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  • Univ. Bremen  (66)
  • Univ. Berlin  (46)
  • English  (68)
  • German  (44)
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  • 2020-2023
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  • 2010  (112)
  • 1
    Publication Date: 2021-03-29
    Description: This work focuses on the distribution of atomic hydrogen in the exosphere of Saturns̉ moon Titan. This work is based on measurements performed by the Hydrogen Deuterium Absorption Cell (HDAC) aboard the Cassini spacecraft, that should directly determine the D/H ratio from the UV emission of atomic hydrogen and deuterium at 121.567 and 121.533 nm, respectively. HDAC measurements were performed on December 26, 2005 during the ninth Titan flyby of the Cassini orbiter. Unfortunately the amount of deuterium in the absorption cell could not be determined. Thus, the purpose, HDAC was designed for could not be achieved. For this reason, HDAC has performed measurements only once. However, the amount of atomic hydrogen in the absorption cell is well known, hence the data using only the hydrogen cell can be used in order to investigate Titans̉ exosphere. This work aims at simulating the HDAC measurements performed in order to investigate Titan’s exosphere, e.g. to determine the distribution of atomic hydrogen. A model of Titan’s exosphere including atomic hydrogen and methane has been developed and the transfer of solar radiation is calculated in order to simulate the HDAC measurements. The radiative transfer is solved using the Monte Carlo method. For the exospheric model, two different atomic hydrogen density distributions were applied, which determine the distribution in the exosphere by different approaches. Density profiles calculated by both models mainly differ in the lower exosphere ...
    Description: thesis
    Keywords: 523 ; TGG 655 ; Saturnmonde {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 171 S.
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  • 2
    Publication Date: 2021-03-29
    Description: This thesis discusses dust formation in binary systems, in particular for binary systems consisting of a Mira like star and a brown dwarf. A Mira-like star is an intermediate mass star in a late stage of their stellar evolution on the Asymptotic Giant Branch (AGB), and a brown dwarf, is a sub-stellar object with a mass below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores. In their radial pulsating elevated convective atmospheres, Mira-stars often develop strong stellar winds, which are driven by radiation pressure on the dust and lead to a substantial mass-loss of the star. Stellar winds are of central importance for the development of medium-heavy-AGB stars. Also, they are a reliable source for the production of dust particles and heavy elements for the interstellar medium and the chemical evolution of galaxies. In fact, most stars are in binary or multiple star systems.For a complete description of the processes of dust formation in binary star systems it is necessary to study the perturbative influence of a second star in the vicinity of a AGB-star with a strong stellar wind. This endeavour is embedded in a long standing tradition of scientific investigation of dust formation at the Zentrum für Astronomie und Astrophysik (ZAA) at the Technical University of Berlin...
    Description: thesis
    Keywords: 523 ; THT 900 ; TII 900 ; Doppelsterne {Astronomie} ; Interstellarer Staub {Astronomie: Interstellare Materie}
    Language: English
    Type: monograph , publishedVersion
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  • 3
    Publication Date: 2021-03-29
    Description: The first extrasolar planet 51 Peg b around the G-type star has been reported in 1995. The planet with few Jupiter masses orbiting its star very closely was detected by measurement of the oscillation in the radial velocity of the host star. In 1999 the first transit, when the planet is eclipsing the host star, of the extrasolar planet HD209458 b was observed with a small ground based photometric telescope. Ever since, new planets in distant systems are continuously being detected with new high precision instruments from the ground and from space. The department of Extrasolar Planets and Atmospheres at Deutsches Zentrum für Luft- und Raumfahrt, Berlin (DLR) is involved in the detection and characterization of extrasolar planets, through participation in the CoRoT space mission. Furthermore, two ground based photometric telescope systems are operated as a ground based support for the space mission CoRoT, dedicated to asteroseismology and to extrasolar planet search with the help of the transit method. The BEST project consists of two small aperture wide field-of-view photometric telescopes devoted to the search for transiting Jupiter-sized extrasolar planets and to the characterization of variable stars in CoRoT target fields...
    Description: thesis
    Keywords: 523 ; THX 100 ; TJ 900 ; TCE 220 ; Detektionsmethoden {Astronomie: Extrasolare Planetensysteme} ; Einzelne Weltraumprojekte ; Bodenständige UV-, Optische und Infrarotteleskope {Astronomische Instrumente}
    Language: English
    Type: monograph , publishedVersion
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  • 4
    Publication Date: 2021-03-29
    Description: Das Antarctic Muon And Neutrino Detector Array (AMANDA) ist ein Cherenkov Detektor, der sich im Gletscher der Antarktis am Südpol befindet. Wir präsentieren die Analyse von Daten, die in den Jahren 2000 bis 2004 gesammelt wurden, die einer effektiven Detektorlaufzeit von 1001 Tagen entsprechen. Die Suche zielt auf den Nachweis von elektomagnetische und hadronische Teilchenschauern, so gennante Kaskaden, die durch Elektron- und Tauneutrinowechselwirkung produziert werden können. Die hadronischen Kaskaden können auch über neutrale Ströme Wechselwirkung von Neutrinos aller Arten produziert werden. Der Kaskadenkanal hat einige Vorteile in der Suche nach einem diffusen Fluss von astrophysikalischen Neutrinos. Durch die gute Energieauflösung des AMANDA Detektors kann man zwischen einem harten astrophysikalische Spektrum und einem weichen atmosphärischen Spektrum unterscheiden. Außerdem ist der atmosphärischen Elektronneutrinos Fluss um eine Gößenordnung kleiner als der atmosphärische Myonneutrinofluss. Der Untergrund von atmosphärischem Myonen aus Luftschauern kann unterdrückt werden, weil diese als Spuren im Detektor erscheinen und leicht zu identifizieren sind...
    Description: thesis
    Keywords: 539.7215 ; 523 ; 550 ; TBN 000 ; TCE 500 ; Neutrino-Astronomie ; Sonstige Instrumente {Astronomische Instrumente}
    Language: English
    Type: monograph , publishedVersion
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  • 5
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    Univ. Berlin
    Publication Date: 2021-03-29
    Description: Magnetic cataclysmic variables, also called AM Her stars or 'polars', are close binaries with mass transfer (accretion), consisting of a late-type main-sequence star (commonly called secondary)and a more massive white dwarf with a strong magnetic field. The late-type star is losing mass to the white dwarf. The overflowing matter firstly follows a ballistic trajectory and is then captured by the magnetic field of the white dwarf and guided along the field lines onto the white dwarf. The released gravitational energy is radiated away in all wavelength ranges from infra-red to X-ray. The observed light of an AM Her system is composed of the contributions from the stellar components and the contributions of the accretion column and the accretion region on the white dwarf. The last two components are not only depending on the actual mass transfer rate but also from the spatial orientation of the magnetic field. Since the white dwarf is locked in synchronous rotation, this leads to emission that varies with orbital phase. The decomposition of the observed light from an AM Her system makes it possible to analyse the different components within this system...
    Description: thesis
    Keywords: 523 ; THK 000 ; Spektren und Spektroskopie von Sternen {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 140 S.
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  • 6
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    Univ. Berlin
    Publication Date: 2021-03-29
    Description: This work covers the dominant aspects of landforms and processes related to the cold-climate (periglacial) and hyperarid environment of Mars and relates the knowledge obtained from terrestrial research to possible Martian analogue landforms. Among the plethora of landforms related to cold-climate environments and subsurface permafrost on Mars, those features have been investigated in detail that are related to the creep of ice and debris at the Martian dichotomy escarpment and the southern-hemispheric impact basins, especially Hellas Planitia, and which have been described controversially as either glacial or periglacial in nature. Structures related to seasonal freeze-thaw cycles on Mars which are generally known as thermal contraction polygons form a second major focus of this work. Research presented on this topic focuses on the northern hemispheric Utopia Planitia area and the south-polar cap of Mars. This work was carried out on the basis of observational and geomorphometrical analyses by utilizing imaging-sensor and topographic data in order to address questions regarding the history, development, and current state of cold-climate landforms on Mars. This work provides new insights with respect to age, composition, source of debris and ice, and the deformational and degradational history of lobate debris aprons and similar landforms. It is shown that processes which led to creep of debris and ice at the northern hemispheric dichotomy boundary are transitional in nature and are not easily categorized using standard definitions commonly used in terrestrial research...
    Description: thesis
    Keywords: 523 ; 550 ; V 600 ; VAR 800 ; TGG 545 ; Grenzgebiete. Beziehungen. Wirkungen. Einflüsse {Geologische Wissenschaften} ; Periglazialerscheinungen ; Marsoberfläche {Astronomie}
    Language: German
    Type: monograph , publishedVersion
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  • 7
    Publication Date: 2021-03-29
    Description: The subject of this work is the physical characterization of asteroids, with an emphasis on the thermal inertia of near-Earth asteroids (NEAs). Thermal inertia governs the Yarkovsky effect, a non-gravitational force which significantly alters the orbits of asteroids up to ~20 km in diameter. Yarkovsky-induced drift is important in the assessment of the impact hazard which NEAs pose to Earth. Yet, very little has previously been known about the thermal inertia of small asteroids including NEAs.Observational and theoretical work is reported. The thermal emission of asteroids has been observed in the mid-infrared (5-35 æm) wavelength range using the Spitzer Space Telescope and the 3.0 m NASA Infrared Telescope Facility, IRTF; techniques have been established to perform IRTF observations remotely from Berlin. A detailed thermophysical model (TPM) has been developed and extensively tested; this is the first detailed TPM shown to be applicable to NEA data.
    Description: thesis
    Keywords: 523 ; 550 ; TGG 900 ; Planetoide {Astronomie}
    Language: English
    Type: monograph , publishedVersion
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  • 8
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 523 ; 550 ; TH0 000 ; THP 000 ; THT 600 ; Asteroseismologie, Oszillation {Sterne} ; Thermodynamische Vorgänge in Sternen {Astronomie} ; Riesensterne {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 135 S.
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  • 9
    Publication Date: 2021-03-29
    Description: In dieser Doktorarbeit wurden im Rahmen des MAGIC Experimentes neue Datenanalysemethoden implementiert, die sich insbesondere fuer die Analyse von Ereignissen niedriger Gammastrahlungsenergie eignen. Die Methoden konnten erfolgreich in Monte Carlo Studien getestet und auf Beobachtungsdaten des Krebsnebels und der extragalaktischen Gammastrahlungsquelle PG1553+113 angewandt werden. Diese Methoden reichen von ''image cleaning'' Techniken und der Nutzung neuer Bildparameter bis zu fortgeschrittenen g/h-Separations- und Energieabschaetzungsverfahren. Zum ersten Mal wurden die Vorteile von Klassifikations- und Regressionsbaeumen in der Gamma-Astrophysik ausgenutzt, um existierende klassische Methoden zu verbessern. Die Analyse - getestet an Monte Carlo Daten - bewies ihre Zuverlaessigkeit bei der Untersuchung der Gammastrahlungsemission des Krebsnebels, wobei ein hochsignifikanter Exzess im Energiebereich unterhalb 100 GeV in nur 1.7 h nachgewiesen werden konnte. Die Analyse von Daten des BL Lac Objekts PG1553+113 ergab signifikante Exzesse fuer Beobachtungen in den Jahren 2005 und 2006. Das kombinierte alpha-Histogramm zeigt ein Signal mit einer Signifikanz, die 8 sigma ueberschreitet...
    Description: thesis
    Keywords: 523 ; TBK 000 ; THT 200 ; Hochenergieastronomie ; Sterne einzelner Spektralklassen {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 195 S.
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  • 10
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 523 ; THP 000 ; Thermodynamische Vorgänge in Sternen {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 76 S.
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  • 11
    Publication Date: 2021-03-29
    Description: Lambert, cosmological letters, fixed stars, nebulae, island universe, teleology, teleological, enlightenment, enlightened, romanticism, romantic, hypothesis, physical-teleological, speculation, imagination, stability, solar system, cosmology, astronomy, comet, magic, alchemy, pietism, science, arts, philosophy, Newtonian. - Johann Heinrich Lamberts Cosmological Letters was published 1761 in Augsburg. Lambert tried to expose a theory of the structure of the universe as a whole, that is, a theory that was able to involucrate all sorts of observed celestial bodies, like 'fixed stars' und nebulae. Lambert tackles his task mixing two disciplines, which in principle seem to be incompatible: Newtonian physics and teleology. Lambert's speculative and imaginative way to formulate his hypotheses shows resemblances to the way of making science developed during the romantic period, disagreeing with the methods of enlightenment, movement to which Lambert is usually associated. A central aspect of this thesis is to study Lambert's figure in relation to this two traditions, with the finality to deal with the compression of his ideas in depth, in light of the transition between the enlightened vision of the world and the romantic one.
    Description: thesis
    Keywords: 520 ; TA 100 ; TA 400 ; Theoretische Grundlagen {Astronomie} ; Wissenschaftsgeschichte {Astronomie}
    Language: German
    Type: monograph , publishedVersion
    Format: 302 S.
