2007,81(6-8):409-421

This paper compares estimated terrestrial reference frames (TRF) and celestial reference frames (CRF) as well as position time-series in terms of systematic differences, scale, annual signals and station position repeatabilities using four different tropospheric mapping functions (MF): The NMF (Niell Mapping Function) and the recently developed GMF (Global Mapping Function) consist of easy-to-handle stand-alone formulae, whereas the IMF (Isobaric Mapping Function) and the VMF1 (Vienna Mapping Function 1) are determined from numerical weather models. All computations were performed at the Deutsches Geodätisches Forschungsinstitut (DGFI) using the OCCAM 6.1 and DOGS-CS software packages for Very Long Baseline Interferometry (VLBI) data from 1984 until 2005. While it turned out that CRF estimates only slightly depend on the MF used, showing small systematic effects up to 0.025 mas, some station heights of the computed TRF change by up to 13 mm. The best agreement was achieved for the VMF1 and GMF results concerning the TRFs, and for the VMF1 and IMF results concerning scale variations and position time-series. The amplitudes of the annual periodical signals in the time-series of estimated heights differ by up to 5 mm. The best precision in terms of station height repeatability is found for the VMF1, which is 5–7% better than for the other MFs.  相似文献   

Comparisons of homogeneously reprocessed GPS and VLBI long time-series of troposphere zenith delays and gradients     

Peter Steigenberger  Volker Tesmer  Manuela Krügel  Daniela Thaller  Ralf Schmid  Sibylle Vey  Markus Rothacher 《Journal of Geodesy》2007,81(6-8):503-514

Troposphere parameters estimated from space-geodetic techniques, like the Global Positioning System (GPS) or Very Long Baseline Interferometry (VLBI), can be used to monitor the atmospheric water vapor content. Although the troposphere can only be monitored at discrete locations, the distribution of the instruments, at least the GPS antennas, can be assumed to be quasi-global. Critical in the data analysis are systematic effects within each single technique that significantly degrade the accuracy and especially the long-term stability of the zenith delay determination. In this paper, consistent time-series of troposphere zenith delays and gradients from homogeneously reprocessed GPS and VLBI solutions are compared for a time period of 11 years. The homogeneity of these completely reprocessed time-series is essential to avoid misinterpretations due to individual model changes. Co-located sites are used to investigate systematic effects and the long-term behavior of the two space-geodetic techniques. Both techniques show common signals in the troposphere parameters at a very high level of precision. The biases between the troposphere zenith delays are at the level of a few millimeters. On the other hand, long-term trends significantly differ for the two techniques, preventing climatological interpretations at present. Tests assume these differences to be due to mathematical artifacts such as different sampling rates and unmodeled semi-annual signals with varying amplitudes.  相似文献   

Organic Geochemical Microanalysis by Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS)     

Peter Sjövall  Volker Thiel  Sandra Siljeström  Christine Heim  Tomas Hode  Jukka Lausmaa 《Geostandards and Geoanalytical Research》2008,32(3):267-277

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) is a powerful method for the chemical analysis of solid surfaces. In this paper, the capabilities and limitations of this technique and the potential for its use in geochemical research are outlined. Using ToF‐SIMS, the chemical composition of sample structures down to 10–100 μm can be determined, without the need for pre‐selection or labelling of the analysed substances. In addition, the lateral distribution of organic and inorganic compounds can be mapped in geochemical samples at a resolution in the micrometre range. The capabilities of the technique in geochemistry are illustrated by two examples. In the first example, it is shown that ToF‐SIMS can be used to detect biomarkers in oil samples, making it a promising method for the analysis of biomarkers in fluid inclusions. In the second example, a number of specific lipid biomarkers were identified and mapped on the surface of a microbial mat cryosection surface. Post‐measurement optical microscopy correlated the localisation of the lipids with the presence of methanotrophic archaea in the microbial mat.  相似文献   

