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Interannual variability of the Ocean Circulation in the Atlantic-Arctic Ocean Gateways
No full textThe northward transport of warm and saline water from the Atlantic Ocean into the Arctic Ocean is a crucial element of the Arctic climate system. On its way north, the Atlantic Water (AW) is either transported through the Barents Sea (BS), a shallow Arctic shelf sea, or with the West Spitsbergen Current through eastern Fram Strait (FS). The temperature and volume of the two-branched AW flow depict pronounced interannual variability, affecting the downstream water properties in the Arctic Ocean and the Arctic sea ice. In the first part of my thesis, I examine a potential positive feedback in the ice-ocean-atmosphere system of the BS. Using satellite data, atmospheric reanalysis, and a special setup of a global ocean and sea ice model I test whether the pronounced local decrease in sea ice in the BS can trigger a local feedback. It was hypothesized that reduced sea ice increases ocean-to-atmosphere heat flux, reduces the air pressure, alters the local wind field, and finally increases the warm water transport into the BS resulting in even less sea ice. The results of my study contradict the existence of this feedback but indicate that air pressure anomalies centered over the north-western BS can modify the Atlantic Water re-circulation in both, the Barents Sea Opening (BSO) and FS. In the second part of my thesis, I investigate the interannual variability of the transport through the BSO and its link to the North Atlantic Oscillation (NAO), using special setups of a global ocean and sea ice model. By combining different atmospheric forcing fields, the transport anomalies are split into local and upstream forced contributions. With the help of the simulations, I show that a previously detected loss of co-variability between the NAO and the BSO AW transport around the year 2000 can be attributed to the upstream forced BSO transport anomalies. These anomalies are strongly affected by atmospheric blocking events in this period. Atmospheric blocking deflects synoptic-scale cyclones that usually maintain the control of the NAO on the BSO AW transport. In the final part of my thesis, I examine the role of the westward-directed AW return-flow in the northern BSO on the Barents-Kara-Sea (BKS) sea ice. Due to insufficient observations, the magnitude and variability of the return-flow are largely unknown. Here, a model-based attempt is made to quantify the transport and temperature of the return-flow and the respective variability. A previously unknown, pronounced co-variation between the return-flow and the BKS sea ice is found. This co-variability is not only evident in the BSO but part of a quasi-simultaneous flow variability along the entire AW pathways through the Barents Sea. In general, my thesis aims at improving our understanding of AW transport variability in the Atlantic-Arctic ocean gateways
The ocean mesoscale in a warming world: insights from multiscale modeling
No full textState-of-the-art climate models and computing infrastructure are now able to resolve mesoscale ocean eddy activity in many contexts. However, in computationally intensive model applications, such as the Coupled Model Intercomparison Project (CMIP) or simulations of the high latitudes, grid resolutions largely remain eddy-parameterizing due to resource constraints. These missing mesoscale processes are understood to be crucial drivers of ocean circulation and climate and may become still more relevant in the context of anthropogenic climate change. To overcome the computational limitations of traditional models, multiscale modeling strategies have been developed which can distribute grid resolution and resources based on resolution requirements and research goals. Here, several strategies for resolving the mesoscale using multiscale methods are described and the results of their implementation with the Finite volumE Sea ice Ocean Model (FESOM) are reported. In the first application, FESOM participates in CMIP6 with the strategy of concentrating computational resources on the major eddy-rich regions of the ocean. The resulting simulations are able to reproduce between 51 and 82% of observed eddy kinetic energy (EKE) in each region and project substantial climate change impacts on mesoscale activity for the first time at such a scale. The results include a poleward shift of eddy activity in most western boundary currents; EKE intensification in the Antarctic Circumpolar Current (ACC), Brazil and Malvinas Currents, and Kuroshio Current; EKE decline in the Gulf Stream; and intensification of Agulhas leakage. In a second application, FESOM is used to concentrate computational resources in the Southern Ocean and cost-reducing modeling strategies are used to enable fully eddy-resolving climate change projections with the regionally focused grid. The simulations faithfully reproduce EKE in the Southern Ocean and project intensified eddy activity