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  • 1
    Publication Date: 2022-10-06
    Description: Trade wind convection organises into a rich spectrum of spatial patterns, often in conjunction with precipitation development. Which role spatial organisation plays for precipitation and vice versa is not well understood. We analyse scenes of trade‐wind convection scanned by the C‐band radar Poldirad during the EUREC4A field campaign to investigate how trade‐wind precipitation fields are spatially organised, quantified by the cells' number, mean size, and spatial arrangement, and how this matters for precipitation characteristics. We find that the mean rain rate (i.e., the amount of precipitation in a scene) and the intensity of precipitation (mean conditional rain rate) relate differently to the spatial pattern of precipitation. Whereas the amount of precipitation increases with mean cell size or number, as it scales well with the precipitation fraction, the intensity increases predominantly with mean cell size. In dry scenes, the increase of precipitation intensity with mean cell size is stronger than in moist scenes. Dry scenes usually contain fewer cells with a higher degree of clustering than moist scenes do. High precipitation intensities hence typically occur in dry scenes with rather large, few, and strongly clustered cells, whereas high precipitation amounts typically occur in moist scenes with rather large, numerous, and weakly clustered cells. As cell size influences both the intensity and amount of precipitation, its importance is highlighted. Our analyses suggest that the cells' spatial arrangement, correlating mainly weakly with precipitation characteristics, is of second‐order importance for precipitation across all regimes, but it could be important for high precipitation intensities and to maintain precipitation amounts in dry environments.
    Description: We analyse scenes of trade‐wind convection scanned by the C‐band radar Poldirad during the EUREC4A field campaign to investigate how trade‐wind precipitation fields are spatially organised, quantified by the cells' number, mean size, and spatial arrangement, and how this matters for precipitation characteristics. We conclude that the cells' size is important for both the amount and intensity of precipitation, whereas the cells' spatial arrangement is of second‐order importance for precipitation across all regimes, but possibly important for precipitation in dry environments.
    Description: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC 2037 'CLICCS—Climate, Climatic Change, and Society'
    Description: https://doi.org/10.25326/217
    Description: https://doi.org/10.25326/79
    Keywords: ddc:551.5
    Language: English
    Type: doc-type:article
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  • 2
    Publication Date: 2021-03-29
    Keywords: Eastern Sierras Pampeanas; Provenance; Tectonic setting; Gondwana margin; Geodynamic evolution ; 551 ; Earth Sciences; Geophysics/Geodesy; Geology
    Language: English
    Type: article , publishedVersion
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  • 3
    Publication Date: 2021-03-29
    Description: Die Beziehungen zwischen der Mikrostruktur und der kristallografischen Vorzugsorientierung (Textur) von Hämatiterzen der gebänderten Eisenerzformation (BIF) in Brasilien wurden in vielen Veröffentlichungen behandelt, z.B. Quade et. al. 2000, Rosière et al. 2001, Bascou et al. 2002. Polfiguren dieser Hämatiterze zeigen kreisförmige bis elliptische c-Achsen-Maxima, die um den Pol der Foliation liegen. Die Pole der Prismenflächen liegen auf Großkreisen in der Foliationsebene und die Maxima auf diesen fallen mit der Lineation zusammen. Die Entstehung dieser Regelung wird auf Scherverformungprozesse zurückgeführt. Bei experimentellen Stauchversuchen an polykristallinem Hämatit gab es Anzeichen der Bildung eines c-Achsenmaximums senkrecht zur Kompressionsrichtung (Siemes et al. 2003). Da zu vermuten war, dass Gleiten parallel zur Basis des Hämatits Ursache der Regelung ist, wurden die Gleitmechanismen an experimentell verformten Hämatiteinkristallen bestimmt (Siemes et al. 2006). In diesem Beitrag werden neue Scherexperimente an polykristallinen Hämatitaggregaten vorgestellt...
