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  • Articles  (45)
  • GFZ OAI  (45)
  • Articles: DFG German National Licenses
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  • Technische Universität Berlin  (2)
  • 1
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    Unknown
    Technische Universität Berlin
    Publication Date: 2021-03-08
    Description: Background: Agriculture is a large and dynamic sector, essential for the supply of the population and thus in a complex area of tension. The growing population and the resulting need for optimization, greater efficiency and intensification are in direct conflict with the demand for sustainability, environmental compatibility and, above all, mitigation of climate change and its consequences. Precision agriculture can make a decisive contribution to increasing efficiency in particular. Because through the targeted and demand-oriented application of fertilizers and pesticides, but also spatially variable sowing, resources can be used better and in the best case even increase yields. Above all, if fertilizers are applied in the way that the plants need and can absorb them, in contrast to uniform application across the entire field, a surplus that can be washed into the groundwater can be avoided. A basis is therefore needed on which this variable application of resources can be determined. In practice, maps of current condition in the form of zones in the field or on-the-go measurements from sensors on the tractor are often used here. However, for comprehensive planning and holistic cultivation of crop, current and past spatial information maps, such as zone maps, are necessary. Satellite data are a data basis for such zones, as they are available in various types, current and retrospective and cover large areas spatially. Objective: This work explores possibilities to derive this zoning from satellite data and developes different approaches. The interrelations between satellite data, geoinformation data and agricultural data such as yield will be investigated and combined. The focus of the method development is the applicability in practice and the associated requirements of the farmer. Data: For method development and analysis 179 RapidEye scenes, 512 Landsat scenes, 43 Sentinel-2 scenes and 21 Planetscope scenes were used. Furthermore, the soil map „Bodenschätzung“, which not only transmits the information about the respective soil type, but also a quantification of the fertility respectively the yield potential in the form of „Bodenzahl“ and „Ackerzahl“. Digital terrain models in different spatial resolutions were used as well as in-situ measurements of nutrients, electrical conductivity and phenology. Methods and Results: In this thesis two methods and a data analysis are presented. The first method uses only optical satellite data (RapidEye) and processes these automatically into five relative yield zones, which reflect the expected relative yield averaged over several years. The method independently selects the appropriate data sets for a prescribed field, using different thresholds resulting from the reflectance values of individual bands. The zones are then separated on the basis of quantile values using an synthetic, averaged raster of the near infrared bands. The method is validated with actual yield data using the characteristics of box plots. The yield zones generated can then be used as management zones in precision farming. The second method also generates relative yield zones, suitable for use as a management zone, using RapidEye satellite data as well as soil map and relief information. This data fusion for yield zone modeling is based on belief structures and uses the Transferable Belief Model. Thus, individual expert knowledge from practical agriculture can be integrated into the fusion process. The knowledge generated in the course of method development about the relationship between remote sensing and GIS data and the actual yield on the field will be extended and consolidated in a large-scale data analysis with a time series of 13 years and 755 satellite scenes. It shows that there is a strong correlation between satellite data and yield data (up to a correlation value of r = 0.75, some values even higher). However, this correlation depends strongly on the phenological timing of - in this case - cereals and canola. In addition, the spectral and spatial resolution, as well as the growing conditions and the soil available water. Conclusion: Satellite data are very well suited for agricultural applications and for the derivation of management zones for precision crop cultivation. However, a lot of expert knowledge has to be applied in the selection of the appropriate remote sensing data as well as in the processing and methodology. The scientific and practical use of remote sensing data should be adapted to the specific problem and external conditions.
