06 Fakultät Luft- und Raumfahrttechnik und Geodäsie

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    ItemOpen Access
    "A la recherche du temps perdu" : on geological condensation, with examples from the Jurassic Subbetic Plateau in Southeastern Spain
    (1993) Fels, Alexander; Seyfried, Hartmut
    Eine kondensierte Ablagerung ist eine marine Rückstandsbildung, die sich autochthon und kontinuierlich über einen längeren Zeitraum hinweg gebildet hat. Kondensation kann synsedimentar durch Abschirmung, Ablenkung oder Abtragung von Schlamm erfolgen; diagenetisch läuft Kondensation vor allem über Bioerosion auf Hartboden in Verbindung mit unterschiedlich tiefgreifender Erosion ab. Im Jura des subbetischen Plateaus (früher "externes Subbetikum") wird das Umkippen in eine Kondensations-Situation durch tektonische Bewegungen gesteuert, indem benachbarte Plattformen den Export von Schlamm selbssteuernd regulieren. Das subbetische Plateau durchlief vier Phasen stark reduzierter Sedimentation: Carixien - Unter-Domerien(Kondensatlonsepisode 1), Obertoarcien - Unter-Bajocien (Kondensationsepisode 2), Unterbathonien - Unter-Oxfordien (Kondensationsepisode 3) und unterstes Kimmeridgien (Kondensationsepisode 4). Hartboden, die sich während dieser Episoden bildeten, sind meistens von Goethitkrusten und Goethitonkoiden bedeckt. Die meisten Goethitkrusten bestehen entweder aus sehr dünnen (20 - 50 p.) Laminae mit krümeligem und pseudofilamentösem Gefüge, die für einen mikrobiellen Ursprung der Krusten sprechen, oder sie bestehen aus strukturlosem, "sterilen" Goethiterz. Aus einer Abschätzung der Wachstumsraten folgern wir, daß der überwiegende Teil der Zeit, die in solchen Krusten versteckt ist, entweder im nur wenige Milimeter dicken Goethiterz dokumentlert ist oder in Hartböden bzw. Erosionsflächen gelöscht wurde. Kondensierte Abfolgen zelgen meistens eine hierarchische Gliederung in Sequenzen, die vom Meter- bis zum Millimeterbereich reichen und nahezu stets denselben Aufbau haben: sie beginnen mit reduzierter Sedimentation, auf die ein Omissionsstadium folgt und schließen melstens mlt Goethitkrusten ab. Unter den vielen Faktoren, die für eine solche Abfolge verantwortlich sein konnen, kristallisiert sich als kleinster gemeinsamer Nenner ein (nicht eindeutig kalibrierbares) eustatisches Signal heraus. Wir betrachten deshalb kondensierte Sequenzen, die Goethitkrusten enthalten, als pelagische Parasequenzen.
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    Using GRACE data to study the impact of snow and rainfall on terrestrial water storage in Northeast China
    (2020) Qian, An; Yi, Shuang; Chang, Le; Sun, Guangtong; Liu, Xiaoyang
    Water resources are important for agricultural, industrial, and urban development. In this paper, we analyzed the influence of rainfall and snowfall on variations in terrestrial water storage (TWS) in Northeast China from Gravity Recovery and Climate Experiment (GRACE) gravity satellite data, GlobSnow snow water equivalent product, and ERA5-land monthly total precipitation, snowfall, and snow depth data. This study revealed the main composition and variation characteristics of TWS in Northeast China. We found that GRACE provided an effective method for monitoring large areas of stable seasonal snow cover and variations in TWS in Northeast China at both seasonal and interannual scales. On the seasonal scale, although summer rainfall was 10 times greater than winter snowfall, the terrestrial water storage in Northeast China peaked in winter, and summer rainfall brought about only a sub-peak, 1 month later than the maximum rainfall. On the interannual scale, TWS in Northeast China was controlled by rainfall. The correlation analysis results revealed that the annual fluctuations of TWS and rainfall in Northeast China appear to be influenced by ENSO (EI Niño-Southern Oscillation) events with a lag of 2-3 years. In addition, this study proposed a reconstruction model for the interannual variation in TWS in Northeast China from 2003 to 2016 on the basis of the contemporary terrestrial water storage and rainfall data.