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  • 12
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    Univ. Berlin
    Publication Date: 2021-03-29
    Description: Comets belong to the most pristine objects in the Solar System. The study of comets therefore allows one to put constraints to the physical and chemical conditions in the pre-planetary disc. In this work, a one-dimensional simplified multi-fluid model for the analysis of the chemistry in cometary comae was constructed. This model was used for the study of the formation of the C3 and C2 radicals. For this purpose, radial profiles of the optical emissions of C3 and C2 in comets C/2001 Q4 NEAT, C/2002 T7 LINEAR, and 9P/Tempel 1 at heliocentric distances between 1.0 AU and 1.5 AU were analysed. These profiles were obtained by means of long-slit spectroscopy. A reaction network for the formation of C3 and C2 at larger heliocentric distances (Helbert 2002) was updated and extended. Molecules and radicals were identified for which photodissociation reaction rates have to be further constrained before the formation of C3 and C2 can be understood. As comets of special interest, the comets 67P/Churyumov-Gerasimenko and 9P/Tempel 1 were studied in more detail. Both comets are targets of space missions...
    Description: thesis
    Keywords: 523 ; TGL 200 ; Kometen {Astronomie}
    Language: English
    Type: monograph , publishedVersion
    Format: 227 S.
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  • 13
    Publication Date: 2021-03-29
    Description: Diese Arbeit beschreibt die Verbesserung der Richtungsstabilisierung des Flugzeugteleskops SOFIA. Das Ziel des Flugzeugteleskops SOFIA sind astronomische Beobachtungen im Infrarotbereich. Da der Wasserdampf der Erdatmosphäre den Großteil der Infrarotstrahlung absorbiert, sind solche Beobachtungen mit herkömmlichen Teleskopen von der Erdoberfläche aus kaum möglich. Um unerwünschte Drehbewegungen des Flugzeugteleskops, z.B. hervorgerufen durch Luftturbulenzen, auszugleichen, ist zuerst eine genaue Messung bzw. Schätzung derselben notwendig. Diese Informationen werden dann mittels Computer in Echtzeit weiterverarbeitet. Anschließend sorgen dann Motoren dafür, das Teleskop wieder in die gewünschte Lage zu drehen. Die Motoren können das Teleskop nur so genau ausrichten, wie es die Genauigkeit des Meßsystems zuläßt. Die Messung der Drehbewegungen geschieht mit drei zueinander senkrecht angeordneten Gyroskopen. Diese weisen jedoch Fehler auf, so daß sich die Ausrichtgenauigkeit verschlechtert. Deshalb werden mit Hilfe einer auf das Teleskop montierten Kamera in regelmäßigen Zeitabständen Bilder des Sternhimmels aufgenommen. Aus diesen Bildern wird dann mit Hilfe der dort sichtbaren Sterne die aktuelle Orientierung des Teleskops bestimmt. Mittels dieser Orientierung werden dann die Fehler der Gyroskope korrigiert und der lineare Fehleranteil für die Zukunft extrapoliert. Dieser Fehler wird dann schon im Voraus vom Teleskoplageregler berücksichtigt. Dadurch wird der quasikonstante Fehleranteil minimiert. Je besser dieser Fehler geschätzt wird, desto geringer ist die Drift des Teleskops um seine Achsen. Dadurch erhöht sich die Richtungsstabilisierung ...
    Description: thesis
    Keywords: 522 ; TCE 200 ; Teleskope {Astronomische Instrumente}
    Language: German
    Type: monograph , publishedVersion
    Format: 125 S.
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  • 14
    Publication Date: 2021-03-29
    Description: Die Untersuchung der Oberflächenzusammensetzung von Ganymed basiert auf Daten des abbildenden Spektrometers NIMS an Bord der Raumsonde Galileo, das die Ganymedoberfläche im Spektralbereich des Nahen Infrarot detektiert. Die Verarbeitung der vorliegenden Spektraldaten einschließlich der quantitativen Analyse der spektralen Signaturen in den Reflexionsspektren von Ganymed wie deren Charakterisierung in Abhängigkeit der geologischen Oberflächenstrukturen bildet den zentralen Teil der Arbeit. Die Ergebnisse zeigen, dass Veränderungen der Reflexionseigenschaften der Ganymedoberfläche auf den wechselnden Anteil von Wassereis und Gesteinsmaterial und dem Gehalt an CO2 zurückzuführen sind. Die simultane Analyse der Absorptionen von Wassereis erlaubt es ferner, erstmals Veränderungen des relativen Anteils und der Partikelgröße von Wassereis getrennt voneinander zu erfassen...
    Description: thesis
    Keywords: 523.45 ; 550 ; TGG 605 ; Jupitermonde {Astronomie}
    Language: German
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  • 15
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    Unknown
    Univ. Berlin
    Publication Date: 2021-03-29
    Description: AM Herculis stars (or 'polars') are close binaries consisting of a white dwarf with a strong magnetic field and a main sequence star (the 'secondary') which is losing mass to the white dwarf. The magnetic field channels the matter to the magnetic poles, where the released potential energy is radiated away - mainly in X-rays and the UV. The spatial structure of these objects cannot be observed directly, because their apparent size is too small. Indirect imaging methods are capable of restoring information which is only contained in observational data as projections onto a sub-space. These tomographic methods are known from medicine, but can also be applied to astronomical data, when a number of measurements can be regarded as views of the same object under different aspect angles. In this work tomographic methods are applied to time-resolved spectroscopic data of polars. Spectral lines seen in the radiation emitted by the constituents of these systems are notably Doppler-shifted. The Doppler-shift is depending on the viewing angle of the system ('inclination') and is varying with orbital phase. Time-series of one-dimensional data (spectra) can be used to create a two-dimensional map of the intensity distribution in velocity-space (Doppler-tomography), or a map of the line-flux on the assumed surface of the mass-losing star (Roche-tomography) from the line profile changes ...
    Description: thesis
    Keywords: 523 ; THT 900 ; THU 155 ; Doppelsterne {Astronomie} ; Eruptionsveränderliche {Astronomie: Sterne}
    Language: English
    Type: monograph , publishedVersion
    Format: 124 S.
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  • 16
    Publication Date: 2021-03-29
    Description: The aim of this thesis is to obtain as much information as possible, about global solutions of the Cauchy problem for the Einstein-Vlasov-scalar field system with spherical, plane and hyberbolic symmetries written in areal coordinates. The sources of this system are generated by both a distribution function and a linear scalar field subject to the Vlasov and wave equations respectively. This system describes the evolution of self-gravitating collisionless matter and scalar waves within the context of general relativity. We consider the cosmological case. That is spacetimes possess a compact Cauchy hypersurface and then, data are given on a compact 3-manifold. We extend the local-in-time results obtained by G. Rein for the Einstein-Vlasov system with collisionless matter alone. This extension concerns pointwise estimates for hyperbolic equations by the method of characteristics. This means that the system is transformed to a system of ordinary differential equations which are integrated along characteristics ...
    Description: thesis
    Keywords: 523 ; TFA 000 ; Relativistische Astrophysik, Gravitation
    Language: English
    Type: monograph , publishedVersion
    Format: 85 S.
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  • 17
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    Univ. Bremen
    Publication Date: 2017-06-09
    Description: The different benthic foraminiferal species (epibenthic as well as endobenthic) colonize wide areas of the ocean floor and are widely used for paleoceanographic reconstructions. To improve these reconstructions, it is an important part in research to continuously develop and refine proxies by e.g. improving measuring techniques as well as introducing other species in paleoceanograhpy. The main focus of the presented thesis is a regional examination of the trace element ratios of the rarely used benthic foraminifer Oridorsalis umbonatus and the investigation of their suitability for paleoceanographic applications. Since O. umbonatus is not very abundant in the sediments, it was necessary . as a prerequisite for such studies . to investigate, whether laser ablation ICP-MS can be used for trace element measurements on benthic foraminifera. Therefore, as a first step, trace elements were measured using laser ablation ICP-MS on a set of modern core top samples collected along a depth transect on the continental slope off Namibia at 25.5.S (320 . 2300m water depth; 2.9. to 10.4.C). The Mg/Ca ratios where than calibrated against bottom water temperatures (BWT). The study demonstrates clearly that benthic foraminiferal trace elements can be reliably measured with the laser ablation technique and that the Mg/Ca ratio of O. umbonatus has the potential to be used as a proxy for BWTs...
    Description: thesis
    Keywords: 579.44 ; 579.44 ; UHG 000 ; VXE 000 ; UHG 000 ; VXE 000 ; Paläoozeanologie ; Protozoa {Paläozoologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 81 S.
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  • 18
    Publication Date: 2017-06-09
    Description: In the early 1990`s the first IPCC report stated the effect of anthropogenic CO2 emissions on global warming and John Martin`s Iron Hypothesis (Martin and J.H 1990), relating atmospheric dust deposition, a major source of iron to the surface ocean, to the CO2 concentration in the atmosphere and the last ice age, culminating in the well known sentence Give me (half) a tanker of iron and I’ll give you a new ice age!. Since then, several large-scale in situ Fe fertilisation experiments revealed that in large areas of the ocean, the so called high nutrient low chlorophyll (HNLC) areas, phytoplankton growth is partly limited by depleted Fe conditions (Geider et al. 1994; De Baar and Boyed 2000; Boyd et al. 2007). The ocean receives Fe from upwelling, riverine input, melting icebergs, atmospheric dust input, input from anoxic sediments, hydrothermal vents and direct recycling by organisms(Tovar-Sanchez et al. 2007). However, in HNLC regions the Fe input to surface waters is very low resulting in Fe limitation of phytoplankton growth. Fe is an important nutrient for marine phytoplankton (Geider et al. 1994; Falkowski et al. 1998; Morel and Price 2003), being essential in metabolic reactions like the photosynthetic electron transport and the assimilation of nitrogen. It is also required for the synthesis of chlorophyll (Martin et al. 1988; Maldonado et al. 1999) as well as for the functioning of the enzyme superoxide dismutase which inhibits the breakdown of chlorophyll by superoxide radicals (Coale 1991)...
    Description: thesis
    Keywords: 577.14 ; VJE 000 ; VJC 210 ; VJE 000 ; VJC 210 ; Organische Geochemie ; Geochemie des Meerwassers
    Language: English
    Type: monograph , publishedVersion
    Format: 106 S.
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  • 19
    Publication Date: 2021-03-29
    Description: Mg/Ca ratios in benthic foraminiferal shells are frequently used in paleoceanographic studies to estimate past bottom water temperatures. Apart from temperature, other factors may exert additional influences on foraminiferal Mg/Ca. These include the Mg/Ca ratio of seawater, partial dissolution of shell calcite, salinity, physiological effects, and, probably of capital importance, the carbonate chemistry of seawater. In this context, the seperate effects of temperature and seawater carbonate chemistry on the magnesium incorporation into benthic foraminideral calcite are unraveled and quantified in this thesis...
    Description: thesis
    Keywords: 579.44 ; 579.44 ; 560 ; VXE 000 ; VJE 220 ; VXE 000 ; VJE 220 ; Protozoa {Paläozoologie} ; Geochemie der Fauna
    Language: English
    Type: monograph , publishedVersion
    Format: 88 S.
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  • 20
    Publication Date: 2021-03-29
    Description: Organic-walled dinoflagellate cysts, oxidation, degradation, organic matter. - Species-selective aerobic decomposition affects fossil organic-walled dinoflagellate cyst (dinocyst) records and hence dinocyst-based interpretations of primary productivity and oceanographic conditions. However, since the recognition of dinocyst species sensitive and resistant to oxic degradation (S- and R-cysts, respectively) it has become apparent that R-cysts may still serve as reliable productivity and oceanographic conditions proxies. On the other hand S-cysts provide a way to quantify aerobic degradation of organic matter (OM) and past bottom-water O2 concentrations. OM degradation plays a key role in global carbon cycling and is important for global climate change. Therefore dinocysts are a valuable tool for estimating the rate of diagenetic process. Questions concerning species-selective aerobic degradation still remain and will be adressed here. To obtain information on the rate of S-cyst decomposition, the relationship between S-cyst degradation and O2 concentrations, and the aerobic degradation of extinct dinocyst species, a natural exposure experiment has been conducted and studies of both Quaternary and pre-Quaternary material from sediment cores were executed. The exposure experiment was conducted in the natural setting of the Eastern Mediterranean. During a 15 month exposure period to oxic water masses, concentrations of S-cysts (Brigantedinium spp. and Echinidinium granulatum) decreased by 24 to 57%. However, taxa such as Nematosphaeropsis labyrinthus, Echinidinium aculeatum, Operculodinium israelianum and Impagidinium aculeatum demonstrated a slight increase in concentration, indicating resistance to aerobic degradation. These results show that even short-term exposure to oxygen may cause considerable changes in the dinocyst assemblage ...
    Description: thesis
    Keywords: 560 ; VVA 560 ; VXE 000 ; VVA 560 ; VXE 000 ; Aktuopaläontologie ; Protozoa {Paläozoologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 159 S.
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  • 21
    Publication Date: 2021-03-29
    Description: Marine snow, underwater cameras, particle flux, aggregation, suspended particulate matter, particle transport. - This study focusses on the vertical distribution and transportation pathways of marine particles off NW-Africa with aid of optical methodologies. A profiling camera system and a remotely operated vehicle (ROV) was used for in-situ observations on the distribution, transport processes and sinking behaviour of marine particulate matter. Between the regional areas of investigation Cape Blanc, Dakhla and Cape Bojador significant differences could be observed with respect to distribution and transportation patterns. These differences are primarily related to the different primary production conditions between the investigation areas. Primary production is the most important factor for the abundance of particulate matter, where highest particle concentrations in the entire water column were seen off Cape Blanc. Next to primary production, water depth, currents and density gradients are factors influencing the particle distribution patterns. With respect to the prevailing transport processes, the Cape Blanc region is characterised by vertically orientated transport patterns. In addition to the continuous supply of large, relatively fast sinking particle aggregates a sinking event could be documented for the first time in-situ in the water column. These events deliver huge amounts of particulate matter from the ocean surface ...