    Description: Hintergrund: Die Landwirtschaft ist ein großer und dynamischer Sektor, essentiell für die Versorgung der Bevölkerung und dadurch in einem komplexen Spannungsfeld. Die steigende Bevölkerung und der dadurch bestehende Bedarf an Optimierung, mehr Effizienz und Intensivierung steht im direkten Konflikt mit dem Anspruch nach Nachhaltigkeit, Umweltverträglichkeit aber vor allem der Eindämmung des Klimawandels und seiner Folgen. Gerade bei Fragen der Effizienzsteigerung kann der Bereich der Präzisionslandwirtschaft einen entscheidenden Beitrag leisten. Denn durch die gezielte und bedarfsorientierte Anwendung von Dünger und Pflanzenschutzmitteln, aber auch die gezielte und räumlich variable angepasste Aussaat, können Ressource besser genutzt werden und im besten Falle den Ertrag sogar steigern. Vor allem wenn Düngemittel so ausgebracht werden, wie die Pflanzen ihn benötigen und aufnehmen können, im Gegensatz zu einer uniformen Ausbringung über das ganze Feld hinweg, kann ein Überschuss, welcher in das Grundwasser ausgewaschen werden kann, vermieden werden. Es braucht also eine Grundlage, auf welcher diese variable Ausbringung von Ressourcen bestimmt wird. Hier werden in der Praxis oft Zustandskarten in Form von Zonen im Feld verwendet oder „on-the-go“-Messungen von Sensoren auf dem Traktor. Für die umfassende Planung und eine holistische Bearbeitung der Bestände sind aber aktuelle und zurückliegende, wie zusammenfassende Zustandskarten, beziehungsweise Zonenkarten nötig. Eine Datengrundlage für solche Zonen sind Satellitendaten, da sie in verschiedenster Art, aktuell und retroperspektiv vorliegen und große Flächen räumlich erfassen. Ziel: Diese Arbeit erforscht Möglichkeiten aus Satellitendaten eben diese Zonierung abzuleiten und sucht dabei verschiedene Herangehensweisen. Es sollen die Zusammenhänge zwischen Satellitendaten, Daten der Geoinformation und landwirtschaftlicher Daten wie Ertrag untersucht und miteinander kombiniert werden. Im Fokus der Methodenentwicklung steht die Anwendbarkeit in der Praxis und die somit einhergehenden Anforderungen des Landwirtes. Daten: Für die Methodenentwicklung und die Analyse wurden 179 RapidEye Szenen, 512 Landsat-Szenen, 43 Sentinel-2 Szenen und 21 Planetscope-Szenen verwendet. Weiterhin die Bodenkarte Bodenschätzung, welche nicht nur die Informationen über die jeweilige Bodenart übermittelt, aber auch eine Quantifizierung der Fruchtbarkeit beziehungsweise des Ertragspotentials in Form von „Bodenzahl“ und „Ackerzahl“. Digitale Geländemodell in unterschiedlichen räumlichen Auflösungen wurden verwendet, ebenso wie in-situ-Messungen von Nährstoffen, elektrischer Leitfähigkeit und Phänologie. Methoden und Ergebnisse: In dieser Doktorarbeit werden zwei Methoden und eine Datenanalyse vorgestellt. Die erste Methode verwendet einzig optische Satellitendaten (RapidEye) und verarbeitet diese automatisiert zu fünf relativen Ertragszonen, welche den zu erwartenden relativen Ertrag gemittelt über mehrere Jahre spiegelt. Die Methode wählt dabei eigenständig die passenden Datensätze für ein vorgeschriebenes Feld aus, unter Verwendung verschiedener Schwellwerte, die sich aus den Rückstrahlwerten einzelner Bänder ergeben. Auf Basis eines gemittelten Rasters der Bänder des nahen Infrarots werden dann auf Basis von Quartilswerten die Zonen separiert. Die Methode wird mit tatsächlichen Ertragsdaten mithilfe der Charakteristika von Boxplots validiert Die erzeugten Ertragszonen können dann als Bearbeitungszonen in der Präzisionslandwirtschaft verwendet werden. Die zweite Methode erzeugt ebenfalls relative Ertragszonen, geeignet für die Verwendung als Management Zone, verwendet neben RapidEye Satellitendaten auch die Informationen der Bodenkarte und des Reliefs. Diese Datenfusion zur Modellierung von Ertragszonen basiert auf Überzeugungsstrukturen und verwendet das Transferable Belief Model. Somit kann individuelles Expertenwissen aus der praktischen Landwirtschaft in den Fusionsprozess integrieren werden. Die Erkenntnisse, die im Laufe der Methodenentwicklung über die Zusammenhänge von Fernerkundungs- und GIS Daten und dem tatsächlichen Ertrag auf dem Feld generiert wurden, werden in einer