Shock-capturing Boussinesq-type model for nearshore wave processes

This paper describes the formulation and validation of a nearshore wave model for tropical coastal environment. The governing Boussinesq-type equations include the conservative form of the nonlinear shallow-water equations for shock capturing. A Riemann solver supplies the inter-cell flux and bathymetry source term, while a Godunov-type scheme integrates the evolution variables in time. The model handles wave breaking through momentum conservation with energy dissipation based on an eddy viscosity concept. The computed results show very good agreement with laboratory data for wave propagation over a submerged bar, wave breaking and runup on plane beaches as well as wave transformation over fringing reefs. The model accurately describes transition between supercritical and subcritical flows as well as development of dispersive waves in the processes.     

Die Faziesentwicklung der Reichenhaller Schichten und die Tektonik im Süden des Achensees,Tirol

Zusammenfassung Im östlichsten Karwendel setzen sich die oberostalpinen, unteranisischen Reichenhaller Schichten aus einer mächtigen Folge mariner dolomitischer Kalke, sandiger Mergelkalke sowie sedimentärer Brekzien zusammen, die mehr oder weniger tektonisch überprägt sind.Die Brekzien treten in mehrfachem rhythmischem Wechsel zwischen Mergelkalken auf und erreichen erst im obersten Drittel der Schichtserie, die das gesamte Hydasp umfaßt, größere Mächtigkeiten. Ihr polymikter Komponentenbestand wird sowohl aus skythischen Gesteinen als auch aus Aufarbeitungsmaterial der besprochenen Serie gebildet. Ein rein tektonischer Charakter der Brekzien scheidet aus.Relativ rascher, z. T. periodischer Fazieswechsel deutet veränderliche paläogeographische Verhältnisse an.Der tektonische Bau erwies sich einfacher, als früher angenommen wurde.An die Hauptstörungszonen (Inntaleinheit über Lechtaleinheit) sind besondere tektonische Körper gebunden.

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In the extreme eastern Karwendel Range the subanisian Reichenhall Layers (Oberostalpin) are composed of an imposing sequence of initially marine dolomitic limes, sabulous marlaceous limes and sedimentary breccias more or less tectonically marked. The breccias appear in multiple rhythmic alternation between marlaceous limes. A purely tectonic character of the breccias is ruled out.

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Résumé Dans la partie la plus à l'est du Karwendel les couches anisiennes inférieures de Reichenhall (Oberostalpin) se composent d'une énorme masse d'abord de calcaires marins des Dolomites, puis de calcaires de marnes sablonneuses ainsi que de brèches sédimentaires qui sont plus ou moins structurées. Les brèches apparaissent par périodes régulières entre les calcaires de marne. Il est exclu que les brèches aient un caractère purement tectonique.

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Reichenhaller Achensee (). , , .

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Erweitertes Manuskript eines Vortrags, gehalten auf der 56. Jahrestagung der Geologischen Vereinigung in Wien am 26. Februar 1966.     

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

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.     

New remote sensing techniques for the detection and quantification of earth surface CO2 degassing

Earth degassing specifically of carbon dioxide CO₂ is of increasing interest with respect to the global carbon budget, related climate effects, earthquake and volcano eruption mechanisms, as well as plant physiological reactions in gas-rich environments. Investigations in all of these disciplines require the detection of surface CO₂ degassing structures and quantification of their emissions. We introduce minimal thermal change detection based on infrared imaging as a new remote sensing tool for the detection of earth surface thermal anomalies suiting among others to discover earth degassing locations of any origin. The method allows for seamless areal search and monitoring of degassing structures in any terrain. As proof of concept infrared imaging measurements were performed at the Bossoleto vent on the eastern master fault of the Siena Graben (Tuscany, Italy). It is known for the migration of a large amount of CO₂-rich gas from deep geothermal reservoirs. Field data acquired confirmed the qualification of the method. Detection of CO₂ degassing locations from infrared image time series worked reliably and optimal detection conditions were identified (dry, calm, cloudless weather between dusk and dawn). A simple model of heat exchange processes involved and observed was developed. In a first attempt this model was applied to determine the gas exit temperature, the area of gas thermal reach and the gas flux from recorded image series. It is the first method that allows remote areal survey of mofette fields and the associated CO₂ flux quantification sole from infrared image time series.     

The simulation of European heat waves from an ensemble of regional climate models within the EURO-CORDEX project

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.     

Uncertainty in an emissions-constrained world

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.     

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

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.     

Tracing element sources of hydrothermal mineral deposits: REE and Y distribution and Sr-Nd-Pb isotopes in fluorite from MVT deposits in the Pennine Orefield,England

Fluorite from Mississippi Valley Type (MVT) deposits in the South Pennine Orefield, England, displays significantly different distributions of rare earths and yttrium (REY) compared to fluorite from similar MVT deposits in the North Pennine Orefield. Samples from the South Pennine Orefield display negative Ce and positive Gd and Y anomalies but lack any Eu anomaly, indicating that the REY were mobilized from relatively pure marine sedimentary carbonates. In marked contrast, fluorite from the North Pennine Orefield lacks any Ce and Gd anomalies but shows a pronounced positive Eu anomaly, suggesting that the REY were provided by different source rock(s), that the mineralizing hydrothermal fluid had experienced higher temperatures prior to fluorite precipitation, and that it was derived from deeper crustal levels in the north compared to the south. The isotopic composition of Sr in Blue John fluorite from the South Pennine Orefield suggests that Sr was mobilized from Lower Carboniferous (Tournaisian) limestones, whereas Pb isotopes suggest that in contrast to REY and Sr, Pb was derived from aluminosilicate rocks. Neither Nd nor Sr or Pb isotopes can be used to radiometrically date the formation of Blue John fluorite. All isotope systems studied indicate that the limestone host rock of this fluorite mineralization did not contribute to the trace element budget of the hydrothermal fluid. Our results show that different solutes in a natural water (hydrothermal fluid, groundwater, etc.) may be derived from different sources, and that the study of a small set of elements or isotope ratios may not provide full insight into the genesis or history of a mineralization or a hydrothermal fluid. Our data provide evidence for the uncoupling of Sr, Nd and Pb during fluid-rock interaction and fluid migration, and show that the use of plots such as ⁸⁷Sr/⁸⁶Sr vs. _Nd. to learn about mixing relationships (as is commonly done in igneous geochemistry) is unreliable when applied to natural waters and their precipitates.Editorial handling: B. Lehmann