Erratum to: The year-long unprecedented European heat and drought of 1540 – a worst case     

Oliver Wetter  Christian Pfister  Johannes P. Werner  Eduardo Zorita  Sebastian Wagner  Sonia I. Seneviratne  Jürgen Herget  Uwe Grünewald  Jürg Luterbacher  Maria-Joao Alcoforado  Mariano Barriendos  Ursula Bieber  Rudolf Brázdil  Karl H. Burmeister  Chantal Camenisch  Antonio Contino  Petr Dobrovolný  Rüdiger Glaser  Iso Himmelsbach  Andrea Kiss  Oldřich Kotyza  Thomas Labbé  Danuta Limanówka  Laurent Litzenburger  Øyvind Nordli  Kathleen Pribyl  Dag Retsö  Dirk Riemann  Christian Rohr  Werner Siegfried  Johan Söderberg  Jean-Laurent Spring 《Climatic change》2014,125(3-4):365-367

  相似文献   

A new geospatial overlay method for the analysis and visualization of spatial change patterns using object-oriented data modeling concepts     

Dirk Tiede 《制图学和地理信息科学》2014,41(3):227-234

Traditional geographic information system (GIS)-overlay routines usually build on relatively simple data models. Topology is – if at all – calculated on the fly for very specific tasks only. If, for example, a change comparison is conducted between two or more polygon layers, the result leads mostly to a complete and also very complex from–to class intersection. A lot of additional processing steps need to be performed to arrive at aggregated and meaningful results. To overcome this problem a new, automated geospatial overlay method in a topologically enabled (multi-scale) framework is presented. The implementation works with polygon and raster layers and uses a multi-scale vector/raster data model developed in the object-based image analysis software eCognition (Trimble Geospatial Imaging, Munich, Germany). Advantages are the use of the software inherent topological relationships in an object-by-object comparison, addressing some of the basic concepts of object-oriented data modeling such as classification, generalization, and aggregation. Results can easily be aggregated to a change-detection layer; change dependencies and the definition of different change classes are interactively possible through the use of a class hierarchy and its inheritance (parent–child class relationships). Implementation is exemplarily shown for a change comparison of CORINE Land Cover data sets. The result is a flexible and transferable solution which is – if parameterized once – fully automated.  相似文献   

Suitability of Existing Numerical Model Codes and Thermodynamic Databases for the Prognosis of Calcite Dissolution Processes in Near-Surface Sediments Due to a CO2 Leakage Investigated by Column Experiments     

Christoph Haase  Andreas Dahmke  Markus Ebert  Dirk Schäfer  Frank Dethlefsen 《Aquatic Geochemistry》2014,20(6):639-661

Among the risks of CO₂ storage is the potential of CO₂ leakage into overlaying formations and near-surface potable aquifers. Through a leakage, the CO₂ can intrude into protected groundwater resources, which can lead to groundwater acidification followed by potential mobilisation of heavy metals and other trace metals through mineral dissolution or ion exchange processes. The prediction of pH buffer reactions in the formations overlaying a CO₂ storage site is essential for assessing the impact of CO₂ leakages in terms of trace metal mobilisation. For buffering the pH-value, calcite dissolution is one of the most important mechanisms. Although calcite dissolution has been studied for decades, experiments conducted under elevated CO₂ partial pressures are rare. Here, the first study for column experiments is presented applying CO₂ partial pressures from 6 to 43 bars and realising a near-natural flow regime. Geochemical calculations of calcite dissolution kinetics were conducted using PHREEQC together with different thermodynamic databases. Applying calcite surface areas, which were previously acquired by N₂-BET or calculated based on grain diameters, respectively, to the rate laws according to Plummer et al. (Am J Sci 278:179–216, doi:10.2475/ajs.278.2.179, 1978) or Palandri and Kharaka (US Geol Surv Open file Rep 2004–1068:71, 2004) in the numerical simulations led to an overestimation of the calcite dissolution rate by up to three orders of magnitude compared to the results of the column experiments. Only reduction of the calcite surface area in the simulations as a fitting procedure allowed reproducing the experimental results. A reason may be that the diffusion boundary layer (DBL), which depends on the groundwater flow velocity and develops at the calcite grain surface separating it from the bulk of the solution, has to be regarded: The DBL leads to a decrease in the calcite dissolution rate under natural laminar flow conditions compared to turbulent mixing in traditional batch experiments. However, varying the rate constants by three orders of magnitudes in a field scale PHREEQC model simulating a CO₂ leakage produced minor variations in the pH buffering through calcite dissolution. This justifies the use of equilibrium models when calculating the calcite dissolution in CO₂ leakage scenarios for porous aquifers and slow or moderate groundwater flow velocities. However, the selection of the thermodynamic database has an impact on the dissolved calcium concentration, leading to an uncertainty in the simulation results. The resulting uncertainty, which applies also to the calculated propagation of an aquifer zone depleted in calcite through dissolution, seems negligible for shallow aquifers of approximately 60 m depth, but amounts to 35 % of the calcium concentration for aquifers at a depth of approximately 400 m.  相似文献   