    Description: thesis
    Keywords: 551
    Language: English
    Type: monograph , publishedVersion
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  • 22
    facet.materialart.
    Unknown
    Univ. Bremen
    Publication Date: 2021-03-29
    Description: The dissolution kinetics of gypsum and anhydrite have been measured under various conditions. For gypsum an almost linear rate equation R=ks1(1-c/ceq)n1 is valid, where R is the surface rate, n1 1 is the kinetics order, c is the total calcium concentration at the surface, and ceq the equilibrium concentration with respect to gypsum. For the determination of the entire dissolution kinetics a batch set-up was used. This batch experiment reveals a dissolution rate equation R=ks1(1-c/ceq)n1 which switch close to equilibrium to a nonlinear rate equation R=ks2(1-c/ceq)n2 with n2 4.5. The experimentally observed dissolution rates from the batch experiment could be fitted by only minor variations with a mixed kinetics model. The rotating disk experiment on anhydrite reveals a surface controlled rate equation. For anhydrite the observed experimentally dissolution rates by a batch experiment are described by R=ks(1-c/ceq})n, where ks is the surface rate constant and n 4.2 is the kinetic order. Furthermore, a method for the determination of the rate equation parameters was developed ...
    Description: thesis
    Keywords: 549 ; VJK 000 ; VHB 600 ; VGC 000 ; Experimentelle Geochemie ; Sulfate, Chromate, Molybdate und Wolframate {Mineralogie} ; Mineralchemie
    Language: German
    Type: monograph , publishedVersion
    Format: 120 S.
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  • 23
    Publication Date: 2021-03-29
    Description: Madagascar; Jurassic; Karoo; Gondwana; Breakup; Rift; Microfauna; Macrofauna; Ammonites; Indian Ocean. - The breakup of Gondwana along the former East African Orogen is widely interpreted to have lasted from the Late Palaeozoic to the Callovian. The present study indicates that the Permian-Triassic or Karoo phase of rifting was not responsible for the separation of East- and West-Gondwana, since that rift system failed in the Late Triassic. Instead the breakup of Gondwana occurred in the Late Liassic. The pre-rift phase in the Morondava Basin is represented by the Karoo deposits, and the syn-rift phase is recorded by Toarcian marine shales, locally overlain by Aalenian sandstones. A major Early Bajocian unconformity is interpreted as the breakup unconformity. The initial post-rift or drift phase is represented by the Bajocian-Bathonian carbonates, marls and sandstones of coastal plain environment and a coastal barrier/lagoon complex. During the Bathonian the siliciclastic shoreface system moved basinward. Callovian-Early Kimmeridgian shales with interbedded iron-oolites represent ...
    Description: thesis
    Keywords: 551 ; VAE 500 ; VDB 100 ; VEQ 300 ; Geotektonische Entwicklung der Erdkruste {Geologie} ; Gondwana ; Madagaskar {Geologie}
    Language: English
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  • 24
    Publication Date: 2021-03-29
    Description: Turbulence, ice ridge, polynja, drag coefficient. - Polarstern (PS) cruise ARK XII led into the Laptev Sea and into the Kara Sea. Measurements of atmospheric processes within the polar surface layer were performed by a turbulence probe mounted at the bow crane of the ship.The meteorological conditions during the cruise were characterised by moderate winds and low temperature differences between the atmosphere and the underlying surface.Detailed information about the variation of meteorological parameters and of the surface fluxes were achieved as a function of the surface characteristics. The measurements are used to analyse ...
    Description: thesis
    Keywords: 551.5 ; VAQ 990 ; TYZ 400 ; TVH 500 ; Meereis {Glaziologie} ; Nordpolarmeer {Meteorologie und Klimatologie} ; Temperatur der Wasseroberfläche als meteorol. Element
    Language: German
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  • 25
    facet.materialart.
    Unknown
    Univ. Bremen
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.9 ; VJE 200 ; VJC 210 ; Geochemie Lebender Materie ; Geochemie des Meerwassers
    Language: English
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  • 26
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 560 ; VYF 200 ; Pyrrophyceae {Paläobotanik}
    Language: English
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  • 27
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VBQ 900 ; VBQ 800 ; VEO 170 ; Hydrogeologie einzelner Regionen ; Aquifere {Hydrogeologie} ; Sudan {Geologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 133 S.
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  • 28
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 560 ; VDH 200 ; VEX 100 ; VWH 200 ; VZX 100 ; VKB 380 ; Jura ; Anden {Geologie} ; Jura {Stratigraphische Paläontologie} ; Anden {Paläontologie} ; Sedimente bestimmter Regionen
    Language: German
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  • 29
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 910 ; 551 ; VBQ 900 ; VEB 213 ; VJC 110 ; Hydrogeologie einzelner Regionen ; Brandenburg, Sachsen-Anhalt & Mecklenburg-Vorpommern {Geologie} ; Geochemie des Grundwassers, Porenwassers
    Language: German
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  • 30
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 549 ; VGB 700 ; VGA 300 ; VHB 820 ; Spektroskopische Methoden {Mineralogie} ; Kristallstrukturen ; Inselsilikate {Mineralogie}
    Language: German
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  • 31
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 549 ; VHB 850 ; VGF 200 ; Kettensilikate {Mineralogie} ; Phasengleichgewichte und Umbildungen {Mineralogie}
    Language: English
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  • 32
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VQC 000 ; VRA 110 ; VTG 000 ; Lagerstättengenese ; Eisenerz {Lagerstättenkunde} ; Osteuropa und Asiatische Teile der ehemaligen Sowjetrepubliken {Rohstoffgeologie}
    Language: German
    Type: monograph , publishedVersion
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  • 33
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VAQ 990 ; Meereis {Glaziologie}
    Language: German
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  • 34
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VGA 420 ; Optische Methoden {Mineralogie: Kristallographie}
    Language: German
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  • 35
    facet.materialart.
    Unknown
    Univ. Bremen
    Publication Date: 2021-03-29
    Description: This thesis describes the adaptive shallow water model PLASMA-FEMmE. It solves on the sphere the shallow water equations, the prototype for partial differential equations in atmospheric modeling, using a semi-implicit semi-Lagrangian time step and linear finite elements. Both statically and dynamically adapted grids created by the grid generator amatos are investigated. The results are compared with those of the predecessor model FEMmE that uses a static uniform grid. The outcome demonstrates the capability of the chosen approach as well as its limits. Grid adaptation can easily be achieved with amatos. No reflexions at the grid interfaces are observed. Though in one test case instabilities are released at the grid interfaces. The numerical errors are reduced without a considerable enhancement of the computational effort in another test case with a well-known analytical solution. In respect to the conservation properties the results are more complicated. Mass conservation can be achieved in one test case with an appropriate static grid. In case of complex flow regimes all conservation properties are weakened during the simulation using dynamic grid adaptation...
    Description: thesis
    Keywords: 532.5 ; 551.46 ; 550 ; Meteorologische Modelle ; Fluiddynamik {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 135 S.
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  • 36
    Publication Date: 2021-03-29
    Description: The polar ice sheets are unique paleoclimatic archives and play an important role in recent and future climate. The melting of the big freshwater reservoirs will not only increase the global sea level, but will also influence the ocean currents. Therefore, it will be of particular interest to improve the currently available numeric climate models to achieve more accurate statements about climatic change and its consequences. In this work, the evaluation and the different applications of GPS and altimetry data will be described in respect to enhance models. The antarctic area of investigation, Dronning Maud Land (DML), is of particular interest for German polar research, because both the overwintering station Neumayer and the summer station Kohnen are located within it. In the surroundings of these two stations, highly accurate kinematic GPS measurement were made, which will be the basis for the digital elevation model presented here. Because these data are spatially limited, they are supplemened with remotely sensed data. For this purpose, two airborne altimetry data sets and spaceborne laser altimetry data of the Ice, Cloud, and land Elevation Satellite (ICESat) are used...
    Description: thesis
    Keywords: 551.312 ; 551 ; 550 ; TWC 600 ; VAR 980 ; TQI 000 ; TSY 200 ; Geophysikalische Satellitenfernerkundung ; Antarktis {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 140 S.
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  • 37
    Publication Date: 2021-03-29
    Description: Marine sediments, diagenesis, anoxic environments, paleomagnetism, low-temperature magnetism, magnetic Fe-Ti-Oxides. - Magnetic particles usually occur in very minor concentrations in igneous and sedimentary rocks, soils, volcanic ashes, dusts and even in living organisms. Many of these magnetic grains are capable of carrying a stable permanent magnetization and therefore act as recorders of the recent and ancient Earth's magnetic field. Thus paleomagnetism refers to the study of this remanent magnetization in sedimentary and volcanic rocks through time. From this magnetization, directional intensity information can be recovered concerning the geomagnetic field that prevailed at the sample location at the time of the rock formation. The magnetic parameter on which such paleomagnetic studies are based is the natural remanent magnetization (NRM). In continental margin regions the remanence acquisition process is often complicated by post-depositional modifications of the original magnetic material. After deposition magnetic minerals can be altered or new magnetic phases can be formed. Consequently the original NRM might be obscured or even fully erased. The process of diagenesis and authigenesis may thus seriously compromise paleomagnetic interpretation. Therefore our knowledge of the geomagnetic field behavior based on sediment records from continental margin regions remains limited. To obtain fully reliable information about the geomagnetic field or paleoenvironmental conditions from continental margin regions, the effect of early diagenetic processes occurring after deposition of the sediment must be understood in detail.
    Description: thesis
    Keywords: 551.4686 ; 538.727 ; 550 ; TOT 320 ; VKB 380 ; TSZ 100 ; Paläomagnetismus {Geophysik} ; Sedimente bestimmter Regionen ; Atlantischer Ozean {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 113 S.
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  • 38
    Publication Date: 2021-03-29
    Description: Anaerobe Oxidation of Methane, AOM, methanotrophy, stable isotope labeling, stable isotope probing, carbon assimilation, flow-through columns, ANME, Seep-SRB, Gullfaks, Tommeliten. - Anaerobic oxidation of methane (AOM) performed by consortia of methanotrophic archaea (ANME) and sulfate reducing bacteria (SRB) is the major sink of methane in marine sediments. This thesis describes methane consumption at two of the most active North Sea cold seeps (Gullfaks, Tommeliten), their microbial community and the resulting lipid biomarker patterns. Experiments in flow-through setups are presented, focusing on physiological parameters of AOM activity such as different methane and sulfate concentrations and on the tolerance of AOM to starvation periods. The roles of inorganic carbon (DIC) and methane as carbon sources for the microbial community performing AOM were examined combining stable isotope probing and lipid biomarker analyses. For archaea substantial uptake of carbon from DIC and methane was found, indicting a novel carbon assimilation pathway. Biomass from SRB was exclusively labeled by DIC indicating a methane dependent, but autotrophic growth consortial SRB.
    Description: thesis
    Keywords: 551.9
    Language: English
    Type: monograph , publishedVersion
    Format: 153 S.
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  • 39
    facet.materialart.
    Unknown
    Univ. Bremen
    Publication Date: 2021-03-29
    Description: Black Sea, seafloor seepage, mud volcanoes, seeps, fluid migration, gas hydrates, diapirs. - The Black Sea is the worldwide largest anoxic basin with thick gas rich sediments facilitating seafloor seepage, which is widely distributed along the continental slopes of the Black Sea. In two areas, the Sorokin Trough off Crimea and at the continental slope off Batumi (Georgia), the distribution, structure and evolution of two different vent systems and their relation to fluid migration pathways and gas/gas hydrate occurrences have been investigated by means of high resolution multichannel seismic data. In both regions, the distribution of seafloor seepage is controlled by fluid migration along permeable pathways associated with diapiric uplift in the subsurface. In the Sorokin Trough, seepage is expressed by intensive material upflow and the formation of mud volcanoes; offshore Batumi, gas seeps with low material flux dominate. In the Sorokin Trough, most mud volcanoes are associated with near-subsurface mud diapirs. The great morphological variability of the mud volcanoes reflects different driving mechanisms, which depend on the availability of permeable fluid migration pathways and the depositional environment. A 3D seismic dataset images the detailed three-dimensional ...
    Description: thesis
    Keywords: 551.466 ; 550 ; TSZ 100 ; VAT 300 ; VEZ 120 ; TQC 600 ; Atlantischer Ozean {Geophysik} ; Geologie des Meeresboden ; Randmeere {Geologie} ; Tiefseeseismik {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 154 S.
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  • 40
    Publication Date: 2021-03-29
    Description: Ozone, balloon-borne measurements, atmospheric trace gases, concentration profiles, climate change. - In the frame of this work, a new small-size balloon-borne sonde was developed. A miniature grating spectrometer in the sonde measures simultaneously the solar spectral irradiance at a wide wavelength range from 200 to 850. As a first application, ozone profiles have been determined by measuring the changes in the spectral irradiance, caused by ozone absorption in the Huggins band. The wide spectral coverage of the spectrometer offers the possibility for measurements of other trace gases which absorb within the wavelength range, e.g. NO2 and BrO. The low weight of the new sonde (1.7 kg), the moderate price, and the autonomous portable telemetry system makes it a very versatile tool for satellite validation and for case studies, which requires a high number of launches. The newly developed sonde works well without temperature stabilisation, even so the spectrometer experiences rather large temperature changes (15 - 20 K) during the ascent through the atmosphere. Laboratory measurements were performed in ...