großangelegten Datenanalyse mit einer Zeitreihe von 13 Jahren und 755 Satellitenszenen erweitert und gefestigt. Sie zeigt, dass es einen starken Zusammenhang zwischen Satellitendaten und Ertragsdaten gibt (bis zu einem Korrelationswert von r = 0.75, einzelne Werte höher). Diese Korrelation hängt aber stark ab vom phänologischen Zeitpunkt von – in diesem Falle – Getreide und Raps. Außerdem von der spektralen und räumlichen Auflösung, sowie den Wachstumsbedingungen und dem bodenverfügbaren Wasser. Fazit: Satellitendaten eignen sich sehr gut für die Anwendung in der Landwirtschaft und für die Ableitung von Bearbeitungszonen für den Präzisionspflanzenbau. Allerdings muss in der Auswahl der passenden Fernerkundungsdaten und auch der Verarbeitung und Methodik viel Expertenwissen angewandt werden. Die wissenschaftliche und praktische Verwendung von Fernerkundungsdaten sollte an die spezifische Fragestellung und die äußeren Bedingungen angepasst werden.
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  • 2
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    Unknown
    Deutsches GeoForschungsZentrum GFZ
    Publication Date: 2020-02-12
    Language: English
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  • 3
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    Technische Universität Berlin
    Publication Date: 2021-06-16
    Description: The ability to measure multiple environmental parameters, such as atmospheric water vapour, soil moisture and snow height with the same hardware is the main advantage of Global Navigation Satellite System (GNSS) environmental measurements over other observation techniques. In this thesis state-of-art ground-based GNSS methods for environmental monitoring are used to derive atmospheric water vapour and soil moisture, to observe their dynamics on local, regional and global scales and to analyse both short-term case studies and long-term climatological monitoring. The GNSS Meteorology method of observing the atmospheric water vapour through the GNSS signal delay in the atmosphere is applied to several stations in Bulgaria and compared to simulations with the Weather Research and Forecast (WRF) model, as well as to radiosonde measurements. All the data from these experiments is stored in the Sofia University Atmospheric Data Archive (SUADA), specifically developed as a foundation for the atmospheric studies in this work. A study of the 2007 heatwave for station Sofia shows 6% lower Integrated Water Vapour (IWV), compared to the 2001-2010 mean. A trend analysis of all available GNSS and radiosonde time series for station Sofia for the time period between 2000-2019 shows an increase in the IWV of 0.8kg/m^2/decade on average from reprocessed GNSS datasets and an increase of 0.6kg/m^2/decade from the radiosonde measurements. A dedicated GNSS processing campaign using the NAPEOS software and employing a Precise Point Positioning (PPP) strategy is undertaken for measurements of IWV over a network of Bulgarian stations for one year. The GNSS derived IWV is used to evaluate the seasonal and diurnal variations of the WRF model and to analyse severe weather events. The single antenna ground-based GNSS Reflectometry (GNSS-R) method is used to estimate the soil moisture Volumetric Water Content (VWC) and snow height in GNSS stations in Germany and on a global scale. A dedicated software package for processing signal strength observations from GNSS ground stations is further developed to estimate soil moisture and snow height using the GNSS-R method. The software is validated, showing 0.98 correlation with data from an independent processing center. The GFZ Reflectometry and Atmospheric Database (GRAD) is designed to archive soil moisture observations from GNSS-R and Time Domain Reflectometry (TDR), as well as atmospheric parameters and model data. In two experimental stations (Marquardt and Furstensee) in Germany, VWC is monitored between 2014-2019 with specially installed high-end and low-cost GNSS antennae and receivers. The GNSS-R VWC retrievals are compared to collocated TDR and gravimetric measurements. The results show that the soil moisture retrievals, obtained from the low-cost receivers, show