Variscan orogeny in Corsica: new structural and geochronological insights,and its place in the Variscan geodynamic framework     

Michel Faure  Philippe Rossi  Julien Gaché  Jérémie Melleton  Dirk Frei  Xianhua Li  Wei Lin 《International Journal of Earth Sciences》2014,103(6):1533-1551

In Western Corsica, remnants of pre-batholitic lithological and metamorphic assemblages are preserved as km-scale septa enclosed within Lower Carboniferous to Early Permian plutons. Two groups of septa were recognized: (1) the Argentella and Agriates-Tenda fragments correspond to Neoproterozoic rocks deformed and metamorphosed during the Cadomian–Panafrican orogeny, and (2) the Zicavo, Porto-Vecchio, Solenzara–Fautea, Belgodère, Topiti, and Vignola fragments consist of Variscan metamorphic rocks. The lithological content and the main ductile deformation events for each septum are presented. In the Zicavo, Porto-Vecchio, and Topiti septa, a top-to-the-SW ductile shearing (D1 event) coeval with an amphibolite facies metamorphism is responsible for crustal thickening at ca 360 Ma. This main event was preceded by eclogite and granulite facies metamorphic events preserved as restites within migmatites dated at ca 345–330 Ma. A top-to-the-SE ductile shearing (D2 event) coeval with the crustal melting accommodated the exhumation of the D1 event. In contrast, the Belgodère segment is peculiar as it exhibits a top-to-the-E vergence, although retrogressed high-pressure rocks are also recognized. The pre-Permian fragments are arranged in four NW–SE-striking stripes that define a SW–NE zoning with (1) a Western domain in Topiti, Vignola, Zicavo, Porto-Vecchio, and Solenzara–Fautea; (2) a Neoproterozoic basement with its unconformable Early Paleozoic sedimentary cover in Argentella; (3) an Eastern metamorphic domain in Belgodère; (4) another Neoproterozoic basement with its Upper Paleozoic sedimentary cover in Agriates-Tenda. The Argentella basement is separated from the Western and Eastern domains by two sutures: S1 and S2. The Variscan Corsica represents the Eastern part of the Sardinia–Corsica–Maures segment. The comparison of this segment with other Variscan domains allows us to propose some possible correlations. We argue that the Western domain, Argentella, Belgodère, and Agriates-Tenda domains can be compared with the Southern Variscan belt exposed in French Massif Central–Southern Massif Armoricain, Armorica microblock, Léon block, respectively.  相似文献   

Resolution Improvement of Solar Images     

Miura  Noriaki  Baba  Naoshi  Sakurai  Takashi  Ichimoto  Kiyoshi  Soltau  Dirk  Brandt  Peter 《Solar physics》1999,187(2):347-356