in line with the CMIP6 analysis. The climate change signal is difficult to reliably discern from natural variability after 1 °C of warming, but becomes clear after 4 °C. Finally, the high-resolution Southern Ocean simulations are used to investigate high-latitude eddy activity where ice cover and low eddy size make observations and traditional modeling methods difficult. Detailed, near circumpolar mesoscale activity is detected and related to gyre circulation, the Antarctic Slope Current, and bathymetry. There is a strong seasonal cycle which suppresses winter eddy activity at the surface and selectively dampens cyclonic eddies. After prolonged anthropogenic warming, broad intensification of eddy activity occurs alongside regional decline, ACC eddy activity encroaches further into the high latitudes, and the seasonal cycle is diminished. Collectively, this work demonstrates the effectiveness of multiscale modeling in reducing the cost of resolving mesoscale ocean activity, facilitating the study of eddy activity and its interactions with the broader climate in previously unachievable contexts
Physiochemische Reaktionen eines Asteriniden-Seesterns (Echinodermata: Asteroidea) auf globale Ozeanveränderungen
No full textThe continuous increase in greenhouse gas (GHG) emissions, especially carbon dioxide (CO2), since the beginning of global industrialization has resulted in significant alterations in seawater physicochemical properties, particularly elevated seawater temperatures (ocean warming, OW) and ocean acidification (OA). These changes have wide-ranging consequences for marine organisms, affecting their biological functions and ecological roles. The combined effects of OW and OA may amplify adverse outcomes compared to individual stressors due to the complex reorganization of cellular mechanisms and molecular pathways, which subsequently appear in behavioral modifications. However, organismal reactions and thresholds to these stressors are variable, which might differ within organism ontogeny or among taxa, making predictions challenging. Therefore, increasing research has been performed to better understand the potential mechanisms underlying the ability of marine organisms to alleviate the effects of environmental change, mainly due to OW and OA. Thus, employing multiple bioindicators, specifically keystone species such as starfish, to evaluate the impacts of OW and OA offers a comprehensive approach to examining their effects not simply on the organism concerned but also on the broader ecosystem.
The presented studies in this thesis aim to contribute to the understanding the role of physiochemistry and trade-offs on marine ectotherms, particularly asterinid starfish, in coping with environmental stress. For this purpose, mineralogic, metabolic, behavioral, lipidomics, and enzymatic activity approaches are used. The research summarized in this thesis provides the first investigation of the effects of global ocean change on biomineralization and physiological traits through long-term experiments using asterinid starfish species, Aquilonastra yairi, distributed in tropical to subtropical regions (across the Mediterranean Sea, Red Sea, and Gulf of Suez). The starfish were exposed to two temperature levels (27 °C and 32 °C) crossed with three pCO2 regimes (455 µatm, 1052 µatm, and 2066 µatm), representing factorial combinations of ambient conditions and future levels of CO2 and temperature change according to the IPCC-Representative Concentration Pathways (RCPs) 8.5 greenhouse gas emission scenario for the year 2100.
The present work revealed that asterinid starfish demonstrate high stressor tolerance and resilience to increased temperature and pCO2 through adaptive adjustments in physiological functions or behavioral activities, suggesting high homeostatic capacities and the ability to regulate physiochemical response to maintain survival, fitness, and metabolic biosynthesis under chronic conditions. The temperature was the predominant factor, exerting a significant effect on the magnitude and frequency of the affected physiological-related processes; however, concurrent exposure to OA and OW stress produced synergistic effects on some of the starfish physiology-related responses tested. While decreased pH negatively affects starfish calcification performance, the increased temperature potentially mitigates these effects. However, increased temperature might also lead to more magnesium (Mg2+) incorporation into the calcite lattice, potentially compromising the starfish skeleton. Furthermore, it was revealed that starfish can preserve lipid-associated biochemistry (FAs) under elevated temperature and pCO2, which potentially provides molecular instruments to cope with future OA and OW scenarios. However, combined OA and OW significantly affected Ca-ATPase and Mg-ATPase enzyme activities, which are recognized to play an important role in the biomineralization pathway, raising concerns about potential susceptibilities in skeletal development and preservation.