lower correlation (0.67), than the high-end receivers (0.75) when compared to TDR. Gravimetric measurements are used to calibrate the residual VWC from GNSS-R. An analysis of the error budget of the GNSS-R observations of soil moisture is done, based on the high-end receiver results. All stations in the International GNSS Service (IGS) global network are individually tested for soil moisture observation capabilities. Out of 506 stations in this global network only 30 stations (6\%) are found to satisfy the requirements for GNSS-R observations, namely: reflections coming from flat grasslands. The Volumetric Water Content (VWC) observations are compared with results from the ECMWF Reanalysis model's 5th implementation - ERA5. The comparisons show fair correlation between the two datasets with ERA5 overestimating the residual VWC in most sites. Each station is discussed separately with an emphasis on station surroundings and climate conditions. A new 1-dimensional empirical soil moisture model is developed to quantify the relation between VWC in the soil and atmospheric water vapour. Several different implementations of the model, based on temperature, water vapour and precipitation are discussed and compared to GNSS-R and TDR soil moisture observations in experimental station Marquardt. The resulting model is applied to GNSS stations from the IGS network for further assessment. The comparisons with GNSS-R derived soil moisture show higher correlation, than the soil moisture, derived in the ERA5 and are higher than 0.6. Contrary to the ERA5, the model does not overestimate the residual soil moisture in the stations. A new technique for snow height measurement is validated in a GNSS-R setup in Antarctic station Neumayer III. This new technique shows improved characteristics to the classical single antenna ground-based GNSS-R snow height determination method. The validation is done in an environment of constant snow accumulation. The results from the different techniques show very similar results with correlation between the de-trended GNSS-R and snow buoy measurements of above 0.85. Snow height is also determined in the 7 IGS stations within the continental climate zones. The results are compared with the ERA5, local snow height measurements and climate normals.
    Description: Das Erfassen von Umweltdaten mit dem Globale Navigationssatellitensystem (GNSS) hat gegenüber anderen Beobachtungstechniken einen entscheidenden Vorteil: es können mehrere Parameter wie zum Beispiel der atmosphärischer Wasserdampf, Bodenfeuchtigkeit und Schneehöhen mit einem einzigen Hardwaresystem erfasst werden. In dieser Arbeit wird aufgezeigt wie modernste bodengestützte GNSS-Methoden zur Umweltüberwachung eingesetzt werden können um atmosphärischen Wasserdampf und Bodenfeuchte abzuleiten und deren Variabilität auf lokaler, regionaler und globaler Ebene zu analysieren und sie sowohl in kurzfristige Fallstudien als auch in langfristige klimatologische Beobachtungen zu implementieren. Die GNSS-Meteorologie-Technologie nutzt Verzögerungen in den GNSS Signalen zur Beobachtung des atmosphärischen Wasserdampfs in der Atmosphäre. Diese Methode wird auf mehrere Stationen in Bulgarien angewandt und mit Simulationen mit dem Modell für Wetterforschung und -vorhersage (WRF) sowie mit Radiosondenmessungen verglichen. Alle Daten aus diesen Experimenten werden im Atmosphärendatenarchiv der Universität Sofia (SUADA) gespeichert, welches speziell für die atmosphärischen Studien in dieser Arbeit angelegt wurde. Eine Untersuchung der Hitzewelle im Sommer 2007 für die Station Sofia zeigt eine um 6% niedrigere integrierte Wasserdampfmenge (IWV) im Vergleich zum Mittelwert von 2001-2010. Eine Trendanalyse aller verfügbaren GNSS- und Radiosonden-Zeitreihen für die Station Sofia im Zeitraum zwischen 2000-2019 zeigt einen Anstieg des IWV von durchschnittlich 0,8kg/m^2/Dekade aus den wiederaufbereiteten GNSS-Datensätzen und einen Anstieg von 0,6kg/m^2/Dekade aus den Radiosonden-Messungen. Eine Kampagne zur Messungen des IWV wird über die Dauer von einem Jahr über ein Netzwerk bulgarischer Stationen durchgeführt. Das Ziel ist es die Verarbeitung der GNSS-Signale mit der