A method for the improvement of resolution in an observed solar image is proposed. A blind deconvolution method is used for restoration of an atmospherically-degraded solar image, and a super-resolution method is applied to its restored image to improve the resolution. It is confirmed that a blind deconvolution process can restore fine structures that are blurred in an observed image, and that the super-resolution process can make a cutoff frequency in a blind-deconvolved image higher. A time series of super-resolved images of a sunspot observed with the 70-cm Vacuum Tower Telescope at Teide Observatory is presented.  相似文献   

Scale Dependency of Hydraulic Conductivity in Heterogeneous Media   总被引：8，自引：0，他引：8  

Dirk Schulze-Makuch  Douglas A. Carlson  Douglas S. Cherkauer  Peter Malik 《Ground water》1999,37(6):904-919

  相似文献   

Noise transfer in variable‐depth streamer deghosting          下载免费PDF全文

Ralf Ferber  Dirk‐Jan van Manen 《Geophysical Prospecting》2017,65(4):903-912

Single‐component towed‐streamer marine data acquisition records the pressure variations of the upgoing compressional waves followed by the polarity‐reversed pressure variations of downgoing waves, creating sea‐surface ghost events in the data. The sea‐surface ghost for constant‐depth towed‐streamer marine data acquisition is usually characterised by a ghost operator acting on the upgoing waves, which can be formulated as a filtering process in the frequency–wavenumber domain. The deghosting operation, usually via the application of the inverse Wiener filter related to the ghost operator, acts on the signal as well as the noise. The noise power transfer into the deghosted data is proportional to the power spectrum of the inverse Wiener filter and is amplifying the noise strongly at the notch wavenumbers and frequencies of the ghost operator. For variable‐depth streamer acquisition, the sea‐surface ghost cannot be described any longer as a wavenumber–frequency operator but as a linear relationship between the wavenumber–frequency representation of the upgoing waves at the sea surface and the data in the space–frequency domain. In this article, we investigate how the application of the inverse process acts on noise. It turns out that the noise magnification is less severe with variable‐depth streamer data, as opposed to constant depth, and is inversely proportional to the local slant of the streamer. We support this statement via application of the deghosting process to real and numerical random noise. We also propose a more general concept of a wavenumber–frequency ghost power transfer function, applicable for variable‐depth streamer acquisition, and demonstrate that the inverse of the proposed variable‐depth ghost power transfer function can be used to approximately quantify the action of the variable‐depth streamer deghosting process on noise.  相似文献   

SPM response to tide and river flow in the hyper-turbid Ems River     

Johan C. Winterwerp  Julia Vroom  Zheng-B. Wang  Martin Krebs  Erik C.M. Hendriks  Dirk S. van Maren  Kerstin Schrottke  Christine Borgsmüller  Andreas Schöl 《Ocean Dynamics》2017,67(5):559-583

In this paper, we analyse the behaviour of fine sediments in the hyper-turbid Lower Ems River, with focus on the river’s upper reaches, a stretch of about 25 km up-estuary of Terborg. Our analysis is based on long records of suspended particulate matter (SPM) from optical backscatter (OBS) measurements close to the bed at seven stations along the river, records of salinity and water level measurements at these stations, acoustic measurements on the vertical mud structure just up-estuary of Terborg and oxygen profiles in the lower 3 m of the water column close to Leerort and Terborg. Further, we use cross-sectionally averaged velocities computed with a calibrated numerical model. Distinction is made between four timescales, i.e. the semi-diurnal tidal timescale, the spring–neap tidal timescale, a timescale around an isolated peak in river flow (i.e. about 3 weeks) and a seasonal timescale. The data suggest that a pool of fluid/soft mud is present in these upper reaches, from up-estuary of Papenburg to a bit down-estuary of Terborg. Between Terborg and Gandersum, SPM values drop rapidly but remain high at a few gram per litre. The pool of fluid/soft mud is entrained/mobilized at the onset of flood, yielding SPM values of many tens gram per litre. This suspension is transported up-estuary with the flood. Around high water slack, part of the suspension settles, being remixed during ebb, while migrating down-estuary, but likely not much further than Terborg. Around low water slack, a large fraction of the sediment settles, reforming the pool of fluid mud. The rapid entrainment from the fluid mud layer after low water slack is only possible when the peak flood velocity exceeds a critical value of around 1 m/s, i.e. when the stratified water column seems to become internally supercritical. If the peak flood velocity does not reach this critical value, f.i. during neap tide, fluid mud is not entrained up to the OBS sensors. Thus, it is not classical tidal asymmetry, but the peak flood velocity itself which governs the hyper-turbid state in the Lower Ems River. The crucial role of river flow and river floods is in reducing these peak flood velocities. During elongated periods of high river flow, in e.g. wintertime, SPM concentrations reduce, and the soft mud deposits consolidate and possibly become locally armoured as well by sand washed in from the river. We have no observations that sediments are washed out of the hyper-turbid zone. Down-estuary of Terborg, where SPM values do not reach hyper-turbid conditions, the SPM dynamics are governed by classical tidal asymmetry and estuarine circulation. Hence, nowhere in the river, sediments are flushed from the upper reaches of the river into the Ems-Dollard estuary during high river flow events. However, exchange of sediment between river and estuary should occur because of tide-induced dispersion.  相似文献   