    Description: conference
    Keywords: 551 ; VAE 120 ; VAE 140 ; VBB 000 ; VKB 270 ; VKB 120 ; Methodik {Strukturgeologie} ; Gesteinsdeformation {Strukturgeologie} ; Experimentelle Geologie ; Produkte mechanischer Deformation {Petrologie} ; Petrologie der Vulkanite ; Eisenerz ; Hämatit ; Torsionsversuch ; Scherung 〈Geologie〉 ; Experiment ; Texturanalyse ; Mikrostruktur
    Language: German
    Type: anthologyArticle , publishedVersion
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  • 4
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    Unknown
    Kraatz, Berlin
    In:  SUB Göttingen | KART B 140:4440[1922];KART H 140:Delitzsch
    Publication Date: 2021-07-22
    Description: Geologische Karte 1: 25 000 mit Erläuterungen. Digitalisat des FID GEO (Fachinformationsdienst Geowissenschaften der festen Erde), erstellt durch das GDZ (Göttinger Digitalisierungszentrum), Karte aus dem Bestand der SUB Göttingen. Koordinaten Vorlage: Nullmeridian Ferro E 030 0 - E 030 10 / N 051 36 - N 051 30
    Description: map
    Description: DFG, SUB Göttingen
    Keywords: 912 ; 554.3 ; Geologische Karte ; Delitzsch ; FID-GEO-DE-7
    Language: German
    Type: map_digi
    Format: 79
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  • 5
    Publication Date: 2021-05-07
    Description: Die an der südwestlichen Ostseeküste gelegene Halbinsel Bug/NW Rügen wurde untersucht, um die Entwicklung von Haken und Nehrungen unter dem Einfluss des holozänen Meeresspiegelanstiegs zu studieren. Als Datengrundlage dienten 25 Sedimentkerne, sowie sieben Georadar- und sechs Sedimentecholotprofile, aus denen sechs Lithofaziestypen abgeleitet wurden. Danach besteht die Nehrung aus einer durchschnittlich 10 m mächtigen holozänen Sedimentfolge, die auf pleistozäner Basis aus Geschiebemergel und (glazi-)fluviolimnischen Feinsanden lagert. Obwohl keine absoluten Altersdaten gewonnen wurden, kann die Sedimentabfolge mit der lokalen relativen Meeresspiegelkurve problemlos korreliert und eine Modellvorstellung für die Nehrungsentwicklung geschlussfolgert werden. Die marine Inundation des Untersuchungsgebietes erfolgte um 7.000 BC während der Littorina-Transgression. In diesem Stadium stieg der Meeresspiegel rapide an und generierte einen schnell wachsenden Akkumulationsraum, in dem feinklastisches Material an oder unter der Wellenbasis akkumulierte und zu einem Reliefausgleich beitrug. Akkumulative Küstenformen bildeten sich nur in geringem Maße, da der Akkumulationsraum schneller wuchs als er durch das aus der Küstenerosion stammende Material aufgefüllt werden konnte. In dem Maße, indem der Meeresspiegelanstieg sich verlangsamte, gewann die Akkumulation an Bedeutung und der Hauptteil der Nehrung wurde innerhalb von rund zweitausend Jahren landfest. Entsprechend dem Verlauf von Strandwällen auf seiner heutigen Oberfläche lassen sich zwei Entwicklungsphasen aushalten, die von unterschiedlichen wellenenergetischen, erosiven und overwash-Prozessen bestimmt werden. Gegenwärtig besitzt die Nehrung ein Volumen von 66,4 Mio m³, woraus sich auf einen Rückgang des benachbarten Kliffs von rund 2000 m schließen lässt. Obwohl die Nehrung entwicklungsmäßig in ihrem Reifestadium angelangt zu sein scheint, deuten einige Merkmale auf zunehmende Instabilität hin. Im nördlichen Bereich verhindern Küstenschutzmaßnahmen einen Nehrungsdurchbruch und beginnende Auflösung. Im Süden haben Fahrwasserbaggerungen eine weitere Längenzunahme und das Zusammenwachsen mit Haken von Hiddensee verhindert. Ohne diese Maßnahmen würde die Nehrung durch Seegattbildung und zunehmende Erosion im Norden und Seegattschließung und zunehmende Uferprogradation im Süden eine neue Gestalt annehmen.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; holocene ; baltic sea ; sea-level rise ; coastal evolution ; barrier ; lagoon ; rügen
    Language: English
    Type: article , publishedVersion
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  • 6
    Publication Date: 2021-03-29
    Description: Severe stone deterioration is evident at the Cologne cathedral. In particular, the “Drachenfels” trachyte, which was the building material of the medieval construction period, shows significant structural deterioration as well as massive formation of gypsum crusts. The present article investigates crust formation on limestone, sandstone, and volcanic rock from the Cologne cathedral as well as from the Xanten and Altenberg cathedrals. These three buildings, showing varying degrees of deterioration, are located in different areas and exposed to varying industrial, urban, and rural pollution. Thin laminar and black framboidal crusts form on calcareous as well as silicate stone. The lack of a significant intrinsic calcium and sulfur source for the formation of the gypsum crusts on the Drachenfels trachyte indicates major extrinsic environmental impact: a sufficient offer of SOx from pollutant fluxes as well as external calcium sources (e.g., pollution, mortars, neighboring calcite stones). Chemical analyses reveal strong gypsum enrichment within the crusts as well as higher concentrations of lead and other pollutants (arsenic, antimony, bismuth, tin, etc.), which generally can be linked to traffic and industry. The formation of weathering crusts in an industrial environment is clearly distinguishable from that in rural areas. Scanning electron microscopy observations confirm that the total amount of pollution is less at the Altenberg cathedral than at the Cologne and Xanten cathedrals. XRF analyses show that the formation of gypsum occurs in lower amounts at Altenberg. This correlates well with the measured SO2 content and the intensity of the decay at the different locations. Furthermore, the different types of crusts, e.g., framboidal and laminar, can be differentiated and assigned to the different locations. The black weathering crusts on the silicate Drachenfels trachyte contribute to the degradation of the historic building material. They enhance mechanical moisture-related deterioration processes and the decay by chemical corrosion of rock-forming minerals. Although SO2 concentrations in air have shown a strong decrease over the past 30 years, degradation in connection with weathering crusts is still observed. This indicates that not only contemporary or recent emissions, but also past pollutant concentrations have to be considered.