    Description: thesis
    Keywords: 551.5 ; 551.8 ; 550
    Language: English
    Type: monograph , publishedVersion
    Format: 148 S.
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  • 41
    Publication Date: 2021-03-29
    Description: Photooxidants play an important role for the oxidation capacity of the troposphere. The presented work deals with seasonal changes of atmospheric photooxidants like hydrogen peroxide (H2O2), methylhydroperoxide (MHP) and formaldehyde (HCHO). The principal purpose was to follow and quantify the mixing-ratios of these photochemical species for the first time over a complete annual cycle in Antarctica. During two field campaigns at the German Antarctic station Neumayer (overwintering campaign from January 1997 until March 1998 and a shorter campaign from January to March 1999) continuous measurements of atmospheric mixing-ratios were performed. A continuous wet-chemical technique was used for peroxides and formaldehyde sampling and analysis. Species were quantified by fluorescence detection. In order to compare the results and measurements with well-known reaction mechanisms a photochemical box model was applied. The obtained time series show a pronounced seasonal variation with higher values during summer. For the first time atmospheric concentrations of H2O2, MHP and HCHO were documented during polar night in winter. The mixing-ratios were significantly higher than expected due to missing actinic radiation essential for photochemical production. Trajectory analyses and calculations with a three-dimensional model showed that during winter the mixing-ratios of photooxidants are mainly affected by long-range transport in the free troposphere. Investigations during the Antarctic ó́zone hole period ́́show no significant impact of the increased UV-B radiation on the photooxidants. The findings of this work contribute to a better understanding of the photochemistry of the investigated trace gases in the clean troposphere of Antarctica and provide a useful data record for further photochemical modeling.
    Description: thesis
    Keywords: 551.5 ; 551.9 ; 550 ; TYY 200 ; TVA 210 ; Antarktis {Meteorologie und Klimatologie} ; Chemische Zusammensetzung der Atmosphäre {Meteorologie}
    Language: German
    Type: monograph , publishedVersion
    Format: 176 S.
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  • 42
    Publication Date: 2021-03-29
    Description: Besides measurements of atmospheric trace gases and laboratory studies of chemical reactions, modelling has been recognised to be of increasing importance to improve our knowledge of the atmosphere and the capabilities of photochemical models. Main scope of this work was the development of a photochemical atmospheric model, which was especielly designed for the interpretation of Differential Optical Absorption measurments (DOAS). This model has been used to improve our knowledge of atmospheric chemistry. For example, for the first time it was possible to demonstrate that a significant amount of IO in a range of 0.65 to 0.8 pptv is present in the stratosphere in the polar region (Ny-Alesund,Spitzbergen). Moreover it has been shown that such amounts of stratospheric IO lead to an additional Ozone loss in the range of 10 % in cold arctic winters.
    Description: thesis
    Keywords: 551.5 ; 550 ; TUA 700 ; TVA 210 ; Verfahren zur Untersuchung der freien Atmosphäre {Meteorologie} ; Chemische Zusammensetzung der Atmosphäre {Meteorologie}
    Language: German
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  • 43
    Publication Date: 2021-03-29
    Description: Ozone profile retrieval, ERS-2, GOME, FURM, ozone decline, Northern hemisphere. - Measurements of stratospheric ozone over the Northern hemisphere forthe winter/spring periods of 1997 to 2000 taken with the GOMEinstrument were used to derive the chemical ozone depletion inside thepolar vortex. GOME onboard the ERS-2 satellite measures radiationcoming from the Earth in the UV/vis spectral range.To discern the chemical depletion from dynamical influences, a modelwas developed to calculate vortex averaged diabatic descent ratesusing the radiative transfer model MIDRAD and the FURM ozoneprofiles. The permeability of the Arctic vortex was analysed by usingthe trajectory model TANGO in conjunction with a reverse domainfilling algorithm, developed within the framework of this thesis.The chemical ozone ...
    Description: thesis
    Keywords: 551.5 ; 550 ; TUA 850 ; TVA 210 ; TY 100 ; Satellitenmeteorologie ; Chemische Zusammensetzung der Atmosphäre {Meteorologie} ; Nördliche Hemisphäre {Meteorologie und Klimatologie}
    Language: German
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  • 44
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.1 ; 550 ; VKA 150 ; TOO 000 ; Physikalische Petrologie ; Geothermik {Geophysik}
    Language: German
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  • 45
    Publication Date: 2021-03-29
    Description: Sea ice is a very important component of the climate system. While the Arctic sea ice extent has retreated during the past 20 years, it has remained constant in the Antarctic. In order to better understand the role of sea ice in the climate system in the context of global warming currently used coupled Atmosphere-Ocean Global Circulation Models have to be improved. This requires to know the sea ice concentration C for a long period for both hemispheres and at the best possible spatial resolution. Currently used methods to obtain C like the NASA Team (NT) algorithm are based on data acquired by the Special Sensor Microwave/Imager (SSM/I) at 19 and 37GHz. The SEA LION (SL) algorithm presented here allows to infer C from the polarization P at 85GHz taking advantage of the higher spatial resolution at this frequency. However, the decrease of P caused by the weather influence leads to an overestimation of C. Therefore, P is corrected using a radiative transfer model and atmospheric data taken from Numerical Weather Prediction models and/or derived from SSM/I measurements. The various sea ice and snow properties are considered calculating monthly sea ice tie points. The average standard deviation of C derived with the SL algorithm is 12% for C 〈 50% and below 5% for C 〉 90%. The SL ice edge agrees within 10km with the one evident in VIS/IR images. The SL ice concentration gradient across the marginal ice zone (MIZ) agrees much better with the one evident in SAR images compared to results of the NT algorithm. Using the higher spatial resolution at 85GHz the SL algorithm allows to detect smaller open water areas than known algorithms. A major limitation of the SL algorithm arises from the quality of atmospheric data needed for the weather correction. A spatial resolution of these data lower than the 85GHz SSM/I channels and/or a time lag larger than half an hour between both data sets can cause relative errors above 100%, particulary in the cloud-covered parts of the MIZ.
    Description: thesis
    Keywords: 550.28 ; 551.31 ; 550 ; TWH 500 ; TWC 100 ; Einfluss von Eis {Klimatologie} ; Instr. Ergebn. zu Klimaänderungen und Klimaschwankungen
    Language: English
    Type: monograph , publishedVersion
    Format: 186 S.
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  • 46
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 622.15 ; 552.5 ; 624.51 ; 550 ; VBP 800 ; TQJ 000 ; Ingenieurgeologie bei der unterirdischen Speicherung und Lagerung ; Geophysikalische Methoden in anderen Wissenschaftsgebieten
    Language: German
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  • 47
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.5 ; 550 ; TUA 700 ; TVH 300 ; Verfahren zur Untersuchung der freien Atmosphäre {Meteorologie} ; Lufttemperatur {Meteorologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 153 S.
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  • 48
    Publication Date: 2021-03-29
    Description: With regard to geodesy optimizing procedures for nonlinear adjustment problems are presented. The procedures can be divided into local and global optimization techniques according to the type of the problem. If good initial values are given, the usage of local optimization techniques, (e.g., the Gauß-Newton procedure) is justified. If this is not the case, and the minimizing function has various local minimums, a global strategy must be implemented. Applying global optimization techniques one will not yield the global solution with certainty; only a probabilistic solution will be obtained. Nevertheless, combining local and global strategy and inclusion of all available a priori-information, a global optimizing system can be established that yields practical results for a wide area of problems. With the increase of the capacity of modern computers the efficiency of global optimization algorithms comes along ...
    Description: thesis
    Keywords: 526.9 ; 550 ; UND 000 ; Fehlertheorie {Praktische Geodäsie}
    Language: German
    Type: monograph , publishedVersion
    Format: 85 S.
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  • 49
    Publication Date: 2021-03-29
    Description: Ozone chemistry, tracer measurements, radiometry, airborne,submillimeterwave, Arctic, stratosphere. - The Airborne Submillimeter Radiometer (ASUR) is a passive heterodyne instrument using a superconducting detector with an instrumental frequency range from 604.3 to 662.3 GHz.Operating onboard an aircraft to avoid absorption by tropospheric water vapor key species of the stratospheric ozone chemistry can be detected for a vertical altitude range from 15 to 55 km. In the winter 1999/2000 the ASUR instrument participated in the THESEO 2000/SOLVE project onboard the NASA research aircraft DC-8. Three deployments were carried ...
    Description: thesis
    Keywords: 551.5 ; 550 ; TUA 800 ; TVA 210 ; TYY 100 ; Radarmeteorologie ; Chemische Zusammensetzung der Atmosphäre {Meteorologie} ; Arktis {Meteorologie und Klimatologie}
    Language: German
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  • 50
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 622.15 ; 550 ; Elektrische Verfahren {Geophysik} ; Mitteleuropa {Geophysik}
    Language: German
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  • 51
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.5 ; 550 ; TUA 850 ; TUA 500 ; TVA 210 ; Satellitenmeteorologie ; Meteorologische Modelle ; Chemische Zusammensetzung der Atmosphäre {Meteorologie}
    Language: German
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  • 52
    Publication Date: 2021-03-29
    Description: WSDW, water mass spreading, numerical model, lagrangian trajectories, Weddell Scotia Confluence. - The deep Scotia Sea is filled with ventilated Weddell Sea Deep Water (WSDW). This in turn is an essential contributor to the ventilation of the World Ocean abyss. A primitive equation, hydrostatic, ocean general circulation model (BRIOS1.1) with terrain-following coordinate is used to investigate the water mass export from the Weddell Sea. The model is circumpolar focusing on the Weddell Sea, with particularly high resolution (2̃0 km) in the DOVETAIL area. The northern limb of the Weddell Gyre exhibits an eastward Weddell Sea Deep Water transport across 44ʿW of 24 Sv. Export rates of Weddell Sea Deep Water through gaps in theSouth Scotia Ridge are estimated to be 6.4 Sv with a semi-annual cycle of ± 0.6 Sv, which can be correlated to atmospheric cyclone activity and Weddell Gyre strength. Sensitivity studies considering extreme sea ice conditions in the Weddell Sea show higher (lower) exports in years of minimum (maximum) winter sea ice extent. This can be attributed to the local change of the surface stress achieved by wind and ice. Lagrangian ...
    Description: thesis
    Keywords: 910 ; QGZ 420 ; UKG 200 ; Physische Geographie der Antarktis ; Teilfragen {Regionale Ozeanologie, Südpolarmeer}
    Language: German
    Type: monograph , publishedVersion
    Format: 142 S.
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  • 53
    Publication Date: 2021-03-29
    Description: Carbon export; SeaWiFS; variability; upwelling; Atlantic Ocean; chlorophyll filament; SeaWiFS; SST. - The North Atlantic off NW Africa is characterized by the trade wind induced upwelling of cold and nutrient rich waters. As one of most strongest eastern boundary upwelling areas it is marked by low sea surface temperature and high bio-production, both subject to strong seasonal and interannual variations.Satellite measurements of sea surface temperature (SST) and chlorophyll-a (Chl-a) in the upper water-column were used to (a) recognize the upwelling of deep water and its distribution and mixing in the surface, (b) identify the development of phytoplankton blooms and (c) provide further insights in the characteristics of its variations.Measurements of surface Chl-a were compared to deep-sea fluxes of organic carbon in order to determine the relationship between both parameters and to further calculate the export of Corg and the export variation strength.The off-shore extension of SST-defined upwelling from 1988 through 1999 between 18ʿ and 25ʿN shows maxima in January and May/June with an average area of 140,000 km2 (standard deviation of 20,000 km2). Minima in August exhibit an extension of 43,000 km2 (15,000 km2 standard deviation). A correlation between ...
    Description: thesis
    Keywords: 910 ; UKB 100 ; Nordatlantik {Regionale Ozeanologie}
    Language: English
    Type: monograph , publishedVersion
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  • 54
    Publication Date: 2021-03-29
    Description: Am Ausgangspunkt dieser Arbeit stand die Frage, ob und in welcher Form beim Bau der Autobahnen vor 1933 in Deutschland, Frankreich und Italien die Wahrnehmung von Landschaft' berücksichtigt wurde. Da die Diskussion um die veränderte Wahrnehmung von Landschaft' bei steigender Reisegeschwindigkeit erstmals intensiv im Zusammenhang mit dem Bau der Eisenbahnen im 19. Jahrhundert geführt wurde, leitet ein Rückblick auf diese Zeit die Arbeit ein. Hier konnte die historische Dimension des Untersuchungsthemas verdeutlicht sowie dessen wesentliche Diskussionspunkte aufzeigt werden, die - in modifizierter Form - ein knappes Jahrhundert später bei der Planung und beim Bau der Autobahnen erneut aufgegriffen wurden. Der italienische Futurismus wurde anschließend daraufhin untersucht, ob er neue Darstellungsformen für die veränderte Wahrnehmung von Landschaft' hervorgebracht hat. Das nachfolgende Kapitel diente dazu, die Bedeutung des Themas der Arbeit aufzuzeigen. Eine zusammenstellende Übersicht über den Status des Autobahnbaus und der Autobahnplanungen in Deutschland Frankreich und Italien vor 1933, die bis dato fehlte, wurde hier gegeben. Von zentraler Bedeutung war im Rahmen dieser Arbeit die Analyse der Gestaltungselemente ...
