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  • 2025-2025  (10)
  • 2020-2022  (1,819)
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  • 1
    Publication Date: 2024-05-29
    Description: Media inform the public, thereby influencing societal debates and political decisions. Despite climate change’s importance, drivers of media attention to climate change remain differently understood. Here we assess how different sociopolitical and extreme weather events affect climate change media coverage, both immediately and in the weeks following the event. To this end, we construct a data set of over 90,000 climate change articles published in nine major German newspapers over the past three decades and apply fixed effects panel regressions to control for confounders. We find that United Nations Climate Change Conferences affect coverage most strongly and most persistently. Climate protests incite climate coverage that extends well beyond the reporting on the event itself, whereas many articles on weather extremes do not mention climate change. The influence of all events has risen over time, increasing the media prominence of climate change.
    Language: English
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  • 2
    Journal available for loan
    Journal available for loan
    Tübingen : Mohr Siebeck ; 1.1884 - 48.1931; N.F. 1.1932/33 - 10.1943/44(1945),3; 11.1948/49(1949) -
    Call number: ZS 22.95039
    Type of Medium: Journal available for loan
    Pages: Online-Ressource
    ISSN: 1614-0974 , 0015-2218 , 0015-2218
    Language: German , English
    Note: N.F. entfällt ab 57.2000. - Volltext auch als Teil einer Datenbank verfügbar , Ersch. ab 2000 in engl. Sprache mit dt. Hauptsacht.
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  • 3
    Publication Date: 2021-12-23
    Description: The target of zero emissions sets a new standard for industry and industrial policy. Industrial policy in the twenty-first century must aim to achieve zero emissions in the energy and emissions intensive industries. Sectors such as steel, cement, and chemicals have so far largely been sheltered from the effects of climate policy. A major shift is needed, from contemporary industrial policy that mainly protects industry to policy strategies that transform the industry. For this purpose, we draw on a wide range of literatures including engineering, economics, policy, governance, and innovation studies to propose a comprehensive industrial policy framework. The policy framework relies on six pillars: directionality, knowledge creation and innovation, creating and reshaping markets, building capacity for governance and change, international coherence, and sensitivity to socio-economic implications of phase-outs. Complementary solutions relying on technological, organizational, and behavioural change must be pursued in parallel and throughout whole value chains. Current policy is limited to supporting mainly some options, e.g. energy efficiency and recycling, with some regions also adopting carbon pricing, although most often exempting the energy and emissions intensive industries. An extended range of options, such as demand management, materials efficiency, and electrification, must also be pursued to reach zero emissions. New policy research and evaluation approaches are needed to support and assess progress as these industries have hitherto largely been overlooked in domestic climate policy as well as international negotiations.
    Keywords: ddc:300
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
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  • 4
    Publication Date: 2021-12-23
    Description: Hydrological transformations induced by climate warming are causing Arctic annual fluvial energy to shift from skewed (snowmelt-dominated) to multimodal (snowmelt- and rainfall-dominated) distributions. We integrated decade-long hydrometeorological and biogeochemical data from the High Arctic to show that shifts in the timing and magnitude of annual discharge patterns and stream power budgets are causing Arctic material transfer regimes to undergo fundamental changes. Increased late summer rainfall enhanced terrestrial-aquatic connectivity for dissolved and particulate material fluxes. Permafrost disturbances (〈3% of the watersheds’ areal extent) reduced watershed-scale dissolved organic carbon export, offsetting concurrent increased export in undisturbed watersheds. To overcome the watersheds’ buffering capacity for transferring particulate material (30 ± 9 Watt), rainfall events had to increase by an order of magnitude, indicating the landscape is primed for accelerated geomorphological change when future rainfall magnitudes and consequent pluvial responses exceed the current buffering capacity of the terrestrial-aquatic continuum.
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  • 5
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    GFZ Data Services
    Publication Date: 2021-12-23
    Description: Definitive digital values of the Earth's magnetic field recorded from 1991 to 2015 at INTERMAGNET observatories around the world. Data includes minute, hourly and daily vector values, along with observatory baseline values for quality control. Annual means are also included. All data is included on the single downloadable archive file (gzipped tar format) available from this landing page. This is the 25th annual publication in the series. Some national data institutions may have related DOIs that describe subsets of the data. These DOIs are shown under "Related DOIs to be quoted". For more information on the data formats used in this publication and the technical standards used to create the data, please refer to the INTERMAGNET Technical Manual and the Technical note TN6 "INTERMAGNET Definitive One-second Data Standard".
    Language: English
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  • 6
    Publication Date: 2021-12-23
    Description: Earthquakes are major hazards to humans, buildings and infrastructure. Early warning methods aim to provide advance notice of incoming strong shaking to enable preventive action and mitigate seismic risk. Their usefulness depends on accuracy, the relation between true, missed and false alerts, and timeliness, the time between a warning and the arrival of strong shaking. Current approaches suffer from apparent aleatoric uncertainties due to simplified modelling or short warning times. Here we propose a novel early warning method, the deep-learning based transformer earthquake alerting model (TEAM), to mitigate these limitations. TEAM analyzes raw, strong motion waveforms of an arbitrary number of stations at arbitrary locations in real-time, making it easily adaptable to changing seismic networks and warning targets. We evaluate TEAM on two regions with high seismic hazard, Japan and Italy, that are complementary in their seismicity. On both datasets TEAM outperforms existing early warning methods considerably, offering accurate and timely warnings. Using domain adaptation, TEAM even provides reliable alerts for events larger than any in the training data, a property of highest importance as records from very large events are rare in many regions.
    Language: English
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  • 7
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    In:  IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
    Publication Date: 2021-12-23
    Description: The Tianjin coastal region in Bohai Bay, Northern China, is increasingly affected by storm-surge flooding which is exacerbated by anthropogenic land subsidence and global sea-level rise (SLR). We use a combination of InSAR (Synthetic Aperture Radar Interferometry), CGPS (continuous GPS), and tide-gauge observations to evaluate the spatial variability of relative SLR (RSLR) along the coastline of Tianjin. Land motion obtained by integration of two tracks of Sentinel-1 SAR images and nineteen CGPS stations shows that the recent land subsidence in Tianjin downtown is less than 8 mm/yr, which has significantly decreased with respect to the last 50 years (up to 110 mm/yr in the 1980s). This might benefit from the South-to-North Water Transfer Project which has provided more than 1.8 billion cubic meters of water for Tianjin city since 2014 and reduced groundwater consumption. However, subsidence centers have shifted to suburbs, especially along the coastline dominated by reclaimed harbors and aquaculture industry, with localized subsidence up to 170 mm/yr. Combining InSAR observations with sea level records from tide-gauge stations reveals spatial variability of RSLR along the coastline. We find that, in the aquaculture zones along the coastline, the rates of land subsidence are as high as 82 mm/yr due to groundwater extraction for fisheries, which subsequently cause local sea levels to rise nearly 30 times faster than the global average. New insights into land subsidence and local sea-level rise could help the countrys regulators to make decisions on ensuring the sustainable development of the coastal aquaculture industry.
    Language: English
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  • 8
    Publication Date: 2021-12-22
    Description: Wetland methane (CH4) emissions (FCH4) are important in global carbon budgets and climate change assessments. Currently, FCH4 projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent FCH4 temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that FCH4 are often controlled by factors beyond temperature. Here, we evaluate the relationship between FCH4 and temperature using observations from the FLUXNET-CH4 database. Measurements collected across the globe show substantial seasonal hysteresis between FCH4 and temperature, suggesting larger FCH4 sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH4 production are thus needed to improve global CH4 budget assessments.
    Language: English
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  • 9
    Publication Date: 2021-12-22
    Description: The regional research network Water in Central Asia (CAWa) funded by the German Federal Foreign Office consists of 18 remotely operated multi-parameter stations (ROMPSs) in Central Asia. These stations were installed by the German Research Centre for Geosciences (GFZ) in Potsdam, Germany, in close cooperation with the Central-Asian Institute for Applied Geosciences (CAIAG) in Bishkek, Kyrgyzstan; the national hydrometeorological services in Tajikistan and Uzbekistan; the Ulugh Beg Astronomical Institute in Tashkent, Uzbekistan; and the Kabul Polytechnic University, Afghanistan. The primary objective of these stations is to support the establishment of a reliable data basis of meteorological and hydrological data especially in remote areas with extreme climate conditions for applications in climate and water monitoring in Central Asia. Up to now, 10 years of data have been provided for an area of scarce station distribution and with limited open-access data which can be used for a wide range of scientific or engineering applications. The data described in this paper are made publicly available with the digital object identifier (DOI) https://doi.org/10.5880/GFZ.1.2.2020.002 (Zech et al., 2020) or via the Sensor Data Storage System (SDSS) at http://sdss.caiag.kg (last access: 22 February 2021).
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  • 10
    Publication Date: 2021-12-22
    Description: Weathering and oxidation of sulphide minerals in mine wastes release toxic elements in surrounding environments. As an alternative to traditional sampling and chemical analysis methods, the capability of proximal and remote sensing techniques was investigated in this study to predict Chromium (Cr) concentration in 120 soil samples collected from a dumpsite in Sarcheshmeh copper mine, Iran. The samples’ mineralogy and Cr concentration were determined and were then subjected to laboratory reflectance spectroscopy in the range of Visible–Near Infrared–Shortwave Infrared (VNIR–SWIR: 350–2500 nm). The raw spectra were pre-processed using Savitzky-Golay First-Derivative (SG-FD) and Savitzky-Golay Second-Derivative (SG-SD) algorithms. The important wavelengths were determined using Partial Least Squares Regression (PLSR) coefficients and Genetic Algorithm (GA). Artificial Neural Networks (ANN), Stepwise Multiple Linear Regression (SMLR) and PLSR data mining methods were applied to the selected spectral variables to assess Cr concentration. The developed models were then applied to the selected bands of Aster, Hyperion, Sentinel-2A, and Landsat 8-OLI satellite images of the area. Afterwards, rasters obtained from the best prediction model were segmented using a binary fitness function. According to the outputs of the laboratory reflectance spectroscopy, the highest prediction accuracy was obtained using ANN applied to the SD pre-processed spectra with R2 = 0.91, RMSE = 8.73 mg/kg and RPD = 2.76. SD-ANN also showed an acceptable performance on mapping the spatial distribution of Cr using the ordinary kriging technique. Using satellite images, SD-SMLR provided the best prediction models with R2 values of 0.61 and 0.53 for Hyperion and Sentinel-2A, respectively. This led to the higher visual similarity of the segmented Hyperion and Sentinel-2A images with the Cr distribution map. This study’s findings indicated that applying the best prediction models obtained by spectroscopy to the selected wavebands of Hyperion and Sentinel-2A satellite imagery could be considered a promising technique for rapid, cost-effective and eco-friendly assessment of Cr concentration in highly heterogeneous mining areas.
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  • 11
    Publication Date: 2021-12-22
    Description: It is widely hypothesised that primeval life utilised small organic molecules as sources of carbon and energy. However, the presence of such primordial ingredients in early Earth habitats has not yet been demonstrated. Here we report the existence of indigenous organic molecules and gases in primary fluid inclusions in c. 3.5-billion-year-old barites (Dresser Formation, Pilbara Craton, Western Australia). The compounds identified (e.g., H2S, COS, CS2, CH4, acetic acid, organic (poly-)sulfanes, thiols) may have formed important substrates for purported ancestral sulfur and methanogenic metabolisms. They also include stable building blocks of methyl thioacetate (methanethiol, acetic acid) – a putative key agent in primordial energy metabolism and thus the emergence of life. Delivered by hydrothermal fluids, some of these compounds may have fuelled microbial communities associated with the barite deposits. Our findings demonstrate that early Archaean hydrothermal fluids contained essential primordial ingredients that provided fertile substrates for earliest life on our planet.
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  • 12
    Publication Date: 2021-12-22
    Description: The Northern Chilean subduction zone is characterized by long-term subduction erosion with very little sediment input at the trench and the lack of an accretionary prism. Here, multichannel seismic reflection (MCS) data were acquired as part of the CINCA (Crustal Investigations off- and onshore Nazca Plate/Central Andes) project in 1995. These lines cover among others the central part of the MW 8.1 Iquique earthquake rupture zone before the earthquake occurred on 1 April 2014. We have re-processed one of the lines crossing the updip parts of this earthquake at 19°40′S, close to its hypocentre. After careful data processing and data enhancement, we applied a coherency-based pre-stack depth migration algorithm, yielding a detailed depth image. The resulting depth image shows the subduction interface prior to the Iquique megathrust earthquake down to a depth of approximately 16 km and gives detailed insight into the characteristics of the seismogenic coupling zone. We found significantly varying interplate reflectivity along the plate interface which we interpret to be caused by the comparably strong reflectivity of subducted fluid-rich sediments within the grabens and half-grabens that are predominant in this area due to the subduction-related bending of the oceanic plate. No evidence was found for a subducted seamount associated to the Iquique Ridge along the slab interface at this latitude as interpreted earlier from the same data set. By comparing relocated fore- and aftershock seismicity of the Iquique earthquake with the resulting depth image, we can divide the continental wedge into two domains. First, a frontal unit beneath the lower slope with several eastward dipping back-rotated splay faults but no seismicity in the upper plate as well as along the plate interface. Secondly, a landward unit beneath the middle slope with differing reflectivity that shows significant seismicity in the upper plate as well as along the plate interface. Both units are separated by a large eastward dipping mega splay fault, the root zone of which shows diffuse seismicity, both in the upper plate and at the interface. The identification of a well-defined nearly aseismic frontal unit sheds new light on the interplate locking beneath the lower continental slope and its controls.
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  • 13
    Publication Date: 2021-12-22
    Description: Global seismicity models provide scientific hypotheses about the rate, location and magnitude of future earthquakes to occur worldwide. Given the aleatory variability of earthquake activity and epistemic uncertainties in seismicity forecasting, the veracity of these hypotheses can only be confirmed or rejected after prospective forecast evaluation. In this study, we present the construction of and test results for two updated global earthquake models, aimed at providing mean estimates of shallow (d ≤ 70 km) seismicity for seismic hazard assessment. These approaches, referred to as the Tectonic Earthquake Activity Model (TEAM) and the World Hybrid Earthquake Estimates based on Likelihood scores (WHEEL) model, use the Subduction Megathrust Earthquake Rate Forecast (SMERF2), an earthquake-rate model for subduction zones constrained by geodetic strain measurements and earthquake-catalogue information. Thus, these global ensemble seismicity models capture two independent components necessary for long-term earthquake forecasting, namely interseismic crustal strain accumulation and sudden lithospheric stress release. The calibration period for TEAM and WHEEL extends from 1977 January 1 to 2013 December 31. Accordingly, we use m ≥ 5.95 earthquakes recorded during the 2014–2019 period to pseudo-prospectively evaluate the forecasting skills of these earthquake models, and statistically compare their performances to that of the Global Earthquake Activity Rate (GEAR1) model. As a result, GEAR1 and WHEEL are the most informative global seismicity models during the pseudo-prospective test period, as both rank with the highest information scores among all participant earthquake-rate forecasts. Nonetheless, further prospective evaluations are required to more accurately assess the abilities of these global ensemble seismicity models to forecast long-term earthquake activity.