NAPEOS-Software unter Anwendung der präzisen Punktpositionierung (PPP) zu testen. Der abgeleitete IWV wird zur Validierung der jahreszeitlichen und tageszeitlichen Schwankungen des WRF-Modells und zur Analyse von Unwetterereignissen verwendet. Die bodengebundene GNSS Reflektometrie (GNSS-R) Methode wird zur Abschätzung des volumetrischen Wassergehalts (VWC) und der Schneehöhe an GNSS-Stationen in Deutschland und auf globaler Ebene verwendet. Ein spezielles Software-Paket zur Verarbeitung von Signalstärke-Beobachtungen von GNSS-Bodenstationen wird weiterentwickelt, um Bodenfeuchte und Schneehöhe mit Hilfe der GNSS-R-Methode abzuschätzen. Die Software ist validiert und zeigt eine Korrelation von 0,98 mit Daten eines unabhängigen Verarbeitungszentrums. Die GFZ-Reflektometrie- und Atmosphärendatenbank (GRAD) wurde erstellt um Bodenfeuchtigkeitsbeobachtungen von GNSS-R und Time Domain Reflectometry (TDR) sowie atmosphärische Parameter und Modelldaten zu archivieren. Zwischen 2014-2019 wurde der VWC an zwei Messstationen (Marquardt und Fürstensee) in Deutschland mit speziell installierten hochwertigen sowie kostengünstigen GNSS-Antennen und -Empfängern überwacht. Die GNSS-R Messungen des VWC- werden mit Ergebnissen der TDR- sowie gravimetrischen Methoden verglichen. Im Vergleich zu den TDR Messungen des Bodenfeuchtegehalts weisen die kostengünstigen Empfänger eine geringere Korrelation (0,67) als die High-End-Empfänger (0,75) auf. Die gravimetrischen Messungen werden zur Kalibrierung der VWC-Restbodenfeuchte von GNSS-R verwendet. Eine Analyse des Fehlerbudgets der GNSS-R-Beobachtungen der Bodenfeuchte wird auf der Grundlage der Ergebnisse der High-End-Empfänger durchgeführt. Alle Stationen im globalen Netzwerk des Internationalen GNSS-Dienstes (IGS) werden einzeln auf ihre Tauglichkeit zur Beobachtung der Bodenfeuchte getestet. Von den 506 Stationen in diesem globalen Netzwerk erfüllen nur 30 Stationen (6%) die Voraussetzung für GNSS-R Beobachtungen: die Reflexionen sollten von flachem Grasland kommen. Die Beobachtungen des volumetrischen Wassergehalts (VWC) werden mit den Ergebnissen der 5. Version des ECMWF-Reanalysemodells - ERA5 - verglichen. Die Vergleiche zeigen eine gute Korrelation zwischen beiden Datensätzen, wobei ERA5 den Restwassergehalt an den meisten Standorten überschätzt. Die Korrelationen werden in der Arbeit für jede Station separat diskutiert, wobei der Schwerpunkt auf dem Einfluss der Umgebungsbedingungen der Station und den klimatischen Bedingungen liegt. Ein neues 1-dimensionales empirisches Bodenfeuchtemodell wird entwickelt, um die Beziehung zwischen der Bodenfeuchte und dem Wassergehalt der Atmosphäre zu quantifizieren. Verschiedene Modellversionen, die auf Temperatur, Wasserdampf und Niederschlag basieren, werden diskutiert und mit GNSS-R- und TDR-Bodenfeuchtigkeitsbeobachtungen in der Versuchsstation Marquardt verglichen. Das resultierende Modell wird zur weiteren Bewertung auf GNSS-Stationen aus dem IGS-Netz angewendet. Vergleiche mit der von GNSS-R abgeleiteten Bodenfeuchte zeigen eine höhere Korrelation (〉0,6) als die aus ERA5 abgeleitete Bodenfeuchte. Im Gegensatz zum ERA5 überschätzt das neue Modell die Restbodenfeuchte in den Stationen nicht. Eine neue Methode zur Schneehöhenmessung wird in einem GNSS-R-Aufbau in der Antarktisstation Neumayer III validiert. Diese neue Technik zeigt verbesserte Eigenschaften zu der klassischen bodengebundenen GNSS-R-Schneehöhenbestimmung mit einer einzigen Antenne. Die Validierung erfolgt in einer Umgebung mit konstanter Schneedecke. Die Ergebnisse der verschiedenen Messmethoden zeigen sehr ähnliche Ergebnisse mit einer Korrelation von über 0,85 zwischen GNSS-R- und Schneebojenmessungen. Die Schneehöhe wird auch in den 7 IGS-Stationen innerhalb der kontinentalen Klimazonen bestimmt. Die Ergebnisse werden mit dem ERA5, den lokalen Schneehöhenmessungen und den klimatischen Mittelwerten verglichen.
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  • 4
    Publication Date: 2020-02-12