Nickel und Kobalt in Gesteinen des Nördlinger Ries     

Volker Stähle 《Contributions to Mineralogy and Petrology》1970,28(1):72-88

Zusammenfassung Von Glasbomben aus dem Suevit und kristallinen Gesteinen verschiedener Auswurfbreccien des Rieskraters wurden die Nickel- und Kobaltgehalte bestimmt. Die Gläser enthalten 10,0–51,5 ppm Ni (Mittel von 70 Analysen: 30,1 ppmNi) und 4,8–15,8 ppm Co (Mittel von 50 Analysen: 12,1 ppm Co). Die höchsten Nickel- und Kobaltgehalte finden sich in den nicht rekristallisierten und chemisch unveränderten Bomben des Typ I. Die kristallinen Gesteine des Grundgebirges enthalten 2,5–140 ppm Ni (22 Analysen) und 2,2–29,8 ppm Co (22 Analysen).Die Kobaltgehalte der nicht rekristallisierten Gläser sind ziemlich einheitlich (10,7–15,8 ppm) und ebenso hoch wie diejenigen der kristallinen Gesteine ähnlicher Gehalte an MgO, MgO+FeO+Fe₂O₃ und SiO₂. Die Nickelgehalte der nicht rekristallisierten Gläser dagegen streuen inhomogen über einen größeren Bereich (30,0–51,5 ppm). Sie sind im Mittel höher als die der kristallinen Gesteine mit ähnlichen Gehalten an MgO, MgO+FeO+Fe₂O₃ und SiO₂. Der maximale Unterschied beträgt 25 ppm Ni.

---

Ni and Co in rocks from the Nördlinger Ries

Ni and Co have been determined in glass bombs from the suevite and crystalline rocks from different breccia outcrops in the Ries crater. The glasses contain 10.0–51.5 ppm Ni (average of 70 analyses: 30.1 ppm Ni) and 4.8–15.8 ppm Co (average of 50 analyses: 12.1 ppm Co). Highest contents of Ni and Co are to be found in non-recrystallized and chemically unchanged bombs of type I. Crystalline rocks from the basement contain 2.5–140 ppm Ni (22 analyses) and 2.2–29.8 ppm Co (22 analyses).The Co-contents of non-recrystallized glasses are rather uniform (10.7–15.8 ppm) and as high as those of crystalline rocks of similar content of MgO, MgO+FeO+Fe₂O₃ and SiO₂. The Ni-contents of non-recrystallized glasses are inhomogeneously scattered over a larger range (30.0–51.5 ppm). On the average, they are higher than those of crystalline rocks with similar contents of MgO, MgO+FeO+Fe₂O₃ and SiO₂. The maximum difference is 25 ppm Ni.

---

---

Herr Prof. W. von Engelhardt veranlaßte die Bearbeitung dieses interessanten Themas und nahm am Fortgang der Untersuchungen regen Anteil. Herr Dr. D. Stöffler stellte freundlicherweise Probenmaterial zur Verfügung und Herr Dr. H. Puchelt war mir bei analytischen Fragen behilflich. Ihnen allen danke ich für die Förderung dieser Arbeit.  相似文献   

Zur paläogeographischen Rekonstruktion erdgeschichtlicher Ozeane     

Dipl.-Geol. Volker Maack 《International Journal of Earth Sciences》1981,70(1):78-90

Zusammenfassung Für Simulationsrechnungen der Gezeiten erdgeschichtlicher Ozeane werden hinreichend detaillierte paläogeographische Karten vorgestellt, die global die ungefähre Lage der ozeanischen und kontinentalen Bereiche sowie paläobathymetrische Informationen wiedergeben.Ausgehend von vorhandenen paläokontinentalen Karten, die auf den modernen Konzepten der Plattentektonik und des sea-floor spreading basieren, sind für einige erdgeschichtliche Stadien die einstige Verteilung von Land, Flachmeer und Tiefsee dargestellt. Mittels zusammengefaßter Ergebnisse paläobiogeographischer, geotektonischer, geophysikalischer, sedimentologischer und palökologischer Untersuchungen sind paläogeographische Rekonstruktionen für ein pleistozänes Hochglazial (Saale-Eiszeit), für die Obere Kreide (Ober-Campan), für das Obere Perm (Zechstein) sowie für das Mittlere Silur (Wenlock) abgebildet.Die Problematik bei der Rekonstruktion von Paläozeanen sowie die Interpretation und Kompilation paläogeographischer Daten wird diskutiert.