    Language: English
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  • 14
    Publication Date: 2021-12-22
    Description: In this study, we investigate numerically the hydro-mechanical behavior of fractured crystalline rock due to one of the five hydraulic stimulations at the Pohang Enhanced Geothermal site in South Korea. We use the commercial code FracMan (Golder Associates) that enables studying hydro-mechanical coupled processes in fractured media in three dimensions combining the finite element method with a discrete fracture network. The software is used to simulate fluid pressure perturbation at fractures during hydraulic stimulation. Our numerical simulation shows that pressure history matching can be obtained by partitioning the treatment into separate phases. This results in adjusted stress-aperture relationships. The evolution of aperture adjustment implies that the stimulation mechanism could be a combination of hydraulic fracturing and shearing. The simulated extent of the 0.01 MPa overpressure contour at the end of the treatment equals to ∼180 m around the injection point.
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  • 15
    Publication Date: 2021-12-22
    Description: On October 9, 2014, a Mw 7.1–6.7 seismic doublet occurred at the Juan Fernández microplate, close to the triple junction with Pacific and Nazca plates. The Mw 7.1 earthquake is the largest earthquake ever to have been recorded in the region. Its thrust focal mechanism is also unusual for the region, although the northern part of the microplate is expected to undergo compression. The region is remote and seismological data is limited to a seismic station at ~600 km distance on Easter Island and teleseismic observations for the largest events. We use a combination of advanced seismological techniques to overcome the lack of local data and resolve earthquake source parameters for the doublet and its aftershock sequence, being able to reconstruct the chronology of the sequence and the geometry of affected fault segments. Our results depict a complex seismic sequence characterized by the interplay of thrust and strike-slip earthquakes along different structures, including a second, reversed strike slip-thrust seismic doublet in November 2014. Seismicity occurred within the microplate and only in the late part of the sequence migrated northward, towards the microplate boundary. The first largest doublet, whose rupture kinematic is well explained by stress changes imparted by the first subevent on the second one, may have activated unmapped E-W and NE-SW faults or an internal curved pseudofault, attributed to the long-term rotation of the microplate. Few large, thrust earthquakes are observed within the sequence, taking place in the vicinity of mapped compressional ridges. We suggest that compressional stresses in the northern part of the microplate and at its boundary are partially accommodated aseismically. However, the occasional occurrence of large, impulsive thrust earthquakes, with a considerable tsunamigenic potential, poses a relevant hazard for islands in the South Pacific region.
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  • 16
    Publication Date: 2021-12-22
    Description: The cubic diamond (Fd‐3m)group IVA element Si has been the material driver of the electronics industry since its inception. We report synthesis of a new cubic (Im‐3m) group IVA material, a GeSn solid solution, upon heating Ge and Sn at pressures from 13 to 28 GPa using double‐sided diamond anvil laser‐heating and large volume press methods. Both methods were coupled with in‐situ angle dispersive X‐ray diffraction characterization. The new material substantially enriches the seminal group IVA alloy materials landscape by introducing an eightfold coordinated cubic symmetry, which markedly expands on the conventional tetrahedrally coordinated cubic one. This cubic solid solution is formed, despite Ge never adopting the Im‐3m symmetry, melting inhibiting subsequent Im‐3m formation and reactant Ge and Sn having unlike crystal structures and atomic radii at all these pressures. This is hence achieved without adherence to conventional formation criteria and routes to synthesis. This advance creates fertile avenues for new materials development.
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  • 17
    Publication Date: 2021-12-22
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  • 18
    Publication Date: 2021-12-22
    Description: On the basis of Monte Carlo simulations, configurations and pair and triplet correlation functions for a Lennard-Jones fluid are reported over a large range of densities and temperatures (0.002 ≤ ρ* ≤ 1.41 and 0.45 ≤ T* ≤ 25, dimensionless). In total, data for 27 615 ρ*–T*-state points including 750 configurations for each state point are used for the calculation of the pair and triplet correlation functions. For the pair configuration function, an approximation over the whole set of state points is provided, which reproduces the pair configuration with high accuracy (3σ 〈 0.0075). The results for the triplet configuration functions are compared to the Kirkwood superposition approximation. With the exception of low ρ* (〈0.3), the application of the Kirkwood superposition approximation seems not to be a proper choice, showing errors 〉20%. The configurations and pair and triplet correlation functions of all simulations are openly accessible and can be used as a reference for future theoretical developments of Lennard-Jones fluids and, especially, the liquid state.
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  • 19
    Publication Date: 2021-12-22
    Description: As society transitions to low-carbon, renewable energy resources, the demand for metals and minerals is set to increase. Massive quantities of base metals and mineral materials (for example, silica and concrete) along with smaller quantities of precious metals will be required for the construction of wind turbines, solar panels and battery storage facilities to meet the demands of the ‘Electric Planet’ of the future. Harnessing microbe-mineral-metal interactions may offer many opportunities to improve some mining practises and support the long-term sustainability of mining. As easily exploitable, high-grade deposits are becoming increasingly depleted there is a need for new technologies to improve exploration and mining strategies. Microorganisms are ubiquitous and diverse, surviving in almost all environments in the Earth's crust and recent advances in molecular techniques have enabled scientists to study these communities is extraordinary detail. Microorganisms also interact directly with their environment; both responding to and changing the environment around them. These responses and their influences on the surrounding environment are preserved within their genome (a complete set of the DNA of the microorganism). Here, we discuss using state-of-the-art sequencing techniques to identify key microbial genes that have been demonstrated to correlate with metal concentrations. These genetic-based bioindicators may provide additional tools to guide and improve the success rate of mineral exploration programmes. Advances in molecular techniques will also improve existing biohydrometallurgical techniques and expand the commodity range for which biohydrometallurgy are currently economically viable. Finally, microorganisms may be used in a number of strategies for mine remediation; specifically, we review in detail microbially accelerated carbon capture and storage strategies and mine waste stabilisation.
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  • 20
    Publication Date: 2021-12-21
    Description: In a joint project called OMEGA, between GFZ-Potsdam and the Istituto Nazionale di Geofisica e Vulcanologia (INGV), an experimental seismic monitoring system was installed in 2015 near the power plants of the geothermal area of Mt. Amiata (central Italy). The main objectives of this three-year experiment are: i) to monitor the seismic activity connected to any type of seismicity inside the geothermal field, ii) to verify if the low local seismicity rate near Mt. Amiata reported by the INGV bulletin is natural, or due to the sparse distribution of the INGV network, and iii) to discriminate natural from possibly induced seismicity. The eight-station network was extended by a sevenelement seismic array for the first four weeks. The aim of this paper is to present the first automatic hypocentre locations of the joint network/array analysis.
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  • 21
    Publication Date: 2021-12-21
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  • 22
    Publication Date: 2021-12-21
    Description: Rare earths and yttrium (REY) distribution patterns of the hydrosphere reveal systematic correlations of Gd and Y anomalies besides the non-correlated redox-dependent Ce and Eu anomalies. Eu anomalies are inherited by dissolution of feldspars in igneous rocks, whereas Ce, Gd and Y anomalies develop in aqueous systems in contact with minerals and amorphous matter. Natural, positive Gd and Y anomalies in REY patterns characterize high-salinity fluids from the Dead Sea, Israel/Jordan, the Great Salt Lake, USA, the Aral Sea, Kazakhstan/Uzbekistan, ground- and surface water worldwide. Extreme Gd anomalies mostly originate from anthropogenic sources. The correlation of Gd and Y anomalies at low temperature in water bodies differ from geothermal ones. In nature, dynamic systems prevail in which either solids settle in water columns or water moves through permeable sediments or sedimentary rocks. In both cases, the anomalies in water develop due to repeated equilibration with solid matter. Thus, these anomalies provide information about the hydrological history of seawater, fresh groundwater and continental brines. When migrating, the interaction of aqueous phases with mineral surfaces leads to increasing anomalies because the more hydrophillic Gd and Y preferentially remain in the aqueous phase compared to their nearest neighbors. The correlation coefficients between Gd and Y anomalies in groundwater is 0.5–0.9. In lakes and oceans, it is about 0.1–0.8, under anomalous conditions it can increase to 1.
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  • 23
    Publication Date: 2021-12-21
    Description: The computational costs associated with coupled reactive transport simulations are mostly due to the chemical subsystem: replacing it with a pre-trained statistical surrogate is a promising strategy to achieve decisive speedups at the price of small accuracy losses and thus to extend the scale of problems which can be handled. We introduce a hierarchical coupling scheme in which “full-physics” equation-based geochemical simulations are partially replaced by surrogates. Errors in mass balance resulting from multivariate surrogate predictions effectively assess the accuracy of multivariate regressions at runtime: inaccurate surrogate predictions are rejected and the more expensive equation-based simulations are run instead. Gradient boosting regressors such as XGBoost, not requiring data standardization and being able to handle Tweedie distributions, proved to be a suitable emulator. Finally, we devise a surrogate approach based on geochemical knowledge, which overcomes the issue of robustness when encountering previously unseen data and which can serve as a basis for further development of hybrid physics–AI modelling.
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  • 24
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    GFZ German Research Centre for Geosciences
    Publication Date: 2021-12-21
    Description: MAARE is an interdisciplinary research initiative to enhance our understanding of magma ascent, accumulation and reservoir evolution in intra-continental settings. Examples of core questions addressed by the MAARE research initiative comprise: · What are past and current conditions in transcrustal magmatic reservoirs at different depths? · How do magmatic fluids migrate through the crust and how do they trigger reservoir unrest? · What are the spatio-temporal controls on volcanism in low-flux systems? · What are realistic eruption scenarios and forecast uncertainties in low probability, high impact volcanic regions? · How can distributed volcanic fields be monitored in a comprehensive manner and how can small precursory signals reliably be interpreted? · What are pitfalls in communicating volcanic hazard research and risk? The aim of the lecture series is to develop a common understanding of the key questions, to develop new ideas and to initiate joint research projects.
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  • 25
    Publication Date: 2021-12-21
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  • 26
    Publication Date: 2021-12-20
    Description: The save and effective storage of hydrogen in geological formations is an important part towards the implementation of renewable energy use. Due to fluctuating power supply from wind or solar plants, it is envisaged to use excess energy for electrolytical hydrogen production and the subsequent temporary storage in geological formations, as buffer for energy at “high-demand-low-production-times”. The preferred geological storage formations are either salt deposits or porous sandstones with a gas-tight caprock. To date, these formations are generally confirmed to be appropriate for natural gas storage. However, the deviant physical properties of hydrogen, in terms of density, viscosity and hence mobility, require a reassessment of migration characteristics in these rocks. For this purpose, an experimental set-up was designed, constructed and tested to quantify hydrogen migration rates in rocks. It comprises two gas chambers, separated by a through flange, containing the epoxy-embedded sample section with an exposed area of 7 cm². The retentate chamber is filled with a gas mixture of 2 Vol% hydrogen in synthetic air at 0.1 MPa. The permeate chamber contains air and includes an amperometric hydrogen sensor. Since there is no pressure gradient, the driving force for hydrogen movement is solely the concentration gradient between both sides of the rock sample. The hydrogen break-through and transport rates are monitored. In initial tests, core pieces of various length of sandstone and salt at dry and wet conditions are employed. The results approve the functional capability of the set-up and allow for a first-approach characterisation of hydrogen gas transport.
    Language: English
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  • 27
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    Unknown
    In:  Multidisciplinary Mathematical Modelling : Applications of Mathematics to the Real World | SEMA SIMAI Springer Series
    Publication Date: 2021-12-20
    Description: Power-law-type distributions are extensively found when studying the behavior of many complex systems. However, due to limitations in data acquisition, empirical datasets often only cover a narrow range of observations, making it difficult to establish power-law behavior unambiguously. In this work, we present a statistical procedure to merge different datasets, with two different aims. First, we obtain a broader fitting range for the statistics of different experiments or observations of the same system. Second, we establish whether two or more different systems may belong to the same universality class. By means of maximum likelihood estimation, this methodology provides rigorous statistical information to discern whether power-law exponents characterizing different datasets can be considered equal to each other or not. This procedure is applied to the Gutenberg–Richter law for earthquakes and for synthetic earthquakes (acoustic emission events) generated in the laboratory: labquakes (Navas-Portella et al. Phys Rev E 100:062106, 2019).
    Language: English
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  • 28
    Publication Date: 2021-12-20
    Description: We investigate permafrost surface features revealed from satellite radar data in the Siberian arctic at the Yamal peninsula. Surface dynamic analysis based on SRTM and TanDEM-X DEMs show up to 2 m net loss of surface relief between 2000 and 2014 indicating a highly dynamic landscape. Surface features for the past 14 years reflect an increase of small stream channels and a number of new lakes that developed, likely caused by permafrost thaw. We used Sentinel-1 SAR imagery to measure permafrost surface changes. Due to limited observation data we analyzed only two years. The InSAR time-series has detected surface displacements in three distinct spatial locations during 2017 and 2018. At these three locations, 60-120 mm/yr rates of seasonal surface permafrost changes are observed. Spatial location of seasonal ground displacements align well with lithology. One of them is located on marine sediments and is linked to anthropogenic impact on permafrost stability. Two other areas are located within alluvial sediments and are at the top of topographic elevated zones. We discuss the influence of the geologic environment and the potential effect of local upwelling of gas. This combined analyses of InSAR time series with analysis of geomorphic features from DEMs present an important tool for continuous process monitoring of surface dynamics as part of a global warming risk assessment.
    Language: English
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  • 29
    Publication Date: 2021-12-20
    Description: Using E-W and vertical deformation-rate maps derived from radar interferometric time-series, we analyze the deformation field of an entire orogenic segment, i.e., the Tajik depression and its adjoining mountain belts, Tian Shan, Pamir, and Hindu Kush. The data-base consists of 900+ radar scenes acquired over 2.0–4.5 years and global navigation satellite system measurements. The recent, supra-regional kinematics is visualized in an unprecedented spatio-temporal resolution. We confirm the westward collapse of the Pamir-Plateau crust, inverting the Tajik basin into a fold-thrust belt with shortening rates decaying westward from ∼15 to 2 mm/yr. Vertical rates in the Hindu Kush likely record slab-dynamic effects, i.e., the progressive break-off of the Hindu Kush slab. At least 10 mm/yr of each, uplift and westward motion occur along the western edge of the Pamir Plateau, outlining the crustal-scale ramp along which the Pamir Plateau overrides the Tajik depression. The latter shows a combination of basin-scale tectonics, halokinesis, and seasonal/weather-driven near-surface effects. Abrupt ∼6 mm/yr horizontal-rate changes occur across the kinematically-linked dextral Ilyak strike-slip fault, bounding the Tajik fold-thrust belt to the north, and the Babatag backthrust, the major thrust of the fold-thrust belt, located far west in the belt. The sharp rate decay across the Ilyak fault indicates a locking depth of ≤1 km. The Hoja Mumin salt fountain is spreading laterally at ≤350 mm/yr. On the first-order, the modern 20–5 and fossil (since ∼12 Ma) 12–8 mm/yr shortening rates across the fold-thrust belt correspond.