    Description: thesis
    Keywords: 944 ; QEB 000 ; Geographische Umweltwahrnehmung und Raumbewertung
    Language: German
    Type: monograph , publishedVersion
    Format: 307 S.
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  • 55
    Publication Date: 2021-03-29
    Description: Thermohaline circulation, variability, energy and moisture balance model, paleoceanography. - Freshening of high latitude surface water can change the large scale oceanic transport of heat and salt. Consequently, atmospheric and sea ice perturbations over the deep water production sites excite a large scale response establishing an oceanic t̀̀eleconnection'' with time scales of years to centuries. To study these feed-backs, an atmospheric energy and moisture balance model (EMBM), predicting the heat and fresh water fluxes at the surface, and a thermodynamic sea ice model were constructed and coupled to the GFDL ocean model MOM2. The heat and moisture transports by transient eddies in the EMBM are parameterized by diffusion. The coupled model reproduces many aspects of today's oceanic circulation. The most interesting features of the coupled model are the sensitivity of the thermohaline circulation to changes in the configuration, the multidecadal variability in the ocean-sea ice system, and the behaviour of the thermohaline circulation during transitions between glacial and interglacial periods. A very strong thermohaline circulation develops in the coupled system that is not evident in the stand-alone ocean model. An interesting aspect of this behaviour is the existence of a maximum strength in the overturning. Beyond this maximum, evaporation in the subtropics cannot balance the northward salt-transport. As a result, the watermasses over the deep water production sites become fresher, leading to a collapse of the thermohaline circulation. The associated changes in the sea ice cover prevent the system to recover. ...
    Description: thesis
    Keywords: 551.6 ; 550 ; QDC 200 ; Synoptische Klimageographie ; Wärme- und Strahlungshaushalt der Atmosphäre {Meteorologie} ; Statistische Klimatologie und Klimatologische Modelle ; Klimaänderungen
    Language: German
    Type: monograph , publishedVersion
    Format: 132 S.
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  • 56
    Publication Date: 2021-03-29
    Description: This study focuses on the interactions between climate and ice sheets in order to obtain a better understanding of the processes involved. Two periods in the geological past are explored; the Middle Miocene and the mid-Pliocene. For both periods, foraminiferal oxygen-isotope records from deep-sea sediment cores as well as stratigraphical data, suggest a global sea-level lowering. The magnitude of these reductions in sea level indicate large-scale ice-sheet build-up. However, the origin of these events and even the geographic locations of the ice sheets, are still under discussion. The ice sheet-climate model developed in this study provides a tool to test some of the hypotheses brought forward to explain the ice-sheet expansion events. It describes the Antarctic ice sheet and is forced by a climate component based on energy and mass balances. Further more, the model computes the oxygen-isotopic composition of the ice-sheet, thereby providing the possibility to compare numerical results directly to deep-sea sediment records. Numerical experiments focus on the interactions between atmospheric CO2, temperature, ice volume (sea-level equivalent) and the isotopic composition of sea water...
    Description: thesis
    Keywords: 551.69 ; 551 ; 550 ; TWC 600 ; VAR 980 ; Paläoklimatologie ; Antarktis {Glazialgeologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 137 S.
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  • 57
    Publication Date: 2021-03-29
    Description: The Late BarremianLate Aptian interval was characterised by several major changes in the ocean/climate system related to the onset of the Mid-Cretaceous greenhouse world. North Africansedimentary deposits offer excellent archives of the ecological changes on the southern Tethyscontinental margin during this time interval. In the present phD thesis sedimentology, palaeontology,biostratigraphy, chemostratigraphy, and geochemistry are combined to reconstruct the palaeoenvironmental evolution and sea-level changes of the Tunisian carbonate platform margin.Respect is paid to major palaeoceanographic and palaeoclimatic events including the late Early Aptian Oceanic Anoxic Event 1a (OAE 1a) and two time intervals associated with widespread carbonate platform drowning in the early- and mid-Late Aptian. The last chapter deals with the cephalopod fauna of the platform margin. Results of the detailed regional investigations are compared to global marine palaeoenvironments and discussed in a broad geological context...
    Description: thesis
    Keywords: 551.77 ; 551 ; 550 ; TWC 600 ; VKB 372 ; VEN 130 ; VDH 300 ; Paläoklimatologie ; Karbonatische Sedimentgesteine ; Tunesien {Geologie} ; Kreide
    Language: English
    Type: monograph , publishedVersion
    Format: 160 S.
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  • 58
    Publication Date: 2021-03-29
    Description: Durch den Prozess der Urbanisierung verändert die Menschheit die Erdoberfläche in großem Ausmaß und auf unwiederbringliche Weise. Die optische Fernerkundung ist eine Art der Erdbeobachtung, die das Verständnis dieses dynamischen Prozesses und seiner Auswirkungen erweitern kann. Die vorliegende Arbeit untersucht, inwiefern hyperspektrale Daten Informationen über Versiegelung liefern können, die der integrierten Analyse urbaner Mensch-Umwelt-Beziehungen dienen. Hierzu wird die Verarbeitungskette von Vorverarbeitung der Rohdaten bis zur Erstellung referenzierter Karten zu Landbedeckung und Versiegelung am Beispiel von Hyperspectral Mapper Daten von Berlin ganzheitlich untersucht. Die traditionelle Verarbeitungskette wird mehrmals erweitert bzw. abgewandelt. So wird die radiometrische Vorverarbeitung um die Normalisierung von Helligkeitsgradienten erweitert, welche durch die direktionellen Reflexionseigenschaften urbaner Oberflächen entstehen. Die Klassifikation in fünf spektral komplexe Landnutzungsklassen wird mit Support Vector Maschinen ohne zusätzliche Merkmalsextraktion oder Differenzierung von Subklassen durchgeführt...
    Description: thesis
    Keywords: 550.28 ; 622.159 ; 550 ; TQH 000 ; Aerogeophysik
    Language: English
    Type: monograph , publishedVersion
    Format: 276 S.
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  • 59
    Publication Date: 2021-03-29
    Description: ICP-MS, Time of Flight, laser ablation, solid and liquid samples, ice cores, Antarctica, mineral dust, trace element analysis. - The analysis of the inorganic composition of climatic archives provides proxies for climate reconstruction. For many applications commercially available inductively coupled plasma quadrupole mass spectrometry (ICP-Q-MS) systems are used for investigations. One aim of this thesis was to test the laser ablation (LA)-ICP-Q-MS method for the analysis of different sample matrices (polar ice cores, bivalves, frozen lake sediment cores). The main limitation of LA-ICP-Q-MS measurements is the number of analysed isotopes, especially for point scan analysis of embedded particles in the ice matrix and the analysis of growth bands of bivalve shells. Analysing as many isotopes as possible is of interest to deduce e.g. the corresponding source region of embedded particles in the ice matrix. The quasi-simultaneous detection of several isotopes of transient signals is realised in ICP-Time of Flight-MS (ICP-TOF-MS) systems. The applicability of the newly developed ICP-TOF-MS system for ice core analysis in climatic research was explored in this thesis. With the present experimental setup the analysis of trace elements in ice core samples is only possible for liquid samples. The accuracy and precision compares to well established ICP-Q-MS systems. Using the Aridus II as sample introduction system the signal sensitivity was 2-10 times lower for the ICP-TOF-MS compared to ICP-Q-MS systems. Calibration studies and investigation of reference materials showed that the calibration range is limited to an order of magnitude of about 10exp4 to 10exp5 except for m/z ratios between 23 amu and 72 amu where it is even lower. The observed ...
    Description: thesis
    Keywords: 551.6 ; VJA 240 ; TWC 100 ; TWC 500 ; VAR 980 ; Spektroskopische Verfahren {Geochemie} ; Instr. Ergebn. zu Klimaänderungen und Klimaschwankungen ; Klimaschwankungen und Klimaänderungen im Quartär ; Antarktis {Glazialgeologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 185 S.
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  • 60
    Publication Date: 2021-03-29
    Description: Sea-ice, Finite Element Sea-Ice Model, Kalman Filter, Data Assimilation. - The Arctic region is sensitive to climate change. Since the Arctic sea-ice cover influences the surface heat budget of the Earth the observed sea-ice decline is seen as an indication of global warming. Furthermore, the dynamics of sea ice plays an important role for the sea-ice mass distribution in the Arctic, for the production of dense, cold, and salty water in the Arctic Ocean, which contributes to the thermohaline circulation, and also for the freshwater budget of the Nordic Seas. Thus, a realistic description of sea-ice motion is important to draw conclusions for the mass transport and sea-ice mass distribution. The Finite-Element Sea-Ice Model simulates the large-scale physical sea-ice processes like the sea-ice growth and circulation realistically. The model domain covers the entire Arctic Ocean and its marginal seas. Together with the Singular Evolutive Interpolated Kalman (SEIK) Filter and remotely sensed sea-ice drift observations this sea-ice model is applied for data assimilation to investigate details of the sea-ice dynamics. So far, drift assimilation has been carried out to analyze and modify only the drift field with subsequent computation of the advection or redistribution of ice mass which corresponds more to the physical model behavior than a statistical analysis that the SEIK Filter provides. The sea-ice drift data assimilation with the SEIK Filter achieves drift modification and furthermore changes in the two other sea-ice variables concentration and thickness. The modifications of these "unobserved variables" (within the meaning of data assimilation) are validated and it is found that they are in good agreement for at least 2 months for the sea-ice thickness and even 4 months for the sea-ice concentration which is the longest period examined. The drift improvement is achieved due to the sea-ice concentration and ...
    Description: thesis
    Keywords: 551 ; 550 ; VAQ 990 ; VAQ 500 ; TVH 100 ; TOY 000 ; Meereis {Glaziologie} ; Gletscherbewegung und Gletscherschwankungen ; Wärme- und Strahlungshaushalt der Atmosphäre {Meteorologie} ; Energiebilanzen in der Geodynamik {Geophysik}
    Language: German
    Type: monograph , publishedVersion
    Format: 141 S.
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  • 61
    Publication Date: 2021-03-29
    Description: Tectonics, marine geophysics, plate-tectonic reconstruction, new zealand, antarctica, seismic refraction/wide-angle reflection, Gondwana break-up. - The last supercontinent fell into pieces with the break-up of Gondwana. In this context, the separation of the microcontinent of New Zealand from Antarctica is a jigsaw puzzle of many pieces. Its parts lay at the convergent margin of East Gondwana, which changed into a divergent margin within a geologically short time. That is why the microcontinent of New Zealand experienced different tectonic regimes and phases of the Wilson cycle. Although it is a good object of investigation due to its changing history, remarkably little is known about the submerged parts of the microcontinent. Knowledge of the magmatic-tectonic development of the submarine plateaux such as Campbell Plateau and Chatham Rise will improve the understanding of the processes that led to the late Gondwana break-up, and, in turn, lead to better reconstructions of East Gondwana, as Zealandia is a key piece in plate-kinematic reconstructions of this part of Gondwana. The central part of this thesis deals with the separation process of Zealandia from Antarctica leading to an improved reconstruction of New Zealand with emphasis on the submarine plateaux. Bounty Trough separating Chatham Rise from Campbell Plateau, and the Great South Basin separating Campbell Plateau from the South Island are investigated with seismic refraction and reflection methods. They are interpreted jointly with magnetic and gravity data. The results of crustal thickness modelling based on satellite gravity data are combined with existing information about crustal thickness of Zealandia. With these data ...
    Description: thesis
    Keywords: 551.136 ; 550 ; TST 000 ; Ozeanien {Geophysik} ; Pazifischer Ozean {Geophysik} ; Geotektonische Entwicklung der Erdkruste {Tektonik}
    Language: German
    Type: monograph , publishedVersion
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  • 62
    Publication Date: 2021-03-29
    Description: Dinoflagellate cysts, paleoceanography, paleoenvironment, Late Quaternary, Norwegian-Greenland Sea. - Dinoflagellate cysts have been investigated in nine short sediment cores as well as two long sediment cores from the Norwegian-Greenland Sea and the North Atlantic to reconstruct the surface water paleoenvironment of the last climatic cycle and the Holocene. Holocene sea-surface temperatures and salinities during summer and winter and the extent of sea-ice cover were reconstructed. On the Rockall Plateau, higher cyst concentrations indicating favourable conditions and increased productivity only occur during parts of stage 5, 4-2, and the Holocene. Only sparse occurrences of dinocysts have been observed in the Norwegian-Greenland Sea before 10000 yr BP. Later, high abundances of O. centrocarpum and N. labyrinthus indicate the increased inflow of relatively warm Atlantic. A change in dominance of these species as well as a distinct increase in cyst concentrations marks the onset of the recent circulation system. In the Norwegian Sea, O. centrocarpum dominates the assemblages since about 7000 yr BP, while assemblages in the Iceland and the Greenland Sea are more complex due to the influence of different surface currents.