    Description: In my thesis, I studied marine and lacustrine sediment cores from different depositional provinces along the south-central Chilean margin with the overall objective to identify their records of paleoclimate and paleotectonics. First of all, I investigated sedimentary sequences that were recovered within the margin-parallel trench system (cp. Figure 1.2) and hence constitute long-term recorders [...] of the sediment transport between the continent and the abyssal zone of the lower plate.
    Language: English
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  • 5
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    Deutsches GeoForschungsZentrum GFZ
    In:  Scientific Technical Report STR
    Publication Date: 2021-08-21
    Description: A set of 59 seismological stations was deployed in the Central Andes region at 21°S (Chile-Bolivia) along a profile ~600 km long and were operated between 2002 and 2004. The teleseismic tomographic images (from P- and S- waves) show low-velocity anomalies that are interpreted as the effects of melting or fluids at both flanks of the Altiplano plateau. Beneath the Central Volcanic Zone (CVZ) a low-velocity anomaly is interpreted to be caused by fluids that are the origin of the volcanic material from the CVZ. A low-velocity anomaly in the upper crust is interpreted as the Altiplano Low-Velocity Zone that appears to extend as far to the east as the Eastern Cordillera. A high-velocity body between 100 km and 150 km depth is interpreted as being part of the old cold lithosphere that detached from the base of the crust. The Brazilian Shield is thought to be responsible for the strong high-velocity anomaly on the eastern side of the Central Andes. In addition, another set of 19 stations was deployed in the southern Argentine Puna along a profile ~200 km long and were run over the same period of time (2002-2004). The intention was to study the crustal thickness at 25.5°S, where delamination of the lithosphere was proposed to explain the higher elevation of the Puna plateau. Beneath the plateau a negative velocity anomaly is observed and interpreted here as being the location of fluid transfer between the deeper and shallower portions of the crust, that emanate from the Benioff zone at depths of ~200 km. This anomaly clearly divides in two branches: one to the west towards the volcanic arc (CVZ) and the other to the east where the back-arc volcanoes are located. On their way to lower depths, the fluid paths are probably influenced by the presence of nearby isotherms. The bifurcation of the ascending path could be related to the presence of the lithosphere-asthenosphere boundary (LAB) at ~100-130 km. Based on our observations, the type and form of the anomaly, it is possible to propose the presence of a return-flow type model for fluid ascent in contraposition to the assumed corner-flow model usually proposed for the Andes. The fluids that cause the seismic anomalies beneath the Puna plateau are generated at deeper levels in the asthenosphere and ascend parallel to the oceanic slab in the manner of a return-flow. In the crust and beneath the Salar de Antofalla (SA), a high-velocity block with seismic activity is interpreted as part of the old and cold Palaeozoic magmatic arc (Faja Eruptiva de la Puna Occidental). The presence of this block is may be responsible for the distribution of volcanic activity localized at both sides of this anomaly. Eastern of the SA, it is possible to recognize a zone with low-velocities beneath the Galan volcano. A sharp limit imposed by high velocities, probably related to metamorphic rocks from the Paleozoic basement (Tacuil and Luracatao ranges) can be detected on the east of the profile. A high-velocity block with seismic activity is located in the crust beneath the Salar de Antofalla (SA) and interpreted as part of the old and cold Palaeozoic magmatic arc (Faja Eruptiva de la Puna Occidental). This block might be responsible for the distribution of volcanic activity localized at both sides of this anomaly. Beneath the Galan volcano and east of the SA, a zone with low-velocities can be recognized. A sharp limit towards high-velocities can be observed on the east of the profile, probably related to metamorphic rocks from the Palaeozoic basement (Tacuil and Luracatao ranges).
    Language: English
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  • 6