    Language: English
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  • 30
    Publication Date: 2021-12-17
    Description: This paper aims to study the effect of silver nanoparticles on the kinetics of CO2 hydrate growth at different P-T conditions using the molecular dynamics (MD) technique.Three nanofluid models containing 2, 4 and 6 nanoparticles (NPs) as well as a base model (without NPs) were designed to study the effect of nanoparticle concentration on the gas hydrate system. The profiles of potential energy (PE), mean squared displacement (MSD) and density along the simulation box, and the number of CO2 molecules at the hydrate-liquid interfaces, diffusion coefficient, three-body structural order (F3) and also radial distribution function (RDF) were calculated from the simulation. The results revealed that the rate of hydrate growth increases as the temperature increases from 250 K to 260 K at a constant pressure of 30 MPa. A similar trend was also achieved for decreasing the pressure from 30 MPa to 15 MPa at constant temperature of 250 K, however, increasing the temperature to 270 K at 30 MPa decreased again the growth rate.Among the simulation models, the 2-NP fluid model at 260 K and 30 MPa was found to have the highest hydrate growth rate. It was found that nanoparticles have several impacts on the CO2 hydrate system as follows: they could lower the potential energy of the system, increase the peak’s height of the carbon–oxygen and carbon–carbon RDFs, facilitate CO2 dissolution, enhance the diffusion coefficient, and improve the migration of CO2 molecules from the bulk of the solution to the interfaces, and also could physically block the CO2 migration at high concentrations. Finally, form the RDF calculations, the results of our simulation are in good agreement with those reported in the literature with an average error of less than 10%.
    Language: English
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  • 31
    Publication Date: 2021-12-17
    Description: Micellization is one of the most challenging promotion mechanisms of surfactants for gas hydrate formation. Surfactants have been reported as the most efficient promoters for the formation of gas hydrates; however, their mechanism of action is not yet clear. The literature review reveals a major gap in the current knowledge for clarifying the effect of micellization on clathrate hydrate formation. Previous studies have mostly focused on hydrate formation in the presence of a special category of compounds that can form micelles, i.e., surfactants (in most cases, sodium dodecyl sulfate (SDS)). However, structures more complex than SDS have not been extensively studied. In other words, the changes in the surfactants’ molecular structure significantly alter their activity in the hydrate formation process. The current study aims to fill this gap by investigating a novel additive, i.e., waterborne polyurea/urethanes (WPUU), which can generate micelles at the hydrate forming temperature. The experimental results show that WPUUs have a surfactant property and form micelles at the hydrate forming temperature. Nonetheless, no promotion effect on methane hydrate formation was observed. The results of the molecular dynamic simulation confirm that WPUU inhibits gas hydrate formation due to its stronger proton-accepting hydrogen bond compared to water molecules. The results indicate that depending on the molecular structure of the additives, their micelles could have an inhibition effect on methane hydrate formation. Our findings present a molecular foundation to guide the molecular design of efficient hydrate inhibitors and promoters for flow assurance and gas storage applications. Moreover, they provide new insight into the inhibition mechanism of kinetic hydrate inhibitors.
    Language: English
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  • 32
    Publication Date: 2021-12-17
    Description: Given the potential importance of solar quiet (Sq) ionospheric current in geomagnetic field modeling, it is vital to obtain accurate parameters characterizing its variations, particularly the spatial and temporal variations. In this paper, we derived the Sq current function based on the spherical harmonic analysis (SHA) technique using a 14-year (2006–2019) quiet geomagnetic field record over the American sector. The empirical orthogonal function (EOF) analysis was then applied to deduce temporal and spatial variations of the Sq current. It is observed that the first EOF mode of the Sq current function is dominated by solar activity, while the second and third EOF modes exhibit annual and semiannual variations, respectively. Also, the artificial neural network (ANN) model of Sq current function was constructed to validate the EOF model predictions. While the Sq current intensity predicted by the ANN model is underestimated by 2.83%, the EOF model underpredicted the Sq current intensity by 1.92% relative to the observation. The root mean square error (RMSE) of the EOF model is 0.64 kA. This RMSE is about 79% smaller than that of the ANN model. In addition, both the EOF and ANN models capture the variation of the total Sq current (Jtotal) intensity with respect to solar activity. In principle, the EOF model had an optimal performance at nearly 98% accuracy, with the ANN model exhibiting almost the same degree of accuracy, which appears to be a reference point for ionospheric conditions when looking for space weather applications.
    Language: English
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  • 33
    Publication Date: 2021-12-17
    Description: Deportment data is essential for the planning of mining and minerals processing operations. This need is particularly tangible for deposits of noble metals, such as gold and silver. Therefore, the current paucity of published gold and silver deportment data for individual ore deposits and districts – and the concomitant lack of understanding how this relates to salient geological and mineralogical features of these deposits – is surprising. In the present study, we apply a combination of bulk geochemistry, laser ablation-inductively coupled plasma-mass spectrometry, electron microprobe analysis, and mineral liberation analysis to gold- and silver-rich samples from the epithermal Freiberg Ag-Pb-Zn district, to investigate variability in gold and silver deportments, as well as the corresponding geological/mineralogical controls. The results show that the main carriers of gold are electrum and arsenopyrite, whereas silver is mostly hosted by Ag-sulfosalts (pyrargyrite, miargyrite, polybasite) and fahlore (freibergite). Deportments vary greatly between samples. These variations can be related to the relative abundances of different minerals within the samples, which in turn reflect their spatio-temporal position within the district. Comparisons with other epithermal Ag-Pb-Zn districts similar to Freiberg indicate that the results presented here are of general significance.
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  • 34
    Publication Date: 2021-12-17
    Description: Density-driven dissolution of carbon dioxide in water is a well-known and much described mechanism in geological sequestration of this greenhouse gas. It is remarkable that such enhanced dissolution does not receive much attention in karst hydrology and speleology. Models and hypotheses on karst development are complex and consider many different processes. We focus here on the influence of CO2 partial gas pressures at the interface between atmosphere and karst water on the dynamics of dissolved CO2 concentrations below the water table. Seasonal variation of microbial soil activity and root respiration or barometric-pressure changes cause fluctuations in CO2 partial pressures. Dependent on the existence and strength of a karst-water background flow, fingering regimes might be triggered causing enhanced dissolution of CO2 This allows replenishment of CO2, and, thus, dissolutional power even deep in the water body without the need for percolating water to transport dissolved CO2. We present and discuss simplified and generic experimental and computational scenarios to strengthen our claim, and we try to give answers to: how much? and under which circumstances? The applied numerical model solves the Navier-Stokes equation with water density dependent on CO2 concentration and temperature. We show that calculated CO2 mass fluxes into the water bodies are dependent on the ratio of P\'{e}clet to Rayleigh numbers (Pe/Ra) and show a local minimum around Pe/Ra=1, i.e. when natural and forced convection are about equal. Concluding, we claim there is sufficient reason to consider density-driven dissolution as a process of relevance in karstification if circumstances are given.
    Language: English
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  • 35
    Publication Date: 2021-12-17
    Description: The current study presents a detailed assessment of risk zones related to karst collapse in Wuhan by analytical hierarchy process (AHP) and logistic regression (LR) models. The results showed that the LR model was more accurate with an area under the receiver operating characteristic (ROC) curve of 0.911 compared to 0.812 derived from the AHP model. Both models performed well in identifying high-risk zones with only a 3% discrepancy in area. However, for the medium- and low-risk classes, although the spatial distribution of risk zoning results were similar between two approaches, the spatial extent of the risk areas varied between final models. The reliability of both methods were reduced significantly by excluding the InSAR-based ground subsidence map from the analysis, with the karst collapse presence falling into the high-risk zone being reduced by approximately 14%, and karst collapse absence falling into the karst area being increased by approximately 6.5% on the training samples. To evaluate the practicality of using only results from ground subsidence maps for the risk zonation, the results of AHP and LR are compared with a weighted angular distortion (WAD) method for karst risk zoning in Wuhan. We find that the areas with relatively large subsidence horizontal gradient values within the karst belts are generally spatially consistent with high-risk class areas identified by the AHP- and LR-based approaches. However, the WAD-based approach cannot be used alone as an ideal karst collapse risk assessment model as it does not include geological and natural factors into the risk zonation.
    Language: English
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  • 36
    Publication Date: 2021-12-17
    Description: Monitoring the phenological development of agricultural plants is of high importance for farmers to adapt their management strategies and estimate yields. The aim of this study is to analyze the sensitivity of remote sensing features to phenological development of winter wheat and winter barley and to test their transferability in two test sites in Northeast Germany and in two years. Local minima, local maxima and breakpoints of smoothed time series of synthetic aperture radar (SAR) data of the Sentinel-1 VH (vertical-horizontal) and VV (vertical-vertical) intensities and their ratio VH/VV; of the polarimetric features entropy, anisotropy and alpha derived from polarimetric decomposition; as well as of the vegetation index NDVI (Normalized Difference Vegetation Index) calculated using optical data of Sentinel-2 are compared with entry dates of phenological stages. The beginning of stem elongation produces a breakpoint in the time series of most parameters for wheat and barley. Furthermore, the beginning of heading could be detected by all parameters, whereas particularly a local minimum of VH and VV backscatter is observed less then 5 days before the entry date. The medium milk stage can not be detected reliably, whereas the hard dough stage of barley takes place approximately 6–8 days around a local maximum of VH backscatter in 2018. Harvest is detected for barley using the fourth breakpoint of most parameters. The study shows that backscatter and polarimetric parameters as well as the NDVI are sensitive to specific phenological developments. The transferability of the approach is demonstrated, whereas differences between test sites and years are mainly caused by meteorological differences.
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  • 37
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    Unknown
    Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Publication Date: 2021-12-15
    Description: Cities and municipalities have had to endure a great deal in recent years, including a global coronavirus pandemic, fire disasters in the US and devastating floods like those in Germany. These are also consequences of anthropogenic climate change, and cities have to be better prepared for such events in future. In particular, the cata-strophic flooding Germany experienced in July 2021 demonstrated how ill-equipped municipalities are for this type of incident. In this paper, we look at how cities can become more resilient, sustainable and ready for the future.
    Keywords: ddc:300
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
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  • 38
    Publication Date: 2021-12-15
    Description: Life on Earth vitally depends on the availability of water. Human pressure on freshwater resources is increasing, as is human exposure to weather-related extremes (droughts, storms, floods) caused by climate change. Understanding these changes is pivotal for developing mitigation and adaptation strategies. The Global Climate Observing System (GCOS) defines a suite of essential climate variables (ECVs), many related to the water cycle, required to systematically monitor Earth’s climate system. Since long-term observations of these ECVs are derived from different observation techniques, platforms, instruments, and retrieval algorithms, they often lack the accuracy, completeness, and resolution, to consistently characterize water cycle variability at multiple spatial and temporal scales. Here, we review the capability of ground-based and remotely sensed observations of water cycle ECVs to consistently observe the hydrological cycle. We evaluate the relevant land, atmosphere, and ocean water storages and the fluxes between them, including anthropogenic water use. Particularly, we assess how well they close on multiple temporal and spatial scales. On this basis, we discuss gaps in observation systems and formulate guidelines for future water cycle observation strategies. We conclude that, while long-term water cycle monitoring has greatly advanced in the past, many observational gaps still need to be overcome to close the water budget and enable a comprehensive and consistent assessment across scales. Trends in water cycle components can only be observed with great uncertainty, mainly due to insufficient length and homogeneity. An advanced closure of the water cycle requires improved model–data synthesis capabilities, particularly at regional to local scales.
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  • 39
    Publication Date: 2021-12-15
    Description: In this study we performed a detailed analysis on the scale-size of field-aligned currents (FACs) at auroral latitudes, using the well-calibrated magnetic data from the non-dedicated magnetic field mission, Gravity Recovery and Climate Experiment Follow-On (GRACE-FO). With two spacecraft following each other, the GRACE-FO provides a good opportunity to identify the variation of FACs with different scale lengths. The results show that the auroral FACs can be classified into two groups: the small-scale ones, shorter than some tens of kilometers, dominated by kinetic Alfvén waves, are quite dynamic; and the large-scale ones, typically larger than 150 km, can be considered as quasi-static and persist longer than 1 min. The GRACE-FO observations also reveal that the small-scale FACs at the same location sometimes can persist over 25 s, e.g., around dusk and dawn hours, which is longer than the typical persistent period (10 s) of kinetic Alfvén waves as earlier reported. The FAC structures show clear magnetic local time dependence, with higher correlations between the spacecraft around dusk and dawn hours; lower correlations are found around midnight and lowest correlations around noon, implying that the small-scale FACs most frequently appear at the noon cusp region. Slightly better correlations of FACs between two spacecraft are found during local summer, and such seasonal dependence is dominated by the correlations of small-scale FACs at noon. However, further analysis shows that the small-scale FACs at noon have largest occurrence and intensity during local summer, which reveals that when interpreting the cross-correlation analysis the intensity of FACs needs to be taken into account.
    Language: English
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  • 40
    Publication Date: 2021-12-15
    Description: 1-D site response analysis dominates earthquake engineering practice, while local 2-D/3-D models are often required at sites where the site response is complex. For such sites, the 1-D representation of the soil column can account neither for topographic effects or dipping layers nor for locally generated horizontally propagating surface waves. It then remains a crucial task to identify whether the site response can be modelled sufficiently precisely by 1-D analysis. In this study we develop a method to classify sites according to their 1-D or 2-D/3-D nature. This classification scheme is based on the analysis of surface earthquake recordings and the evaluation of the variability and similarity of the horizontal Fourier spectra. The taxonomy is focused on capturing significant directional dependencies and interevent variabilities indicating a more probable 2-D/3-D structure around the site causing the ground motion to be more variable. While no significant correlation of the 1-D/3-D site index with environmental parameters and site proxies seems to exist, a reduction in the within-site (singlestation) variability is found. The reduction is largest (up to 20 per cent) for purely 1-D sites. Although the taxonomy system is developed using surface stations of the KiK-net network in Japan as considerable additional information is available, it can also be applied to any (non-downhole array) site.