    Description: thesis
    Keywords: 560
    Language: German
    Type: monograph , publishedVersion
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  • 63
    Publication Date: 2021-03-29
    Description: Slope stability, submarine slides, Svalbard, Arctic Ocean, Sophia Basin. - With increasing interest in slope stability issues on continental shelves the causes and trigger mechanism of submarine slides get more and more into the scientific focus. Within the ESF EUROMARGINS project 'Slope Stabilities on Europe's passive continental Margin' (SPACOMA) sediment dynamics of megaslides along the passive continental margin north of Svalbard have been investigated. The study concentrated on identification and sedimentological characterisation of megafailure events, their dating and interpretation in relation to paleoceanography and climate history of the Svalbard archipelago. Integrated interpretation of multibeam bathymetric, sediment-penetrating acoustic (PARASOUND) and seismic data shows a multiple slope failure on the northern European continental margin, north of Spitsbergen. One huge submarine slide has been identified which was first described by Cherkis et al. (1999) - the Yermak Slide (later named Hinlopen/Yermak Megaslide). The extent of the Hinlopen/Yermak Megaslide has been revised based on new acoustic and detailed bathymetric data. Details from the side's internal structure give evidence for one main slide event followed by repeated minor events. The first slide event occurred during MIS 3 around 30 cal. kyr. BP and was characterised by highly dynamic and rapid evacuation of ca. 1.250 kmÃÂđ of sediment from the lower to the upper part of the shelf slope. During this megaslide event, headwalls up to 1600 m have been created and ca. 1150 kmÃÂđ material from hemipelagic sediments and from the lower preexisting trough mouth fan has been entrained and transported into the semi-enclosed Sophia Basin. This megaslide was followed by a secondary evacuation of debris material to the Nansen Basin accomplished by funnelling of the debris through the Littke Channel between Polarstern Seamount and the adjacent continental slope. The main slide debris is overlain by a set of fining-upwards sequences as evidence for the associated suspension cloud and ...
    Description: thesis
    Keywords: 551.307 ; 551.69 ; 551 ; Nordatlantische Polarinseln {Geologie} ; Sedimente bestimmter Regionen ; Sonstige Sedimentationsprozesse ; Paläoklimatologie
    Language: English
    Type: monograph , publishedVersion
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  • 64
    Publication Date: 2021-03-29
    Description: Sea ice, surface emissivity, emitting layer temperature, temperature profile, microwave radiometry. - Polar regions play a key role in the global climate. The information on atmospheric parameters in these regions is sparse. Among the polar surfaces, sea ice varies in extent and physical properties with region and season and so does the surface emissivity. In the present study a method to retrieve the emissivity is applied over two selected regions in the Arctic, one covered by first-year ice and the other by multiyear ice and it investigates the application of them in the improvement of temperature profile retrieval ver sea ice. The retrieval of surface emissivity is done by combining simulated brightness temperatures with the satellite measured brightness temperature. In order to determine the surface emissivity of sea ice, the observations of the microwave instruments amsu (Advanced Microwave Sounding Unit) and amsr-e (Advanced Microwave Scanning Radiometer- Earth Observing System) are used. Determination of emissivity requires the knowledge of the temperature of the emitting layer. The penetration depth of microwaves in sea ice varies between millimeters and decimeters depending on the frequency and micro-physical structure. A year-round observation of temperature profiles of sea ice from the Surface Heat Budget of the Arctic Ocean (sheba) campaign at a first-year and a multiyear ice site is used to derive a set of coefficients a and b to linearly relate ...
    Description: thesis
    Keywords: 551.343 ; VAQ 990 ; VAQ 100 ; Meereis {Glaziologie} ; Gletscheruntersuchungen im Allgemeinen
    Language: English
    Type: monograph , publishedVersion
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  • 65
    Publication Date: 2021-03-29
    Description: Reflection seismics, sediment drifts, bottom currents. - The region south of South Africa has been a crucial gateway for large scale Thermohaline Circulations since late Eocene times. Here, three of the most important currents for maintaining the global heat exchange, namely the warm and surface related Agulhas Current (AC), and the cold and denser North Atlantic Deep Water (NADW) as well as the Atlantic Bottom Water (AABW), flow around South Africa. Due to the special tectonic and geologic situation, a huge amount of the deep and bottom water masses that flow around South Africa have to pass the narrow Agulhas Passage, located between the South African continental shelf and the submarine Agulhas Plateau. As a result, the sedimentary infill of the Transkei Basin, which is located east of the Agulhas Plateau, has been predominantly influenced by NADW and AABW activity since ~36 Ma. Via the analysis of this sedimentary infill, a palaeo current reconstruction of (proto-) NADW and (proto-) AABW revealed changing flow paths and flow strengths since then. These variations in current attributes were triggered by large scale effects, such as the opening of the Tasman Gateway and the Drake Passage in the Late Eocene, or the closure of the Isthmus of Panama in the Pliocene. A more detailed analysis of the Transkei Basin's depocentre locations and interface outlines resulted in a palaeo flow path reconstruction for this region. Moreover, palaeo climate conditions from the Late Cretaceous were partially reconstructed ...
    Description: thesis
    Keywords: 551.462 ; 551.69 ; 550 ; TSZ 100 ; Atlantischer Ozean {Geophysik}
    Language: German
    Type: monograph , publishedVersion
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  • 66
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    Univ. Bremen
    Publication Date: 2021-03-29
    Description: Ice, microstructures, subgrain boundaries, recrystallization, flow, deformation. - The primary objective of this thesis is the investigation of microstructures obtained from samples from the EPICA Dronning Maud Land ice core from Antarctica. The goal is to gain understanding of deformation processes an deformation-related recrystallization mechanisms using these structures. The structures are visualized with the new microstructure mapping method using the preferred sublimation along defect regions in the crystal. This method enables observation in high resolution as well as overview over a significant sample volume. In order to provide unambiguous proof of their deformational origin and to offer interpretation and characterization, experimental reproduction of the microstructural features are performed using creep tests. Subgrain boundaries and grain-boundary morphology are identified as the most direct effects of deformation and recrystallization processes, which are still easily observable. They can be used additionally to the conventional parameters (grain size, crystal-orientation distribution) to determine these mechanisms. Different sbugrain-boundary types observed in experimentally deformed samples as well as in natural ice indicate several formation processes. Results obtained from this new and novel data suggest a profound reconsideration of the classical tripartition of recrystallization regimes described in the literature in ice sheets. Instead, dynamic recrystallization in two of its forms (rotation recrystallization and strain-induced migration recrystallization) dominates the microstructure evolution in all depth regions of the EDML ice core. Results of systematic microstructure analysis of creep-test samples demonstrate ...
    Description: thesis
    Keywords: 551.312 ; 548.842 ; 551 ; 550 ; VAE 140 ; VAQ 100 ; Gesteinsdeformation {Strukturgeologie} ; Gletscheruntersuchungen im Allgemeinen
    Language: German
    Type: monograph , publishedVersion
    Format: 129 S.
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  • 67
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; 550 ; TOD 400 ; TOE 000 ; TSB 000 ; Erdmantel {Geophysik} ; Physikalisches Verhalten der Erde {Geophysik} ; Mitteleuropa {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 147 S.
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  • 68
    Publication Date: 2021-03-29
    Description: The hyperspectral UV-vis-NIR spectrometer SCIAMACHY will be launched aboard the European satellite Envisat. Its limb measurements will provide vertically resolved profiles of trace gases and other atmospheric parameters. No retrieval algorithms and radiative transfer models have been established for these measurements yet.In this thesis, a unique, fast radiative transfer model for UV-vis-NIR limb radiances has been developed, implemented, and validated. It takes into account the sphericity of the atmosphere and up to two orders of scattering and surface reflection. The weighting functions for all parameters are calculated from analytical formulae. A realistic instrument model with field-of-view integration and signal-to-noise computation and retrieval algorithms have also been implemented. All have been combined in the new program package SCIARAYS. The package has been applied for the characterisation of the limb measurements in several ways:The simulated weighting functions agree well with those due to full multiple scattering. Thus they may be used to calculate theoretical precision estimates and averaging kernels. In conformance with this, test retrievals with approximate weighting functions converge correctly. Therefore, the approximate weighting functions of SCIARAYS are well suited for retrievals from SCIAMACHYś limb measurements.Detailed theoretical retrieval precisions have been calculated for SCIAMACHYś trace gas targets. The conclusion is that a UV-vis-NIR limb sensor like SCIAMACHY is well suited for studying the vertical structure of the stratosphere and also of the upper troposphere above cloud top.Further investigations show that the vertical resolution of retrievals from SCIAMACHYś limb measurements can be improved beyond its geometrical limits. As a trade-off for better vertical resolution, the retrieval precision gets worse. Thus O3 profile features with 1km vertical extent will be detectable with a precision of 20-30%.
    Description: thesis
    Keywords: 551.5 ; 550.28 ; 550 ; TUA 850 ; TQI 000 ; TVA 210 ; Satellitenmeteorologie ; Geophysikalische Satellitenfernerkundung ; Chemische Zusammensetzung der Atmosphäre {Meteorologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 247 S.
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  • 69
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 910 ; QGJ 120 ; Teilfragen zu Indien {Geographie}
    Language: German
    Type: monograph , publishedVersion
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  • 70
    Publication Date: 2021-03-29
    Description: GIS, Geoinformatik, Spatial Theory, Face Intersection, Polygon Clipping, Diagramatic Reasoning. - A Geographic Information System (GIS) is used to handle, analyse and visualize ‘facts’ of the ‘real world’. These ‘facts’ are assumed to be spatial in the sense that they are located at the earth’s surface. The first chapter outlines that the recent success of applied GIS is based on this ‘real world’ approach, which conforms to the tradition of geography as a scientific discipline. While most GIS-applications are pragmatically oriented in solving ‘real-world-problems’, each attempt to implement ‘spatial theories’ of GIS ends up in the well known geographical dilemma ...
    Description: thesis
    Keywords: 910 ; QBD 700 ; Geoinformationssysteme {Geographie}
    Language: German
    Type: monograph , publishedVersion
    Format: 162 S.
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  • 71
    Publication Date: 2021-03-29
    Description: The search for extrasolar planets is a relatively new field in astronomical and astrophysical sciences that was boosted by the first discovery of the exoplanet 51 Peg b in 1995 by radial velocity measurements. The short orbital period of 4.2 days determined for this giant exoplanet encouraged the accelerated development of another search method due to the high probability that such a Hot Jupiter planet would cross its host star in the line of sight yielding a photometrically detectable signal during this crossing. This transit method (also known as the occultation or eclipse method) measures such a darkening signal as an evidence for an orbiting planet allowing the determination of the radius of the planet. Combined with the information obtained with radial velocity measurements the mass and the density of the planet can be calculated. This unique opportunity to study detailed physical properties of exoplanets is advantageous compared to planets proven only by other search methods. In this thesis the establishing of the new ground-based transit survey Berlin Exoplanet Search Telescope (BEST) is described. This system consists of a 20cm Schmidt telescope and a CCD camera covering a field of view (FOV) of 3.1ʿ x 3.1ʿ. The set-up and the successful implementation of the BEST system are described in this work. Furthermore the developed strategies for the photometric observations, the calibration and analysis of the data, follow-up observations and their optimization are commented. During the 2-year observational campaign (2001-2003) from the Thüringer Landessternwarte (TLS) Tautenburg, Germany, three target fields were observed for 90 nights ...
    Description: thesis
    Keywords: 523 ; THX 100 ; Detektionsmethoden {Astronomie: Extrasolare Planetensysteme}
    Language: English
    Type: monograph , publishedVersion
    Format: 269 S.
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  • 72
    Publication Date: 2021-03-29
    Description: Optical counterparts of X-ray selected sources to a large part consist of active galactic nuclei (AGN). A large proportion of these counterparts turns out to be optically variable, and because the timescales and manner of this variability can give important clues regarding the physical nature and structure of the counterparts, searching for variable AGN is a worthwhile undertaking. In order to perform such an optical variability survey, a subset of 167 X-ray sources in an area around the NEP was selected in this work from the X-ray catalogues derived from the ROSAT all-sky survey (RASS). Contemporaneous optical observations were available from a collaboration with the Karl-Schwarzschildt observatory (KSO) Tautenburg. A total of 89 plates were analyzed, covering an area of 35 degrees square around the NEP and spanning a timebase of 30 month ...
    Description: thesis
    Keywords: 523 ; TBK 000 ; TC 200 ; Hochenergieastronomie ; Astronomische Beobachtungen vom Weltraum aus
    Language: English
    Type: monograph , publishedVersion
    Format: 283 S.
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  • 73
    Publication Date: 2021-03-29
    Description: Deep-sea fan, early diagenesis, susceptibility, anaerobic oxidation of methane, black shale, anoxia, oceanic anoxic event, trace elements, iron, phosphorus, sediment source, redox changes, enrichment factors, sequential extraction. - In the context of present-day changes of atmo-, hydro-, geo- and biosphere processes, there is growing interest to decipher rapid paleoenvironmental changes in the geological past. Marine deposits provide valuable insights into paleoenvironmental conditions that prevailed during their deposition, if we know how to read the respective signals in the sedimentary record. However, caution is demanded as primary signals of past environmental conditions can be altered by postdepositional diagenetic processes. In the presented work, we will show the potentials, but also limitations of inorganic geochemical proxies to record signals of abrupt paleoenvironmental shifts in the terrestrially dominated Late Quaternary deposits of the Zambesi deep-sea fan (SE African margin), and in a fully marine Late Cretaceous black shale succession on Demerara Rise (NW South American margin).
    Description: thesis
    Keywords: VAT 200 ; VJB 322 ; VAT 200 ; VJB 322 ; Meeresablagerungen {Geologie} ; Geochemie der ozeanischen Sedimente
    Language: German
    Type: monograph , publishedVersion
    Format: 127 S.
