Soil formation and weathering in a permafrost environment of the Swiss Alps: a multi‐parameter and non‐steady‐state approach          下载免费PDF全文

Barbara Zollinger  Christine Alewell  Christof Kneisel  Dagmar Brandová  Marta Petrillo  Michael Plötze  Marcus Christl  Markus Egli 《地球表面变化过程与地形》2017,42(5):814-835

Spatially discontinuous permafrost conditions frequently occur in the European Alps. How soils under such conditions have evolved and how they may react to climate warming is largely unknown. This study focuses on the comparison of nearby soils that are characterised by the presence or absence of permafrost (active‐layer thickness: 2–3 m) in the alpine (tundra) and subalpine (forest) range of the Eastern Swiss Alps using a multi‐method (geochemical and mineralogical) approach. Moreover, a new non‐steady‐state concept was applied to determine rates of chemical weathering, soil erosion, soil formation, soil denudation, and soil production. Long‐term chemical weathering rates, soil formation and erosion rates were assessed by using immobile elements, fine‐earth stocks and meteoric ¹⁰Be. In addition, the weathering index (K + Ca)/Ti, the amount of Fe‐ and Al‐oxyhydroxides and clay minerals characteristics were considered. All methods indicated that the differences between permafrost‐affected and non‐permafrost‐affected soils were small. Furthermore, the soils did not uniformly differ in their weathering behaviour. A tendency towards less intense weathering in soils that were affected by permafrost was noted: at most sites, weathering rates, the proportion of oxyhydroxides and the weathering stage of clay minerals were lower in permafrost soils. In part, erosion rates were higher at the permafrost sites and accounted for 79–97% of the denudation rates. In general, soil formation rates (8.8–86.7 t/km²/yr) were in the expected range for Alpine soils. Independent of permafrost conditions, it seems that the local microenvironment (particularly vegetation and subsequently soil organic matter) has strongly influenced denudation rates. As the climate has varied since the beginning of soil evolution, the conditions for soil formation and weathering were not stable over time. Soil evolution in high Alpine settings is complex owing to, among others, spatio‐temporal variations of permafrost conditions and thus climate. This makes predictions of future behaviour very difficult. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Solifluction meets vegetation: the role of biogeomorphic feedbacks for turf‐banked solifluction lobe development          下载免费PDF全文

Jana Eichel  Daniel Draebing  Lasse Klingbeil  Markus Wieland  Christian Eling  Sebastian Schmidtlein  Heiner Kuhlmann  Richard Dikau 《地球表面变化过程与地形》2017,42(11):1623-1635

Vegetation is an important factor influencing solifluction processes, while at the same time, solifluction processes and landforms influence species composition, fine‐scale distribution and corresponding ecosystem functioning. However, how feedbacks between plants and solifluction processes influence the development of turf‐banked solifluction lobes (TBLs) and their geomorphic and vegetation patterns is still poorly understood. We addressed this knowledge gap in a detailed biogeomorphic investigation in the Turtmann glacier foreland (Switzerland). Methods employed include geomorphic and vegetation mapping, terrain assessment with unmanned aerial vehicle (UAV) and temperature logging. Results were subsequently integrated with knowledge from previous geomorphic and ecologic studies into a conceptual model. Our results show that geomorphic and vegetation patterns at TBLs are closely linked through the lobe elements tread, risers and ridge. A conceptual four‐stage biogeomorphic model of TBL development with ecosystem engineering by the dwarf shrub Dryas octopetala as the dominant process can explain these interlinked patterns. Based on this model, we demonstrate that TBLs are biogeomorphic structures and follow a cyclic development, during which the role of their components for engineer and non‐engineer species changes. Our study presents the first biogeomorphic model of TBL development and highlights the applicability and necessity of biogeomorphic approaches and research in periglacial environments. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Improved petrographic-coded model and its evaluation to determine a thermal conductivity log     

Nina Gegenhuber  Markus Kienler 《Acta Geophysica》2017,65(1):103-118

Thermal conductivity is one of the crucial properties for thermal modelling as well as tunnelling or geological modelling. Available data are mainly from laboratory measurements. Therefore, additional ways, such as correlations with other properties to derive the petrophysical parameter, will be an advantage. The research presented here continues and improves the petrographic-coded model concept with an increased set of data, including a variety of lithologies, and, furthermore, the correlations, including the electrical resistivity. Input parameters are no longer taken from the literature, but are derived directly from measurements. In addition, the results are compared with other published approaches. Results show good correlations with measured data. The comparison with the multi-linear regression method shows acceptable outcome, in contrast to a geometric-mean method, where data scatter. In summary, it can be said that the improved model delivers for both correlation (compressional wave velocity and electrical resistivity with thermal conductivity) positive results.  相似文献   