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  • 41
    Publication Date: 2021-12-15
    Description: We conducted a systematic review and inventory of recent research achievements related to spaceborne and aerial Earth Observation (EO) data-driven monitoring in support of soil-related strategic goals for a three-year period (2019–2021). Scaling, resolution, data characteristics, and modelling approaches were summarized, after reviewing 46 peer-reviewed articles in international journals. Inherent limitations associated with an EO-based soil mapping approach that hinder its wider adoption were recognized and divided into four categories: (i) area covered and data to be shared; (ii) thresholds for bare soil detection; (iii) soil surface conditions; and (iv) infrastructure capabilities. Accordingly, we tried to redefine the meaning of what is expected in the next years for EO data-driven topsoil monitoring by performing a thorough analysis driven by the upcoming technological waves. The review concludes that the best practices for the advancement of an EO data-driven soil mapping include: (i) a further leverage of recent artificial intelligence techniques to achieve the desired representativeness and reliability; (ii) a continued effort to share harmonized labelled datasets; (iii) data fusion with in situ sensing systems; (iv) a continued effort to overcome the current limitations in terms of sensor resolution and processing limitations of this wealth of EO data; and (v) political and administrative issues (e.g., funding, sustainability). This paper may help to pave the way for further interdisciplinary research and multi-actor coordination activities and to generate EO-based benefits for policy and economy
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  • 42
    Publication Date: 2021-12-15
    Description: We propose the use of variable resolution boundaries based on central Voronoi tessellations (CVTs) to spatially aggregate building exposure models for risk assessment to various natural hazards. Such a framework is especially beneficial when the spatial distribution of the considered hazards presents intensity measures with contrasting footprints and spatial correlations, such as in coastal environments. This work avoids the incorrect assumption that a single intensity value from hazards with low spatial correlation (e.g. tsunami) can be considered to be representative within large-sized geo-cells for physical vulnerability assessment, without, at the same time, increasing the complexity of the overall model. We present decoupled earthquake and tsunami scenario-based risk estimates for the residential building stock of Lima (Peru). We observe that earthquake loss models for far-field subduction sources are practically insensitive to the exposure resolution. Conversely, tsunami loss models and associated uncertainties depend on the spatial correlations of the hazard intensities as well as on the resolution of the exposure models. We note that for the portfolio located in the coastal area exposed to both perils in Lima, the ground shaking dominates the losses for lowermagnitude earthquakes, whilst tsunamis cause the most damage for larger-magnitude events. For the latter, two sets of existing empirical flow depth fragility models are used, resulting in large differences in the calculated losses. This study, therefore, raises awareness about the uncertainties associated with the selection of fragility models and spatial aggregation entities for exposure modelling and loss mapping.
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  • 43
    Publication Date: 2021-12-15
    Description: Severe droughts caused unprecedented impacts on grasslands in Central Europe in 2018 and 2019. Yet, spatially varying drought impacts on grasslands remain poorly understood as they are driven by complex interactions of environmental conditions and land management. Sentinel-2 time series offer untapped potential for improving grassland monitoring during droughts with the required spatial and temporal detail. In this study, we quantified drought effects in a major Central European grassland region from 2017 to 2020 using a regression-based unmixing framework. The Sentinel-2-based intra-annual time series of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), and soil fractional cover provide easily interpretable quantities relevant for understanding drought effects on grasslands. Fractional cover estimates from Sentinel-2 matched in-situ conditions observed during field visits. The comparison to a multitemporal reference dataset showed the best agreement for PV cover (MAE = 7.2%). Agreement was lower for soil and NPV, but we observed positive relationships between fractional cover from Sentinel-2 and the reference data with MAE = 10.1% and MAE = 15.4% for soil and NPV, respectively. Based on the fractional cover estimates, we derived a Normalized Difference Fraction Index (NDFI) time series contrasting NPV and soil cover relative to PV. In line with meteorological and soil moisture drought indices, and with the Normalized Difference Vegetation Index (NDVI), NDFI time series showed the most severe drought impacts in 2018, followed by less severe, but persisting effects in 2019. Drought-specific metrics from NDFI time series revealed a high spatial variability of onset, duration, impact, and end of drought effects on grasslands. Evaluating drought metrics on different soil types, we found that grasslands on less productive, sandy Cambisols were strongly affected by the drought in 2018 and 2019. In comparison, grasslands on Gleysols and Histosols were less severely impacted suggesting a higher drought resistance of these grasslands. Our study emphasizes that the high temporal and spatial detail of Sentinel-2 time series is mandatory for capturing relevant vegetation dynamics in Central European lowland grasslands under drought.
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  • 44
    Publication Date: 2021-12-14
    Description: This compilation contains definitive digital values of the Earth's magnetic field recorded from 1991 to 2016 at INTERMAGNET observatories around the world. Data includes minute, hourly and daily vector values, along with observatory baseline values for quality control. Annual means are also included. All data is included on the single downloadable archive file (gzipped tar format) available from this landing page. Beginning with the publication of the definitive data for 2015, INTERMAGNET stopped publishing individual years of data and started publishing the entire, cumulative definitive data set since INTERMAGNET’s first recorded definitive data in 1991. This data set is known as the "INTERMAGNET Reference Data Set" (IRDS). The IRDS comprises all INTERMAGNET one-minute definitive data since 1991 and is annually updated with a new year and occasional corrections to previous releases. Some national data institutions may have related DOIs that describe subsets of the data. These DOIs are shown under "Related DOIs to be quoted". File names for IRDS data are formatted in the form mag〈year〉_def〈year〉.zip. The mag〈year〉 section of the filename describes the year in which the data was recorded. The def〈year〉 section of the filename describes the most recent annual INTERMAGNET publication in which the data was updated. Files where mag〈year〉 = def〈year〉 have had no corrections since their original publication. For example, "mag2015_def2016" indicates that this file is different from the first release "mag2015_def2015". For more information on the data formats used in this publication and the technical standards used to create the data, please refer to the INTERMAGNET Technical Manual.
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  • 45
    Publication Date: 2021-12-14
    Description: The 100 km wide Mérida Andes extend from the Colombian/Venezuelan border to the Caribbean coast. To the north and south, the Mérida Andes are bound by hydrocarbon-rich sedimentary basins. This mountain chain and its associated major strike-slip fault systems formed by the oblique convergence of the Caribbean with the South American Plate and the north-eastwards expulsion of the North Andean Block in western Venezuela. In 2013, the Integrated Geoscience of the Mérida Andes Project (the GIAME project) was initiated to image the Mérida Andes on a lithospheric scale and to develop a dynamic model of their evolution by integrating wide-angle seismic, magnetotelluric and potential field data. Magnetotelluric (MT) dataset was acquired in 2015 along a 240 km long profile across the Mérida Andes. MT studies of orogens often reveal complex resistivity structures, typically associated with active deformation and characterized by high electrical conductivity zones. Fluids in fault systems and fluids derived from remineralization reactions of hydrous minerals often characterise high conductivity in active tectonic regimes. Cruces-Zabala et al. (2020) identified conductive zones with up to 10 km depth for the Maracaibo Basin and 5 km for the Barinas - Apure Basin. The Mérida Andes are charaterized by high resistivity separated by several conductive anomalies that corelate spatialy to the fault systems at the surface. A conductive zone a great depth (〉50km) was identified as a projection of the detachment surface of the Trujillo Block to the east. This data publication encompasses a detailed report in pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
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  • 46
    Publication Date: 2021-12-14
    Description: This compilation contains definitive digital values of the Earth's magnetic field recorded from 1991 to 2017 at INTERMAGNET observatories around the world. Data includes minute, hourly and daily vector values, along with observatory baseline values for quality control. Annual means are also included. All data is included on the single downloadable archive file (gzipped tar format) available from this landing page. Beginning with the publication of the definitive data for 2015, INTERMAGNET stopped publishing individual years of data and started publishing the entire, cumulative definitive data set since INTERMAGNET’s first recorded definitive data in 1991. This data set is known as the "INTERMAGNET Reference Data Set" (IRDS). The IRDS comprises all INTERMAGNET one-minute definitive data since 1991 and is annually updated with a new year and occasional corrections to previous releases. Some national data institutions may have related DOIs that describe subsets of the data. These DOIs are shown under "Related DOIs to be quoted". File names for IRDS data are formatted in the form mag〈year〉_def〈year〉.zip. The mag〈year〉 section of the filename describes the year in which the data was recorded. The def〈year〉 section of the filename describes the most recent annual INTERMAGNET publication in which the data was updated. Files where mag〈year〉 = def〈year〉 have had no corrections since their original publication. For example, "mag2015_def2016" indicates that this file is different from the first release "mag2015_def2015". For more information on the data formats used in this publication and the technical standards used to create the data, please refer to the INTERMAGNET Technical Manual.
    Language: English
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  • 47
    Publication Date: 2021-12-14
    Description: Definitive digital values of the Earth's mangetic field recorded during 1991..2018 at INTERMAGNET observatories around the world. Data includes minute, hourly and daily vector values, along with observatory baseline values for quality control. Annual means are also included. All data is included on the single downloadable archive files. This is the 28th annual publication in the series. Beginning with the publication of the definitive data for 2015, INTERMAGNET stopped publishing individual years of data and started publishing the entire, cumulative definitive data set since INTERMAGNET’s first recorded definitive data in 1991. This data set is known as the "INTERMAGNET Reference Data Set" (IRDS). The IRDS comprises all INTERMAGNET one-minute definitive data since 1991 and is annually updated with a new year and occasional corrections to previous releases. Some national data institutions may have related DOIs that describe subsets of the data. These DOIs are shown under "Related DOIs to be quoted". File names for IRDS data are formatted in the form mag〈year〉_def〈year〉.zip. The mag〈year〉 section of the filename describes the year in which the data was recorded. The def〈year〉 section of the filename describes the most recent annual INTERMAGNET publication in which the data was updated. Files where mag〈year〉 = def〈year〉 have had no corrections since their original publication. For example, "mag2015_def2016" indicates that this file is different from the first release "mag2015_def2015". For more information on the data formats used in this publication and the technical standards used to create the data, please refer to the INTERMAGNET Technical Reference Manual. This mountain chain and its associated major strike-slip fault systems formed by the oblique convergence of the Caribbean with the South American Plate and the north-eastwards expulsion of the North Andean Block in western Venezuela. In 2013, the Integrated Geoscience of the Mérida Andes Project (the GIAME project) was initiated to image the Mérida Andes on a lithospheric scale and to develop a dynamic model of their evolution by integrating wide-angle seismic, magnetotelluric and potential field data. Magnetotelluric (MT) dataset was acquired in 2015 along a 240 km long profile across the Mérida Andes. MT studies of orogens often reveal complex resistivity structures, typically associated with active deformation and characterized by high electrical conductivity zones. Fluids in fault systems and fluids derived from remineralization reactions of hydrous minerals often characterise high conductivity in active tectonic regimes. Cruces-Zabala et al. (2020) identified conductive zones with up to 10 km depth for the Maracaibo Basin and 5 km for the Barinas - Apure Basin. The Mérida Andes are charaterized by high resistivity separated by several conductive anomalies that corelate spatialy to the fault systems at the surface. A conductive zone a great depth (〉50km) was identified as a projection of the detachment surface of the Trujillo Block to the east. This data publication encompasses a detailed report in pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
    Language: English
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  • 48
    Publication Date: 2021-12-14
    Description: This Arctic-Boreal CO2 fluxes (ABCflux) dataset contains monthly aggregates of terrestrial net ecosystem CO2 exchange and its derived partitioned component fluxes: gross primary productivity (GPP) and ecosystem respiration. Over 70 supporting variables describe key site conditions (e.g., vegetation and disturbance type), micrometeorological and environmental measurements (e.g., air and soil temperatures), and flux measurement techniques. The data contained in this ABCflux dataset form a standardized monthly database of Arctic-Boreal CO2 fluxes (i.e., ABCflux Database) and include 244 sites and 6,309 monthly observations; 136 sites and 2,217 monthly observations represent tundra, and 108 sites and 4,092 observations represent the boreal biome. The data are for the period 1989 to 2020.
    Language: English
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  • 49
    facet.materialart.
    Unknown
    GFZ Data Services
    Publication Date: 2021-12-13
    Description: RST-Stick-Slipy is a software that analyzes the stick-slip characteristics of granular material tested with the ring shear tester RST.pc01 at the Helmholtz Tectonic Laboratory for Tectonic Modelling (HelTec). This software uses the time series created by the machine to automatically detect slip events and analyses several statistical properties depending on the type of test. Using the detected slip events the reloading stiffness and other properties such as recurrence times and stress drops are calculated. Further statistical properties such as the timing and stress level of slow and fast events are determined. Another segment of the module automatically analyses Slide-Hold-Slide experiments and determines the healing rate and other rate-and-state properties.
    Language: English
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  • 50
    Publication Date: 2021-12-13
    Description: Evidence is accumulating about the impacts of plastics on marine life. The prevalence of plastics in seabird nests has been used as an indicator of levels of this pollutant in the ocean. However, the lack of a framework for defining sample sizes and errors associated with estimating the prevalence of plastic in nests prevents researchers from optimising time and reducing impacts of fieldwork. We present a method to determine the confidence intervals for the prevalence of debris in seabird nests and provide, for the first time, information on the prevalence of these items in nests of the Hartlaub’s gull Larus hartlaubii, the African penguin Spheniscus demersus, the great white pelican Pelecanus onocrotalus, and the white-breasted cormorant Phalacrocorax lucidus in South Africa. The method, based on observations and resampling simulations and tested here for nests of 12 seabird species from 15 locations worldwide, allows for straightforward hypothesis testing. Appropriate sample sizes can be defined by combining this method with a Bayesian approach. We show that precise estimates of prevalence of debris in nests can be obtained by sampling around 250 nests. Smaller sample sizes can be useful for obtaining rough estimates. For the Hartlaub’s gull, the African penguin, the great white pelican, and the white-breasted cormorant, debris were present in 0.75%, 3.00%, 6.41%, and 25.62% of the respective nests. Our approach will help researchers to determine errors associated with the prevalence of debris recorded in seabird nests and to optimise time and costs spent collecting data. It can also be applied to estimate confidence intervals and define sample sizes for assessing prevalence of plastic ingestion by any organism.