Investigating the complex impacts of global ocean change on marine organisms requires a comprehensive research approach that encompasses diverse biological, chemical, and physical traits. Understanding the physiological and chemical responses of bioindicator species, e.g., asterinid starfish, to combined stressors OW and OA is important to comprehend the relationships and interactions between biological processes and abiotic environmental conditions, which in turn essential for accurately predicting their resilience, ecological implication, and broader ecosystem dynamics. At the ecosystem scale, this study significantly contributes to the ongoing knowledge for future studies of the impact of climate change on coral reef-associated invertebrates. Specifically, this finding is beneficial for the conservation of coral reef ecosystems under future ocean conditions
Neue Übergangsmetall-vermittelte Umsetzungen hypervalenter Iodverbindungen
No full textMehrere Methoden zur Umsetzung von hypervalenten Iodverbindungen unter Übergangsmetallkatalyse wurden entwickelt und beschrieben. Dazu zählen insbesondere transient-dirigierte CH-Aktivierungen
Collectomics in Mauritania - An integrated biodiversity assessment in underexplored lagoons and the implementation of a scientific reference collection
No full textThe waters of the West African country Mauritania are characterised by a particularly high biodiversity. Due to its geographical location, the distribution of tropical, subtropical, and boreal species overlap off its coast. This resulting species richness is further enhanced by surplus of nutrients, which arises from seasonal upwelling events off Northwest Africa. Consequently, the Mauritanian coastline is home to not only a remarkably high marine biodiversity but also houses some of the most productive fish stocks in the Atlantic Ocean. Despite the significant biodiversity, the coastal areas of Mauritania have been insufficiently studied, as previous research has primarily focused on fisheries, seagrass beds, and the behaviour of migratory birds and their overwintering in Mauritania. To address this gap and to establish an essential foundation for future marine conservation in Mauritania, this dissertation investigates the marine biodiversity of the country and compiles a scientific reference collection of the studied marine fauna, expanded integratively through modern methodologies such as DNA barcoding and digitalisation following the principles of Collectomics. To achieve this, multiple ecosystems along the coast were examined, and artisanal fish markets were surveyed. During the field campaigns conducted for this purpose, new, previously undocumented fish species from Mauritania were discovered and scientifically described. The collected tissue samples of the documented fauna were utilised for species identification and were deposited in a genetic database for future research. Additionally, the marine biodiversity of two different bays was assessed using environmental DNA to examine seasonal dynamics and the impact of anthropogenic stressors on the marine biodiversity.
The gathered data aims to establish a much-needed and solid foundation for biodiversity research in Mauritania, enabling future biodiversity assessments to be referenced and potentially vulnerable marine areas to be identified and designated for protectio
Elektroniker:in - Lern- und Arbeitsaufgaben für das Berufliche Handlungsfeld „Installieren und Inbetriebnehmen von Standard-Elektroanlagen“
No full textLern- und Arbeitsaufgaben sind ein bewährtes didaktisch-methodisches Konzept für eine arbeitsprozessorientierte, projektförmige und gegebenenfalls auch lernortübergreifende Berufsbildung. Das Konzept der Kompetenzwerkstatt bietet ein eigenes Modul, in dem anhand von Fragenkatalogen und Kriterienlisten erklärt wird, wie sich Lern- und Arbeitsaufgaben schrittweise entwickeln lassen
Wie genau sehen solche nach dem Konzept der Kompetenzwerkstatt entwickelte Lern- und Arbeitsaufgaben aber letztendlich eigentlich aus?