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    Editorial for PFG issue 5/2023
    (2023) Gerke, Markus; Cramer, Michael
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    Geospatial information research : state of the art, case studies and future perspectives
    (2022) Bill, Ralf; Blankenbach, Jörg; Breunig, Martin; Haunert, Jan-Henrik; Heipke, Christian; Herle, Stefan; Maas, Hans-Gerd; Mayer, Helmut; Meng, Liqui; Rottensteiner, Franz; Schiewe, Jochen; Sester, Monika; Sörgel, Uwe; Werner, Martin
    Geospatial information science (GI science) is concerned with the development and application of geodetic and information science methods for modeling, acquiring, sharing, managing, exploring, analyzing, synthesizing, visualizing, and evaluating data on spatio-temporal phenomena related to the Earth. As an interdisciplinary scientific discipline, it focuses on developing and adapting information technologies to understand processes on the Earth and human-place interactions, to detect and predict trends and patterns in the observed data, and to support decision making. The authors - members of DGK, the Geoinformatics division, as part of the Committee on Geodesy of the Bavarian Academy of Sciences and Humanities, representing geodetic research and university teaching in Germany - have prepared this paper as a means to point out future research questions and directions in geospatial information science. For the different facets of geospatial information science, the state of art is presented and underlined with mostly own case studies. The paper thus illustrates which contributions the German GI community makes and which research perspectives arise in geospatial information science. The paper further demonstrates that GI science, with its expertise in data acquisition and interpretation, information modeling and management, integration, decision support, visualization, and dissemination, can help solve many of the grand challenges facing society today and in the future.
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    CRBeDaSet : a benchmark dataset for high accuracy close range 3D object reconstruction
    (2023) Gabara, Grzegorz; Sawicki, Piotr
    This paper presents the CRBeDaSet - a new benchmark dataset designed for evaluating close range, image-based 3D modeling and reconstruction techniques, and the first empirical experiences of its use. The test object is a medium-sized building. Diverse textures characterize the surface of elevations. The dataset contains: the geodetic spatial control network (12 stabilized ground points determined using iterative multi-observation parametric adjustment) and the photogrammetric network (32 artificial signalized and 18 defined natural control points), measured using Leica TS30 total station and 36 terrestrial, mainly convergent photos, acquired from elevated camera standpoints with non-metric digital single-lens reflex Nikon D5100 camera (ground sample distance approx. 3 mm), the complex results of the bundle block adjustment with simultaneous camera calibration performed in the Pictran software package, and the colored point clouds (ca. 250 million points) from terrestrial laser scanning acquired using the Leica ScanStation C10 and post-processed in the Leica Cyclone™ SCAN software (ver. 2022.1.1) which were denoized, filtered, and classified using LoD3 standard (ca. 62 million points). The existing datasets and benchmarks were also described and evaluated in the paper. The proposed photogrammetric dataset was experimentally tested in the open-source application GRAPHOS and the commercial suites ContextCapture, Metashape, PhotoScan, Pix4Dmapper, and RealityCapture. As the first experience in its evaluation, the difficulties and errors that occurred in the software used during dataset digital processing were shown and discussed. The proposed CRBeDaSet benchmark dataset allows obtaining high accuracy (“mm” range) of the photogrammetric 3D object reconstruction in close range, based on a multi-image view uncalibrated imagery, dense image matching techniques, and generated dense point clouds.
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    Spatio-temporal evaluation of GPM-IMERGV6.0 final run precipitation product in capturing extreme precipitation events across Iran
    (2022) Bakhtar, Aydin; Rahmati, Akbar; Shayeghi, Afshin; Teymoori, Javad; Ghajarnia, Navid; Saemian, Peyman
    Extreme precipitation events such as floods and droughts have occurred with higher frequency over the recent decades as a result of the climate change and anthropogenic activities. To understand and mitigate such events, it is crucial to investigate their spatio-temporal variations globally or regionally. Global precipitation products provide an alternative way to the in situ observations over such a region. In this study, we have evaluated the performance of the latest version of the Global Precipitation Measurement-Integrated Multi-satellitE Retrievals (GPM-IMERGV6.0 Final Run (GPM-IMERGF)). To this end, we have employed ten most common extreme precipitation indices, including maximum indices (Rx1day, Rx5day, CDD, and CWD), percentile indices (R95pTOT and R99pTOT), and absolute threshold indices (R10mm, R20mm, SDII, and PRCPTOT). Overall, the spatial distribution results for error metrics showed that the highest and lowest accuracy for GPM-IMERGF were reported for the absolute threshold indices and percentile indices, respectively. Considering the spatial distribution of the results, the highest accuracy of GPM-IMERGF in capturing extreme precipitations was observed over the western highlands, while the worst results were obtained along the Caspian Sea regions. Our analysis can significantly contribute to various hydro-metrological applications for the study region, including identifying drought and flood-prone areas and water resources planning.