---

For modeling the paleotides of ancient oceans you need quiet detailed paleogeographical maps projecting the global distribution of oceanic and continental areas as well as some paleobathymetrical informations. Using available paleocontinental maps which are based upon the modern concepts of the plate tectonics and sea-floor spreading, ancient distributions of land, shallow and deep sea are presented for some geological stages. By means of compiling the results of paleobiogeographical, geotectonical, geophysical, sedimentological, and paleoecological investigations paleogeographical reconstructions are shown for a Pleistocene ice-age (Saale stage), the Upper Cretaceous (Upper Campanian), the Upper Permian (Zechstein), and for the Middle Silurian (Wenlockian).Problems of paleoceanical reconstructions as well as the interpretation and compilation of paleogeographical data are discussed.

---

Résumé Des cartes paléogéographiques à point détaillées sont présentées pour le calcul des marées des anciens océans; elles reproduisent globalement la situation approximative des domaines océaniques et continentaux, et donnent aussi des informations paléobathymétriques.Partant de cartes paléocontinentales existantes basées sur les concepts modernes de tectonique de plaques et d'expansion des océans, on a figuré pour quelques périodes géologiques la répartition ancienne des terres, des mers intérieures et des mers profondes. Utilisant les données condensees provenant des recherches paléobiogéographiques, géotectoniques, géophysigues, sédimentologiques et paléoécologiques, on a effectué les reconstructions paléogéographiques relatives à un Pleistocene glaciaire ancien (stade de la Saale), au Crétacique supérieur (Campanien supérieur), au Permien supérieur (Zechstein), ainsi qu au Silurien moyen (Wenlockien).Le problème concernant la reconstruction des paléoocéans ainsi que les interprétations et compilations des données paléogéographiques sont discutés.

---

- , , . , , , . , , , ( ), ( ), () ( ). , , .

  相似文献   

Uncertainty in an emissions-constrained world     

Matthias Jonas  Gregg Marland  Volker Krey  Fabian Wagner  Zbigniew Nahorski 《Climatic change》2014,124(3):459-476

Our study focuses on uncertainty in greenhouse gas (GHG) emissions from anthropogenic sources, including land use and land-use change activities. We aim to understand the relevance of diagnostic (retrospective) and prognostic (prospective) uncertainty in an emissions-temperature setting that seeks to constrain global warming and to link uncertainty consistently across temporal scales. We discuss diagnostic and prognostic uncertainty in a systems setting that allows any country to understand its national and near-term mitigation and adaptation efforts in a globally consistent and long-term context. Cumulative emissions are not only constrained and globally binding but exhibit quantitative uncertainty; and whether or not compliance with an agreed temperature target will be achieved is also uncertain. To facilitate discussions, we focus on two countries, the USA and China. While our study addresses whether or not future increase in global temperature can be kept below 2, 3, or 4 °C targets, its primary aim is to use those targets to demonstrate the relevance of both diagnostic and prognostic uncertainty. We show how to combine diagnostic and prognostic uncertainty to take more educated (precautionary) decisions for reducing emissions toward an agreed temperature target; and how to perceive combined diagnostic and prognostic uncertainty-related risk. Diagnostic uncertainty is the uncertainty contained in inventoried emission estimates and relates to the risk that true GHG emissions are greater than inventoried emission estimates reported in a specified year; prognostic uncertainty refers to cumulative emissions between a start year and a future target year, and relates to the risk that an agreed temperature target is exceeded.  相似文献   

The simulation of European heat waves from an ensemble of regional climate models within the EURO-CORDEX project   总被引：4，自引：1，他引：3  

Robert Vautard  Andreas Gobiet  Daniela Jacob  Michal Belda  Augustin Colette  Michel Déqué  Jesús Fernández  Markel García-Díez  Klaus Goergen  Ivan Güttler  Tomáš Halenka  Theodore Karacostas  Eleni Katragkou  Klaus Keuler  Sven Kotlarski  Stephanie Mayer  Erik van Meijgaard  Grigory Nikulin  Mirta Patarčić  John Scinocca  Stefan Sobolowski  Martin Suklitsch  Claas Teichmann  Kirsten Warrach-Sagi  Volker Wulfmeyer  Pascal Yiou 《Climate Dynamics》2013,41(9-10):2555-2575