    Language: English
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  • 51
    Publication Date: 2021-12-13
    Description: This data set provides two series of experiments from ring-shear tests (RST) on glass beads that are in use at the Helmholtz Laboratory for Tectonic Modelling (HelTec) at the GFZ German Research Centre for Geosciences in Potsdam. The main experimental series contains shear experiments to analyse the slip behaviour of the granular material under analogue experiment conditions. Additionally, a series of slide-hold-slide (SHS) tests was used to determine the rate and state friction properties. A basic characterisation and average friction coefficients of the glass beads are found in Pohlenz et al. (2020). The glass beads show a slip behaviour that is depending on loading rate, normal stress and apparatus stiffness which were varied systematically for this study. The apparatus was modified with springs resulting in 4 different stiffnesses. For each stiffness a set of 4 experiments with different normal stresses (5, 10, 15 and 20 kPa) were performed. During each experiment loading rate was decreased from 0.02 to 0.0008 mm/s resulting in 9 subsets of constant velocity for each experiment. We observe a large variety of slip modes that ranges from pure stick-slip to steady state creep. The main characteristics of these slip modes are the slip velocity and the ratio of slip event duration compared to no slip phases. We find that high loading rates promote stable slip, while low loading rates lead to stick-slip cycles. Lowering the normal stress leads to a larger amount of creep which changes the overall shape of a stick-slip curve and extends the time between slip events. Changing stiffness leads to an overall change in slip behaviour switching from simple stick-slip to more complex patterns of slip modes including oscillations and bimodal slip events with large and small events. The SHS tests were done at maximum stiffness and higher loading rates (〉0.05 mm/s) but at the same normal stress intervals as the main series. Using various techniques, we estimate the rate-and-state constitutive parameters. The peak stress after a certain amount of holding increases with a healing rate of b=0.0057±0.0005. From the increase in peak stress compared to the loading rate in slide-hold-slide tests we compute a direct effect a=-0.0076±0.0005 which leads to (a-b)=-0.0130±0.0006. Using a specific subset of the SHS tests, which have an equal ratio of hold time to reloading rate, we estimate (a-b)=-0.0087±0.0029. Both approaches show that the material is velocity weakening with a reduction in friction of 1.30 to 0.87 % per e-fold increase in loading rate. Additionally, the critical slip distance Dc is estimated to be in the range of 200 µm. With these parameters the theoretical critical stiffness kc is estimated and applied to the slip modes found in the main series. We find that the changes in slip mode are in good agreement with the estimated critical stiffness and thus confirm the findings from the SHS tests.
    Language: English
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  • 52
    facet.materialart.
    Unknown
    In:  Oil & Gas Science and Technology
    Publication Date: 2021-12-13
    Description: In the current global environmental problems, reducing CO2 emissions is an important goal and guide for countries all over the world in developing environmental and economic policies. It has become a global consensus to jointly promote greenhouse gas emission reduction. From 1970 to 2004, CO2 emissions increased yearly, accounting for 76% of the total emissions in 2004. According to the prediction of the International Energy Agency (IEA), the total global CO2 emission reached a record of 30 billion tons in 2010. In 2005, the Intergovernmental Panel on Climate Change (IPCC) specially recommended Carbon Capture and Storage (CCS) technology to achieve significant emission reduction of greenhouse gases. In 2007, the World Wide Fund for Nature (WWF) identified CCS as one of the six ways to deal with global climate change. The global climate conference in Cancun in 2010 incorporated CCS into the Clean Development Mechanism (CDM). The United States, Canada, the European Union, and other countries have taken CCS as an important part of future energy strategies and carbon emission reduction strategies and have formulated corresponding technology research plans that include Research and Development (R&D) and project demonstration. The NET-Zero Emissions (NZE) scenario proposed by the IEA for 2050 puts global CO2 capture at 1.7 gigatonnes per year in 2030 and 7.6 gigatonnes per year in 2050. Presently, CCS is a hot topic all around the world.
    Language: English
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  • 53
    Publication Date: 2021-12-13
    Language: English
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  • 54
    Publication Date: 2021-12-10
    Description: This paper develops policy measures for a "just transition" based on a case study conducted in Germany's Rhineland lignite mining district. Semi-structured guided interviews served as the methodological approach. Expert interviews were conducted with representatives of citizen initiatives, trade unions and the Federal State of North Rhine-Westphalia. The results reveal the need for policy measures in different areas: First, employees working for subcontractors of the lignite industry have a high risk of losing their jobs because there are virtually no support policies for them. Second, there needs to be more input by civic initiatives regarding the process of structural change. And last, land needs to be prevented from becoming a scarce resource in the Rhineland area due to current mining legislation. We use an actor-centred institutionalist framework to derive governance approaches in line with the needs of various stakeholders.
    Keywords: ddc:320
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 55
    Publication Date: 2021-12-10
    Language: English
    Type: info:eu-repo/semantics/lecture
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  • 56
    Publication Date: 2021-12-10
    Description: We investigate the dependence of event-specific ground-motion residuals in the Ridgecrest region, California. We focus on the impact of using either local (ML) or moment (Mw) magnitude, for describing the source scaling of a regional ground-motion model. To analyze homogeneous Mw, we compute the source spectra of about 2000 earthquakes in the magnitude range 2.5–7.1, by performing a nonparametric spectral decomposition. Seismic moments and corner frequencies are derived from the best-fit ω−2 source models, and stress drop is computed assuming standard circular rupture model. The Brune stress drop varies between 0.62 and 24.63 MPa (with median equal to 3.0 MPa), and values for Mw 〉 5 are mostly distributed above the 90th percentile. The median scaled energy for Mw 〈5 is −4.57, and the low values obtained for the Mw 6.4 and 7.1 mainshocks (−5 and −5.2, respectively) agree with previous studies. We calibrate an ad hoc nonparametric ML scale for the Ridgecrest region. The main differences with the standard ML scale for California are observed at distances between 30 and 100 km, in which differences up to 0.4 magnitude units are obtained. Finally, we calibrate ground-motion models for the Fourier amplitude spectra, considering the ML and Mw scales derived in this study and the magnitudes extracted from Comprehensive Earthquake Catalog. The analysis of the residuals shows that ML better describes the interevent variability above 2 Hz. At intermediate frequencies (between about 3 and 8 Hz), the interevent residuals for the model based on Mw show a correlation with stress drop: this correlation disappears, when ML is used. The choice of the magnitude scale has an impact also on the statistical uncertainty of the median model: for any fixed magnitude value, the epistemic uncertainty is larger for ML below 1.5 Hz and larger for Mw above 1.5 Hz.
    Language: English
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  • 57
    Publication Date: 2021-12-09
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  • 58
    Publication Date: 2021-12-08
    Description: The mission of the Helmholtz Open Science Office is to promote the cultural change towards open science. The office, established by the Helmholtz Association in 2005, sees itself as a service provider that supports the community in shaping the cultural change towards open science. The Helmholtz Open Science Office is a partner of all stakeholders involved in this process within Helmholtz. Guided by the motto "Enabling open science practices in Helmholtz!" the Helmholtz Open Science Office works within the Association and promotes the visibility of Helmholtz on a national as well as international level within the context of open science in the spirit of the Helmholtz mission.
    Language: English
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  • 59
    Publication Date: 2021-12-08
    Description: With a homogenization experiment (700°C, 2 kbar) on melt inclusions in polished thick sections of emeralds from the Habachtal, it could be demonstrated that the primary crystallization of emerald started at significantly higher temperatures than previously assumed. This experiment confirms the prediction in the precursor publication on this subject. Supercritical conditions around 700°C and 5 kbar fix the start point for the emerald crystallization.
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  • 60
    Publication Date: 2021-12-08
    Description: The numerous applications of rare earth elements (REE) has lead to a growing global demand and to the search for new REE deposits. One promising technique for exploration of these deposits is laser-induced breakdown spectroscopy (LIBS). Among a number of advantages of the technique is the possibility to perform on-site measurements without sample preparation. Since the exploration of a deposit is based on the analysis of various geological compartments of the surrounding area, REE-bearing rock and soil samples were analyzed in this work. The field samples are from three European REE deposits in Sweden and Norway. The focus is on the REE cerium, lanthanum, neodymium and yttrium. Two different approaches of data analysis were used for the evaluation. The first approach is univariate regression (UVR). While this approach was successful for the analysis of synthetic REE samples, the quantitative analysis of field samples from different sites was influenced by matrix effects. Principal component analysis (PCA) can be used to determine the origin of the samples from the three deposits. The second approach is based on multivariate regression methods, in particular interval PLS (iPLS) regression. In comparison to UVR, this method is better suited for the determination of REE contents in heterogeneous field samples
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  • 61
    Publication Date: 2021-12-08
    Description: On behalf of the journal, AGU, and the scientific community, the editors would like to sincerely thank those who reviewed the manuscripts for Geophysical Research Letters in 2020. The hours reading and commenting on manuscripts not only improve the manuscripts but also increase the scientific rigor of future research in the field. We particularly appreciate the timely reviews in light of the demands imposed by the rapid review process at Geophysical Research Letters. The COVID pandemic imposed additional stresses on the review process, as many reviewers had to juggle increased family commitments, hours of online meetings, remote work and instruction, lack of physical access to library resources, and other hardships to maintain the quality and timeliness of their reviews. Although we witnessed an increase in the number of submissions, the average number of days to complete a review increased by less than one day!! That says a lot about the diligence of our reviewers. We deeply appreciate their contributions in these challenging times. With the advent of AGU's data policy, many reviewers have also helped immensely to evaluate the accessibility and availability of data, and many have provided insightful comments that helped to improve the data presentation and quality. We greatly appreciate the assistance of the reviewers in advancing open science, which is a key objective of AGU's data policy. Individuals in italics provided three or more reviews for Geophysical Research Letters during the year. In total, 5,177 referees contributed to 8,786 individual reviews. Thank you again. We look forward to the coming year of exciting advances in the field and communicating those advances to our community and to the broader public.
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  • 62
    facet.materialart.
    Unknown
    In:  Advances in Space Research
    Publication Date: 2021-12-08
    Description: In situ measurements by the Low Earth Orbital (LEO) satellites, such as CHAMP, GRACE, and C/NOFS satellites have shown that the International Reference Ionosphere (IRI) model has shortcomings in describing the solar activity variation of the topside electron density. In particular IRI overestimates the measured densities in the topside ionosphere during the very low solar activity reached during the last solar minimum (2008–2009). We have used Alouette and ISIS topside sounder data and CHAMP, GRACE, as well as Swarm in situ measurements to deduce a correction term for the IRI electron density topside model that more accurately describes the variation with solar activity. We have used a linear variation with the solar index PF10.7 and described the latitudinal and altitudinal variation of the regression parameters A0 and A1 (intercept and slope). We find good agreement between the regression parameters deduced from the topside sounder and from the CHAMP and GRACE observations. Swarm results show the same latitudinal structure as the other data sets, however, a scaling factor is needed to obtain agreement of the absolute values. The new model was evaluated with Alouette and ISIS topside sounder, as well as LEO satellites in situ data showing a significant improvement over the current IRI model.
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  • 63
    Publication Date: 2021-12-07
    Description: The cultivation of perennial instead of annual energy crops has received growing interest. Previous studies identified numerous beneficial effects of perennial energy crop (PEC) cultivation for the agricultural landscape such as promotion of agrobiodiversity, reduced requirements for agrochemicals and fertilizers as well as a large potential for carbon accumulation in soil. However, the mere presence of soil organic matter (SOM) accumulation gives no indication about the persistence of the SOM for example after a recultivation of the stands. Therefore, this study focused on SOM pools of different density fractions and soil microbial parameters. Six different PECs were tested against a typical benchmark system as feedstock for anaerobic digestion. The study has shown that all PEC species increased soil microbial activity and provided an insight how they sequester carbon in soil. Moreover, significant modifications in basic soil properties caused by plant growth were observed. For example, the cultivation of giant knotweed has lowered the soil pH by more than 0.5 pH units compared to the benchmark system. After 5 years of PEC cultivation, total soil organic carbon stocks were increased between 1,500 ± 400 and 4,500 ± 1,500 kg C ha-1 for the upper 10 centimetres of soil. The distribution among different soil fractions showed species-specific patterns. Tall wheatgrass and Virginia mallow showed particular high accumulation rates in the mineral-associated SOM fraction which indicates long residence times of the SOM after a possible recultivation of the fields.
    Keywords: 631.4 ; perennial energy crop ; soil carbon accumulation ; soil microbiological activity
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  • 64
    Publication Date: 2021-12-07
    Description: The expansion of photovoltaics in German cities has so far fallen short of expectations. The concept of "tenant electricity" ("Mieterstrom" in German), in which tenants of a building are supplied with solar power produced on site, offers great potential here. A study on behalf of the German Federal Ministry for Economic Affairs and Energy estimated the number of tenant households with good conditions for solar tenant electricity at 3.8 million. At the same time, the federal tenant electricity promotion scheme has been in place since 2017, but only about 1% of the annual budget has been claimed. The aim of this study is to identify the barriers for and drivers of diffusion of the tenant electricity model. To this end, a qualitative document analysis and a range of semi-structured expert interviews have been conducted. The theoretical framework used to guide the analysis is the multi-level perspective. The main barrier found for tenant electricity diffusion is the legal framework on the regime level, which also leads to high transaction costs of implementing tenant electricity. A social barrier is the inertia of some residents to actively concern themselves with their electricity supply and switch to a tenant electricity contract. Among its drivers are long-term trends such as the increasing electricity demand in urban areas, technical developments like blockchain technology and the increasing deployment of smart meters, and the EU Renewable Energy Directive. As long as the restrictive legal framework prevails, the further diffusion of tenant electricity will remain limited.
    Keywords: ddc:600
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 65
    Publication Date: 2021-12-07
    Description: Practices and research on measuring traditionally urban sustainability abound, therefore the challenge now is related to how the urban carbon issues are included into current measuring methods, thus there is a need to develop methods for measuring urban low-carbon sustainability. In this paper, a simple method, which is based on low-carbon sustainability index, is developed. The overall urban low-carbon sustainability index is the weighted sum of 11 single indices, and each single index is defined as the indicator assessing the development level against the baseline. The baseline is often the criteria or the minimum requirement of low-carbon sustainability. Case studies in four Chinese cities have put this method into practice, and the results show that all four selected cities fail to pass the testing of sensible low-carbon sustainability rule and they are all in weakly low-carbon sustainable development. Although the four cities have made great progress in their capacity building on pollution control and their capacities on wastewater treatment, main pollutants' removal and household and hazardous wastes treatment are enough to meet the needs of local development, they are all facing the great challenges on using of sustainable energy, offsetting of CO2 emissions and adoptions of nature-based solutions. The method developed by this research is a useful tool for decision makers identifying whether the local development is not on a low-carbon sustainable path.
    Keywords: ddc:600
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 66
    Publication Date: 2021-12-07
    Description: Energy service companies (ESCOs) play crucial role in building energy efficiency retrofit sector. However limited access to green financing has prevented ESCOs in their expansions in China. This paper, based on a survey of 469 samples and on-site visiting to and interviewing relevant 50 actors of ESCOs, financial institutions and local housing authorities, identifies main barriers of accessing to green financing at both systemic policy level and operational meso and micro level in China, and analyzes good practices at local level that overcome the barriers. The paper concludes that, although there are barriers existing at the policy level in China, substantial attentions and priorities should be given to take actions for overcoming the barriers existed at the operational meso and micro level. The paper suggests that the good practices of capacity building for ESCOs and local financial sector, intensifying participation of intermediate organizations or facilitators and diversifying financial sources and funding mechanisms and models that emerge from the local level should be disseminated in China.