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    Deutsches GeoForschungsZentrum GFZ
    In:  Scientific Techncial Report STR
    Publication Date: 2020-02-12
    Description: This thesis summarizes the results of the WSM project’s second phase (1996‐2008). In particular it presents the major achievements that have been accomplished with the WSM 2008 database release that has been compiled under the guidance of the author. Furthermore, the thesis briefly presents three of the author’s numerical models that aim at quantification the temporal changes of the crustal stress field.
    Language: English
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  • 7
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    Deutsches GeoForschungsZentrum GFZ
    In:  Scientific Technical Report
    Publication Date: 2020-02-12
    Description: In order to analyze mineralogical-geochemical changes occurring in whole rock reservoir samples (Stuttgart Formation) from the Ketzin pilot CO2 storage site, Brandenburg/Germany as well as to investigate single fluid-mineral reactions laboratory experiments and geochemical modeling were performed. The whole rock core samples of the Stuttgart Formation were exposed to synthetic brine and pure CO2 at experimental P-T conditions and run durations of 5.5 MPa/40 °C/40 months for sandstone and 7.5 MPa/40 °C/6 months for siltstone, respectively. Mineralogical changes in both sets of experiments are generally minor making it difficult to differentiate the natural variability of the whole rock samples from CO2-induced alterations. Results of sandstone experiments suggest dissolution of analcime, anhydrite, the anorthite component of plagioclase, chlorite + biotite, hematite and K-feldspar. Dissolution of anhydrite, the anorthite component of plagioclase and K-feldspar is also observed in siltstone experiments. During equilibrium simulations best matching models were ranked based on a mathematical statistical dispersion relation. The best matching model comprises a mineral combination of the albite component of plagioclase, anhydrite, dolomite, hematite, and illite. The equilibrium modeling showed that it is difficult to match K+, Fe2+ and SO4 2- brine concentrations simultaneously. The best matching subsets of the equilibrium models were finally run including kinetic rate laws. These kinetic simulations reveal that experimentally determined brine data was well matched, but reactions involving K+ and Fe2+ were not completely covered. Generally larger mismatches for dissolved Al3+ and Si4+ in all the completed simulations are most likely related to the sampling strategy and respective inaccuracies in the measured concentrations of dissolved Al3+ and Si4+. The kinetic simulation suppressing mineral precipitation yields best matches with experimental observations. The modeling shows acceptably well matches with measured brine ion concentrations, and the modeling results identified primary minerals as well as key chemical processes. It was also shown that the modeling approach is not capable of completely covering complex natural systems. Experiments on mineral separates were conducted with 2 M NaCl brine and pure CO2 using siderite, illite and labradorite samples. Experimental P-T conditions were 20 (30) MPa and 80 °C; run durations were one (siderite), two (illite) and three weeks (labradorite), respectively. Based on the acquired set of mineralogical-geochemical data the distinct experiments show: (i) dissolution of ankerite and stable siderite, which is therefore interpreted to be a potential CO2 trapping phase, (ii) preferred dissolution of the Ca-smectite component out of the illite-smectite mixed-layer mineral and (iii) dissolution of labradorite, respectively. No mineral precipitates (e.g. carbonate phases) were detected in any of the conducted laboratory experiments, and only one single kinetic simulation predicts the formation of minute amounts of dolomite. Based on the data acquired during this dissertation the mineralogical-geochemical effects of CO2 are minor, and the (chemical) integrity of the Ketzin reservoir system is not significantly affected by injected CO2.