The ability of a large ensemble of regional climate models to accurately simulate heat waves at the regional scale of Europe was evaluated. Within the EURO-CORDEX project, several state-of-the art models, including non-hydrostatic meso-scale models, were run for an extended time period (20 years) at high resolution (12 km), over a large domain allowing for the first time the simultaneous representation of atmospheric phenomena over a large range of spatial scales. Eight models were run in this configuration, and thirteen models were run at a classical resolution of 50 km. The models were driven with the same boundary conditions, the ERA-Interim re-analysis, and except for one simulation, no observations were assimilated in the inner domain. Results, which are compared with daily temperature and precipitation observations (ECA&D and E-OBS data sets) show that, even forced by the same re-analysis, the ensemble exhibits a large spread. A preliminary analysis of the sources of spread, using in particular simulations of the same model with different parameterizations, shows that the simulation of hot temperature is primarily sensitive to the convection and the microphysics schemes, which affect incoming energy and the Bowen ratio. Further, most models exhibit an overestimation of summertime temperature extremes in Mediterranean regions and an underestimation over Scandinavia. Even after bias removal, the simulated heat wave events were found to be too persistent, but a higher resolution reduced this deficiency. The amplitude of events as well as the variability beyond the 90th percentile threshold were found to be too strong in almost all simulations and increasing resolution did not generally improve this deficiency. Resolution increase was also shown to induce large-scale 90th percentile warming or cooling for some models, with beneficial or detrimental effects on the overall biases. Even though full causality cannot be established on the basis of this evaluation work, the drivers of such regional differences were shown to be linked to changes in precipitation due to resolution changes, affecting the energy partitioning. Finally, the inter-annual sequence of hot summers over central/southern Europe was found to be fairly well simulated in most experiments despite an overestimation of the number of hot days and of the variability. The accurate simulation of inter-annual variability for a few models is independent of the model bias. This indicates that internal variability of high summer temperatures should not play a major role in controlling inter-annual variability. Despite some improvements, especially along coastlines, the analyses conducted here did not allow us to generally conclude that a higher resolution is clearly beneficial for a correct representation of heat waves by regional climate models. Even though local-scale feedbacks should be better represented at high resolution, combinations of parameterizations have to be improved or adapted accordingly.  相似文献   

Nephelines from the Somma-Vesuvius volcanic complex (Southern Italy): crystal-chemical,structural and genetic investigations     

Giuseppina Balassone  Volker Kahlenberg  Angela Altomare  Angela Mormone  Rosanna Rizzi  Michele Saviano  Nicola Mondillo 《Mineralogy and Petrology》2014,108(1):71-90

Sixteen nephelines from different geological occurrences were sampled at the type-locality, the Somma-Vesuvius volcanic complex (southern Italy), and investigated for their chemistry and crystal structure obtained by both single-crystal and powder X-ray diffraction. Nepheline-bearing samples are metamorphic or from magmatic ejecta and pumice deposits. The lower K contents characterize the pumice- and some metamorphic-derived nephelines, whereas the higher ones are found in some samples from magmatic nodules. The amount of the anorthite molecule, quite low on average, can be more variable in the metamorphic nephelines. The crystal-structure investigations on Somma-Vesuvius samples compare well with previous studies of natural nephelines. All 16 nepheline samples adopt space group P6₃. The observed lattice parameters vary between 9.9768–9.9946 Å (for a) and 8.3614–8.3777 Å (for c), respectively. Furthermore, chemical analysis revealed that all specimens exhibit an excess of Si relative the ideal Si:Al ratio of 1:1. The analysis of the T-O distances in our samples clearly indicates a distinct ordering process of aluminium and silicon on the tetrahedral sites which is an agreement with Loewenstein’s rule. A linear correlation between the distance of symmetry equivalent split atoms O(1)-O(1)’ and the T(1)-O(1)-T(2) tilt angle was observed. The average <B-O> (B = Na) distances of all crystals are very similar which is consistent with the outcome of the site population refinement indicating full occupancy with sodium. Oriented precession-type sections of reciprocal space indicated the presence of at least the most intense family of satellite peaks, demonstrating that this group of satellite reflections can occur not only in nephelines from pegmatites and ijolites but also in rocks from completely different petrological settings.  相似文献   

Maurice M. Shapiro,Rein Silberberg,John P. Wefel (Eds.): Particle Astrophysics and Cosmology; Nato AS1 Series C: Mathematical and Physical Sciences - Vol. 394, Kluwer Academic Publishers 1993, VII+168 Seiten (Preis: 79.00 $) ISBN 0-7923-2235-5     

Volker Müller 《Astronomische Nachrichten》1996,317(5):367-368

  相似文献