Cambro‐Ordovician trace fossils from the SW‐Norwegian Caledonides     

Dirk Knaust 《Geological Journal》2004,39(1):1-24

A diverse trace fossil association is described for the first time from low‐grade metamorphic rocks of the SW‐Norwegian Caledonides. The investigated cliff sections with autochthonous to parautochthonous metasediments comprise a coarsening‐ and thickening‐upward succession interpreted as prograding delta deposits. Sedimentary features indicate a tide‐influenced environment. Twenty‐one ichnospecies have been identified and assigned to the Cruziana and Skolithos ichnofacies, including the oldest record of Beaconites capronus and Macaronichnus segregatis. Cruziana ichnostratigraphy (sensu lato), previously rarely used in other palaeocontinents than Gondwana, allows an age determination for these metasediments of Middle Cambrian to Lower Ordovician as indicated by the presence of Cruziana barbata, C. furcifera, C. rugosa, C. semiplicata, Didymaulichnus rouaulti and Rusophycus ramellensis. Baltica was geographically the most isolated from the other three large continents (Gondwana, Laurentia and Siberia) during Cambro‐Ordovician time, and provinciality of faunal assemblages (e.g. brachiopods, conodonts) has been proved and is also supposed for trilobites by some authors. However, although the Cruziana ichnospecies result from a high specialization of their tracemakers, and therefore only a small group of trilobite species is eligible for its origin, the ichnospecies reported from Baltica occur also on other palaeocontinents and do not support the assumption of trilobite provincialism. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

A conceptual framework for studying collective reactions to events in location-based social media     

Alexander Dunkel  Gennady Andrienko  Natalia Andrienko  Dirk Burghardt  Eva Hauthal  Ross Purves 《International journal of geographical information science》2019,33(4):780-804

Events are a core concept of spatial information, but location-based social media (LBSM) provide information on reactions to events. Individuals have varied degrees of agency in initiating, reacting to or modifying the course of events, and reactions include observations of occurrence, expressions containing sentiment or emotions, or a call to action. Key characteristics of reactions include referent events and information about who reacted, when, where and how. Collective reactions are composed of multiple individual reactions sharing common referents. They can be characterized according to the following dimensions: spatial, temporal, social, thematic and interlinkage. We present a conceptual framework, which allows characterization and comparison of collective reactions. For a thematically well-defined class of event such as storms, we can explore differences and similarities in collective attribution of meaning across space and time. Other events may have very complex spatio-temporal signatures (e.g. political processes such as Brexit or elections), which can be decomposed into series of individual events (e.g. a temporal window around the result of a vote). The purpose of our framework is to explore ways in which collective reactions to events in LBSM can be described and underpin the development of methods for analysing and understanding collective reactions to events.  相似文献