    Language: English
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  • 8
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    Deutsches GeoForschungsZentrum GFZ
    In:  Scientific Technical Report STR
    Publication Date: 2021-08-21
    Description: This study focuses on tectonics at the Neogene and late Quaternary time scales in the Main Cordillera and coastal forearc of the south-central Andes. For both domains I document the existence of previously unrecognized active faults and present estimates of deformation rates and fault kinematics. Furthermore these data are correlated to address fundamental mountain building processes like strain partitioning and largescale segmentation.
    Language: English
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  • 9
    Publication Date: 2020-02-12
    Description: The ability of any satellite gravity mission concept to monitor mass transport processes in the Earth system is typically tested well ahead of its implementation by means of various simulation studies. Those studies often extend from the simulation of realistic orbits and instrumental data all the way down to the retrieval of global gravity field solution time-series. Basic requirement for all these simulations are realistic representations of the spatio-temporal mass variability in the different sub-systems of the Earth, as a source model for the orbit computations. For such simulations, a suitable source model is required to represent (i) high-frequency (i.e., subdaily to weekly) mass variability in the atmosphere and oceans, in order to realistically include the effects of temporal aliasing due to non-tidal high-frequency mass variability into the retrieved gravity fields. In parallel, (ii) low-frequency (i.e., monthly to interannual) variability needs to be modelled with realistic amplitudes, particularly at small spatial scales, in order to assess to what extent a new mission concept might provide further insight into physical processes currently not observable. The new source model documented here attempts to fulfil both requirements: Based on ECMWF’s recent atmospheric reanalysis ERA-Interim and corresponding simulations from numerical models of the other Earth system components, it offers spherical harmonic coefficients of the time-variable global gravity field due to mass variability in atmosphere, oceans, the terrestrial hydrosphere including the ice-sheets and glaciers, as well as the solid Earth. Simulated features range from sub-daily to multiyear periods with a spatial resolution of spherical harmonics degree and order 180 over a period of 12 years. In addition to the source model, a de-aliasing model for atmospheric and oceanic high-frequency variability with augmented systematic and random noise is required for a realistic simulation of the gravity field retrieval process, whose necessary error characteristics are discussed. The documentation of the updated ESA Earth System Model (updated ESM) for gravity mission simulation studies is organized as follows: The characteristics of the updated ESM along with some basic validation is presented in Volume 1. A detailed comparison to the original ESA ESM (Gruber et al., 2011) is provided in Volume 2, while Volume 3 contains the description of a strategy to derive realistic errors for the de-aliasing model of high-frequency mass variability in atmosphere and ocean.
    Language: English
    Type: info:eu-repo/semantics/report
    Format: application/pdf
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  • 10
    Publication Date: 2020-02-12
    Type: info:eu-repo/semantics/conferenceObject
    Format: application/pdf
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