Growth history of a cold-water coral covered carbonate mound — Galway Mound, Porcupine Seabight, NE-Atlantic     

Markus Eisele  Dierk Hebbeln  Claudia Wienberg   《Marine Geology》2008,253(3-4):160-169

During the past decade, knowledge about the ecology and the environment of giant carbonate mounds has been growing continuously. However, still little is known about their growth dynamics. Three gravity cores from Galway Mound, Belgica Mound Province in the Porcupine Seabight off Ireland, were investigated for their sedimentological, geophysical and geochemical properties to get insight into the long-term development of this cold-water coral covered carbonate mound. These data were supplemented by radiometric age determinations on planktonic foraminifera and coral skeletons. The records from three different settings on Galway Mound reveal a coherent growth history that in general is similar to what is known from other carbonate mounds at the Irish margin. However, whereas other cores are often disturbed by numerous and not correlateable hiatuses, Galway Mound, in contrast, appears to be characterised by only one major hiatus representing a time gap of ~ 250 kyr. Several mechanisms are discussed in this study as possible causes for the observed stratigraphic record at Galway Mound. The most likely explanation is that the hiatus has its origin in a major mass wasting event on an instable, possibly glacial, unit that could have acted as a slip plane. The overall Late Quaternary growth history of Galway Mound fits well into existing cyclical mound development models, pointing to Galway Mound being an ‘actively growing’ mound (“coral bank stage”) at present.  相似文献   

Green restructuring,innovation, and transitions in Norwegian industry: The role of economic geography     

Markus Steen  Rune Njøs 《Norsk geografisk tidsskrift. Norwegian journal of geography》2019,73(1):1-3

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Coordinated Ocean-ice Reference Experiments (COREs)     

Stephen M. Griffies  Arne Biastoch  Claus Böning  Frank Bryan  Gokhan Danabasoglu  Eric P. Chassignet  Matthew H. England  Rüdiger Gerdes  Helmuth Haak  Robert W. Hallberg  Wilco Hazeleger  Johann Jungclaus  William G. Large  Gurvan Madec  Anna Pirani  Bonita L. Samuels  Markus Scheinert  Alex Sen Gupta  Camiel A. Severijns  Harper L. Simmons  Jianjun Yin 《Ocean Modelling》2009,26(1-2):1-46

Coordinated Ocean-ice Reference Experiments (COREs) are presented as a tool to explore the behaviour of global ocean-ice models under forcing from a common atmospheric dataset. We highlight issues arising when designing coupled global ocean and sea ice experiments, such as difficulties formulating a consistent forcing methodology and experimental protocol. Particular focus is given to the hydrological forcing, the details of which are key to realizing simulations with stable meridional overturning circulations.The atmospheric forcing from [Large, W., Yeager, S., 2004. Diurnal to decadal global forcing for ocean and sea-ice models: the data sets and flux climatologies. NCAR Technical Note: NCAR/TN-460+STR. CGD Division of the National Center for Atmospheric Research] was developed for coupled-ocean and sea ice models. We found it to be suitable for our purposes, even though its evaluation originally focussed more on the ocean than on the sea-ice. Simulations with this atmospheric forcing are presented from seven global ocean-ice models using the CORE-I design (repeating annual cycle of atmospheric forcing for 500 years). These simulations test the hypothesis that global ocean-ice models run under the same atmospheric state produce qualitatively similar simulations. The validity of this hypothesis is shown to depend on the chosen diagnostic. The CORE simulations provide feedback to the fidelity of the atmospheric forcing and model configuration, with identification of biases promoting avenues for forcing dataset and/or model development.  相似文献   

Annual deformation signals from homogeneously reprocessed VLBI and GPS height time series   总被引：3，自引：3，他引：0  

Volker Tesmer  Peter Steigenberger  Markus Rothacher  Johannes Boehm  Barbara Meisel 《Journal of Geodesy》2009,83(10):973-988