Auf diese Frage gibt das vorliegende Handbuch für das Berufsfeld der Elektrotechnik beispielhaft Antworten. Zum Beruflichen Handlungsfeld „Installieren und Inbetriebnehmen von Standard-Elektroanlagen“ des Elektrohandwerks werden drei Lern- und Arbeitsaufgaben vorgestellt. Die Aufgaben sind in den von der Kompetenzwerkstatt zur Verfügung gestellten Vorlagen dokumentiert. Diese Dokumentationen sind in das Handbuch eingebunden, darüber hinaus stehen sie auch als Download zur Verfügung. Außerdem sind die Lern- und Arbeitsaufgaben in einer speziell für ihre Entwicklung und Darstellung konzipierten Online-Plattform – dem Aufgaben-Manager – aufbereitet. Auf diese Plattform kann über einen Link zugegriffen werden, der an entsprechender Stelle ebenfalls angeboten wird
Dynamics in health behavior self-regulation: leveraging intensive longitudinal methods to understand the in situ translation of intentions into behavior
No full textBackground: Health behaviors such as smoking, physical activity, and diet are essential to long-term health. However, many individual, social, and environmental determinants a person encounters in everyday life strongly determine such behaviors and influence, whether a person is able to act in line with their health goals at a given moment. Temporal Self-Regulation Theory thus proposes a dynamic perspective on (health) behavior self-regulation as it understands behavior as a shared function of the interplay of such determinants and intentions as well as goal-related feedback processes over time. Still, an empirical examination with the required 1) density of measurement and 2) in the relevant context of self-regulation, in situ, has been lacking to date.
Methods: I integrate five publications and seven separate intensive-longitudinal studies examining different health-promoting and -risking behaviors to quantitatively assess the three dimensions of dynamics and their influence on the self-regulation of behavior.
Results: Within-person, moment-to-moment fluctuations in behavioral intentions vary meaningfully and interact with momentary contextual determinants in predicting behavior (synchronicity). Evaluative feedback processes based on past behavior facilitate goal-oriented, adaptive changes in intentions, but not behavior, over time (sequentiality). More durable intentions (stability) improve the translation of intentions into behavior.
Conclusions: Integrating dynamic features into theories of (health) behavior self-regulation cannot only provide us with a more nuanced understanding of what drives behavior where it is crucial, in situ, but also facilitates the development of targeted interventions to support individual efforts of behavior change as well as policy-level interventions that aim for such a change across larger groups of the population
On the conceptualization and assessment of personality: a framework for the disentanglement of core dispositions from surface characteristics and validation of the german HEXACO-60 personality inventory-revised and big five inventory-2
No full textZusammenfassung
Die vorliegende Dissertation veranschaulicht wie Konzepte der Persönlichkeit differenziert, organisiert sowie integriert werden können und liefert Belege für die Validität zweier Messinstrumente zur Persönlichkeitsbeurteilung. Ein nützliches Persönlichkeitsmodell muss sowohl breit genug sein, um alle wichtigen Aspekte umfassend zu erfassen, als auch geradlinig genug, um in der Praxis anwendbar zu sein. Hierbei wird argumentiert, dass die Persönlichkeit durch tief verwurzelte Kerndispositionen (core dispositions) und ihre kontextuell variierenden Anpassungen, die als Oberflächenmerkmale (surface characteristics) gelten, zum Ausdruck kommt. Es wird eine Begründung für diese Unterscheidung gegeben und ein Framework angeboten, das die Identifizierung und Differenzierung von Kerndispositionen und Oberflächenmerkmalen ermöglicht. Das vorgestellte Framework besteht aus mehreren Kriterien, die alle von einer angenommenen Kerndisposition erfüllt werden müssen, um als solche anerkannt zu werden. Zwei prominente Ansätze für die Erfassung von Kerndispositionen sind das HEXACO und das Big Five Persönlichkeitsmodell, die Persönlichkeit in sechs beziehungsweise fünf breite Dimensionen unterteilen. Diese können wiederrum in schmalere Facetten untergliedert werden. In diesem Zusammenhang ist es von wesentlicher Bedeutung, dass man sich darauf verlassen kann, dass die zur Messung von Persönlichkeit verwendeten Instrumente zuverlässig, valide und nützlich sind. Daher wurde die psychometrische Qualität des deutschen HEXACO-60 und Big Five Inventar 2 (BFI-2) geprüft. Hierbei wurden die Selbstberichtform und erstmalig auch die Fremdberichtform evaluiert. Jede Form der beiden Fragebögen erwies sich als psychometrisch solide. Die Dissertation bescheinigt somit die solide Grundlage der Selbst-und Fremdberichtformen des deutschen HEXACO-60 und BFI-2, auf der künftige Forschung bei der Untersuchung von Forschungsfragen innerhalb des Frameworks zur Identifizierung von Kerndispositionen und darüber hinaus bauen können.
