Strain Release in the Circum-Pacific Belt: Kern County 1952, Desert Hot Springs 1948, San Francisco 1957     

Seweryn J. Duda  Markus Båth 《Geophysical Journal International》1963,7(5):554-570

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Distinguishing climatic from direct anthropogenic influences during the past 400 years in varved sediments from Lake Holzmaar (Eifel,Germany)   总被引：3，自引：0，他引：3  

Ulrike?KienelEmail author  Markus?J.?Schwab  Georg?Schettler 《Journal of Paleolimnology》2005,33(3):327-347

A 336-year floating varve chronology from Lake Holzmaar (Eifel, Western-Germany) covering the recent period has been established by microfacies analysis of thin sections. This sequence terminates 23 cm below the core top. In the top 23 cm, the varves are disturbed. By means of linear regression, the varve sequence was dated to the period AD 1607–1942. The influences of climatic variability and anthropogenic activities in the lakes catchment (e.g., forestry, agriculture) on lithology, fabric, and microfossil content of the varve sublaminae could be discriminated by applying statistical analyses (ordination and clustering) to the combination of the sublaminae in the varves and their thickness. Four clusters are obtained. Cluster 1 indicates cold springs, and shorter, cooler summers reflected primarily in below-average varve thickness (VT) for two stable phases: from AD 1650–1700 (during the Maunder Minimum) and from AD 1750–1785. Cluster 2 indicates years with conditions transitional to that indicated by cluster 1, characterized by vigorous and prolonged spring circulation with massive blooms of the nordic-alpine Aulacoseira subarctica. The samples assigned to Cluster 3 and Cluster 4 show the imprint of anthropogenic influences. Cluster 3 (AD 1795–1815 and AD 1825–1885) is characterized by above-average VT due to high detritus input throughout the year. The increased soil erosion can be linked to anthropogenic deforestation as a consequence of the production increase of the Eifelian iron industry at the end of the 18th century. This input dampens the climatic signal of a colder Dalton Minimum, which is reflected in a short drop in VT centered around AD 1810. At about AD 1885, Cluster 4 conditions, characterized by increased nutrient concentrations, low detritus input, and longer periods of stable summer stratification, become the stable state in Lake Holzmaar. They indicate the response of the lake to natural reforestation and the use of artificial fertilizers in the catchment, which began, according to historical records, in the 1850s in the Eifel region. The prolonged, stable summer stratification periods may be the first indication of the modern warming trend. A drop in VT centered around AD 1890 and recurring cluster-1 conditions may indicate the Damon Minimum.  相似文献   

Nitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments     

Lepoint G  Vangeluwe D  Eisinger M  Paster M  van Treeck P  Bouquegneau JM  Gobert S 《Marine pollution bulletin》2004,48(5-6):465-470

A (15)N tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement, because leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural re-colonisation processes. The increase of the (15)N content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots).  相似文献   

The Triassic of Monte San Giorgio in the World Heritage List of UNESCO: An opportunity for science, the local people and tourism     

Markus Felber  Heinz Furrer  Andrea Tintori 《Eclogae Geologicae Helvetiae》2004,97(1):1-2

No abstract.  .  相似文献   

Absolute phase center corrections of satellite and receiver antennas   总被引：9，自引：2，他引：9  

Ralf Schmid  Markus Rothacher  Daniela Thaller  Peter Steigenberger 《GPS Solutions》2005,9(4):283-293

Results of the estimation of azimuth-dependent phase center variations (PCVs) of GPS satellite antennas using global GPS data are presented. Significant variations of up to ±3–4 mm that are demonstrated show excellent repeatability over eight years. The application of the azimuthal PCVs besides the nadir-dependent ones will lead to a further reduction in systematic antenna effects. In addition, the paper focuses on the benefit of a possible transition from relative to absolute PCVs. Apart from systematic changes in the global station coordinates, one can expect the GPS results to be less dependent on the elevation cut-off angle. This, together with the significant reduction of tropospheric zenith delay biases between GPS and VLBI, stands for an important step toward more consistency between different space geodetic techniques.  相似文献   

Analysis of heavy rainfall events in North Rhine–Westphalia with radar and raingauge data     

Markus Jessen  Thomas Einfalt  Andr Stoffer  Bernd Mehlig 《Atmospheric Research》2005,77(1-4):337

Five heavy rainfall events were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be difficult in the vicinity of heavy local rain cells. Four adjustment methods were analysed and radar data from different radar stations were compared. As a further result of this project, the spatial extent of the precipitation fields was identified by adjusted radar data and compared to raingauge data. For each rainfall event, radar derived accumulated rainfall images and catchment time series were produced.  相似文献   

A calibrated composite section for the Late Jurassic Reuchenette Formation in northwestern Switzerland (?Oxfordian, Kimmeridgian sensu gallico, Ajoie-Region)     

Markus Jank  Andreas Wetzel  Christian A. Meyer 《Eclogae Geologicae Helvetiae》2006,99(2):175-191

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Possibilities and Limitations of Interdisciplinary, User-oriented Research: Experiences from the German Research Network Natural Disasters     

Bruno Merz  Jana Friedrich  Markus Disse  Jochen Schwarz  Johann G. Goldammer  Jochen Wächter 《Natural Hazards》2006,38(1-2):3-20

The German Research Network for Natural Disasters (DFNK) linked 15 partners with scientific expertise in the field of natural hazards. Main objectives were the development and provision of the scientific fundamentals for an advanced risk management of important natural disasters in Germany, i.e., floods, earthquakes, storms and wildland fires. This included risk analyses, the development of information systems for supporting disaster management, and recommendations for risk reduction measures. This paper gives an overview of DFNK and summarises its experiences concerning multidisciplinarity and user-orientation. It illustrates the concept of risk chains, causally linking the different processes from hazard to risk. The step from hazard to risk requires interdisciplinary research teams. The experiences show that integrative concepts allow results not achievable with mono-disciplinary approaches. Integrative approaches pave the way to harmonised safety considerations taking into account the different hazards in a region within a common framework. User-orientation, policy advice and development of operational tools are key issues of disaster research. The experiences of DFNK illustrate the limitations of a research network in bridging the gap between research and application within rather short-term projects. Successful cooperation with users could be established by those activities where, at the beginning of the project, a user was identified who had a strong interest in solving an urgent problem.  相似文献   

Assessment of Discharge through a Dike Breach and Simulation of Flood Wave Propagation   总被引：2，自引：0，他引：2  

Paul Kamrath  Markus Disse  Matthias Hammer  Jürgen Köngeter 《Natural Hazards》2006,38(1-2):63-78

This paper presents a simple and fast method to calculate flow through a dike breach. The approach was based on two-dimensional numerical simulations of idealized dike breakages at straight river-sections. As a result, computation of discharge through a breach can be achieved by use of the new developed formula (denoted as dike break formula). Furthermore, a methodology that combines one-dimensional hydrodynamic modelling, the dike break formula and a simple GIS-based method to estimate inundation areas is described. This fast and easy-to-handle tool can be utilized for near real-time forecasting or evacuation decisions. Detailed predictions were made for a number of flood and dike break scenarios at the River Rhine to prove the accuracy of the new method compared with two-dimensional numerical models.  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