Assessing the relevance of subsurface processes for the simulation of evapotranspiration and soil moisture dynamics with CLM3.5: comparison with field data and crop model simulations     

Sebastian Gayler  Joachim Ingwersen  Eckart Priesack  Thomas Wöhling  Volker Wulfmeyer  Thilo Streck 《Environmental Earth Sciences》2013,69(2):415-427

  相似文献   

Seismicity and structural complexity of the Dinkelberg block, southern Rhine Graben     

S. Faber  K.-P. Bonjer  W. Brüstle  N. Deichmann 《Geophysical Journal International》1994,116(2):393-408

  相似文献   

Short timescale variability of the mesospheric sodium layer     

C. O'Sullivan  R. M. Redfern  N. Ageorges  H.-C. Holstenberg  W. Hackenberg  T. Ott  S. Rabien  R. Davies  A. Eckart 《Experimental Astronomy》2000,10(1):147-156

In this article we investigate the short-term characteristics of the sodium layer and their implications for laser guide star systems. We report measurements of sodium density andcentroid-height variations on timescales of 100 ms upwards. Significant centroid-height variations on short timescales may necessitate frequent refocussing of the beam and wavefront sensor system.We present results from observations of the mesospheric sodium layer taken at the Max Planck observatory in Calar Alto, Spain in September 1997 and August 1998. We describe our experiment which uses the resonant optical backscatter of 589.2 nm laser light from the upper atmosphere as a measure of sodium abundance.Short-term variations are dominated by the formation of dense sporadic layers in the normal sodium layer. Measurements were made on 3 nights in 1997 and on 2 nights in 1998. Somewhat unexpectedly for a mid-latitude site, sporadic sodium layers were seen on 4 of these 5 nights. One of the sporadic layers was observed for its duration. The 2 km wide layer reached a maximum intensity of approximately two and a half times that of the background layer and could be distinguished from the background for over five hours. Centroid height variations of up to 400 m were observed on timescales of 1–2 min. In 1998 we were sensitive to variations of 5% or more in total sodium abundance on timescales of 100 ms upwards. We found no evidencefor variations of this level on these short timescales.  相似文献   

Stellar dynamics in the Galactic Centre: proper motions and anisotropy     

R. Genzel  C. Pichon  A. Eckart  O. E. Gerhard  T. Ott 《Monthly notices of the Royal Astronomical Society》2000,317(2):348-374

  相似文献   

Impact structures and events - a Nordic perspective     

Henning Dypvik Jueri Plado Claus Heinberg Eckart Hakansson Lauri J. Pesonen Birger Schmitz Selen Raiskila 《《幕》》2008,31(1):107-114

Impact cratering is one of the fundamental processes in the formation of the Earth and our planetary system, as reflected, for example in the surfaces of Mars and the Moon. The Earth has been covered by a comparable number of impact scars, but due to active geological processes, weathering, sea floor spreading etc, the number of preserved and recognized impact craters on the Earth are limited. The study of impact structures is consequently of great importance in our understanding of the formation of the Earth and the planets, and one way we directly, on the Earth, can study planetary geology.
The Nordic-Baltic area have about thirty confirmed impact structures which makes it one of the most densely crater-populated terrains on Earth. The high density of identified craters is due to the level of research activity, coupled with a deterministic view of what we look for. In spite of these results, many Nordic structures are poorly understood due to the lack of 3D-geophysical interpretations, isotopeor other dating efforts and better knowledge of the amount of erosion and subsequent tectonic modifications.
The Nordic and Baltic impact community is closely collaborating in several impact-related projects and the many researchers （about forty） and PhD students （some seventeen） promise that this level will continue for many more years. The main topics of research include geological, geophysical and geochemical studies in combination with modeling and impact experiments. Moreover, the Nordic and Baltic crust contains some hundred suspect structures which call for detailed analysis to define their origin.
New advanced methods of analyzing geophysical information in combination with detailed geochemical analyses and numerical modeling will be the future basic occupation of the impact scientists of the region. The unique Cretaceous/Tertiary boundary （K-T） occurrences in Denmark form an important source of information in explaining one of the major mass extinctions on Earth.  相似文献   

Die Korngrössenverteilung von Einzellagen sandiger Sedimente und ihre genetische Bedeutung     

Dr. Eckart Walger 《International Journal of Earth Sciences》1962,51(2):494-507

Zusammenfassung Der Kömungstyp von Einzellagen wassertransportierter Sedimente ist unabhängig vom Ablagerungsraum. Er läßt sich stets als Summe von drei lognormalen Komponenten beschreiben. Medianwerte und Sortierungsgrade von Einzellagen sind durch eine Funktion miteinander verknüpft, die ebenfalls unabhängig vom Ablagerungsraum ist. Körnungstyp und Sortierungsgrad von dicken Durchschnittsproben dagegen hängen vom Lagenbau des Sediments und damit auch von der Probendicke ab. Die Funktion zwischen Medianwert und Sortierungsgrad von Durchschnittsproben ist vom Ablagerungsraum abhängig, stets gleiche Probenahmetechnik vorausgesetzt. Jedoch steckt immer auch der Einfluß der allgemeingültigen Funktion zwischen Medianwert und Sortierungsgrad der Einzellagen darin, der bei der Deutung berücksichtigt werden muß.  相似文献   

Investigations of S_n and P_n phases in the area of the upper Rhine Graben and northern Switzerland     

T. Plenefisch  S. Faber  K.-P. Bonjer 《Geophysical Journal International》1994,119(2):402-420

  相似文献   

`Once upon a time ...' Interactions of German and American geography in a rapidly changing (academic) world     

Eckart Ehlers 《GeoJournal》2004,59(1):9-13

  相似文献   

Current German geography in a globalizing world of science A documentation and personal interpretation     

Eckart Ehlers 《GeoJournal》1998,45(1-2):57-67

  相似文献   

Hydrothermal gases offshore Milos Island, Greece   总被引：3，自引：0，他引：3  

Reiner Botz  Doris Stüben  Gisela Winckler  Reinhold Bayer  Manfred Schmitt  Eckhard Faber 《Chemical Geology》1996,130(3-4):161-173

Hydrothermal fluids emerge from the seafloor of Paleohori Bay on Milos. The gases in these fluids contain mostly CO₂ but CH₄ concentrations up to 2% are present. The stable carbon isotopic composition of the CO₂ (near 0%) indicates an inorganic carbon source (dissociation of underlying marine carbonates). The carbon and hydrogen isotopes of most CH₄ samples are enriched in the heavy species (δ¹³C = −9.4 to −17.8‰; δD = −102 to −189‰) which is believed to be characteristic for an abiogenic production of CH₄ by CO₂-reduction (Fischer-Tropsch reactions). Depletions in the deuterium content of three CH₄ samples (to −377%) are probably caused by unknown subsurface rock alteration processes. Secondary hydrogen isotope exchange processes between methane, hydrogen and water are most likely responsible for calculated unrealistic methane formation temperatures.

We show that excess helium, slightly enriched in ³He, is present in the hydrothermal fluids emerging the seafloor of Paleohori Bay. When the isotopic ratio of the excess component is calculated a ³He/⁴He_excess of 3.6 · 10⁻⁶ is obtained: This indicates that the excess component consists of about one third of mantle helium and two thirds of radiogenic helium. We infer that the mantle-derived component has been strongly diluted by radiogenic helium during the ascent of the fluids to the surface.  相似文献