Summary
The current dissertation illustrates how personality concepts can be differentiated, organized and integrated and provides evidence for the validity of personality assessment via two measurement instruments. A useful model of personality must be broad enough to comprehensively cover all important aspects yet be parsimonious enough to be applicable in practice. It is argued that personality is expressed by deeply rooted core dispositions and their contextually varying adaptations which are deemed to be surface characteristics. A justification for this distinction is given and a framework is offered that enables the identification of core dispositions by distinguishing them from surface characteristics. This presented framework is composed of several criteria which must all be met by a proposed core disposition in order to be approved as such. Two prominent approaches for comprehending core dispositions are the HEXACO and the Big Five model of personality that categorize personality into six or five broad dimensions, respectively. These in turn can be further subdivided into narrower facets. In this regard, it is essential that one can trust the tools being used for measuring personality to be reliable, valid and useful. Therefore, the psychometric quality of the German HEXACO-60 and Big Five Inventory-2 (BFI-2) was put under close scrutiny. Notably, the self-report forms and for the first time, the informant-report forms were evaluated. Each form of the two questionnaires was demonstrated to be a psychometrically sound measure. The dissertation attested the solid foundation of the German HEXACO-60 and BFI-2 self-and informant-report forms that future research can build upon in the pursuit of research questions within the framework for the identification of core dispositions and beyond
Unraveling atmosphere and sea ice in the Arctic : advancements in a multi-parameter retrieval using satellite microwave radiometer data
No full textThe Arctic undergoes accelerated warming compared to Global Warming, known as Arctic amplification. To understand this phenomenon, studying key variables at various scales is crucial. Every day, satellite radiometers measure Arctic-wide emissions of microwave radiation in terms of brightness temperatures. We use the distinct sensitivities of observations at different frequencies to atmospheric and surface parameters, aiming to disentangle the satellite signal and improve a multi-parameter retrieval. The retrieval involves inverting a forward model with an optimal estimation method to attribute satellite measurements (6.9 to 89 GHz) to a specific geophysical state.
For that, surface emissions need to be well represented in the forward model.
We study surface emissions by considering the theoretical concept of emissivity followed by an analysis of brightness temperature measurements and derived emissivities that we obtained during a summer ship campaign.
In a case study, we examine the impact of changing surface emissions caused by warm air intrusions on sea ice concentration (SIC) satellite retrievals.
We improve the multi-parameter retrieval by a better representation of the sea ice and snow emissions in the forward model for non-melting conditions. Both forward model and retrieval are evaluated against ground truth, including MOSAiC expedition data. The forward model succeeds in simulating realistic brightness temperatures. The retrieval output agrees well with reference data with regard to SIC. While the retrieval of cloud liquid water path and snow depth are promising, some disagreements are identified. Focusing on atmospheric total water vapor, our analysis demonstrates a good agreement with numerous reference datasets. We find a substantial improvement over the previous version of the method.
After applying the retrieval to satellite data from the last two decades we further analyze the spatio-temporal variability of atmospheric water vapor in winter
Education policy in Cambodia: global transformation processes, IOs’ influence and cultural spheres
No full textThis paper examines the development of Cambodia’s education regarding the impact of historical global transformation and international influences on its national education policy. It also studies the inclusiveness and generosity of social groups in Cambodia. The paper argues that Cambodia’s education system today is built upon the modern education model established by the French during the colonial period and is developed to combine with its cultural and religious traditions. The socialist regime caused heavy losses to the state and eliminated most of the education facilities. In the past three decades, with support and funds from the international community, Cambodia’s education was reconstructed along with the international standards on education inclusion and generosity.Deutsche Forschungsgemeinschaft (DFG)4