    Keywords: ddc:320
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
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  • 67
    Publication Date: 2021-12-06
    Description: Abstract Vegetation covers on dikes and embankment dams have proven as sustainable and cost-effective surface protection against external erosion caused by hydraulic, mechanical, or climatic impacts. Determination of the hydraulic loads that act upon these covers requires the knowledge of the flow resistance. While the high-velocity flows on vegetated slopes are often aerated, the flow aeration has rarely been considered, and no direct measurements of the air-water flow properties have been conducted to date. The air-water flow properties are needed for a direct estimation of important design parameters such as friction factors and residual head at the downstream end. Herein, unique air-water flow measurements were conducted in high-velocity air-water flows down a vegetated chute with a 1:3 slope. Several vegetation covers were tested for a range of flow rates. The experiments revealed strong flow aeration within three-dimensional, fragmented flows associated with complex interactions of vegetation and high-velocity flows. The air-water flow properties were measured with phase-detection intrusive probes providing novel insights into aerated flows on vegetated chutes including distributions of void fraction, bubble count rate, and interfacial velocity as well as direct estimates of energy dissipation and flow resistance. The results highlighted strong flow aeration and energy dissipation for all vegetated configurations. The median equivalent Darcy-Weisbach friction factors for all vegetations were within 0.19 to 0.45, comparable to aerated flows on stepped spillways. The present results highlighted the significant flow resistance of vegetated covers and the need to consider air-water flow properties in the design of vegetated chutes.
    Keywords: 550.78 ; vegetated chutes ; air‐water flow properties
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  • 68
    Publication Date: 2021-12-06
    Description: We describe a low-cost three-dimensional underwater particle tracking velocimetry system to directly measure particle settling rate and flux in low-turbulence aquatic environments. The system consists of two waterproof cameras that acquire stereoscopic videos of sinking particles at 48 frames s−1 over a tunable sampling volume of about 45 × 25 × 24 cm. A dedicated software package has been developed to allow evaluation of particle velocities, concentration and flux, but also of morphometric parameters such as particle area, sinking angle, shape irregularity, and density. Our method offers several advantages over traditional approaches, like sediment trap or expensive in situ camera systems: (1) it does not require beforehand particle collection and handling; (2) it is not subjected to sediment trap biases from turbulence, horizontal advection, or presence of swimmers, that may alter particulate load and flux; (3) the camera system enables faster data processing and flux computation at higher spatial resolution; (4) apart from the particle settling rates, the particle size distribution, and morphology is determined. We tested the camera system in Lake Stechlin (Germany) in low turbulence and mean flow, and analyzed the morphological properties and settling rates of particles to determine their sinking behavior. The particle flux assessed from conventional sediment trap measurements agreed well with that determined by our system. By this, the low-cost approach demonstrated its reliability in low turbulence environments and a strong potential to provide new insights into particulate carbon transport in aquatic systems. Extension of the method to more turbulent and advective conditions is also discussed.
    Keywords: 551.48 ; aquatic environments ; particle velocity ; tracking system
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  • 69
    Publication Date: 2021-12-06
    Description: Trait-based approaches have broadened our understanding of how the composition of ecological communities responds to environmental drivers. This research has mainly focussed on abiotic factors and competition determining the community trait distribution, while effects of trophic interactions on trait dynamics, if considered at all, have been studied for two trophic levels at maximum. However, natural food webs are typically at least tritrophic. This enables indirect interactions of traits and biomasses among multiple trophic levels leading to underexplored effects on food web dynamics. Here, we demonstrate the occurrence of mutual trait adjustment among three trophic levels in a natural plankton food web (Lake Constance) and in a corresponding mathematical model. We found highly recurrent seasonal biomass and trait dynamics, where herbivorous zooplankton increased its size, and thus its ability to counter phytoplankton defense, before phytoplankton defense actually increased. This is contrary to predictions from bitrophic systems where counter-defense of the consumer is a reaction to prey defense. In contrast, counter-defense of carnivores by size adjustment followed the defense of herbivores as expected. By combining observations and model simulations, we show how the reversed trait dynamics at the two lower trophic levels result from a “trophic biomass–trait cascade” driven by the carnivores. Trait adjustment between two trophic levels can therefore be altered by biomass or trait changes of adjacent trophic levels. Hence, analyses of only pairwise trait adjustment can be misleading in natural food webs, while multitrophic trait-based approaches capture indirect biomass–trait interactions among multiple trophic levels.
    Keywords: 577.2 ; Lake Constance ; food web dynamics
    Language: English
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  • 70
    Publication Date: 2021-12-06
    Description: Periphytic biofilms are the major resource for many herbivorous invertebrates in both marine and freshwater benthos. They are of crucial importance for benthic food webs, substrate stability, and biogeochemical processes in littoral zones. While the importance of invertebrate grazing on biofilms has been studied extensively using natural, mixed algal communities grown on artificial substrates, there is so far no method available to create defined periphyton communities for these grazing studies. The reason for this is that many benthic algae interact with co-occurring species within the extracellular polymeric substances (EPSs) that form the nonorganismic part of the biofilm. Here, we present a novel method that allows the manufacturing of defined monoculture and multispecies biofilms by using an alginate polymer as artificial EPS structure, into which algal cultures can be embedded. Using confocal laser scanning microscopy, we show that alginate effectively embeds various algal taxa in an EPS matrix that is very similar to natural biofilms. In a grazing experiment, we demonstrate that several common freshwater herbivorous invertebrates can graze these alginate biofilms efficiently. As the method is easy to handle, it allows for highly controlled feeding experiments with benthic herbivores to assess, for example, the role of algal biodiversity on the efficiency of top-down control, the effects of environmental drivers such as nutrients, salinity, or seawater acidification on biofilm community structure, and the impacts of herbivory in benthic communities.
    Keywords: 577.2 ; benthic ecology ; biofilm pads
    Language: English
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  • 71
    Publication Date: 2021-12-06
    Description: Abstract Although the majority of coastal sediments consist of sandy material, in some areas marine ingression caused the submergence of terrestrial carbon-rich peat soils. This affects the coastal carbon balance, as peat represents a potential carbon source. We performed a column experiment to better understand the coupled flow and biogeochemical processes governing carbon transformations in submerged peat under coastal fresh groundwater (GW) discharge and brackish water intrusion. The columns contained naturally layered sediments with and without peat (organic carbon content in peat 39 ± 14 wt%), alternately supplied with oxygen-rich brackish water from above and oxygen-poor, low-saline GW from below. The low-saline GW discharge through the peat significantly increased the release and ascent of dissolved organic carbon (DOC) from the peat (δ13CDOC − 26.9‰ to − 27.7‰), which was accompanied by the production of dissolved inorganic carbon (DIC) and emission of carbon dioxide (CO2), implying DOC mineralization. Oxygen respiration, sulfate (SO42−) reduction, and methane (CH4) formation were differently pronounced in the sediments and were accompanied with higher microbial abundances in peat compared to sand with SO42−-reducing bacteria clearly dominating methanogens. With decreasing salinity and SO42− concentrations, CH4 emission rates increased from 16.5 to 77.3 μmol m−2 d−1 during a 14-day, low-saline GW discharge phase. In contrast, oxygenated brackish water intrusion resulted in lower DOC and DIC pore water concentrations and significantly lower CH4 and CO2 emissions. Our study illustrates the strong dependence of carbon cycling in shallow coastal areas with submerged peat deposits on the flow and mixing dynamics within the subterranean estuary.
    Keywords: 550.724 ; coastal peatlands ; coastal peatlands ; biogeochemical processes ; carbon release ; column experiments
    Language: English
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  • 72
    Publication Date: 2021-12-06
    Description: Potash salts belong to the most soluble minerals and their unintended dissolution can result in a safety risk for the construction and utilisation of salt caverns and mines [1]. One main challenge in modelling the formation of leaching zones within potash seams is the representation of fluid-rock interactions within regions exhibiting highly varying porosities. Chemical reactions cannot take place if small porosities inhibit the inflow of solution, although present solutions may be undersaturated with respect to certain minerals. These porosity variations only occur at the dissolution front in binary systems, such as NaCl solution and solid halite. Its progress can be described by a mass transfer rate, depending on the concentration of present solutions or by assuming a saturated interface between dry rock and solution, subtracting out the diffusive mass transport. In contrast, the dissolution of potash salt results in the formation of a porous rock matrix, consisting of undissolved and precipitated minerals that can further react with the surrounding solution. Accordingly, fluid-rock interactions and largely varying porosities also occur remote from the dissolution front. The interchange approach [2] was developed to describe these interactions. Coupled with a reactive transport model including PHREEQC [3] and TRANSE [4] this approach is capable to quantify, e.g., the leaching process of carnallite-bearing potash seams due to natural density-driven convection. The dissolution rate is essential for both, the timely progress and geometric shape of evolving leaching zones in the potash seam. Therefore, the interchange approach has been adapted in the scope of the present study to consider saturation-dependent dissolution rates for each mineral. In this contribution, we discuss the feasibility and limitations of our approach to represent fluid-rock interactions between brine and different types of potash salts at the metre scale.
    Language: English
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  • 73
    Publication Date: 2021-12-06
    Description: HYPERedu provides online learning materials on principles, methods and applications of imaging spectroscopy at Masters level for students as well as professionals that will be continuously extended and complemented by an online course series.
    Language: English
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  • 74
    Publication Date: 2021-12-06
    Description: Coupled reactive transport simulations are extremely demanding in terms of required computational power, which hampers their application and leads to coarsened and oversimplified domains. The chemical sub-process represents the major bottleneck: its acceleration is an urgent challenge which gathers increasing interdisciplinary interest along with pressing requirements for subsurface utilization such as spent nuclear fuel storage, geothermal energy and CO2 storage. In this context we developed POET (POtsdam rEactive Transport), a research parallel reactive transport simulator integrating algorithmic improvements which decisively speed up coupled simulations. In particular, POET is designed with a master/worker architecture, which ensures computational efficiency in both multicore and cluster compute environments. POET does not rely on contiguous grid partitions for the parallelization of chemistry but forms work packages composed of grid cells distant from each other. Such scattering prevents particularly expensive geochemical simulations, usually concentrated in the vicinity of a reactive front, from generating load imbalance between the available CPUs (central processing units), as is often the case with classical partitions. Furthermore, POET leverages an original implementation of the distributed hash table (DHT) mechanism to cache the results of geochemical simulations for further reuse in subsequent time steps during the coupled simulation. The caching is hence particularly advantageous for initially chemically homogeneous simulations and for smooth reaction fronts. We tune the rounding employed in the DHT on a 2D benchmark to validate the caching approach, and we evaluate the performance gain of POET's master/worker architecture and the DHT speedup on a 3D benchmark comprising around 650 000 grid elements. The runtime for 200 coupling iterations, corresponding to 960 simulation days, reduced from about 24 h on 11 workers to 29 min on 719 workers. Activating the DHT reduces the runtime further to 2 h and 8 min respectively. Only with these kinds of reduced hardware requirements and computational costs is it possible to realistically perform the long-term complex reactive transport simulations, as well as perform the uncertainty analyses required by pressing societal challenges connected with subsurface utilization.
    Language: English
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  • 75
    Publication Date: 2021-12-03
    Description: In recent years, X-ray speckle-tracking techniques have emerged as viable tools for wavefront metrology and sample imaging applications. These methods are based on the measurement of near-field images. Thanks to their simple experimental setup, high angular sensitivity and compatibility with low-coherence sources, these methods have been actively developed for use with synchrotron and laboratory light sources. Not only do speckle-tracking techniques give the potential for high-resolution imaging, but they also provide rapid and robust characterization of aberrations of X-ray optical elements, focal spot profiles, and sample position and transmission properties. In order to realize these capabilities, software implementations are required that are equally rapid and robust. To address this need, a software suite has been developed for the ptychographic X-ray speckle-tracking technique, an X-ray speckle-based method suitable for highly divergent wavefields. The software suite is written in Python 3, with an OpenCL back end for GPU and multi-CPU core processing. It is accessible as a Python module, through the command line or through a graphical user interface, and is available as source code under Version 3 or later of the GNU General Public License.
    Keywords: 548 ; software ; wavefront metrology ; speckle tracking ; ptychography ; X-ray projection imaging
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  • 76
    Publication Date: 2021-12-03
    Description: We examine the relative dispersion and the contribution of tides on the relative diffusivities of surface drifters in the North Sea. The drifters are released in two clusters, yielding 43 pairs, in the vicinity of a tidal mixing front in the German Bight, which is located in the southeastern area of the North Sea. Both clusters indicate decreasing dispersion when crossing the tidal mixing front, followed by exponentially increasing dispersion with e-folding times of 0.5 days for Cluster 1 and 0.3 days for Cluster 2. A transition of the dispersion regimes is observed at scales of the order of the Rossby radius of deformation (10 km). After that, the relative dispersion grows with a power-law dependency with a short period of ballistic dispersion (quadratic growth), followed by a Richardson regime (cubic growth) in the final phase. Scale-dependent metrics such as the relative diffusivities are consistent with these findings, while the analysis of the finite-scale Lyapunov exponents (FSLEs) shows contradictory results for the submesoscales. In summary, the analysis of various statistical Lagrangian metrics suggests that tracer stirring at the submesoscales is nonlocal and becomes local at separation scales larger than 10 km. The analysis of meridional and zonal dispersion components indicates anisotropic dispersion at the submesoscales, which changes into isotropic dispersion on the mesoscales. Spectral analysis of the relative diffusivity gives evidence that semidiurnal and shallow-water tides influence relative diffusivity at the mesoscales, especially for drifter separations above 50 km.
    Keywords: 551.46 ; North Sea ; drifter dispersion
    Language: English
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  • 77
    Publication Date: 2021-12-03
    Description: Micro-macro models for dissolution processes are derived from detailed pore-scale models applying upscaling techniques. They consist of flow and transport equations at the scale of the porous medium (macroscale). Both include averaged time- and space-dependent coefficient functions (permeability, porosity, reactive surface, and effective diffusion). These are in turn explicitly computed from the time- and space-dependent geometry of unit cells and by means of auxiliary cell problems defined therein (microscale). The explicit geometric structure is characterized by a level set. For its evolution, information from the transport equations solutions is taken into account (micro-macro scales). A numerical scheme is introduced, which is capable of evaluating such complex settings. For the level-set equation a second-order scheme is applied, which enables us to accurately determine the dynamic reactive surface. Local mesh refinement methods are applied to evaluate Stokes type cell problems using P2/P1 elements and a Uzawa type linear solver. Applications of our permeability solver to scenarios involving static and evolving geometries are presented. Furthermore, macroscopic flow and transport equations are solved applying mixed finite elements. Finally, adaptive strategies to overcome the computational burden are discussed. We apply our approach to the dissolution of an array of dolomite grains in the micro-macro context and validate our numerical scheme.
