The Mesozoic–Cenozoic structural framework of the Bay of Kiel area, western Baltic Sea     

Martin Bak Hansen  Holger Lykke-Andersen  Ali Dehghani  Dirk Gajewski  Christian Hübscher  Morten Olesen  Klaus Reicherter 《International Journal of Earth Sciences》2005,94(5-6):1070-1082

A dense grid of multichannel high-resolution seismic sections from the Bay of Kiel in the western Baltic Sea has been interpreted in order to reveal the Mesozoic and Cenozoic geological evolution of the northern part of the North German Basin. The overall geological evolution of the study area can be separated into four distinct periods. During the Triassic and the Early Jurassic, E–W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. The deposition ceased during the Middle Jurassic, when the entire area was uplifted as a result of the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic and Lower Jurassic strata. This event is marked by a clear angular unconformity on all the seismic sections. The region remained an area of non-deposition until the end of the Early Cretaceous, when the sedimentation resumed in the area. Throughout the Late Cretaceous the sedimentation took place under tectonic quiescence. Reactivated salt movement is observed at the Cretaceous Cenozoic transition as a result of the change from an extensional to compressional regional stress field. The vertical salt movement influenced the Cenozoic sedimentation and resulted in thin-skinned faulting.  相似文献   

Arsenic fixation on iron-hydroxide-rich and plant litter-containing sediments in natural environments   总被引：2，自引：0，他引：2  

Andreas Fritzsche  Holger Dienemann  Ernst Gert Dudel 《Environmental Geology》2006,51(1):133-142

Iron-hydroxide-rich and plant litter-containing sediments from natural sites contaminated with uranium mine tailing leachates were examined for their ability to adsorb arsenic. The samples with high contents of iron hydroxides (Fe_total concentration, >300 g kg⁻¹) exhibited remarkable fixation of arsenic (up to 40 g As kg⁻¹). This value corresponded approximately to the supersaturation point for natural iron hydroxides under the present conditions, and it was significantly lower than the value found for synthetic iron hydroxides. There was a strong correlation (R=0.8999) between the concentration of iron and that of arsenic at low arsenic contents, indicating adsorption on strong binding sites. Although all the samples had noticeable contents of organic carbon (plant litter), calcium, and manganese, no obvious effect of these elements on arsenic fixation could be detected. The amount of iron hydroxides was found the only fixation-controlling parameter immediately below a leaching water source.  相似文献   

Scaling of N-body calculations     

H. Baumgardt † 《Monthly notices of the Royal Astronomical Society》2001,325(4):1323-1331

We report results of collisional N -body simulations aimed at studying the N dependence of the dynamical evolution of star clusters. Our clusters consist of equal-mass stars and are in virial equilibrium. Clusters moving in external tidal fields and clusters limited by a cut-off radius are simulated. Our main focus is to study the dependence of the lifetimes of the clusters on the number of cluster stars and the chosen escape condition.
We find that star clusters in external tidal fields exhibit a scaling problem in the sense that their lifetimes do not scale with the relaxation time. Isolated clusters show a similar problem if stars are removed only after their distance to the cluster centre exceeds a certain cut-off radius. If stars are removed immediately after their energy exceeds the energy necessary for escape, the scaling problem disappears.
We show that some stars that gain the energy necessary for escape are scattered to lower energies before they can leave the cluster. As the efficiency of this process decreases with increasing particle number, it causes the lifetimes not to scale with the relaxation time. Analytic formulae are derived for the scaling of the lifetimes in the different cases.  相似文献   

Behaviour Of An Ultrasonic Anemometer Under Cloudy Conditions     

Holger Siebert  Ulrich Teichmann 《Boundary-Layer Meteorology》2000,94(1):165-169

The use of ultrasonic anemometers under cloudy weather conditions is often doubted, even rejected or not discussed in the literature. To investigate the influence of liquid water content on the behaviour of sonic anemometers a small intercomparison experiment using an ultrasonic anemometer, a fast response propeller anemometer, and a Particulate Volume Monitor was performed at the German Environmental Research Station Schneefernerhaus near the top of Mt. Zugspitze. The results obtained under different conditions (dry/cloudy) give no significant hint on such an influence.  相似文献   

Double-layer structure in the boundary layer over the baltic sea     

Cecilia Johansson  Barbara Hennemuth  Jens Bösenberg  Holger Linné  Ann-sofi Smedman 《Boundary-Layer Meteorology》2005,114(2):389-412