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  • 74
    Publication Date: 2021-03-29
    Description: Carbon, Upwelling, Namibia, shelf, sediments. - This PhD thesis is an essential component of the 'Namibia Gas' (NAMIBGAS) project, which aims to improve the understanding of the rate and fluxes of hydrogen sulfide and methane to the sediment surface and into the water column on the Namibian shelf, which is one of the most productive upwelling systems on Earth. Organic matter degradation in the sediment drives hydrogen sulfide production, the maintenance of anoxia, and methane formation. Therefore, the primary aims of the thesis are to study carbon transformation processes within the sediment, determine the reactivity of organic carbon in the sediment and, investigate the control of microbial community structure and activity by the amount and accessibility of carbon sources. The emphasis is on linking microbial community structure (identity) to their function (activity) to provide new insights into the microbial ecology that controls carbon turnover in these upwelling sediments. By studying the stepwise degradation of organic carbon a complete process overview of organic carbon mineralization could be obtained. Firstly, the diagenetic transformation of dissolved organic carbon (DOC), in particular dissolved carbohydrates, was studied by using both biogeochemical methods and molecular techniques. The bulk sediment composition, pore water chemistry, polysaccharide hydrolysis rates, 35S-sulfate reduction rates, and the abundance of active bacteria involved in the initial and terminal processes of organic carbon degradation within the top 15 cm of the sediment from two sampling stations were determined (Chapter 2). Secondly, the diversity of bacteria from the same ...
    Description: thesis
    Keywords: 551 ; VAT 270 ; VGE 500 ; Flachsee-Sedimente {Geologie} ; Biomineralisation
    Language: English
    Type: monograph , publishedVersion
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  • 75
    Publication Date: 2021-03-29
    Description: High-resolution climate reconstruction, North Sea, annual banded proxy, Arctica islandica. - Until now, there has been no published documentation of North Sea year-to-year climate variability during the last 8000 to 10000 years. High-resolution instrumental time series of climatic and environmental data for the North Sea and the adjacent North Atlantic are only available for the last decades or a century at best. Long term paleoclimatic reconstructions in higher latitudes have been predominantly undertaken using land-based annually banded archives, such as trees, varves, glaciers, and speleothems. A suitable long-term environmental archive with annual may be provided by CaCO3-skeletons of long-lived marine invertebrates. This study evaluates whether recent and subfossil shells of the long-lived bivalve Arctica islandica from the North Sea carry feasible information on Holocene climatic and oceanographic conditions. I compared modern shells of Arctica islandica from two very different habitats, a near-coastal shallow site (German Bight) and a northerly, more central, deep site (Fladen Ground). From the latter, subfossil shells were analysed, also. This study demonstrates that Arctica from both sites provides suitable archives of marine environmental conditions in the form of (i) variations in annual shell ...
    Description: thesis
    Keywords: 560 ; TWC 500 ; VAR 990 ; VXM 200 ; VZZ 120 ; Klimaschwankungen und Klimaänderungen im Quartär ; Meeresräume {Glazialgeologie} ; Lamellibranchiata {Paläozoologie} ; Randmeere {Paläontologie}
    Language: English
    Type: monograph , publishedVersion
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  • 76
    Publication Date: 2021-03-29
    Description: Calanus simillimus, Rhincalanus gigas, grazing, biogeochemistry, biogenic silica. - The role of copepod grazing, particularly of Calanus simillimus and Rhincalanus gigas, in the biogeochemical cycles of silicon (Si) and carbon (C) in the Antarctic Circumpolar Current (ACC) of the Southern Ocean is investigated. The two grazers show differences in feeding behavior before and in response to a diatom bloom stimulated by in situ iron fertilization. The continuously high feeding activity of C. simillimus on diatoms is conducive to enhance the export of primary produced C and Si. The grazing impact of this key species is high enough to influence population dynamics in the microplankton communities of the ACC. In the pre-bloom situation, R. gigas fulfils most of its carbon requirement through grazing on detritus and thereby effectively reduces the vertical fecal flux produced by C. simillimus. It is proposed that a Copepod-Retention-System for organic material is put in place by the copepod community under High Nutrient Low Chlorophyll (HNLC) conditions. Prey switching by R. gigas from detritus to diatoms in the bloom situation lifts the grazing check on the detritus flux and enables loss of particulate C and Si from the surface layer with fast sinking fecal pellets. Results from dissolution experiments indicate that the enclosure of biogenic silica (BSi) in copepod fecal pellets prevents the dissolution of diatom frustules. Diatoms submitted to grazing of copepods and krill (Euphausia superba) dissolved 4 to 26 times slower than un-grazed controls.
    Description: thesis
    Keywords: 560 ; VJE 220 ; Geochemie der Fauna
    Language: English
    Type: monograph , publishedVersion
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  • 77
    Publication Date: 2021-03-29
    Description: Volcanology, volcanic rift zones, Madeira, fluid inclusions, thermobarometry, geochemistry, geochronology. - Madeira and the Desertas Islands show two well-developed volcanic rift zones which intersect near the eastern tip of Madeira (São Lourenço peninsula). To examine a possible genetic link, volcanic structures, rock ages and rock compositions were investigated at the Desertas and São Lourenço. Barometric data derived from fluid inclusions and clinopyroxene-melt compositions indicate fractionation at multiple levels within the mantle beneath the rift zones, followed by temporary magma stagnation within the crust. Depths of crustal stagnation beneath São Lourenço and the Desertas differ significantly, and there is no evidence for a shallow magma reservoir feeding both rifts. This suggests that Madeira and the Desertas have separated magma supply systems. 40Ar/39Ar age determinations revealed that Desertas volcanism lasted from 〉5.1 to 1.9 Ma overlapping in age with the shield phase of Madeira. Eruptive quiescence between 4 and 2.5 Ma at São Lourenço coincides with the main period of volcanism on the Desertas. Major and trace elements and ...
    Description: thesis
    Keywords: 551 ; VAD 600 ; VAD 700 ; VAE 840 ; VEF 139 ; Paläovulkanismus {Geologie} ; Regionaler Vulkanismus {Geologie} ; Rifts {Geologie} ; Balearen un Pityusen {Geologie}
    Language: English
    Type: monograph , publishedVersion
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  • 78
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VAQ 990 ; Meereis {Glaziologie}
    Language: English
    Type: monograph , publishedVersion
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  • 79
    Publication Date: 2020-10-05
    Description: Coccolithophores, a major group of the nanophytoplankton, belong to the class Prymnesiophyceae.The cells of coccolithophores are typically surrounded by layer(s) of calcium carbonate plates, the coccoliths. Certain coccolithophores can be assigned to particular water masses or to photic zone characteristics and, therefore, single species as well as whole assemblages can be used as oceanographical indicators for the present and the past. Due to their ocean wide distribution, their large contribution to the fine grained carbonate ooze of the deep sea, their ability to photosynthesize and to calcificate they play an important role in the global carbon cycle...
    Description: thesis
    Keywords: 579.17 ; 577.7 ; 577.15 ; 579.82 ; 560 ; VJI 000 ; VU 000 ; VU 000 ; VJI 000 ; Geobiologie ; Geochemische Kreislaufmodelle
    Language: English
    Type: monograph , publishedVersion
    Format: 151 S.
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  • 80
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 560 ; TWC 600 ; VYF 200 ; VYA 500 ; VWH 300 ; VDH 320 ; Paläoklimatologie ; Pyrrophyceae {Paläobotanik} ; Paläökologie {Paläobotanik} ; Kreide {Stratigraphische Paläontologie} ; Oberkreide
    Language: English
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  • 81
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 549 ; VGF 200 ; VHB 830 ; Phasengleichgewichte und Umbildungen {Mineralogie} ; Gruppensilikate {Mineralogie}
    Language: German
    Type: monograph , publishedVersion
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  • 82
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.9 ; VOBC 700 ; VBQ 400 ; Transportvorgänge in Böden ; Grundwassergefährdung {Hydrogeologie}
    Language: German
    Type: monograph , publishedVersion
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  • 83
    Publication Date: 2021-03-29
    Description: The marine carbonate pump includes the production of calcium carbonate, CaCO3 by marine organisms and its subsequent transport to depth. The balance between carbonate production in surface waters and dissolution and accumulation in sediments influences the surface water CO2 concentration and thus the oceanś capacity to take up atmospheric CO2.Models are developed to investigate on calcium carbonate dissolution in the oceanic water column. Model results yield that dissolution in zooplankton guts contributes a significant portion of the proposed carbonate loss. Dissolution fueled by the respiration of organic matter in marine snow aggregates is very sensitive to the size and settling velocity of the aggregate, which determines the boundary layer thickness and the stability of an undersaturated microenvironment. The constraints set by field data yield that the chemical gradients between the aggregate and the bulk seawater are too small to enable significant carbonate dissolution. Furthermore, the role of the carbonate pump in regulating atmospheric pCO2 on glacial to interglacial timescales is investigated ...
    Description: thesis
    Keywords: 551.9 ; VJI 000 ; Geochemische Kreislaufmodelle
    Language: English
    Type: monograph , publishedVersion
    Format: 132 S.
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  • 84
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.9 ; VJF 000 ; VJC 400 ; VEB 217 ; Umweltgeochemie insgesamt ; Fluid-Gestein-Wechselwirkungen {Geochemie} ; Sachsen {Geologie}
    Language: German
    Type: monograph , publishedVersion
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  • 85
    facet.materialart.
    Unknown
    Univ. Berlin
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VAE 850 ; VAE 400 ; VDE 000 ; VEO 170 ; Festländische Lineamente {Geologie} ; Tektogenese {Geologie} ; Proterozoikum ; Sudan {Geologie}
    Language: English
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  • 86
    Publication Date: 2021-03-29
    Description: The major objective of the study is to investigate how near-surface sediment structures and other geological aspects control the nature and occurrence of cold fluid seepage. Mainly high resolution multichannel seismic data and swatch bathymetry data were used to study nearsurface seismostratigraphy, structure and seismic fluid-indicating features in two different fluid seepage provinces: Campeche Knolls, southern Gulf of Mexico and the frontal Makran, offshore Pakistan. The two areas have fundamentally different tectonic settings: The Campeche Knolls, southern Gulf of Mexico represents a passive margin influenced by salt tectonism, while the frontal Makran is the most basinward part of the Makran accretionary prism, characterized by plate subduction, sediment accretion, thrust faulting and development of sediment imbricate slices. However, they share quite a few similarities in shallow sediment structures and fluid seepage patterns...
    Description: thesis
    Keywords: 551.23 ; 553.28 ; 550 ; TSZ 100 ; VAE 880 ; TSZ 200 ; Atlantischer Ozean {Geophysik} ; Passive und aktive Kontinentalränder {Geologie} ; Indischer Ozean {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 125 S.
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  • 87
    Publication Date: 2021-03-29
    Description: To understand processes and dynamics linked to the volumetric water content of soils thorough knowledge of the water distribution inside soils is required. The applicability of the georadar technique for small scale soil heterogeneity mapping and monitoring is investigated using four different methods. Since the uppermost meter of the soil lacks a sufficient amount of spacious reflectors no standard georadar methods can supply adequate coverage of the investigated area under field conditions. Therefore four methods were evaluated to present an assortment of the most promising methods for different case specific problems. Owing to the averaging nature of the georadar technique the introduced methods needed to be adapted to small scale investigations. Based on numerical simulations and concise measurements new processing procedures are applied to achieve the required spatial resolution of less than 0.3 m. All four methods were successfully applied during realistic field measurement conditions. The transmission method is applied to a soil column experiment filled with undisturbed natural soil. In the course of an irrigation experiment the infiltration of the water front as well as the water dynamics afterwards were reproduced. The application of georadar transmission tomography provided spatial allocatable water content distributions over the time of the water seepage with spatial accuracies of approximately 0.1 m and a temporal resolution of approximately 30 min...
    Description: thesis
    Keywords: 551.48 ; 550.28 ; 550 ; TQD 800 ; Georadar {Geophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 146 S.
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  • 88
    Publication Date: 2021-03-29
    Description: Im Rahmen verschiedener Drittelmittelprojekte waren vom Autor Wechselstrommessungen bei z.T. sehr kleinen Signal- zu Rauschverhältnissen durchzuführen. In den ariden Messgebieten (Ägypten, Sudan) waren hierfür die schlechten Ankopplungsbedingungen verantwortlich, in den dicht besiedelten Gebieten (Stadtgebiet Berlin) die hohen Störspannungspegel. Trotz konsequenter Anwendung von Filter- und Stapelungstechniken, blieb die Datenqualität bisweilen unakzeptabel niedrig. Inspiriert durch multivariate Zeitreihenanalysentechniken der Audiomagnetotellurik wurde vom Autor eine geoelektrische Referenztechnik mathematisch formuliert und mit Hilfe von speziell hierfür gefertigten mehrkanaligen Geoelektrikapparaturen erfolgreich eingesetzt. Anhand von Fallbeispielen wurde demonstriert, dass die Anwendung der geoelektrischen Referenztechnik den statistischen Messfehler sowohl im Gelände als auch im Labor um bis zu 2 Größenordnungen verringern kann. Anders als Stapelungstechniken vermindert die Referenztechnik den Messfortschritt jedoch nicht. Ein ungünstig gewählter Referenzstationsstandort kann zu systematisch verfälschten Messwerten führen. Anhand von Modellrechnungen wurde untersucht welche Anordnungen vorteilhaft sind...
    Description: thesis
    Keywords: 537 ; 550 ; TQD 000
    Language: German
    Type: monograph , publishedVersion
    Format: 325 S.