    Keywords: 551.49 ; 550.724 ; porous media ; reactive flow ; dissolution processes ; modeling
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  • 78
    Publication Date: 2021-12-03
    Description: In contrast to seamount chains, small solitary seamounts/seamount groups have rarely been sampled despite their large number and therefore their origins remain enigmatic. Here we present new 40Ar/39Ar, trace element and Nd-Hf-Pb isotope data from the solitary Demenitskoy Seamount, the isolated Tolkien seamount group and the Krylov Seamount and Ridge in the Canary Basin, Central Atlantic Ocean. Their chemical compositions range from intraplate ocean-island-basalt (Demenitskoy) to mid-ocean-ridge-basalt (Tolkien and Krylov) types. Lavas from all three seamount groups, however, show geochemical evidence for involvement of enriched Canary/Cape Verde plume material. Seismic tomography shows that large areas around these mantle plumes consist of dispersed low-velocity material, which could represent diffusely-upwelling plume mantle. Melts from such upwelling mantle could form isolated seamounts. Diffuse upwelling of plume material is likely to be extremely widespread but has been poorly studied to date. Significance Statement A fundamental question concerns the origin of the hundreds of thousands of solitary seamounts and small isolated clusters of such seamounts on the seafloor of the world's ocean basins. Most of them do not fit into any currently accepted models (e.g. they are not associated with a linear hotspot track or plate boundary processes). Their formation could therefore represent a new kind of intraplate volcanism that in fact could be extremely widespread but has been thus far largely neglected. In this manuscript, we report geochemical data from three isolated seamount sites in the Canary Basin and propose a provocative model for their formation that can also be applied to isolated seamounts elsewhere. Our study is therefore also a plea for the long overdue systematic investigation of small seamount volcanism in the world's ocean basins. I hereby confirm that all the data and interpretations are new and have not been published elsewhere. All co-authors have been actively involved in this work, have approved the manuscript and agreed to this submission.
    Keywords: 551 ; Canary Basin ; seamounts ; isotopic compositions
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  • 79
    Publication Date: 2021-12-03
    Description: Coupled groundwater flow and heat transport within hyporheic zones extensively affect water, energy, and solute exchange with surrounding sediments. The local and cumulative implications of this tightly coupled process strongly depend on characteristics of drivers (i.e., discharge and temperature of the water column) and modulators (i.e., hydraulic and thermal properties of the sediment). With this in mind, we perform a systematic numerical analysis of hyporheic responses to understand how the temporal variability of river discharge and temperature affect flow and heat transport within hyporheic zones. We identify typical time series of river discharge and temperature from gauging stations along the headwater region of Mississippi River Basin, which are characterized by different degrees of flow alteration, to drive a physics-based model of the hyporheic exchange process. Our modeling results indicate that coupled groundwater flow and heat transport significantly affects the dynamic response of hyporheic zones, resulting in substantial differences in exchange rates and characteristic time scales of hyporheic exchange processes. We also find that the hyporheic zone dampens river temperature fluctuations increasingly with higher frequency of temperature fluctuations. This dampening effect depends on the system transport time scale and characteristics of river discharge and temperature variability. Furthermore, our results reveal that the flow alteration reduces the potential of hyporheic zones to act as a temperature buffer and hinders denitrification within hyporheic zones. These results have significant implications for understanding the drivers of local variability in hyporheic exchange and the implications for the development of thermal refugia and ecosystem functioning in hyporheic zones.
    Keywords: 551.48 ; hyporheic exchange ; numerical analysis
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  • 80
    Publication Date: 2021-12-03
    Description: Numerical analysis of spatial pattern is widely used in ecology to describe the characteristics of floral and faunal distributions. These methods allow attribution of pattern to causal mechanisms by uncovering the specific signatures of patterns and causal agents. For example, grassland-gap patterns called fairy circles (FCs) in Namibia and Australia are characterized by highly regular and homogenous distributions across landscapes that show spatially periodic ordering. These FCs have been suggested to be caused by both social insects and competitive plant interactions. We compared eight Namibian and Australian FC patterns and also modeled FCs to 16 patterns of social insect nests in Africa, Australia, and America that include the most regular termite mound patterns known. For pattern-process inference, we used spatial statistics based on both nearest-neighbor analysis and neighborhood-density functions. None of the analyzed insect-nest distributions attain the spatially periodic ordering that is typical of FCs. The inherently more variable patterns of termite and ant nests are commonly attributable to well documented aspects of the faunal life-history. Our quantitative evidence from drylands shows that the more variable insect-nest distributions in water-limited environments cannot explain the characteristic spatial signature of FCs. The analysis demonstrates the interpretation of scale-dependent neighborhood-density functions and that it is the identification of unique spatial signatures in regular patterns that need to be linked to process. While our results cannot verify a specific hypothesis, they support the hypothesis that FCs in these drylands are more likely an emergent vegetation pattern caused by strong plant competition for water.
    Keywords: 577.54 ; Namibia ; Australia ; fairy circles
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  • 81
    Publication Date: 2021-12-03
    Description: The first step of complete transformation will be utilizing digital technologies and applications to improve current procedures, processes, and structures (Improve). Next, complete digitalisation will pave the way for new business models and framework conditions (Convert). Finally, comprehensive transformation of the economy and value creation will ensure the effective reorientation of society and lifestyles towards sustainability (Transform). This last step is critical for a successful ecological transformation, or a "green transformation", must be placed front and centre during international debate. Through this report, we aim to highlight and discuss the opportunities that digitalisation can bring to Germany. In particular, we will discuss three exemplary areas of ecological transformation where action is necessary: 1) A digital and circular economy that uses data to increase resource efficiency. 2) Intelligent, sustainable mobility that connects us in eco-friendly ways. 3) Transparent transitions towards sustainable food chains and agriculture. This report represents the first phase of the Shaping Digital Transformation project. In this report, we will outline the framework of our project to create a starting point for further debates.
    Keywords: ddc:600
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: report , doc-type:report
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  • 82
    Publication Date: 2021-12-03
    Description: The rising popularity and strong increase in the number of electric bicycles make it necessary to consider the built-in resources as well as possible treatments after the use phase. The time lag between the purchase and the occurrence of relevant defects suggests significant increases in defective components. Especially the great dynamics of the market due to regular innovations, product renewals, and the lack of spare parts availability for older models make the long-term use by customers much more difficult than for conventional bicycles. Therefore, it is necessary to analyze circular business models for the electric bicycle market. In this way, the required structures for a sustainable electric bicycle industry can be created so that valuable materials do not go into disposal but undergo a new use phase. Based on the results of "AddRE-Mo-Value Preservation Scenarios for Urban Electromobility of Persons and Loads through Additive Manufacturing and Remanufacturing," a research project funded by the German Federal Ministry of Education and Research, this paper addresses four circular business models, two sales models, and two service models. The guiding research interest of this paper is the combination of remanufacturing and additive manufacturing from a business model perspective, analyzing the extent to which additive remanufacturing can be considered a solution for electric bicycles' circularity. After describing the approach and methods used to develop these four circular business models the business models are described and analyzed using the Business Model Canvas. Based on this analysis, it is shown that the combination of remanufacturing and additive manufacturing can be applied to the electric bicycle market and be integrated into both sales and service models. The description of these business models will help managers design viable business models in the context of sustainable electric bicycles. It also shows that the individual partners within the value chain must collaborate more closely. In the electric bicycle industry, a single company will probably not be able to close the product cycle completely. Further research is needed to develop concepts of the business models and examine their practical feasibility in technical and organizational operations to achieve a circular economy.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
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  • 83
    Publication Date: 2021-12-02
    Description: We performed an in-depth investigation and analysis of the effect of temperature on the Raman-active A-modes of bulk kesterite-type Cu2ZnSnS4 within the 300–460 K temperature range. We acquired the individual contributions to each Raman mode, namely, the thermal expansion and anharmonic interactions terms responsible for the Raman shift and broadening with temperature. Our results indicate that the Raman shift with temperature is dominated by the thermal expansion term, whereas the broadening is mainly governed by three-phonon damping processes in this material. Considering relevant results from the literature, it appears that dimensionality is a key factor in regulating the dominant phonon decay mechanism.
    Language: English
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  • 84
    Publication Date: 2021-12-01
    Description: Flow is an important physical driver of biofilm communities. Here, we tested the effects of the near bed flows in two mountainous stream reaches on the structure of biofilm microbial guilds (autotrophs, heterotrophic bacteria, and heterotrophic protists) within and across trophic levels. Near bed flow velocity and turbulent kinetic energy were important physical drivers for structuring the communities within and across guilds of the multitrophic fluvial biofilms. The effects of flow were nested in a seasonal and spatial (across-streams) context. Changes in physicochemical factors (temperature, light, dissolved carbon, and nutrients) along the reaches were alike in both streams suggesting that environmental boundary conditions at larger temporal scales were responsible for the seasonal differences of biofilm communities, whereas locally microbial diversity was shaped by near bed flow. Typically, the abundance of autotrophs increased with flow, indicating that biofilms shifted toward increasing autotrophy with increasing shear forces. Filamentous autotrophs seemed to provide protected habitats from the shear forces for smaller sized bacteria. Heterotrophic protist abundance decreased with flow leading to decreasing grazer to prey ratio. Bacteria thus benefitted from a reduction in grazing pressure at faster flowing, more turbulent sites. Our results suggest that near bed flow can impact the magnitude and direction of matter fluxes through the microbial food web and possibly affect ecosystem functioning of fluvial biofilms.
    Keywords: 577.2 ; mountainous stream ; biofilm microbial guilds ; flow impacts
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  • 85
    Publication Date: 2021-12-01
    Description: Species identification using matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) data strongly relies on reference libraries to differentiate species. Because comprehensive reference libraries, especially for metazoans, are rare, we explored the accuracy of unsupervised diversity estimations of communities using MALDI-TOF MS data in the absence of reference libraries to provide a method for future application in ecological research. To discover the best analysis strategy providing high congruence with true community structures, we carried out a simulation with more than 30,000 analyses using different combinations of data transformations, dimensionality reductions, and cluster algorithms. Species profile, Hellinger, and presence/absence transformations were applied to raw data and dimensions were reduced using principal component analysis (PCA), t-distributed stochastic neighbor embedding, and uniform manifold approximation and projection. To estimate biodiversity, data were clustered making use of partitioning around medoids, model-based clustering, and K-means clustering. The analyses were carried out on published mass spectrometry data of harpacticoid copepods. Most successful combinations (Hellinger transformation + PCA or raw data + partitioning around medoids) returned good values even for difficult species distributions containing numerous singleton species. Nevertheless, errors occurred most frequently because of such singleton taxa. Hence, replicative sampling in wide sampling areas for analysis is emphasized to increase the minimum number of specimens per species, thus reducing putative sources of errors. Our results demonstrate that MALDI-TOF MS data can be used to accurately estimate the biodiversity of unknown communities using unsupervised learning methods. The provided approach allows the biodiversity comparison of sampled regions for which no reference libraries are available. Hence, especially data on groups which demand a time-consuming identification or are highly abundant can be analyzed within short working time, accelerating ecological studies.
    Keywords: 577 ; biodiversity estimation ; metazoans ; methods
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  • 86
    Publication Date: 2021-12-01
    Description: The duration and magnitude of the North Atlantic spring bloom impacts both higher trophic levels and oceanic carbon sequestration. Nutrient exhaustion offers a general explanation for bloom termination, but detail on which nutrients and their relative influence on phytoplankton productivity, community structure, and physiology is lacking. Here, we address this using nutrient addition bioassay experiments conducted across the midlatitude North Atlantic in June 2017 (late spring). In four out of six experiments, phytoplankton accumulated over 48–72 h following individual additions of either iron (Fe) or nitrogen (N). In the remaining two experiments, Fe and N were serially limiting, that is, their combined addition sequentially enhanced phytoplankton accumulation. Silicic acid (Si) added in combination with N + Fe led to further chlorophyll a (Chl a) enhancement at two sites. Conversely, addition of zinc, manganese, cobalt, vitamin B12, or phosphate in combination with N + Fe did not. At two sites, the simultaneous supply of all six nutrients, in combination with N + Fe, also led to no further Chl a enhancement, but did result in an additional 30–60% particulate carbon accumulation. This particulate carbon accumulation was not matched by a Redfield equivalent of particulate N, characteristic of high C:N organic exudates that enhance cell aggregation and sinking. Our results suggest that growth rates of larger phytoplankton were primarily limited by Fe and/or N, making the availability of these nutrients the main bottom-up factors contributing to spring bloom termination. In addition, the simultaneous availability of other nutrients could modify bloom characteristics and carbon export efficiency.
    Keywords: 577.7 ; mid-latitude North Atlantic ; phytoplankton ; diatom blooming ; experiments
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  • 87
    Publication Date: 2021-12-01
    Description: We studied the role of oceanographic conditions and life history strategies on recovery after extinction in a metapopulation of marine organisms dispersing as pelagic larvae. We combined an age-structured model with scenarios defined by realistic oceanographic conditions and species distribution along the Irish Sea coast (North Europe). Species life history strategies were modeled combining the dispersal behaviors with two levels of fecundity. Recovery times were quantified after simulating extinction in four regions. Two alternative strategies (high fecundity or larval tidal transport) led to short recovery times, irrespective of the effects of other drivers. Other strategies and low larval survival exacerbated the effects of oceanographic conditions on recovery times: longer times were associated with for example the presence of frontal zones isolating regions of extinction. Recovery times were well explained by the connectivity of each focal population with those located outside the area of extinction (which was higher in the so-called small world topologies), but not by subsidies (direct connections with populations located nearby). Our work highlights the complexities involved in population recovery: specific trait combinations may blur the effects of the habitat matrix on recovery times; K-strategists (i.e., with low fecundities) may achieve quick recovery if they possess the appropriate dispersal traits. High larval mortality can exacerbate the effect of oceanographic conditions and lead to heterogeneity in recovery times. Overall, processes driving whole network topologies rather than conditions surrounding local populations are the key to understand patterns of recovery.
    Keywords: 577.7 ; marine organism ; extinction ; recovery patterns ; simulation ; effects of oceanographic conditions
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  • 88
    Publication Date: 2021-12-01
    Description: Methane (CH4) production in the ocean surface mixed layer is a widespread but still largely unexplained phenomenon. In this context marine algae have recently been described as a possible source of CH4 in surface waters. In the present study we investigated the effects of temperature and light intensity (including daylength) on CH4 formation from three widespread marine algal species Emiliania huxleyi, Phaeocystis globosa, and Chrysochromulina sp. Rates of E. huxleyi increased by 210% when temperature increased in a range from 10°C to 21.5°C, while a further increase in temperature (up to 23.8°C) showed reduction of CH4 production rates. Our results clearly showed that CH4 formation of E. huxleyi is controlled by light: When light intensity increased from 30 to 2,670 μmol m−2 s−1, CH4 emission rates increased continuously by almost 1 order of magnitude and was more than 1 order of magnitude higher when the daylength (light period) was extended from 6/18 hr light-dark cycle to continuous light. Furthermore, light intensity is also an important factor controlling CH4 emissions of Chrysochromulina sp. and P. globosa and could therefore be a species-independent regulator of phytoplankton CH4 production. Based on our results, we might conclude that extensive blooms of E. huxleyi could act as a main regional source of CH4 in surface water, since blooming of E. huxleyi is related to the seasonal increase in both light and temperature, which also stimulate CH4 production. Under typical global change scenarios, E. huxleyi will increase its CH4 production in the future.