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    Method of development of a new regional ionosphere model (RIM) to improve static single-frequency precise point positioning (SF-PPP) for Egypt using Bernese GNSS software
    (2023) Abdallah, Ashraf; Agag, Tarek; Schwieger, Volker
    Due to the lack of coverage of IGS in Africa, especially over North Africa, and the construction revolution of infrastructure in Egypt, a geodetic CORS stations network was established in 2012. These CORS stations are operated by the Egyptian Surveying Authority (Egy. SA) and cover the whole of Egypt. The paper presents a fully developed regional ionosphere model (RIM) depending on the Egyptian CORS stations. The new model and the PPP solution were obtained using Bernese GNSS V. 5.2 software. An observation data series of eight days (DOY 201-208)/2019 was used in this study. Eighteen stations were used to develop the RIM model for each day; fifteen stations were used to validate the new RIM model. A static SF-PPP solution was obtained using the CODE-GIM and RIM models. Comparing the outcomes to the reference network solution, based on the recently developed RIM model, the solution showed a mean error of 0.06 m in the East direction, 0.13 m in the North direction, and 0.21 m in the height direction. In the East, North, and height directions, this solution improves the SF-PPP result achieved by the Global Ionosphere Maps (CODE-GIM) model by 60%, 68%, and 77%, respectively.
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    Sea level change : a philosophical approach
    (1993) Leinfelder, Reinhold; Seyfried, Hartmut
    The present Cenozoic era is an lsquoicehousersquo episode characterized by a low sea level. Since the beginning of the industrial revolution, the human race has been emitting greenhouse gases, increasing the global atmospheric temperature, and causing a rise in sea level. If emissions continue to increase at the present rate, average global temperatures may rise by 1.5°C by the year 2050, accompanied by a rise of about 30 cm in sea level. However, the prediction of future climatic conditions and sea level is hampered by the difficulty in modelling the interactions between the lithosphere, kryosphere, biosphere and atmosphere; in addition, the buffering capacity of our planet is still poorly understood. As scientists cannot offer unambiguous answers to simple questions, sorcerer's apprentices fill in the gaps, presenting plans to save planet without inconveniencing us. The geological record can help us to learn about the regulation mechanisms of our planet, many of which are connected with or expressed as sea level changes. Global changes in sea level are either tectono-eustatic or glacioeustatic. Plate tectonic processes strongly control sea levels and climate in the long term. There is a strong feed-back mechanism between sea level and climate; both can influence and determine each other. Although high sea levels are a powerful climatic buffer, falling sea levels accelerate climatic accentuation, the growth of the polar ice caps and will hence amplify the drop in sea level. Important sources of fossil greenhouse gases are botanic CO2 production, CO2 released by volcanic activity, and water vapour. The latter is particularly important when the surface area of the sea increases during a rise in sea level (lsquomaritime greenhouse effectrsquo). A lsquovolcanogenic greenhouse effectrsquo (release of volcanogenic CO2) is possibly not equally important, as intense volcanic activity may take place both during icehouse episodes as well as during greenhouse episodes. The hydrosphere, land vegetation and carbonate platforms are major CO2 buffers which may both take up and release CO2. CO2 can be released from the ocean due to changes in the pCO2 caused by growth of coral reefs and by uptake of CO2-rich freshwater from karst provinces. Efficient sinks of CO2 are the weathering products of silicate rocks; long-term sinks are organic deposits caused by regional anoxic events which preferrably develop during sea level rises and highstands; and coal-bearing strata. Deposition of limestone also removes CO2 from the atmospheric-hydrospheric cycle at a long term. Biotic crises are often related to either sea-level lows or sea-level highs. Long-term sea-level lows, characteristic of glacial periods, indicate cooling as major cause of extinction. During verly long-lasting greenhouse episodes the sea level is very high, climate and circulation systems are stable and biotic crises often develop as a consequence of oxygen depletion. On land, niche-splitting, complex food web structures and general overspecialization of biota will occur. Whether the crisis is caused by a single anoxic event (e.g. in the Late Devonian) or a disturbance by an asteroid impact (e.g. the Cretaceous/Tertiary boundary), it will only trigger total collapse of an ecosystem if a large part of it was already in decline. The regulatory mechanisms and buffers are thermodynamically extremely efficient if they are given sufficient time in which to deploy their power. However, after major catastrophes the re-establishment of successful ecosystems will take millions of years. The present rate of sea level and associated temperature rise is much too fast to be compensated and buffered by the network of natural controls. It is likely that the transitional time towards a new steady state will be an extremely variable and chaotic episode of unpredictable duration.