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  • 89
    Publication Date: 2021-03-29
    Description: Deformation, shear zone, granular, micromechanic, numerical model, discrete element method, distinct element method. - This thesis was inspired by the lack of detailed (i.e. particle scale) knowledge concerning deformation processes of mechanically weak sediments, especially intrinsically weak layers on the basal shear plane of submarine landslides. It has been known for some time that many different parameters influence shear strength and localization features. This is true not only for sediments, but also for other kinds of weak layers, such as fault gouge. These parameters include for example mineralogy (e.g. smectite, illite, quartz), sediment composition (clay, silt), sediment structure and texture (microfabric), grain size distribution, excess pore pressure, magnitude of effective stress, and deformation history. However, to date it has not been possible to rank or to quantify the influence of each of these parameters. The main goal of this study is to analyze the influence of some of these parameters and, if possible, rank and quantify them. Standard methods to examine shear strength of sediments and fault gouge are various geotechnical shear experiments. In these, a sample is sheared under defined conditions and resulting coefficient of friction, void ratio change, and other meaningful parameters are analyzed. Unfortunately, it is not possible to 'look' inside a shear box during a test and to analyze grain deformation behaviour on a microscopic scale. Therefore, this study employs a different approach to specifically address the problem of microscopic deformation processes. Here, a numerical modelling technique, the Discrete Element Method (DEM), is used. The DEM is a numerical tool based on the ...
    Description: thesis
    Keywords: 551.8 ; VAE 130 ; VAE 130 ; Geomechanik
    Language: English
    Type: monograph , publishedVersion
    Format: 138 S.
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  • 90
    facet.materialart.
    Unknown
    Univ. Berlin
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 550.28 ; 550 ; VBH 000 ; VBH 000 ; Fernerkundung
    Language: English
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  • 91
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 622.15 ; 551.1 ; 550 ; TQG 000 ; TOO 000 ; TOD 410 ; TSV 000 ; TSZ 300 ; TQG 000 ; TOO 000 ; TOD 410 ; TSV 000 ; TSZ 300 ; Geophysikalische Bohrlochmessungen ; Geothermik {Geophysik} ; Oberer Erdmantel {Geophysik} ; Nordamerika {Geophysik} ; Pazifischer Ozean {Geophysik}
    Language: German
    Type: monograph , publishedVersion
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  • 92
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551.701 ; 549 ; VBN 200 ; VHC 200 ; VBN 200 ; VHC 200 ; Radiometrische Altersbestimmung ; Schwerminerale
    Language: English
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  • 93
    Publication Date: 2021-03-29
    Description: During the last years and decades issues related to the physics and chemistry of the Earthś atmosphere have attracted much scientific and public interest. The most important problems are stratospheric ozone loss and the ò̀zone hole ́́above Antarctica, global warming and climate change, and tropospheric air pollution. The understanding of the impact of human activities on the Earthś atmosphere requires measurements on a global scale. These enable the spatial and temporal variability of the atmospheric constituents to be investigated. Recently efforts have been made to establish a global observation system comprising satellite instruments and ground-based networks. To process data supplied by the instruments which belong to the global observation system, the development of radiative transfer models and retrieval algorithms is essential. This thesis contributes to the development of the radiative transfer models and retrieval algorithms intended to interprete measurements of the spectral radiance scattered in the atmosphere or transmitted through the atmosphere in UV-Vis-NIR spectral region performed by a new-generation remote sensing satellite spectrometer SCIAMACHY. In this study, main problems of radiative transfer through a spherical planetary atmosphere compared to a plane-parallel atmosphere are investigated. An efficient spherical radiative transfer model intended to simulate SCIAMACHY limb measurements was developed and validated. The model can also be used for the interpretation of measurements performed by other space-borne instruments as well as to compute air mass factors for ground-based measurements. An approximate approach allowing the simulation of limb measurements to be substantially accelerated was developed and its accuracy was investigated. Furthermore, a numerical radiative transfer model intended to simulate SCIAMACHY occultation measurements was developed and then coupled with an appropriate selected inverse technique.
    Description: thesis
    Keywords: 551.5 ; 550.28 ; 550 ; TQI 000 ; Geophysikalische Satellitenfernerkundung
    Language: English
    Type: monograph , publishedVersion
    Format: 150 S.
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  • 94
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 551 ; VAE 840 ; VEO 170 ; Rifts {Geologie} ; Sudan {Geologie}
    Language: German
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  • 95
    Publication Date: 2021-03-29
    Description: Giant shear processes shaped Africa's southern margin during the breakup of the supercontinent Gondwana. They acted along a more than 1000 km long transform fault, whose remnant structure the Agulhas-Falkland Fracture Zone stretches today from the Falkland Plateau to the southeastern margin of Africa. A study of the processes which initiated such a long-offset transform fault and acted during their active phase is essential to understand how this sheared margin developed. Africa’s southern margin is not only one of the best examples to study the sharp continent-ocean-transition zones, the marginal ridge, fracture zone, and basin structures usually associated with transform margins, but it provides the unique opportunity to study how excessive magmatic processes acted which formed a Large Igneous Province at a sheared margin. In this thesis, I use seismic refraction, seismic reflection data and plate-tectonic reconstructions to investigate the structure and dynamics of this margin. These are ideal methods as they lead to high-quality velocity-depth models showing the present-day structure across the margin and provide timing and geometries by means of plate kinematics...
    Description: thesis
    Keywords: 550 ; TSR 000 ; TSZ 200 ; VAE 880 ; VAE 890 ; VER 100 ; VEZ 200 ; Südafrika {Geophysik} ; Indischer Ozean {Geophysik} ; Passive und aktive Kontinentalränder {Geologie} ; Ozeanische Kruste {Tektonik} ; Republik Südafrika {Geologie} ; Indischer Ozean {Geologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 157 S.
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  • 96
    Publication Date: 2021-03-29
    Description: Im ersten Kapitel erfolgt nach der Zielsetzung und Motivation für die vorliegende Dissertation eine kurze geographische Beschreibung des Arktischen Ozeans und dessen tektonischer Entwicklung.Das Augenmerk gilt dabei dem ca. 1800 km langen Gakkel-Rücken, der sich von der Nordküste Grönlands bis zum Schelf der Laptewsee erstreckt und die Grenze zwischen Nordamerikanischer und Eurasischer Platte bildet. Die Spreizungsgeschwindigkeiten dieses Rückensystems, welche für geowissenschaftliche Untersuchungen von besonderer Bedeutung sind, betragen nur etwa einen Zentimeter pro Jahr und sind damit die langsamsten weltweit. Eine kurze Vorstellung von geophysikalischen und geodätischen Messverfahren zeigt, wie man zu solchen präzisen Spreizungsraten gelangt. Im Anschluss erfolgt eine kurze Beschreibung der Arctic Mid-Ocean Ridge Expedition (AMORE), welche die Forschungsschiffe Healy (USA) und Polarstern (Deutschland) im Sommer 2001 in den zentralen Arktischen Ozean und zum Nordpol führte. Die Sonarmessdaten und Bodenproben, die auf der AMORE-Expedition gesammelt und in dieser Arbeit ausgewertet wurden, stammen hauptsächlich aus dem ca. 32 000 km2 großen Gebiet entlang des Gakkel-Rückens (7°W85°E, 82°N87°N), zum Teil aber auch aus dem Amundsen- und Nansen-Becken. In Kapitel Zwei werden hydroakustische Grundlagen erläutert, die für das Verständnis dieser Arbeit unabdingbar sind und auf die später zurückgegriffen wird. Nach der Beschreibung von physikalischen Größen und Verhältnissen, der Wellengleichung, der Ausbreitung von Unterwasserschall und der Reflexion und Rückstreuung von Schallwellen am Meeresboden erfolgt eine Formulierung der Sonargleichung ...
    Description: thesis
    Keywords: 551.46 ; TQD 800 ; TSZ 100 ; VAT 300 ; Georadar {Geophysik} ; Atlantischer Ozean {Geophysik} ; Geologie des Meeresboden
    Language: German
    Type: monograph , publishedVersion
    Format: 231 S.
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  • 97
    Publication Date: 2021-03-29
    Description: Antarctica represents a key component in the investigation of the geological history and reconstruction of the supercontinents Rodinia and Gondwana. Remnants of the formation and disintegration of these former land masses can be found, although great uncertainties remain in the location of tectonic boundaries beneath the ice sheet of Antarctica due to general lack of outcrops and the limited amount of geological data. Space and airborne measurements are the only possibility to obtain comprehensive spatial data coverage of geophysical data over the extensive large polar areas. Common knowledge of the geological framework displays three major tectonic events which formed Dronning Maud Land (DML): the Grenvillian Orogen (1.1 Ga) build up Rodinia, the Pan-African-Antarctic Orogen (EAAO, 500 Ma) rose in the supercontinent Gondwana and finally the breakup of Gondwanaland, at around 180 Ma...
    Description: thesis
    Keywords: 526.7 ; 559 ; 538.87 ; 550 ; TSY 200 ; Antarktis {Geophysik} ; Aerogeophysik
    Language: English
    Type: monograph , publishedVersion
    Format: 174 S.
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  • 98
    Publication Date: 2021-03-29
    Description: Integrated studies of conjugate margins provide important constraints for the sequence of events of synrift tectonic and magmatic processes. The northeast Greenland margin is investigated based on seismic refraction data acquired across the continent ocean transition zone between the Jan Mayen and Greenland fracture zones. Transects of seismic velocity models reveal a clear segmentation of the margin, which is compatible with the potential field data. A crucially important observation is a thick high velocity lower crustal body which clearly decreases northwards. Excessive magmatism is inferred to have occurred during long-term rifting in the south, while reduced syn-rift intrusions account for the norhtern magma-starved margin. Asymmetries and variations across the adjacent and conjugate East Greenland and Norwegian margins, are controversially discussed in terms of the origin of the lower crustal body and magnetic spreading anomalies. Three hypothetical scenarios for the timing and formation of the high velocity lower crustal body are presented. A comprehensive subsidence analysis is established which quantifies the amount of magmatic underplating.
    Description: thesis
    Keywords: 551.136 ; VAE 880 ; TSY 100 ; VBM 000 ; VAE 880 ; TSY 100 ; VBM 000 ; Passive und aktive Kontinentalränder {Geologie} ; Arktis {Geophysik} ; Geologische Interpretation geophysikalischer Beobachtungen
    Language: English
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  • 99
    Publication Date: 2021-03-29
    Description: Antarctica, Dronning Maud Land, anisotropy, seismic anisotropy, shear wave splitting, receiver functions, moho, moho depth, crust, upper mantle, refraction seismic, gravity, 3D-gravity, igmas, bouguer anomaly, seismology. - The area of investigation, Dronning Maud Land (DML), comprises with the Weddell Sea and the Lazarev Sea approximately the region between 15 degrees W and 15 degrees E longitude and 68 degrees and 75 degrees latitude - a surface area of more than 1.500.000 qkm. Three major events formed the present-day geology and tectonic settings of DML: (1) the Grenvillian Orogeny, ca. 1.1 Ga ago, caused by the formation of the supercontinent Rhodinia, (2) the Panafrican Orogeny 500 Ma ago, forming the supercontinent Gondwana due to the collison of West and East Gondwana, and (3) the break-up of Gondwana 180 Ma ago, which started in the present-day Lazarev Sea. Seismological, refraction seismic and aerogravity data-sets form the basis of this thesis. The combination of these data-sets allows to investigate the structural composition and the spatial variation of the lithospheric thickness. The latter is essential for the determination of the regional geoid, which is the main objective of the VISA-project. Within the framework of this project airborne measurements of the potential field as well as ice-penetrating radar and GPS-measurements have been carried out. Moreover, seismographic stations were temporarily deployed in various parts of DML. Despite their very short operation time, applications of seismological methods to the recorded teleseismic events yielded conclusions about the structure and dynamic of the deeper subsurface. By analyses of seismic anisotropy, which investigates the splitting of shear waves traversing an anisotropic medium (so-called shear wave splitting) conclusions ...
    Description: thesis
    Keywords: 551.1 ; 550 ; TSY 200 ; Antarktis {Geophysik}
    Language: German
    Type: monograph , publishedVersion
    Format: 150 S.
    Format: application/pdf
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  • 100
    Publication Date: 2021-03-29
    Description: Radiocarbon, reservoir age, ocean circulation, projection age, top-to-bottom age, B-P age. - In paleoceanography and paleoclimatology radiocarbon is frequently used to date carbonaceous samples of the past 50,000 years and as a proxy to reconstruct circulation states of the ocean. Temporal variations of the atmospheric radiocarbon concentration, caused by a varying radiocarbon production rate or changes in the global carbon cycle, lead to dating uncertainties and also limit the usability of radiocarbon as an oceanographic proxy. In order to analyze and correct the influence of varying atmospheric radiocarbon on the ocean, radiocarbon has been included as a tracer to a global climate model (University of Victoria Earth System Climate Model). This model was forced by the reconstructed atmospheric radiocarbon production rate, to predict differences between atmospheric and marine radiocarbon age, the so-called reservoir age, spatially and temporally.
    Description: thesis
    Keywords: 551.701 ; 550 ; Geochronologie einzelner Regionen ; Holozän ; Isotopengeologie ; Geochemische Kreislaufmodelle
    Language: German
    Type: monograph , publishedVersion
    Format: 124 S.
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