    Keywords: Cologne cathedral; Xanten cathedral; Altenberg cathedral; Weathering crusts; Pollution impact; Stone decay processes; Drachenfels trachyte ; 551 ; Earth Sciences; Geology
    Language: English
    Type: article , publishedVersion
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  • 7
    Publication Date: 2021-03-29
    Description: The St. Servatius Church in Quedlinburg (UNESCO’s World Heritage Site, Germany) is characterised by long-standing stability problems and structural damages, which have been known over the last several centuries. The monotonous Cretaceous sandstone with its poor lithification is considered to be the main factor. The sandstone is characterised by a high porosity of around 30 Vol.% (max. ca. 35 Vol.%) and a corresponding high w-value. The porosity and the degree of cementation are responsible for the very low compressive strength of around 8 MPa at maximum, whereas under moisture these values are significantly reduced up to 40%. The freeze–thaw tests indicate a very poor resistance to frost weathering, which may explain the near-surface softening of the sandstone. Direct shear experiments with an approximate 60° angle of friction on the sandstone clearly demonstrate the safety margins. Initial geotechnical modelling does not favour the hypothesis that a landslide of the hill parallel to the southward dipping bedding planes (i.e. shear failure along weak zones) can occur. A prominent clay layer (also with a southward dip) below the entire castle hill is monitored to determine the possible amount of movement with respect to the geological discontinuities (e.g. joints, fractures). At present, a combination of foundation problems are being considered for the stability situation at the church. These include construction deficiencies due to deformation or softening of the foundation of the forerunner churches and missing or faulty connections from building additions. Geological factors responsible for the stability problems include the softening of the sandstone by the influence of weathering and penetrating water as well as the presence of possible shear planes and joints.
    Keywords: Cretaceous sandstone; Lithology; Diagenetic processes; Weathering; Petrophysical properties; Stability assessment ; 551 ; Earth Sciences; Geology
    Language: English
    Type: article , publishedVersion
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  • 8
    Publication Date: 2021-11-03
    Description: Semi-enclosed marginal seas like the Baltic Sea are often characterized by permanently anoxic deep layers, and may therefore serve as important model systems to study the causes and consequences of the predicted global expansion of oxygen minimum zones. Here, we focus on the role of lateral intrusions in maintaining the “hypoxic transition zone” (HTZ) of the Baltic Sea, which characterizes the quasi-permanent hypoxic region located between the oxygenized surface layer and the sulfidic deep-water region. Based on long-term deployments of an autonomous profiling system in the central Baltic Sea, we show that oxic mid-water intrusions are ubiquitous features, providing the most important oxygen source for the HTZ, and largely control the vertical and lateral extent of the hypoxic areas. An oxygen budget for the HTZ suggests that oxygen turnover in the HTZ is, to first order, determined by a long-term balance between sedimentary oxygen demand and oxygen import by intrusions. The downward mixing of oxygen into the HTZ is generally non-negligible but unlikely to provide a first-order contribution to the HTZ oxygen budget. On the long-term average, mid-water intrusions were shown to inject 30–60 Gmol of oxygen per year into the deep-water region below the permanent halocline. This is approximately one order of magnitude larger than the average amount of oxygen imported during the massive deep-water inflow events (Major Baltic Inflows) that occur on an approximately decadal time scale, highlighting the HTZ as a hotspot for biogeochemical turnover.
    Keywords: 551.46 ; Baltic Sea ; hydrography ; hypoxic transistion zone (HTZ) ; biogeochemical turnover
    Language: English
    Type: map
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  • 9
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    Unknown
    In:  Geophys. Res. Lett., Roma, Polish Geothermal Association, vol. 32, no. 24, pp. 12,269-12,289, pp. L24301, (ISSN: 1340-4202)
    Publication Date: 2005
    Keywords: Physical properties of rocks ; Fluids ; Laboratory measurements ; hydrocarbons ; GFZ ; GRL ; 3004 ; Marine ; Geology ; and ; Geophysics: ; Gas ; and ; hydrate ; systems ; 3022 ; Marine ; sediments: ; processes ; and ; transport ; 5194 ; Physical ; Properties ; of ; Rocks: ; Instruments ; and ; techniques ; 9805 ; General ; or ; Miscellaneous: ; Instruments ; useful ; in ; three ; or ; more ; fields
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  • 10
    Publication Date: 2005-11-27
    Description: Basic vibration characteristics and random response in thin panels
    Keywords: STRUCTURAL MECHANICS
    Type: SPACE TRANSPORTATION SYSTEM TECHNOL. SYMP., VOL. 2 JUL. 1970; P 43-57
    Format: text
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