    Keywords: 551.9 ; 557.7 ; marine phytoplacton ; CH4 production ; temperature influence ; light intensity influence ; daylength influence
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  • 89
    Publication Date: 2021-12-01
    Keywords: 577.1 ; streams ; microbial community structure ; microbial community function ; environmental impacts
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  • 90
    Publication Date: 2021-12-01
    Description: Following a sequence of seismic events detected by the National Geographic Institute (IGN Spain), on 13.09.2021 the new volcano Cumbre Vieja initiated an eruption, located on the mid-western flank at a location just to the north of the 1949 eruption site. The eruption fed a lava flow that buried already some hundreds of houses, with a high economic estimated loss. Previous studies have shown that La Palma was the source of 3 or 4 large sector collapses associated with avalanches under see and tsunami generation. This volcanic activity is accompanied with an increased seismic activity. The GFZ contributes to the monitoring of the seismic activity by sending experts in the frame of a Hazard and Risk Team (HART). Our partner is the National Geographic Institute. Besides tiltmeters, a temporary 4 station seismic network with TrilliumCompact 20 sec posthole seismometers, D-Cube digitisers (100 sample/sec) and C-Cubes LTE communication for real-time data transmission is being deployed near the Cumbre Vieja volcano, increasing the station density of the IGN network. Data access is being restricted for some time.
    Language: English
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  • 91
    Publication Date: 2021-12-01
    Description: In this case study a method to estimate the geothermal potential is presented for the capital city of Berlin, Germany. Therefore, it is essential to know the temperature distribution in the subsurface which has been studied intensively in the past. Building on this knowledge, newly available subsurface temperature predictions have been used along with updated geometries and geophysical properties as input data for the application case of hydrothermal doublets and their comparison to earlier realizations. This shows how considering more complex geometries, boundary conditions and processes in numerical 3D thermohydraulic simulations leads to significant changes in the predicted geothermal potential and the associated controlling factors. The model area is part of the Northeast German Basin which consists of a thick sequence (up to 10 km) of differently consolidated sedimentary deposits. This sequence is made up of alternating aquifers and aquitards, wherein several encompass promising targets for different geothermal application scenarios. Namely these include the Jurassic, Middle Buntsandstein and the Sedimentary Rotliegend aquifers. The former two of these reservoirs depict a complex geometry (mainly due to deeper salt movements) leading to a wide range of predicted temperatures, while the latter (situated below the salt) has a more homogenous topography and temperature distribution. This is also connected to the efficacy of different heat transport processes at different depths. The predicted heating power is therefore also distributed heterogeneously and reaches maxima as large as 1.25 MWth for the Jurassic, 10 MWth for the Middle Buntsandstein and 2.2 MWth for the Sedimentary Rotliegend. The models further show that the geothermal potential (or the heating power) of a hydrothermal doublet is controlled by more than merely the reservoir temperature but also the producible mass flux, which in turn depends highly on the reservoir transmissivity. Due to the high variability of predicted geothermal potentials, different utilization scenarios should be investigated in future studies, such as aquifer thermal energy storage or low enthalpy geothermal utilizations.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 92
    Publication Date: 2021-11-30
    Description: Storms are infrequent, intense, physical forcing events that represent a potentially significant driver of ocean ecosystems. The objective of this study was to assess changes in water column structure and turbulent fluxes caused by storms using an autonomous underwater glider, as well as the chlorophyll a (Chl a) response to the altered physical environment. The glider was able to measure throughout the complete life cycle of Storm Bertha as it passed over the North Sea in August 2014, from its arrival to dissipation. Storm Bertha triggered rapid mixing of the thermocline through shear instability, increasing vertical fluxes by nearly an order of magnitude, and promoting increases in surface layer Chl a. The results demonstrate that storms represent a significant fraction of seasonal vertical turbulent fluxes, with potentially important consequences for biological production in shelf seas.
    Keywords: 551.46 ; 551.46 ; North Sea ; storm Bertha ; thermocline fluxes ; thermocline mixing ; storm Bertha ; North Sea
    Language: English
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  • 93
    Publication Date: 2021-11-30
    Description: We have used stable water isotopes (δ18O, δ2H) in combination with lumped-parameter modeling for characterizing unsaturated flow in two lysimeters vegetated with maize. The lysimeters contained undisturbed soil cores dominated by sandy gravel (Ly1) and clayey sandy silt (Ly2). Stable water isotopes were analyzed in precipitation and lysimeter outflow water over about 3 years. The mean transit time of water T and dispersion parameter PD, obtained from modeling, were higher for the silt soil in Ly2 than for the gravel soil in Ly1 (T of 362 vs. 129 d, PD of 0.7 vs. 0.12). The consideration of preferential flow (PF) paths could substantially improve the model curve fits, with 13 and 11% contribution of PF for Ly1 and Ly2 as best estimates. Different assumptions were compared to estimate the input function, that is, stable water isotope content in the recharging water. Using the isotopic composition of precipitation as input (no modification) resulted in reasonable model estimations. Best model fits for the entire observation were obtained by weighting the recharging isotopes according to average precipitation within periods of 3 and 6 months, in correspondence to changing vegetation phases and seasonal influences. Input functions that consider actual evapotranspiration could significantly improve modeling at some periods, however, this led to deviations between modeled and observed δ18O at other periods. This may indicate the influence of variable flow, so that dividing the whole observation period into hydraulically characteristic sub-periods for lumped-parameter modeling (which implements steady-state flow) is recommended for possible further improvement.
    Keywords: 551.49 ; groundwater flow modeling
    Language: English
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  • 94
    Publication Date: 2021-11-30
    Description: Abstract The manuscript analyzes the stimulation for an Enhanced Geothermal System development in Acoculco, Mexico. Using an analytical penny-shaped hydraulic fracture model covering different propagation regimes, we computed the final fracture length and width by varying fluid properties with temperature. Our analysis indicates that for the given scenario, the fluid viscosity plays a minor role and instead flow rate and time of the stimulation are the controlling variables. We computed the fracture reopening as a consequence of water reinjection in the second stage of the stimulation through numerical computations based on the enriched discontinuity method. The computation shows that a single isolated fracture will not provide sufficient permeability, as the continuous injection will quickly fill and pressurize the crack. We demonstrate that the fracture needs to be connected to a permeable network to avoid excessive pressurization and achieve a commercially exploitable reservoir for Enhanced Geothermal System.
    Keywords: 622,15 ; 622.15 ; Mexico ; volcanic belt ; geothermal energy exploration ; fluid reinjection simulation
    Language: English
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  • 95
    Publication Date: 2021-11-30
    Description: The Deep Blue (DB) aerosol retrieval algorithm has recently been applied to Advanced Very High Resolution Radiometer (AVHRR) data to produce a first version (V001) of a global aerosol optical thickness (AOT) data set. In this paper, we critically evaluate these AVHRR AOT data over China by comparison with ground-based reference data from China Aerosol Remote Sensing Network for the period 2006–2011. The evaluation considers the impact of the surface (type and reflectance) and the aerosol properties (aerosol loading, aerosol absorption) on the quality of the retrieved AOT. We also compare the AVHRR-retrieved AOT with that from Moderate Resolution Imaging Spectroradiometer over major aerosol source regions in China. We further consider seasonal variations and find, in general, a good agreement between AVHRR AOT and the reference data sets. The AVHRR retrieval algorithm performs well over dark vegetated surfaces, but over bright surfaces (e.g., desert regions) the results are less good. The AVHRR algorithm underestimates the AOT, with 32.1% of the values lower than the estimated error envelope of ±0.05 ± 0.25τ. In particular over the desert, the AVHRR-retrieved AOT is frequently underestimated and for AOT ≤ 0.6 the values are on average 0.05 too low due to the pixel filtering, and dust storms are missed. The comparison of the AVHRR AOT with MODIS collection 6 and CARSNET data indicates that improvements are needed for, for example, AVHRR calibration and cloud/aerosol flagging. The analysis presented in this paper contributes to a better understanding of the AVHRR AOT product over China.
    Keywords: 551.5 ; China ; AVHRR aerosol data ; data quality validation
    Language: English
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  • 96
    Publication Date: 2021-11-30
    Description: The Indonesian Throughflow (ITF) operates as an important link in global thermohaline circulation, and ITF variability probably modulated Pliocene climate change. Yet, whether ITF variability accounted for oceanographic change south of Northwest Cape remains controversial. Here, we present a multiproxy oceanographic reconstruction from the Perth Basin and reconstruct the Pliocene history of the Leeuwin Current (LC). We show that the LC was active throughout the Pliocene, albeit with fluctuations in intensity and scope. Three main factors controlled LC strength. First, a tectonic ITF reorganization caused an abrupt and permanent LC reduction at 3.7 Ma. On shorter timescales, eustatic sea level and direct orbital forcing of wind patterns hampered or promoted the LC. At 3.3 Ma, for instance, LC intensity plunged in response to a eustatic ITF restriction. Site U1459 then fell outside the extent of a weakened LC, and the latitudinal sea surface temperature gradient along West Australia doubled its steepness.
    Keywords: 551 ; Perth Basin ; sediment core ; multiproxy geochemical records ; Pliocene ; Leeuwin Current (LC)
    Language: English
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  • 97
    Publication Date: 2021-11-30
    Description: The Ural Mountains are an important climatic and biogeographical barrier between European and Siberian forests. In order to shed light on the postglacial formation and evolution of the boreal forests in the European pre-Urals, we obtained a peat sediment core, Chernaya, from the Paltinskoe bog located between the southern taiga and hemiboreal forest zone in the mid-Kama region. We carried out pollen analysis, non-pollen palynomorph analysis, loss-on-ignition tests and radiocarbon dating. Radiocarbon dated records provide centennial to decennial resolution of the vegetation and environmental history of the European pre-Urals for the last 8.8 ka. The postglacial formation of the pre-Uralian hemiboreal forests reveals four important phases: (i) the dominance of Siberian taiga and forest-steppe in the Early Holocene and beginning of the Middle Holocene (8.8–6.9 ka), indicating a dry climate; (ii) the spread of spruce and European broadleaved trees in the Middle Holocene (6.9–4 ka) under wetter climate conditions; (iii) the maximum extent of broadleaved trees coinciding with the arrival and spread of Siberian fir in the Late Holocene (4–2.3 ka); and (iv) the decline of broadleaved trees since the Early Iron Age (2.3 ka – present) possibly due to general climate cooling and logging. While temperate broadleaved trees possibly spread from local refugia in the Urals, fir arrived from Siberia and spread further west. The carbon accumulation rate of Paltinskoe bog (18.9±10.16 g C m−2 a−1) is close to the average value of carbon accumulation of northern peatlands. Local development of peat is characterized by non-gradual growth with a phase of intensive carbon accumulation between 3.5 and 2.3 ka. The vegetation was strongly influenced by fire in the Early Holocene and by humans since the Early Iron Age practicing deforestation, agriculture and pasture. Phases of increased anthropogenic activity correlate well with the local archaeological data.
    Keywords: 561 ; mid-Kama region ; Paltinskoe peat bog ; sediment core ; pollen data ; holocene ; vegetation development
    Language: English
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  • 98
    Publication Date: 2021-11-26
    Description: More and more companies are announcing their intention to become climate-neutral and numerous companies already offer climate-neutral products or services: From climate-neutral parcel delivery to air travel. But what exactly do the companies' net-zero targets mean? Is the target set ambitious? And what role does offsetting play, i.e., purchasing carbon credits that are accounted against the company's own climate target? The approaches behind the proclaimed targets are often difficult to understand. Against this background, this Zukunftsimpuls provides ten recommendations for the definition and implementation of neutrality targets. Among other things, the authors advocate the use of a robust database as the basis for net-zero targets, emphasize the importance of transparent communication, and highlight the role that offsetting should play. Purchased carbon credits should make as limited a contribution as possible for meeting climate targets and should only be used to offset emissions that cannot be reduced or avoided. More generally, net-zero targets should not be made the sole criterion for ambitious climate strategies. Rather, they are a building block of a much more comprehensive strategy of corporate climate action.
    Keywords: ddc:330
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
    Type: workingpaper , doc-type:workingPaper
    Format: application/pdf
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  • 99
    Publication Date: 2021-11-26
    Description: To expand the newly developed ARM glasses as reference materials for in situ microanalysis of isotope ratios and iron oxidation state by a variety of techniques such as SIMS, LA-MC-ICP-MS and EPMA, we report Li-B-Si-O-Mg-Sr-Nd-Hf-Pb isotope data and Fe2+/ΣFe ratios for these glasses. The data were mainly obtained by TIMS, MC-ICP-MS, IR-MS and wet-chemistry colorimetric techniques. The quality of these data was cross-checked by comparing different techniques or by comparing the results from different laboratories using the same technique. All three glasses appear to be homogeneous with respect to the investigated isotope ratios (except for B in ARM-3) and Fe2+/ΣFe ratios at the scale of sampling volume and level of the analytical precision of each technique. The homogeneity of Li-B-O-Nd-Pb isotope ratios at the microscale (30–120 μm) was estimated using LA-MC-ICP-MS and SIMS techniques. We also present new EPMA major element data obtained using three different instruments for the glasses. The determination of reference values for the major elements and their uncertainties at the 95% confidence level closely followed ISO guidelines and the Certification Protocol of the International Association of Geoanalysts. The ARM glasses may be particularly useful as reference materials for in situ isotope ratio analysis.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 100
    Publication Date: 2021-11-26
    Description: In the frame of the AlpArray project we analyse teleseismic data from permanent and temporary stations of the Alpine region to study seismic discontinuities down to about 140 km depth. We average broadband teleseismic S-waveform data to retrieve S-to-P converted signals from below the seismic stations. In order to avoid processing artefacts, no deconvolution or filtering is applied, and S arrival times are used as reference for stacking. We show a number of north–south and east-west profiles through the Alpine area. The Moho signals are always seen very clearly, and negative velocity gradients below the Moho depth are also visible in a number of profiles. A Moho depression is visible along larger parts of the Alpine chain. It reaches its largest depth of 60 km beneath the Tauern Window. However, the Moho depression ends abruptly near about 13∘ E below the eastern Tauern Window. This Moho depression may represent the crustal trench, where the Eurasian lithosphere is subducted below the Adriatic lithosphere. East of 13∘ E an important along-strike change occurs; the image of the Moho changes completely. No Moho deepening is found in this easterly region; instead the Moho bends up along the contact between the European and the Adriatic lithosphere all the way to the Pannonian Basin. An important along-strike change was also detected in the upper mantle structure at about 14∘ E. There, the lateral disappearance of a zone of negative velocity gradient in the uppermost mantle indicates that the S-dipping European slab laterally terminates east of the Tauern Window in the axial zone of the Alps. The area east of about 13∘ E is known to have been affected by severe late-stage modifications of the structure of crust and uppermost mantle during the Miocene when the ALCAPA (Alpine, Carpathian, Pannonian) block was subject to E-directed lateral extrusion.
    Language: English
    Type: info:eu-repo/semantics/article
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