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    S wave velocity structure of the crust and upper mantle beneath Shanxi rift, central North China Craton and its tectonic implications
    (2021) Cai, Yan; Wu, Jianping; Rietbrock, Andreas; Wang, Weilai; Fang, Lihua; Yi, Shuang; Liu, Jing
    The Shanxi rift is located in the central part of the North China Craton (NCC). With strong tectonic deformation and intense seismic activity, its crust‐mantle deformation and deep structure have always attracted wide attention. Using teleseismic events observed in a dense network of 610 temporary and 127 permanent stations in the central NCC, we obtained the crust‐mantle S wave velocity structures by the joint inversion method of receiver functions and surface wave dispersion data. Our results show that the crust thickens in the northern part of the Shanxi rift (41 km) and thins in the southern part (35 km). The Taiyuan and Linfen basins, located in the central part, have high‐velocity zones in the lower crust and upper mantle; beneath the Yuncheng basin in the south, there are low‐velocity zones in the lower crust and uppermost mantle (30-80 km); the Datong basin, located in the northern part of the rift, exhibits a wide range of low‐velocity anomalies in the middle to lower crust and upper mantle. We speculate that the destruction of the NCC and associated lithospheric thinning had a significant impact on the southern part of the rift, but is still in its early stage in the central part, which retains most of the craton features. An upwelling of the asthenospheric magma occurred beneath the western part of the Datong basin. The horizontal deflection of the asthenospheric flow causes low‐velocity anomalies in its surrounding area, which is consistent with LAB topography.
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    Detection, analysis, and removal of glitches from InSight's seismic data from Mars
    (2020) Scholz, John‐Robert; Widmer‐Schnidrig, Rudolf; Davis, Paul; Lognonné, Philippe; Pinot, Baptiste; Garcia, Raphaël F.; Hurst, Kenneth; Pou, Laurent; Nimmo, Francis; Barkaoui, Salma; de Raucourt, Sébastien; Knapmeyer‐Endrun, Brigitte; Knapmeyer, Martin; Orhand‐Mainsant, Guénolé; Compaire, Nicolas; Cuvier, Arthur; Beucler, Éric; Bonnin, Mickaël; Joshi, Rakshit; Sainton, Grégory; Stutzmann, Eléonore; Schimmel, Martin; Horleston, Anna; Böse, Maren; Ceylan, Savas; Clinton, John; Driel, Martin van; Kawamura, Taichi; Khan, Amir; Stähler, Simon C.; Giardini, Domenico; Charalambous, Constantinos; Stott, Alexander E.; Pike, William T.; Christensen, Ulrich R.; Banerdt, W. Bruce
    The instrument package SEIS (Seismic Experiment for Internal Structure) with the three very broadband and three short‐period seismic sensors is installed on the surface on Mars as part of NASA's InSight Discovery mission. When compared to terrestrial installations, SEIS is deployed in a very harsh wind and temperature environment that leads to inevitable degradation of the quality of the recorded data. One ubiquitous artifact in the raw data is an abundance of transient one‐sided pulses often accompanied by high‐frequency spikes. These pulses, which we term “glitches”, can be modeled as the response of the instrument to a step in acceleration, while the spikes can be modeled as the response to a simultaneous step in displacement. We attribute the glitches primarily to SEIS‐internal stress relaxations caused by the large temperature variations to which the instrument is exposed during a Martian day. Only a small fraction of glitches correspond to a motion of the SEIS package as a whole caused by minuscule tilts of either the instrument or the ground. In this study, we focus on the analysis of the glitch+spike phenomenon and present how these signals can be automatically detected and removed from SEIS's raw data. As glitches affect many standard seismological analysis methods such as receiver functions, spectral decomposition and source inversions, we anticipate that studies of the Martian seismicity as well as studies of Mars' internal structure should benefit from deglitched seismic data.