Double-layered structures found over the Baltic Sea are investigated using radiosoundings and lidar measurements. Situations with double-layer structures are also simulated with the regional model REMO in a realistic manner. The double layer consists of two adjacent well-mixed layers, with a sharp inversion in between.Results from radiosoundings show that the double-layer structure over the Baltic Sea mainly occurs during the autumn with thermally unstable stratification near the surface. The structure is present in about 50 % of the radiosoundings performed during autumn. The presence of the double-layer structure cannot be related to any specific wind direction, wind speed or sea surface temperature.The lidar measurements give a more continuous picture of the time evolution of the double-layer structure, and show that the top of the lower layer is not a rigid lid for vertical transport. Two possible explanations of the double-layer structure are given, (i) the structure is caused by `advection' of land boundary-layer air over the convective marine boundary layer or, (ii) by development of Sc clouds in weak frontal zones connected to low pressure systems. Also the forming of Cu clouds is found to be important for the development of a double-layer structure.  相似文献   

Glacial isostatic adjustment of Scandinavia and northwestern Europe and the radial viscosity structure of the Earth's mantle   总被引：6，自引：0，他引：6  

Holger Steffen  Georg Kaufmann 《Geophysical Journal International》2005,163(2):801-812

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Transit times of water under steady stormflow conditions in the Gårdsjön G1 catchment          下载免费PDF全文

Benny Selle  Holger Lange  Gunnar Lischeid  Michael Hauhs 《水文研究》2015,29(22):4657-4665

In this paper we report on a series of replicated tracer experiments with deuterium conducted under controlled, steady stormflow conditions at the Gårdsjön G1 catchment in south‐western Sweden. In five different years, these experiments were carried out in a subcatchment of G1. Deuterium was applied as a narrow pulse so that distributions of water transit times could be directly inferred from the observed tracer breakthrough curves. Significantly different transit times of water were observed under similar experimental conditions. Coefficients of variation for estimated mean transit times were greater than 60%, which can be understood as a measure of the interannual variability for this type of experiments. Implications for water transit times under more natural flow conditions as wells as for future experimentation are discussed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Modelling the potential impact of global warming on Ips typographus voltinism and reproductive diapause     

Anna Maria Jönsson  Susanne Harding  Paal Krokene  Holger Lange  Åke Lindelöw  Bjørn Økland  Hans Peter Ravn  Leif Martin Schroeder 《Climatic change》2011,109(3-4):695-718

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Merging Timescales and Merger Rates of Star Clusters in Dense Star Cluster Complexes     

M. Fellhauer  H. Baumgardt  P. Kroupa  R. Spurzem 《Celestial Mechanics and Dynamical Astronomy》2002,82(2):113-131

Interacting galaxies like the famous Antennae (NGC 4038/4039) or Stephan's Quintet (HCG 92) show considerable star forming activity in their tidal arms. High resolution images (e.g. from HST-observations) indicate that these regions consist of up to hundreds of massive stellar clusters or tidal dwarf galaxies (TDG). In this paper we want to investigate the future fate of these clusters of massive star clusters (in this work called super-clusters). We simulate compact super-clusters in the tidal field of a host-galaxy and investigate the influence of orbital and internal parameters on the rate and timescale of the merging process. We show that it is possible that such configurations merge and build a dwarf galaxy, which could be an important mechanism of how long-lived dwarf satellite galaxies form. A detailed study of the merger object will appear in a follow-up paper.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

OBSERVATION OF THE UV SOLAR SPECTRAL IRRADIANCE BETWEEN 200 AND 350 nm DURING THE ATLAS I MISSION BY THE SOLSPEC SPECTROMETER     

Thuillier  Gérard  Hersé  Michel  Simon  Paul C.  Labs  Dietrich  Mandel  Holger  Gillotay  Didier 《Solar physics》1997,171(2):283-302

The SOLSPEC instrument has been built to carry out solar spectral irradiance measurements from space. It consists of three spectrometers designed to measure the solar spectral irradiance from 180 to 3000 nm. It flew for the first time in December 1983 with the SpaceLab 1 mission (SL1) and later with the ATLAS missions after significant improvement of the instrument optics and calibration procedures. For the ATLAS 1 mission in March 1992, the thermal conditions encountered during the measurements were better than those of SL1, leading to better data quality. Furthermore, other Sun spectrometers, two on the same platform and two others on board the Upper Atmosphere Research Satellite, have also carried out UV absolute spectral measurements at the same time. These opportunities allowed comparisons of solar irradiance determinations. The UV part of the measurements made during that mission is presented here as well as its calibration and accuracy analysis.  相似文献