The first part of this paper compares homogeneously reprocessed Very Long Baseline Interferometry (VLBI) and Global Positioning System (GPS) long-term height series from 1994 to 2007. The data analysis used fully adapted state-of-the-art models (like VMF1 and a priori zenith delays from ECMWF) for the GPS and VLBI processing. The series are compared in terms of long-term non-linear behaviour, harmonic and mean annual signals (not necessarily of harmonic nature). The similarity between both techniques is very good (especially the mean annual signals), which is assumed to be due to the adapted models and consistent reprocessing of both series. As two almost independent observing techniques see the same annually recurring signals at almost all co-located sites, we expect a good geophysical interpretability as integral vertical deformation. For the second part of this paper, the height time series of 161 suitable GPS sites (of the same solution as before) are used to determine a harmonic and a mean annual signal for each of them. Comparing the annual signals for this big dataset visually to GRACE-determined load deformations described in other publications, we find good agreement. This puts emphasis to the assumption that our height data have a lot of potential to be interpreted as geophysical signals. Out of these 161, 131 are grouped to 55 clusters, if at least two nearby (some thousand kilometres) sites show similar mean annual signals, which are thus confirmed to be real regional deformation, not local or technical artefacts. These 55 signals are presented on a “world map” of regional average mean annual height signals, as easy-to-handle tool to validate geophysical models. The data of these measured regional mean annual signals can be downloaded from a web-page for numerical analysis.  相似文献   

Non‐stationary hydrological model parameters: a framework based on SOM‐B          下载免费PDF全文

Markus Wallner  Uwe Haberlandt 《水文研究》2015,29(14):3145-3161

The application of stationary parameters in conceptual hydrological models, even under changing boundary conditions, is a common yet unproven practice. This study investigates the impact of non‐stationary model parameters on model performance for different flow indices and time scales. Therefore, a Self‐Organizing Map based optimization approach, which links non‐stationary model parameters with climate indices, is presented and tested on seven meso‐scale catchments in northern Germany. The algorithm automatically groups sub‐periods with similar climate characteristics and allocates them to similar model parameter sets. The climate indices used for the classification of sub‐periods are based on (a) yearly means and (b) a moving average over the previous 61 days. Classification b supports the estimation of continuous non‐stationary parameters. The results show that (i) non‐stationary model parameters can improve the performance of hydrological models with an acceptable growth in parameter uncertainty; (ii) some model parameters are highly correlated to some climate indices; (iii) the model performance improves more for monthly means than yearly means; and (iv) in general low to medium flows improve more than high flows. It was further shown how the gained knowledge can be used to identify insufficiencies in the model structure. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Image Processing Techniques and Feature Recognition in Solar Physics     

Markus J. Aschwanden 《Solar physics》2010,262(2):235-275

This review presents a comprehensive and systematic overview of image-processing techniques that are used in automated feature-detection algorithms applied to solar data: i) image pre-processing procedures, ii) automated detection of spatial features, iii) automated detection and tracking of temporal features (events), and iv) post-processing tasks, such as visualization of solar imagery, cataloguing, statistics, theoretical modeling, prediction, and forecasting. For each aspect the most recent developments and science results are highlighted. We conclude with an outlook on future trends.  相似文献   

Precision spacecraft navigation using a low-cost GPS receiver   总被引：1，自引：1，他引：0  

Oliver Montenbruck  Paul Swatschina  Markus Markgraf  Stefano Santandrea  Joris Naudet  Etienne Tilmans 《GPS Solutions》2012,16(4):519-529

Within the PROBA-2 microsatellite mission, a miniaturized single-frequency GPS receiver based on commercial-off-the-shelf (COTS) technology is employed for onboard navigation and timing. A rapid electronic fuse protects against destructive single-event latch-ups (SEL) and enables a quasi-continuous receiver operation despite the inherent sensitivity to space radiation. While limited to single-frequency C/A-code tracking with a narrow-band frontend, the receiver is able to provide precision navigation services through processing of raw GPS measurements on ground as well as a built-in real-time navigation system. In both cases, ionospheric path delays are eliminated through a combination of L1 pseudorange and carrier phase measurements, which also offers a factor-of-two noise reduction relative to code-only processing. By comparison with satellite laser ranging (SLR) measurements, a 0.3-m (3D rms) accuracy is demonstrated for the PROBA-2 reduced dynamic orbit determinations using post-processed GPS orbit and clock products. Furthermore, the experimental onboard navigation system is shown to provide real-time position information with a 3D rms accuracy of about 1?m, which notably outperforms the specification of the Standard Positioning Service (SPS). In view of their lower hardware complexity, mass budget and power requirements as well as the reduced interference susceptibility, legacy C/A-code receivers can thus provide an attractive alternative to dual-frequency receivers even for demanding navigation applications in low Earth orbit.  相似文献